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android-kvm/linux/4dfdee23989224860d5ca897350863dd222736a3/./kernel/bpf/fixups.c
blob: 3cf2cc6e3ab66a1c2e34ce1ed75266dbcff633a4 [file]
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <linux/vmalloc.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/perf_event.h>
#include <net/xdp.h>
#include "disasm.h"
#define verbose(env, fmt, args...) bpf_verifier_log_write(env, fmt, ##args)
static bool is_cmpxchg_insn(const struct bpf_insn *insn)
{
return BPF_CLASS(insn->code) == BPF_STX &&
BPF_MODE(insn->code) == BPF_ATOMIC &&
insn->imm == BPF_CMPXCHG;
}
/* Return the regno defined by the insn, or -1. */
static int insn_def_regno(const struct bpf_insn *insn)
{
switch (BPF_CLASS(insn->code)) {
case BPF_JMP:
case BPF_JMP32:
case BPF_ST:
return -1;
case BPF_STX:
if (BPF_MODE(insn->code) == BPF_ATOMIC ||
BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) {
if (insn->imm == BPF_CMPXCHG)
return BPF_REG_0;
else if (insn->imm == BPF_LOAD_ACQ)
return insn->dst_reg;
else if (insn->imm & BPF_FETCH)
return insn->src_reg;
}
return -1;
default:
return insn->dst_reg;
}
}
/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_insn *insn)
{
int dst_reg = insn_def_regno(insn);
if (dst_reg == -1)
return false;
return !bpf_is_reg64(insn, dst_reg, NULL, DST_OP);
}
static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b)
{
const struct bpf_kfunc_desc *d0 = a;
const struct bpf_kfunc_desc *d1 = b;
if (d0->imm != d1->imm)
return d0->imm < d1->imm ? -1 : 1;
if (d0->offset != d1->offset)
return d0->offset < d1->offset ? -1 : 1;
return 0;
}
const struct btf_func_model *
bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
const struct bpf_insn *insn)
{
const struct bpf_kfunc_desc desc = {
.imm = insn->imm,
.offset = insn->off,
};
const struct bpf_kfunc_desc *res;
struct bpf_kfunc_desc_tab *tab;
tab = prog->aux->kfunc_tab;
res = bsearch(&desc, tab->descs, tab->nr_descs,
sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off);
return res ? &res->func_model : NULL;
}
static int set_kfunc_desc_imm(struct bpf_verifier_env *env, struct bpf_kfunc_desc *desc)
{
unsigned long call_imm;
if (bpf_jit_supports_far_kfunc_call()) {
call_imm = desc->func_id;
} else {
call_imm = BPF_CALL_IMM(desc->addr);
/* Check whether the relative offset overflows desc->imm */
if ((unsigned long)(s32)call_imm != call_imm) {
verbose(env, "address of kernel func_id %u is out of range\n",
desc->func_id);
return -EINVAL;
}
}
desc->imm = call_imm;
return 0;
}
static int sort_kfunc_descs_by_imm_off(struct bpf_verifier_env *env)
{
struct bpf_kfunc_desc_tab *tab;
int i, err;
tab = env->prog->aux->kfunc_tab;
if (!tab)
return 0;
for (i = 0; i < tab->nr_descs; i++) {
err = set_kfunc_desc_imm(env, &tab->descs[i]);
if (err)
return err;
}
sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
kfunc_desc_cmp_by_imm_off, NULL);
return 0;
}
static int add_kfunc_in_insns(struct bpf_verifier_env *env,
struct bpf_insn *insn, int cnt)
{
int i, ret;
for (i = 0; i < cnt; i++, insn++) {
if (bpf_pseudo_kfunc_call(insn)) {
ret = bpf_add_kfunc_call(env, insn->imm, insn->off);
if (ret < 0)
return ret;
}
}
return 0;
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
static int get_callee_stack_depth(struct bpf_verifier_env *env,
const struct bpf_insn *insn, int idx)
{
int start = idx + insn->imm + 1, subprog;
subprog = bpf_find_subprog(env, start);
if (verifier_bug_if(subprog < 0, env, "get stack depth: no program at insn %d", start))
return -EFAULT;
return env->subprog_info[subprog].stack_depth;
}
#endif
/* single env->prog->insni[off] instruction was replaced with the range
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
* [0, off) and [off, end) to new locations, so the patched range stays zero
*/
static void adjust_insn_aux_data(struct bpf_verifier_env *env,
struct bpf_prog *new_prog, u32 off, u32 cnt)
{
struct bpf_insn_aux_data *data = env->insn_aux_data;
struct bpf_insn *insn = new_prog->insnsi;
u32 old_seen = data[off].seen;
u32 prog_len;
int i;
/* aux info at OFF always needs adjustment, no matter fast path
* (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
* original insn at old prog.
*/
data[off].zext_dst = insn_has_def32(insn + off + cnt - 1);
if (cnt == 1)
return;
prog_len = new_prog->len;
memmove(data + off + cnt - 1, data + off,
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
memset(data + off, 0, sizeof(struct bpf_insn_aux_data) * (cnt - 1));
for (i = off; i < off + cnt - 1; i++) {
/* Expand insni[off]'s seen count to the patched range. */
data[i].seen = old_seen;
data[i].zext_dst = insn_has_def32(insn + i);
}
/*
* The indirect_target flag of the original instruction was moved to the last of the
* new instructions by the above memmove and memset, but the indirect jump target is
* actually the first instruction, so move it back. This also matches with the behavior
* of bpf_insn_array_adjust(), which preserves xlated_off to point to the first new
* instruction.
*/
if (data[off + cnt - 1].indirect_target) {
data[off].indirect_target = 1;
data[off + cnt - 1].indirect_target = 0;
}
}
static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
{
int i;
if (len == 1)
return;
/* NOTE: fake 'exit' subprog should be updated as well. */
for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start <= off)
continue;
env->subprog_info[i].start += len - 1;
}
}
static void adjust_insn_arrays(struct bpf_verifier_env *env, u32 off, u32 len)
{
int i;
if (len == 1)
return;
for (i = 0; i < env->insn_array_map_cnt; i++)
bpf_insn_array_adjust(env->insn_array_maps[i], off, len);
}
static void adjust_insn_arrays_after_remove(struct bpf_verifier_env *env, u32 off, u32 len)
{
int i;
for (i = 0; i < env->insn_array_map_cnt; i++)
bpf_insn_array_adjust_after_remove(env->insn_array_maps[i], off, len);
}
static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
{
struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
int i, sz = prog->aux->size_poke_tab;
struct bpf_jit_poke_descriptor *desc;
for (i = 0; i < sz; i++) {
desc = &tab[i];
if (desc->insn_idx <= off)
continue;
desc->insn_idx += len - 1;
}
}
struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
const struct bpf_insn *patch, u32 len)
{
struct bpf_prog *new_prog;
struct bpf_insn_aux_data *new_data = NULL;
if (len > 1) {
new_data = vrealloc(env->insn_aux_data,
array_size(env->prog->len + len - 1,
sizeof(struct bpf_insn_aux_data)),
GFP_KERNEL_ACCOUNT | __GFP_ZERO);
if (!new_data)
return NULL;
env->insn_aux_data = new_data;
}
new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
if (IS_ERR(new_prog)) {
if (PTR_ERR(new_prog) == -ERANGE)
verbose(env,
"insn %d cannot be patched due to 16-bit range\n",
env->insn_aux_data[off].orig_idx);
return NULL;
}
adjust_insn_aux_data(env, new_prog, off, len);
adjust_subprog_starts(env, off, len);
adjust_insn_arrays(env, off, len);
adjust_poke_descs(new_prog, off, len);
return new_prog;
}
/*
* For all jmp insns in a given 'prog' that point to 'tgt_idx' insn adjust the
* jump offset by 'delta'.
*/
static int adjust_jmp_off(struct bpf_prog *prog, u32 tgt_idx, u32 delta)
{
struct bpf_insn *insn = prog->insnsi;
u32 insn_cnt = prog->len, i;
s32 imm;
s16 off;
for (i = 0; i < insn_cnt; i++, insn++) {
u8 code = insn->code;
if (tgt_idx <= i && i < tgt_idx + delta)
continue;
if ((BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) ||
BPF_OP(code) == BPF_CALL || BPF_OP(code) == BPF_EXIT)
continue;
if (insn->code == (BPF_JMP32 | BPF_JA)) {
if (i + 1 + insn->imm != tgt_idx)
continue;
if (check_add_overflow(insn->imm, delta, &imm))
return -ERANGE;
insn->imm = imm;
} else {
if (i + 1 + insn->off != tgt_idx)
continue;
if (check_add_overflow(insn->off, delta, &off))
return -ERANGE;
insn->off = off;
}
}
return 0;
}
static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env,
u32 off, u32 cnt)
{
int i, j;
/* find first prog starting at or after off (first to remove) */
for (i = 0; i < env->subprog_cnt; i++)
if (env->subprog_info[i].start >= off)
break;
/* find first prog starting at or after off + cnt (first to stay) */
for (j = i; j < env->subprog_cnt; j++)
if (env->subprog_info[j].start >= off + cnt)
break;
/* if j doesn't start exactly at off + cnt, we are just removing
* the front of previous prog
*/
if (env->subprog_info[j].start != off + cnt)
j--;
if (j > i) {
struct bpf_prog_aux *aux = env->prog->aux;
int move;
/* move fake 'exit' subprog as well */
move = env->subprog_cnt + 1 - j;
memmove(env->subprog_info + i,
env->subprog_info + j,
sizeof(*env->subprog_info) * move);
env->subprog_cnt -= j - i;
/* remove func_info */
if (aux->func_info) {
move = aux->func_info_cnt - j;
memmove(aux->func_info + i,
aux->func_info + j,
sizeof(*aux->func_info) * move);
aux->func_info_cnt -= j - i;
/* func_info->insn_off is set after all code rewrites,
* in adjust_btf_func() - no need to adjust
*/
}
} else {
/* convert i from "first prog to remove" to "first to adjust" */
if (env->subprog_info[i].start == off)
i++;
}
/* update fake 'exit' subprog as well */
for (; i <= env->subprog_cnt; i++)
env->subprog_info[i].start -= cnt;
return 0;
}
static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off,
u32 cnt)
{
struct bpf_prog *prog = env->prog;
u32 i, l_off, l_cnt, nr_linfo;
struct bpf_line_info *linfo;
nr_linfo = prog->aux->nr_linfo;
if (!nr_linfo)
return 0;
linfo = prog->aux->linfo;
/* find first line info to remove, count lines to be removed */
for (i = 0; i < nr_linfo; i++)
if (linfo[i].insn_off >= off)
break;
l_off = i;
l_cnt = 0;
for (; i < nr_linfo; i++)
if (linfo[i].insn_off < off + cnt)
l_cnt++;
else
break;
/* First live insn doesn't match first live linfo, it needs to "inherit"
* last removed linfo. prog is already modified, so prog->len == off
* means no live instructions after (tail of the program was removed).
*/
if (prog->len != off && l_cnt &&
(i == nr_linfo || linfo[i].insn_off != off + cnt)) {
l_cnt--;
linfo[--i].insn_off = off + cnt;
}
/* remove the line info which refer to the removed instructions */
if (l_cnt) {
memmove(linfo + l_off, linfo + i,
sizeof(*linfo) * (nr_linfo - i));
prog->aux->nr_linfo -= l_cnt;
nr_linfo = prog->aux->nr_linfo;
}
/* pull all linfo[i].insn_off >= off + cnt in by cnt */
for (i = l_off; i < nr_linfo; i++)
linfo[i].insn_off -= cnt;
/* fix up all subprogs (incl. 'exit') which start >= off */
for (i = 0; i <= env->subprog_cnt; i++)
if (env->subprog_info[i].linfo_idx > l_off) {
/* program may have started in the removed region but
* may not be fully removed
*/
if (env->subprog_info[i].linfo_idx >= l_off + l_cnt)
env->subprog_info[i].linfo_idx -= l_cnt;
else
env->subprog_info[i].linfo_idx = l_off;
}
return 0;
}
/*
* Clean up dynamically allocated fields of aux data for instructions [start, ...]
*/
void bpf_clear_insn_aux_data(struct bpf_verifier_env *env, int start, int len)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
struct bpf_insn *insns = env->prog->insnsi;
int end = start + len;
int i;
for (i = start; i < end; i++) {
if (aux_data[i].jt) {
kvfree(aux_data[i].jt);
aux_data[i].jt = NULL;
}
if (bpf_is_ldimm64(&insns[i]))
i++;
}
}
static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
unsigned int orig_prog_len = env->prog->len;
int err;
if (bpf_prog_is_offloaded(env->prog->aux))
bpf_prog_offload_remove_insns(env, off, cnt);
/* Should be called before bpf_remove_insns, as it uses prog->insnsi */
bpf_clear_insn_aux_data(env, off, cnt);
err = bpf_remove_insns(env->prog, off, cnt);
if (err)
return err;
err = adjust_subprog_starts_after_remove(env, off, cnt);
if (err)
return err;
err = bpf_adj_linfo_after_remove(env, off, cnt);
if (err)
return err;
adjust_insn_arrays_after_remove(env, off, cnt);
memmove(aux_data + off, aux_data + off + cnt,
sizeof(*aux_data) * (orig_prog_len - off - cnt));
return 0;
}
static const struct bpf_insn NOP = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
static const struct bpf_insn MAY_GOTO_0 = BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 0, 0);
bool bpf_insn_is_cond_jump(u8 code)
{
u8 op;
op = BPF_OP(code);
if (BPF_CLASS(code) == BPF_JMP32)
return op != BPF_JA;
if (BPF_CLASS(code) != BPF_JMP)
return false;
return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
}
void bpf_opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
struct bpf_insn *insn = env->prog->insnsi;
const int insn_cnt = env->prog->len;
int i;
for (i = 0; i < insn_cnt; i++, insn++) {
if (!bpf_insn_is_cond_jump(insn->code))
continue;
if (!aux_data[i + 1].seen)
ja.off = insn->off;
else if (!aux_data[i + 1 + insn->off].seen)
ja.off = 0;
else
continue;
if (bpf_prog_is_offloaded(env->prog->aux))
bpf_prog_offload_replace_insn(env, i, &ja);
memcpy(insn, &ja, sizeof(ja));
}
}
int bpf_opt_remove_dead_code(struct bpf_verifier_env *env)
{
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
int insn_cnt = env->prog->len;
int i, err;
for (i = 0; i < insn_cnt; i++) {
int j;
j = 0;
while (i + j < insn_cnt && !aux_data[i + j].seen)
j++;
if (!j)
continue;
err = verifier_remove_insns(env, i, j);
if (err)
return err;
insn_cnt = env->prog->len;
}
return 0;
}
int bpf_opt_remove_nops(struct bpf_verifier_env *env)
{
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
bool is_may_goto_0, is_ja;
int i, err;
for (i = 0; i < insn_cnt; i++) {
is_may_goto_0 = !memcmp(&insn[i], &MAY_GOTO_0, sizeof(MAY_GOTO_0));
is_ja = !memcmp(&insn[i], &NOP, sizeof(NOP));
if (!is_may_goto_0 && !is_ja)
continue;
err = verifier_remove_insns(env, i, 1);
if (err)
return err;
insn_cnt--;
/* Go back one insn to catch may_goto +1; may_goto +0 sequence */
i -= (is_may_goto_0 && i > 0) ? 2 : 1;
}
return 0;
}
int bpf_opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
const union bpf_attr *attr)
{
struct bpf_insn *patch;
/* use env->insn_buf as two independent buffers */
struct bpf_insn *zext_patch = env->insn_buf;
struct bpf_insn *rnd_hi32_patch = &env->insn_buf[2];
struct bpf_insn_aux_data *aux = env->insn_aux_data;
int i, patch_len, delta = 0, len = env->prog->len;
struct bpf_insn *insns = env->prog->insnsi;
struct bpf_prog *new_prog;
bool rnd_hi32;
rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
zext_patch[1] = BPF_ZEXT_REG(0);
rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
for (i = 0; i < len; i++) {
int adj_idx = i + delta;
struct bpf_insn insn;
int load_reg;
insn = insns[adj_idx];
load_reg = insn_def_regno(&insn);
if (!aux[adj_idx].zext_dst) {
u8 code, class;
u32 imm_rnd;
if (!rnd_hi32)
continue;
code = insn.code;
class = BPF_CLASS(code);
if (load_reg == -1)
continue;
/* NOTE: arg "reg" (the fourth one) is only used for
* BPF_STX + SRC_OP, so it is safe to pass NULL
* here.
*/
if (bpf_is_reg64(&insn, load_reg, NULL, DST_OP)) {
if (class == BPF_LD &&
BPF_MODE(code) == BPF_IMM)
i++;
continue;
}
/* ctx load could be transformed into wider load. */
if (class == BPF_LDX &&
aux[adj_idx].ptr_type == PTR_TO_CTX)
continue;
imm_rnd = get_random_u32();
rnd_hi32_patch[0] = insn;
rnd_hi32_patch[1].imm = imm_rnd;
rnd_hi32_patch[3].dst_reg = load_reg;
patch = rnd_hi32_patch;
patch_len = 4;
goto apply_patch_buffer;
}
/* Add in an zero-extend instruction if a) the JIT has requested
* it or b) it's a CMPXCHG.
*
* The latter is because: BPF_CMPXCHG always loads a value into
* R0, therefore always zero-extends. However some archs'
* equivalent instruction only does this load when the
* comparison is successful. This detail of CMPXCHG is
* orthogonal to the general zero-extension behaviour of the
* CPU, so it's treated independently of bpf_jit_needs_zext.
*/
if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn))
continue;
/* Zero-extension is done by the caller. */
if (bpf_pseudo_kfunc_call(&insn))
continue;
if (verifier_bug_if(load_reg == -1, env,
"zext_dst is set, but no reg is defined"))
return -EFAULT;
zext_patch[0] = insn;
zext_patch[1].dst_reg = load_reg;
zext_patch[1].src_reg = load_reg;
patch = zext_patch;
patch_len = 2;
apply_patch_buffer:
new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
insns = new_prog->insnsi;
aux = env->insn_aux_data;
delta += patch_len - 1;
}
return 0;
}
/* convert load instructions that access fields of a context type into a
* sequence of instructions that access fields of the underlying structure:
* struct __sk_buff -> struct sk_buff
* struct bpf_sock_ops -> struct sock
*/
int bpf_convert_ctx_accesses(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprogs = env->subprog_info;
const struct bpf_verifier_ops *ops = env->ops;
int i, cnt, size, ctx_field_size, ret, delta = 0, epilogue_cnt = 0;
const int insn_cnt = env->prog->len;
struct bpf_insn *epilogue_buf = env->epilogue_buf;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_insn *insn;
u32 target_size, size_default, off;
struct bpf_prog *new_prog;
enum bpf_access_type type;
bool is_narrower_load;
int epilogue_idx = 0;
if (ops->gen_epilogue) {
epilogue_cnt = ops->gen_epilogue(epilogue_buf, env->prog,
-(subprogs[0].stack_depth + 8));
if (epilogue_cnt >= INSN_BUF_SIZE) {
verifier_bug(env, "epilogue is too long");
return -EFAULT;
} else if (epilogue_cnt) {
/* Save the ARG_PTR_TO_CTX for the epilogue to use */
cnt = 0;
subprogs[0].stack_depth += 8;
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_1,
-subprogs[0].stack_depth);
insn_buf[cnt++] = env->prog->insnsi[0];
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
delta += cnt - 1;
ret = add_kfunc_in_insns(env, epilogue_buf, epilogue_cnt - 1);
if (ret < 0)
return ret;
}
}
if (ops->gen_prologue || env->seen_direct_write) {
if (!ops->gen_prologue) {
verifier_bug(env, "gen_prologue is null");
return -EFAULT;
}
cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
env->prog);
if (cnt >= INSN_BUF_SIZE) {
verifier_bug(env, "prologue is too long");
return -EFAULT;
} else if (cnt) {
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
env->prog = new_prog;
delta += cnt - 1;
ret = add_kfunc_in_insns(env, insn_buf, cnt - 1);
if (ret < 0)
return ret;
}
}
if (delta)
WARN_ON(adjust_jmp_off(env->prog, 0, delta));
if (bpf_prog_is_offloaded(env->prog->aux))
return 0;
insn = env->prog->insnsi + delta;
for (i = 0; i < insn_cnt; i++, insn++) {
bpf_convert_ctx_access_t convert_ctx_access;
u8 mode;
if (env->insn_aux_data[i + delta].nospec) {
WARN_ON_ONCE(env->insn_aux_data[i + delta].alu_state);
struct bpf_insn *patch = insn_buf;
*patch++ = BPF_ST_NOSPEC();
*patch++ = *insn;
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
/* This can not be easily merged with the
* nospec_result-case, because an insn may require a
* nospec before and after itself. Therefore also do not
* 'continue' here but potentially apply further
* patching to insn. *insn should equal patch[1] now.
*/
}
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
insn->code == (BPF_LDX | BPF_MEM | BPF_DW) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_B) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_H) ||
insn->code == (BPF_LDX | BPF_MEMSX | BPF_W)) {
type = BPF_READ;
} else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
type = BPF_WRITE;
} else if ((insn->code == (BPF_STX | BPF_ATOMIC | BPF_B) ||
insn->code == (BPF_STX | BPF_ATOMIC | BPF_H) ||
insn->code == (BPF_STX | BPF_ATOMIC | BPF_W) ||
insn->code == (BPF_STX | BPF_ATOMIC | BPF_DW)) &&
env->insn_aux_data[i + delta].ptr_type == PTR_TO_ARENA) {
insn->code = BPF_STX | BPF_PROBE_ATOMIC | BPF_SIZE(insn->code);
env->prog->aux->num_exentries++;
continue;
} else if (insn->code == (BPF_JMP | BPF_EXIT) &&
epilogue_cnt &&
i + delta < subprogs[1].start) {
/* Generate epilogue for the main prog */
if (epilogue_idx) {
/* jump back to the earlier generated epilogue */
insn_buf[0] = BPF_JMP32_A(epilogue_idx - i - delta - 1);
cnt = 1;
} else {
memcpy(insn_buf, epilogue_buf,
epilogue_cnt * sizeof(*epilogue_buf));
cnt = epilogue_cnt;
/* epilogue_idx cannot be 0. It must have at
* least one ctx ptr saving insn before the
* epilogue.
*/
epilogue_idx = i + delta;
}
goto patch_insn_buf;
} else {
continue;
}
if (type == BPF_WRITE &&
env->insn_aux_data[i + delta].nospec_result) {
/* nospec_result is only used to mitigate Spectre v4 and
* to limit verification-time for Spectre v1.
*/
struct bpf_insn *patch = insn_buf;
*patch++ = *insn;
*patch++ = BPF_ST_NOSPEC();
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
continue;
}
switch ((int)env->insn_aux_data[i + delta].ptr_type) {
case PTR_TO_CTX:
if (!ops->convert_ctx_access)
continue;
convert_ctx_access = ops->convert_ctx_access;
break;
case PTR_TO_SOCKET:
case PTR_TO_SOCK_COMMON:
convert_ctx_access = bpf_sock_convert_ctx_access;
break;
case PTR_TO_TCP_SOCK:
convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
break;
case PTR_TO_XDP_SOCK:
convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
break;
case PTR_TO_BTF_ID:
case PTR_TO_BTF_ID | PTR_UNTRUSTED:
/* PTR_TO_BTF_ID | MEM_ALLOC always has a valid lifetime, unlike
* PTR_TO_BTF_ID, and an active referenced id, but the same cannot
* be said once it is marked PTR_UNTRUSTED, hence we must handle
* any faults for loads into such types. BPF_WRITE is disallowed
* for this case.
*/
case PTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED:
case PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED:
if (type == BPF_READ) {
if (BPF_MODE(insn->code) == BPF_MEM)
insn->code = BPF_LDX | BPF_PROBE_MEM |
BPF_SIZE((insn)->code);
else
insn->code = BPF_LDX | BPF_PROBE_MEMSX |
BPF_SIZE((insn)->code);
env->prog->aux->num_exentries++;
}
continue;
case PTR_TO_ARENA:
if (BPF_MODE(insn->code) == BPF_MEMSX) {
if (!bpf_jit_supports_insn(insn, true)) {
verbose(env, "sign extending loads from arena are not supported yet\n");
return -EOPNOTSUPP;
}
insn->code = BPF_CLASS(insn->code) | BPF_PROBE_MEM32SX | BPF_SIZE(insn->code);
} else {
insn->code = BPF_CLASS(insn->code) | BPF_PROBE_MEM32 | BPF_SIZE(insn->code);
}
env->prog->aux->num_exentries++;
continue;
default:
continue;
}
ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
size = BPF_LDST_BYTES(insn);
mode = BPF_MODE(insn->code);
/* If the read access is a narrower load of the field,
* convert to a 4/8-byte load, to minimum program type specific
* convert_ctx_access changes. If conversion is successful,
* we will apply proper mask to the result.
*/
is_narrower_load = size < ctx_field_size;
size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
off = insn->off;
if (is_narrower_load) {
u8 size_code;
if (type == BPF_WRITE) {
verifier_bug(env, "narrow ctx access misconfigured");
return -EFAULT;
}
size_code = BPF_H;
if (ctx_field_size == 4)
size_code = BPF_W;
else if (ctx_field_size == 8)
size_code = BPF_DW;
insn->off = off & ~(size_default - 1);
insn->code = BPF_LDX | BPF_MEM | size_code;
}
target_size = 0;
cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
&target_size);
if (cnt == 0 || cnt >= INSN_BUF_SIZE ||
(ctx_field_size && !target_size)) {
verifier_bug(env, "error during ctx access conversion (%d)", cnt);
return -EFAULT;
}
if (is_narrower_load && size < target_size) {
u8 shift = bpf_ctx_narrow_access_offset(
off, size, size_default) * 8;
if (shift && cnt + 1 >= INSN_BUF_SIZE) {
verifier_bug(env, "narrow ctx load misconfigured");
return -EFAULT;
}
if (ctx_field_size <= 4) {
if (shift)
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
insn->dst_reg,
shift);
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
(1 << size * 8) - 1);
} else {
if (shift)
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
insn->dst_reg,
shift);
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
(1ULL << size * 8) - 1);
}
}
if (mode == BPF_MEMSX)
insn_buf[cnt++] = BPF_RAW_INSN(BPF_ALU64 | BPF_MOV | BPF_X,
insn->dst_reg, insn->dst_reg,
size * 8, 0);
patch_insn_buf:
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
/* keep walking new program and skip insns we just inserted */
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
}
return 0;
}
static u32 *bpf_dup_subprog_starts(struct bpf_verifier_env *env)
{
u32 *starts = NULL;
starts = kvmalloc_objs(u32, env->subprog_cnt, GFP_KERNEL_ACCOUNT);
if (starts) {
for (int i = 0; i < env->subprog_cnt; i++)
starts[i] = env->subprog_info[i].start;
}
return starts;
}
static void bpf_restore_subprog_starts(struct bpf_verifier_env *env, u32 *orig_starts)
{
for (int i = 0; i < env->subprog_cnt; i++)
env->subprog_info[i].start = orig_starts[i];
/* restore the start of fake 'exit' subprog as well */
env->subprog_info[env->subprog_cnt].start = env->prog->len;
}
struct bpf_insn_aux_data *bpf_dup_insn_aux_data(struct bpf_verifier_env *env)
{
size_t size;
void *new_aux;
size = array_size(sizeof(struct bpf_insn_aux_data), env->prog->len);
new_aux = __vmalloc(size, GFP_KERNEL_ACCOUNT);
if (new_aux)
memcpy(new_aux, env->insn_aux_data, size);
return new_aux;
}
void bpf_restore_insn_aux_data(struct bpf_verifier_env *env,
struct bpf_insn_aux_data *orig_insn_aux)
{
/* the expanded elements are zero-filled, so no special handling is required */
vfree(env->insn_aux_data);
env->insn_aux_data = orig_insn_aux;
}
static int jit_subprogs(struct bpf_verifier_env *env)
{
struct bpf_prog *prog = env->prog, **func, *tmp;
int i, j, subprog_start, subprog_end = 0, len, subprog;
struct bpf_map *map_ptr;
struct bpf_insn *insn;
void *old_bpf_func;
int err, num_exentries;
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn))
continue;
/* Upon error here we cannot fall back to interpreter but
* need a hard reject of the program. Thus -EFAULT is
* propagated in any case.
*/
subprog = bpf_find_subprog(env, i + insn->imm + 1);
if (verifier_bug_if(subprog < 0, env, "No program to jit at insn %d",
i + insn->imm + 1))
return -EFAULT;
/* temporarily remember subprog id inside insn instead of
* aux_data, since next loop will split up all insns into funcs
*/
insn->off = subprog;
/* remember original imm in case JIT fails and fallback
* to interpreter will be needed
*/
env->insn_aux_data[i].call_imm = insn->imm;
/* point imm to __bpf_call_base+1 from JITs point of view */
insn->imm = 1;
if (bpf_pseudo_func(insn)) {
#if defined(MODULES_VADDR)
u64 addr = MODULES_VADDR;
#else
u64 addr = VMALLOC_START;
#endif
/* jit (e.g. x86_64) may emit fewer instructions
* if it learns a u32 imm is the same as a u64 imm.
* Set close enough to possible prog address.
*/
insn[0].imm = (u32)addr;
insn[1].imm = addr >> 32;
}
}
err = bpf_prog_alloc_jited_linfo(prog);
if (err)
goto out_undo_insn;
err = -ENOMEM;
func = kzalloc_objs(prog, env->subprog_cnt);
if (!func)
goto out_undo_insn;
for (i = 0; i < env->subprog_cnt; i++) {
subprog_start = subprog_end;
subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
/* bpf_prog_run() doesn't call subprogs directly,
* hence main prog stats include the runtime of subprogs.
* subprogs don't have IDs and not reachable via prog_get_next_id
* func[i]->stats will never be accessed and stays NULL
*/
func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
if (!func[i])
goto out_free;
memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
len * sizeof(struct bpf_insn));
func[i]->type = prog->type;
func[i]->len = len;
if (bpf_prog_calc_tag(func[i]))
goto out_free;
func[i]->is_func = 1;
func[i]->sleepable = prog->sleepable;
func[i]->blinded = prog->blinded;
func[i]->aux->func_idx = i;
/* Below members will be freed only at prog->aux */
func[i]->aux->btf = prog->aux->btf;
func[i]->aux->subprog_start = subprog_start;
func[i]->aux->func_info = prog->aux->func_info;
func[i]->aux->func_info_cnt = prog->aux->func_info_cnt;
func[i]->aux->poke_tab = prog->aux->poke_tab;
func[i]->aux->size_poke_tab = prog->aux->size_poke_tab;
func[i]->aux->main_prog_aux = prog->aux;
for (j = 0; j < prog->aux->size_poke_tab; j++) {
struct bpf_jit_poke_descriptor *poke;
poke = &prog->aux->poke_tab[j];
if (poke->insn_idx < subprog_end &&
poke->insn_idx >= subprog_start)
poke->aux = func[i]->aux;
}
func[i]->aux->name[0] = 'F';
func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
if (env->subprog_info[i].priv_stack_mode == PRIV_STACK_ADAPTIVE)
func[i]->aux->jits_use_priv_stack = true;
func[i]->jit_requested = 1;
func[i]->blinding_requested = prog->blinding_requested;
func[i]->aux->kfunc_tab = prog->aux->kfunc_tab;
func[i]->aux->kfunc_btf_tab = prog->aux->kfunc_btf_tab;
func[i]->aux->linfo = prog->aux->linfo;
func[i]->aux->nr_linfo = prog->aux->nr_linfo;
func[i]->aux->jited_linfo = prog->aux->jited_linfo;
func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
func[i]->aux->arena = prog->aux->arena;
func[i]->aux->used_maps = env->used_maps;
func[i]->aux->used_map_cnt = env->used_map_cnt;
num_exentries = 0;
insn = func[i]->insnsi;
for (j = 0; j < func[i]->len; j++, insn++) {
if (BPF_CLASS(insn->code) == BPF_LDX &&
(BPF_MODE(insn->code) == BPF_PROBE_MEM ||
BPF_MODE(insn->code) == BPF_PROBE_MEM32 ||
BPF_MODE(insn->code) == BPF_PROBE_MEM32SX ||
BPF_MODE(insn->code) == BPF_PROBE_MEMSX))
num_exentries++;
if ((BPF_CLASS(insn->code) == BPF_STX ||
BPF_CLASS(insn->code) == BPF_ST) &&
BPF_MODE(insn->code) == BPF_PROBE_MEM32)
num_exentries++;
if (BPF_CLASS(insn->code) == BPF_STX &&
BPF_MODE(insn->code) == BPF_PROBE_ATOMIC)
num_exentries++;
}
func[i]->aux->num_exentries = num_exentries;
func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb;
func[i]->aux->changes_pkt_data = env->subprog_info[i].changes_pkt_data;
func[i]->aux->might_sleep = env->subprog_info[i].might_sleep;
func[i]->aux->token = prog->aux->token;
if (!i)
func[i]->aux->exception_boundary = env->seen_exception;
func[i] = bpf_int_jit_compile(env, func[i]);
if (!func[i]->jited) {
err = -ENOTSUPP;
goto out_free;
}
cond_resched();
}
/* at this point all bpf functions were successfully JITed
* now populate all bpf_calls with correct addresses and
* run last pass of JIT
*/
for (i = 0; i < env->subprog_cnt; i++) {
insn = func[i]->insnsi;
for (j = 0; j < func[i]->len; j++, insn++) {
if (bpf_pseudo_func(insn)) {
subprog = insn->off;
insn[0].imm = (u32)(long)func[subprog]->bpf_func;
insn[1].imm = ((u64)(long)func[subprog]->bpf_func) >> 32;
continue;
}
if (!bpf_pseudo_call(insn))
continue;
subprog = insn->off;
insn->imm = BPF_CALL_IMM(func[subprog]->bpf_func);
}
/* we use the aux data to keep a list of the start addresses
* of the JITed images for each function in the program
*
* for some architectures, such as powerpc64, the imm field
* might not be large enough to hold the offset of the start
* address of the callee's JITed image from __bpf_call_base
*
* in such cases, we can lookup the start address of a callee
* by using its subprog id, available from the off field of
* the call instruction, as an index for this list
*/
func[i]->aux->func = func;
func[i]->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
func[i]->aux->real_func_cnt = env->subprog_cnt;
}
for (i = 0; i < env->subprog_cnt; i++) {
old_bpf_func = func[i]->bpf_func;
tmp = bpf_int_jit_compile(env, func[i]);
if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
err = -ENOTSUPP;
goto out_free;
}
cond_resched();
}
/*
* Cleanup func[i]->aux fields which aren't required
* or can become invalid in future
*/
for (i = 0; i < env->subprog_cnt; i++) {
func[i]->aux->used_maps = NULL;
func[i]->aux->used_map_cnt = 0;
}
/* finally lock prog and jit images for all functions and
* populate kallsysm. Begin at the first subprogram, since
* bpf_prog_load will add the kallsyms for the main program.
*/
for (i = 1; i < env->subprog_cnt; i++) {
err = bpf_prog_lock_ro(func[i]);
if (err)
goto out_free;
}
for (i = 1; i < env->subprog_cnt; i++)
bpf_prog_kallsyms_add(func[i]);
/* Last step: make now unused interpreter insns from main
* prog consistent for later dump requests, so they can
* later look the same as if they were interpreted only.
*/
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (bpf_pseudo_func(insn)) {
insn[0].imm = env->insn_aux_data[i].call_imm;
insn[1].imm = insn->off;
insn->off = 0;
continue;
}
if (!bpf_pseudo_call(insn))
continue;
insn->imm = env->insn_aux_data[i].call_imm;
subprog = bpf_find_subprog(env, i + insn->imm + 1);
insn->off = subprog;
}
prog->jited = 1;
prog->bpf_func = func[0]->bpf_func;
prog->jited_len = func[0]->jited_len;
prog->aux->extable = func[0]->aux->extable;
prog->aux->num_exentries = func[0]->aux->num_exentries;
prog->aux->func = func;
prog->aux->func_cnt = env->subprog_cnt - env->hidden_subprog_cnt;
prog->aux->real_func_cnt = env->subprog_cnt;
prog->aux->bpf_exception_cb = (void *)func[env->exception_callback_subprog]->bpf_func;
prog->aux->exception_boundary = func[0]->aux->exception_boundary;
prog->aux->stack_arg_sp_adjust = func[0]->aux->stack_arg_sp_adjust;
bpf_prog_jit_attempt_done(prog);
return 0;
out_free:
/* We failed JIT'ing, so at this point we need to unregister poke
* descriptors from subprogs, so that kernel is not attempting to
* patch it anymore as we're freeing the subprog JIT memory.
*/
for (i = 0; i < prog->aux->size_poke_tab; i++) {
map_ptr = prog->aux->poke_tab[i].tail_call.map;
map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
}
/* At this point we're guaranteed that poke descriptors are not
* live anymore. We can just unlink its descriptor table as it's
* released with the main prog.
*/
for (i = 0; i < env->subprog_cnt; i++) {
if (!func[i])
continue;
func[i]->aux->poke_tab = NULL;
bpf_jit_free(func[i]);
}
kfree(func);
out_undo_insn:
bpf_prog_jit_attempt_done(prog);
return err;
}
int bpf_jit_subprogs(struct bpf_verifier_env *env)
{
int err, i;
bool blinded = false;
struct bpf_insn *insn;
struct bpf_prog *prog, *orig_prog;
struct bpf_insn_aux_data *orig_insn_aux;
u32 *orig_subprog_starts;
if (env->subprog_cnt <= 1)
return 0;
prog = orig_prog = env->prog;
if (bpf_prog_need_blind(prog)) {
orig_insn_aux = bpf_dup_insn_aux_data(env);
if (!orig_insn_aux) {
err = -ENOMEM;
goto out_cleanup;
}
orig_subprog_starts = bpf_dup_subprog_starts(env);
if (!orig_subprog_starts) {
vfree(orig_insn_aux);
err = -ENOMEM;
goto out_cleanup;
}
prog = bpf_jit_blind_constants(env, prog);
if (IS_ERR(prog)) {
err = -ENOMEM;
prog = orig_prog;
goto out_restore;
}
blinded = true;
}
err = jit_subprogs(env);
if (err)
goto out_jit_err;
if (blinded) {
bpf_jit_prog_release_other(prog, orig_prog);
kvfree(orig_subprog_starts);
vfree(orig_insn_aux);
}
return 0;
out_jit_err:
if (blinded) {
bpf_jit_prog_release_other(orig_prog, prog);
/* roll back to the clean original prog */
prog = env->prog = orig_prog;
goto out_restore;
} else {
if (err != -EFAULT) {
/*
* We will fall back to interpreter mode when err is not -EFAULT, before
* that, insn->off and insn->imm should be restored to their original
* values since they were modified by jit_subprogs.
*/
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
if (!bpf_pseudo_call(insn))
continue;
insn->off = 0;
insn->imm = env->insn_aux_data[i].call_imm;
}
}
goto out_cleanup;
}
out_restore:
bpf_restore_subprog_starts(env, orig_subprog_starts);
bpf_restore_insn_aux_data(env, orig_insn_aux);
kvfree(orig_subprog_starts);
out_cleanup:
/* cleanup main prog to be interpreted */
prog->jit_requested = 0;
prog->blinding_requested = 0;
return err;
}
int bpf_fixup_call_args(struct bpf_verifier_env *env)
{
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
struct bpf_prog *prog = env->prog;
struct bpf_insn *insn = prog->insnsi;
bool has_kfunc_call = bpf_prog_has_kfunc_call(prog);
int depth;
#endif
int i, err = 0;
for (i = 0; i < env->subprog_cnt; i++) {
struct bpf_subprog_info *subprog = &env->subprog_info[i];
u16 outgoing = subprog->stack_arg_cnt - bpf_in_stack_arg_cnt(subprog);
if (subprog->max_out_stack_arg_cnt > outgoing) {
verbose(env,
"func#%d writes %u stack arg slots, but calls only require %u\n",
i, subprog->max_out_stack_arg_cnt, outgoing);
return -EINVAL;
}
}
if (env->prog->jit_requested &&
!bpf_prog_is_offloaded(env->prog->aux)) {
err = bpf_jit_subprogs(env);
if (err == 0)
return 0;
if (err == -EFAULT)
return err;
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
if (has_kfunc_call) {
verbose(env, "calling kernel functions are not allowed in non-JITed programs\n");
return -EINVAL;
}
for (i = 0; i < env->subprog_cnt; i++) {
if (bpf_in_stack_arg_cnt(&env->subprog_info[i])) {
verbose(env, "stack args are not supported in non-JITed programs\n");
return -EINVAL;
}
}
if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
/* When JIT fails the progs with bpf2bpf calls and tail_calls
* have to be rejected, since interpreter doesn't support them yet.
*/
verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
return -EINVAL;
}
for (i = 0; i < prog->len; i++, insn++) {
if (bpf_pseudo_func(insn)) {
/* When JIT fails the progs with callback calls
* have to be rejected, since interpreter doesn't support them yet.
*/
verbose(env, "callbacks are not allowed in non-JITed programs\n");
return -EINVAL;
}
if (!bpf_pseudo_call(insn))
continue;
depth = get_callee_stack_depth(env, insn, i);
if (depth < 0)
return depth;
err = bpf_patch_call_args(insn, depth);
if (err) {
verbose(env, "stack depth %d exceeds interpreter stack depth limit\n",
depth);
return err;
}
}
err = 0;
#endif
return err;
}
/* The function requires that first instruction in 'patch' is insnsi[prog->len - 1] */
static int add_hidden_subprog(struct bpf_verifier_env *env, struct bpf_insn *patch, int len)
{
struct bpf_subprog_info *info = env->subprog_info;
int cnt = env->subprog_cnt;
struct bpf_prog *prog;
/* We only reserve one slot for hidden subprogs in subprog_info. */
if (env->hidden_subprog_cnt) {
verifier_bug(env, "only one hidden subprog supported");
return -EFAULT;
}
/* We're not patching any existing instruction, just appending the new
* ones for the hidden subprog. Hence all of the adjustment operations
* in bpf_patch_insn_data are no-ops.
*/
prog = bpf_patch_insn_data(env, env->prog->len - 1, patch, len);
if (!prog)
return -ENOMEM;
env->prog = prog;
info[cnt + 1].start = info[cnt].start;
info[cnt].start = prog->len - len + 1;
env->subprog_cnt++;
env->hidden_subprog_cnt++;
return 0;
}
/* Do various post-verification rewrites in a single program pass.
* These rewrites simplify JIT and interpreter implementations.
*/
int bpf_do_misc_fixups(struct bpf_verifier_env *env)
{
struct bpf_prog *prog = env->prog;
enum bpf_attach_type eatype = prog->expected_attach_type;
enum bpf_prog_type prog_type = resolve_prog_type(prog);
struct bpf_insn *insn = prog->insnsi;
const struct bpf_func_proto *fn;
const int insn_cnt = prog->len;
const struct bpf_map_ops *ops;
struct bpf_insn_aux_data *aux;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_prog *new_prog;
struct bpf_map *map_ptr;
int i, ret, cnt, delta = 0, cur_subprog = 0;
struct bpf_subprog_info *subprogs = env->subprog_info;
u16 stack_depth = subprogs[cur_subprog].stack_depth;
u16 stack_depth_extra = 0;
if (env->seen_exception && !env->exception_callback_subprog) {
struct bpf_insn *patch = insn_buf;
*patch++ = env->prog->insnsi[insn_cnt - 1];
*patch++ = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1);
*patch++ = BPF_EXIT_INSN();
ret = add_hidden_subprog(env, insn_buf, patch - insn_buf);
if (ret < 0)
return ret;
prog = env->prog;
insn = prog->insnsi;
env->exception_callback_subprog = env->subprog_cnt - 1;
/* Don't update insn_cnt, as add_hidden_subprog always appends insns */
bpf_mark_subprog_exc_cb(env, env->exception_callback_subprog);
}
for (i = 0; i < insn_cnt;) {
if (insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) && insn->imm) {
if ((insn->off == BPF_ADDR_SPACE_CAST && insn->imm == 1) ||
(((struct bpf_map *)env->prog->aux->arena)->map_flags & BPF_F_NO_USER_CONV)) {
/* convert to 32-bit mov that clears upper 32-bit */
insn->code = BPF_ALU | BPF_MOV | BPF_X;
/* clear off and imm, so it's a normal 'wX = wY' from JIT pov */
insn->off = 0;
insn->imm = 0;
} /* cast from as(0) to as(1) should be handled by JIT */
goto next_insn;
}
if (env->insn_aux_data[i + delta].needs_zext)
/* Convert BPF_CLASS(insn->code) == BPF_ALU64 to 32-bit ALU */
insn->code = BPF_ALU | BPF_OP(insn->code) | BPF_SRC(insn->code);
/* Make sdiv/smod divide-by-minus-one exceptions impossible. */
if ((insn->code == (BPF_ALU64 | BPF_MOD | BPF_K) ||
insn->code == (BPF_ALU64 | BPF_DIV | BPF_K) ||
insn->code == (BPF_ALU | BPF_MOD | BPF_K) ||
insn->code == (BPF_ALU | BPF_DIV | BPF_K)) &&
insn->off == 1 && insn->imm == -1) {
bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
bool isdiv = BPF_OP(insn->code) == BPF_DIV;
struct bpf_insn *patch = insn_buf;
if (isdiv)
*patch++ = BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_NEG | BPF_K, insn->dst_reg,
0, 0, 0);
else
*patch++ = BPF_MOV32_IMM(insn->dst_reg, 0);
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Make divide-by-zero and divide-by-minus-one exceptions impossible. */
if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
bool isdiv = BPF_OP(insn->code) == BPF_DIV;
bool is_sdiv = isdiv && insn->off == 1;
bool is_smod = !isdiv && insn->off == 1;
struct bpf_insn *patch = insn_buf;
if (is_sdiv) {
/* [R,W]x sdiv 0 -> 0
* LLONG_MIN sdiv -1 -> LLONG_MIN
* INT_MIN sdiv -1 -> INT_MIN
*/
*patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
*patch++ = BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_ADD | BPF_K, BPF_REG_AX,
0, 0, 1);
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JGT | BPF_K, BPF_REG_AX,
0, 4, 1);
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, BPF_REG_AX,
0, 1, 0);
*patch++ = BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_MOV | BPF_K, insn->dst_reg,
0, 0, 0);
/* BPF_NEG(LLONG_MIN) == -LLONG_MIN == LLONG_MIN */
*patch++ = BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_NEG | BPF_K, insn->dst_reg,
0, 0, 0);
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = *insn;
cnt = patch - insn_buf;
} else if (is_smod) {
/* [R,W]x mod 0 -> [R,W]x */
/* [R,W]x mod -1 -> 0 */
*patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
*patch++ = BPF_RAW_INSN((is64 ? BPF_ALU64 : BPF_ALU) |
BPF_ADD | BPF_K, BPF_REG_AX,
0, 0, 1);
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JGT | BPF_K, BPF_REG_AX,
0, 3, 1);
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, BPF_REG_AX,
0, 3 + (is64 ? 0 : 1), 1);
*patch++ = BPF_MOV32_IMM(insn->dst_reg, 0);
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = *insn;
if (!is64) {
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = BPF_MOV32_REG(insn->dst_reg, insn->dst_reg);
}
cnt = patch - insn_buf;
} else if (isdiv) {
/* [R,W]x div 0 -> 0 */
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JNE | BPF_K, insn->src_reg,
0, 2, 0);
*patch++ = BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg);
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = *insn;
cnt = patch - insn_buf;
} else {
/* [R,W]x mod 0 -> [R,W]x */
*patch++ = BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
BPF_JEQ | BPF_K, insn->src_reg,
0, 1 + (is64 ? 0 : 1), 0);
*patch++ = *insn;
if (!is64) {
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = BPF_MOV32_REG(insn->dst_reg, insn->dst_reg);
}
cnt = patch - insn_buf;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Make it impossible to de-reference a userspace address */
if (BPF_CLASS(insn->code) == BPF_LDX &&
(BPF_MODE(insn->code) == BPF_PROBE_MEM ||
BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {
struct bpf_insn *patch = insn_buf;
u64 uaddress_limit = bpf_arch_uaddress_limit();
if (!uaddress_limit)
goto next_insn;
*patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
if (insn->off)
*patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_AX, insn->off);
*patch++ = BPF_ALU64_IMM(BPF_RSH, BPF_REG_AX, 32);
*patch++ = BPF_JMP_IMM(BPF_JLE, BPF_REG_AX, uaddress_limit >> 32, 2);
*patch++ = *insn;
*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*patch++ = BPF_MOV64_IMM(insn->dst_reg, 0);
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */
if (BPF_CLASS(insn->code) == BPF_LD &&
(BPF_MODE(insn->code) == BPF_ABS ||
BPF_MODE(insn->code) == BPF_IND)) {
cnt = env->ops->gen_ld_abs(insn, insn_buf);
if (cnt == 0 || cnt >= INSN_BUF_SIZE) {
verifier_bug(env, "%d insns generated for ld_abs", cnt);
return -EFAULT;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Rewrite pointer arithmetic to mitigate speculation attacks. */
if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
struct bpf_insn *patch = insn_buf;
bool issrc, isneg, isimm;
u32 off_reg;
aux = &env->insn_aux_data[i + delta];
if (!aux->alu_state ||
aux->alu_state == BPF_ALU_NON_POINTER)
goto next_insn;
isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
BPF_ALU_SANITIZE_SRC;
isimm = aux->alu_state & BPF_ALU_IMMEDIATE;
off_reg = issrc ? insn->src_reg : insn->dst_reg;
if (isimm) {
*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
} else {
if (isneg)
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
*patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
*patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
*patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
}
if (!issrc)
*patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
insn->src_reg = BPF_REG_AX;
if (isneg)
insn->code = insn->code == code_add ?
code_sub : code_add;
*patch++ = *insn;
if (issrc && isneg && !isimm)
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
cnt = patch - insn_buf;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (bpf_is_may_goto_insn(insn) && bpf_jit_supports_timed_may_goto()) {
int stack_off_cnt = -stack_depth - 16;
/*
* Two 8 byte slots, depth-16 stores the count, and
* depth-8 stores the start timestamp of the loop.
*
* The starting value of count is BPF_MAX_TIMED_LOOPS
* (0xffff). Every iteration loads it and subs it by 1,
* until the value becomes 0 in AX (thus, 1 in stack),
* after which we call arch_bpf_timed_may_goto, which
* either sets AX to 0xffff to keep looping, or to 0
* upon timeout. AX is then stored into the stack. In
* the next iteration, we either see 0 and break out, or
* continue iterating until the next time value is 0
* after subtraction, rinse and repeat.
*/
stack_depth_extra = 16;
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_AX, BPF_REG_10, stack_off_cnt);
if (insn->off >= 0)
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off + 5);
else
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off - 1);
insn_buf[2] = BPF_ALU64_IMM(BPF_SUB, BPF_REG_AX, 1);
insn_buf[3] = BPF_JMP_IMM(BPF_JNE, BPF_REG_AX, 0, 2);
/*
* AX is used as an argument to pass in stack_off_cnt
* (to add to r10/fp), and also as the return value of
* the call to arch_bpf_timed_may_goto.
*/
insn_buf[4] = BPF_MOV64_IMM(BPF_REG_AX, stack_off_cnt);
insn_buf[5] = BPF_EMIT_CALL(arch_bpf_timed_may_goto);
insn_buf[6] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_AX, stack_off_cnt);
cnt = 7;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
} else if (bpf_is_may_goto_insn(insn)) {
int stack_off = -stack_depth - 8;
stack_depth_extra = 8;
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_AX, BPF_REG_10, stack_off);
if (insn->off >= 0)
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off + 2);
else
insn_buf[1] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_AX, 0, insn->off - 1);
insn_buf[2] = BPF_ALU64_IMM(BPF_SUB, BPF_REG_AX, 1);
insn_buf[3] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_AX, stack_off);
cnt = 4;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (insn->code != (BPF_JMP | BPF_CALL))
goto next_insn;
if (insn->src_reg == BPF_PSEUDO_CALL)
goto next_insn;
if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
ret = bpf_fixup_kfunc_call(env, insn, insn_buf, i + delta, &cnt);
if (ret)
return ret;
if (cnt == 0)
goto next_insn;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Skip inlining the helper call if the JIT does it. */
if (bpf_jit_inlines_helper_call(insn->imm))
goto next_insn;
if (insn->imm == BPF_FUNC_get_route_realm)
prog->dst_needed = 1;
if (insn->imm == BPF_FUNC_get_prandom_u32)
bpf_user_rnd_init_once();
if (insn->imm == BPF_FUNC_override_return)
prog->kprobe_override = 1;
if (insn->imm == BPF_FUNC_tail_call) {
/* If we tail call into other programs, we
* cannot make any assumptions since they can
* be replaced dynamically during runtime in
* the program array.
*/
prog->cb_access = 1;
if (!bpf_allow_tail_call_in_subprogs(env))
prog->aux->stack_depth = MAX_BPF_STACK;
prog->aux->max_pkt_offset = MAX_PACKET_OFF;
/* mark bpf_tail_call as different opcode to avoid
* conditional branch in the interpreter for every normal
* call and to prevent accidental JITing by JIT compiler
* that doesn't support bpf_tail_call yet
*/
insn->imm = 0;
insn->code = BPF_JMP | BPF_TAIL_CALL;
aux = &env->insn_aux_data[i + delta];
if (env->bpf_capable && !prog->blinding_requested &&
prog->jit_requested &&
!bpf_map_key_poisoned(aux) &&
!bpf_map_ptr_poisoned(aux) &&
!bpf_map_ptr_unpriv(aux)) {
struct bpf_jit_poke_descriptor desc = {
.reason = BPF_POKE_REASON_TAIL_CALL,
.tail_call.map = aux->map_ptr_state.map_ptr,
.tail_call.key = bpf_map_key_immediate(aux),
.insn_idx = i + delta,
};
ret = bpf_jit_add_poke_descriptor(prog, &desc);
if (ret < 0) {
verbose(env, "adding tail call poke descriptor failed\n");
return ret;
}
insn->imm = ret + 1;
goto next_insn;
}
if (!bpf_map_ptr_unpriv(aux))
goto next_insn;
/* instead of changing every JIT dealing with tail_call
* emit two extra insns:
* if (index >= max_entries) goto out;
* index &= array->index_mask;
* to avoid out-of-bounds cpu speculation
*/
if (bpf_map_ptr_poisoned(aux)) {
verbose(env, "tail_call abusing map_ptr\n");
return -EINVAL;
}
map_ptr = aux->map_ptr_state.map_ptr;
insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
map_ptr->max_entries, 2);
insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
container_of(map_ptr,
struct bpf_array,
map)->index_mask);
insn_buf[2] = *insn;
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
if (insn->imm == BPF_FUNC_timer_set_callback) {
/* The verifier will process callback_fn as many times as necessary
* with different maps and the register states prepared by
* set_timer_callback_state will be accurate.
*
* The following use case is valid:
* map1 is shared by prog1, prog2, prog3.
* prog1 calls bpf_timer_init for some map1 elements
* prog2 calls bpf_timer_set_callback for some map1 elements.
* Those that were not bpf_timer_init-ed will return -EINVAL.
* prog3 calls bpf_timer_start for some map1 elements.
* Those that were not both bpf_timer_init-ed and
* bpf_timer_set_callback-ed will return -EINVAL.
*/
struct bpf_insn ld_addrs[2] = {
BPF_LD_IMM64(BPF_REG_3, (long)prog->aux),
};
insn_buf[0] = ld_addrs[0];
insn_buf[1] = ld_addrs[1];
insn_buf[2] = *insn;
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto patch_call_imm;
}
/* bpf_per_cpu_ptr() and bpf_this_cpu_ptr() */
if (env->insn_aux_data[i + delta].call_with_percpu_alloc_ptr) {
/* patch with 'r1 = *(u64 *)(r1 + 0)' since for percpu data,
* bpf_mem_alloc() returns a ptr to the percpu data ptr.
*/
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
insn_buf[1] = *insn;
cnt = 2;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto patch_call_imm;
}
/* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
* and other inlining handlers are currently limited to 64 bit
* only.
*/
if (prog->jit_requested && BITS_PER_LONG == 64 &&
(insn->imm == BPF_FUNC_map_lookup_elem ||
insn->imm == BPF_FUNC_map_update_elem ||
insn->imm == BPF_FUNC_map_delete_elem ||
insn->imm == BPF_FUNC_map_push_elem ||
insn->imm == BPF_FUNC_map_pop_elem ||
insn->imm == BPF_FUNC_map_peek_elem ||
insn->imm == BPF_FUNC_redirect_map ||
insn->imm == BPF_FUNC_for_each_map_elem ||
insn->imm == BPF_FUNC_map_lookup_percpu_elem)) {
aux = &env->insn_aux_data[i + delta];
if (bpf_map_ptr_poisoned(aux))
goto patch_call_imm;
map_ptr = aux->map_ptr_state.map_ptr;
ops = map_ptr->ops;
if (insn->imm == BPF_FUNC_map_lookup_elem &&
ops->map_gen_lookup) {
cnt = ops->map_gen_lookup(map_ptr, insn_buf);
if (cnt == -EOPNOTSUPP)
goto patch_map_ops_generic;
if (cnt <= 0 || cnt >= INSN_BUF_SIZE) {
verifier_bug(env, "%d insns generated for map lookup", cnt);
return -EFAULT;
}
new_prog = bpf_patch_insn_data(env, i + delta,
insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
(void *(*)(struct bpf_map *map, void *key))NULL));
BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
(long (*)(struct bpf_map *map, void *key))NULL));
BUILD_BUG_ON(!__same_type(ops->map_update_elem,
(long (*)(struct bpf_map *map, void *key, void *value,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_push_elem,
(long (*)(struct bpf_map *map, void *value,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
(long (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
(long (*)(struct bpf_map *map, void *value))NULL));
BUILD_BUG_ON(!__same_type(ops->map_redirect,
(long (*)(struct bpf_map *map, u64 index, u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_for_each_callback,
(long (*)(struct bpf_map *map,
bpf_callback_t callback_fn,
void *callback_ctx,
u64 flags))NULL));
BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem,
(void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL));
patch_map_ops_generic:
switch (insn->imm) {
case BPF_FUNC_map_lookup_elem:
insn->imm = BPF_CALL_IMM(ops->map_lookup_elem);
goto next_insn;
case BPF_FUNC_map_update_elem:
insn->imm = BPF_CALL_IMM(ops->map_update_elem);
goto next_insn;
case BPF_FUNC_map_delete_elem:
insn->imm = BPF_CALL_IMM(ops->map_delete_elem);
goto next_insn;
case BPF_FUNC_map_push_elem:
insn->imm = BPF_CALL_IMM(ops->map_push_elem);
goto next_insn;
case BPF_FUNC_map_pop_elem:
insn->imm = BPF_CALL_IMM(ops->map_pop_elem);
goto next_insn;
case BPF_FUNC_map_peek_elem:
insn->imm = BPF_CALL_IMM(ops->map_peek_elem);
goto next_insn;
case BPF_FUNC_redirect_map:
insn->imm = BPF_CALL_IMM(ops->map_redirect);
goto next_insn;
case BPF_FUNC_for_each_map_elem:
insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
goto next_insn;
case BPF_FUNC_map_lookup_percpu_elem:
insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem);
goto next_insn;
}
goto patch_call_imm;
}
/* Implement bpf_jiffies64 inline. */
if (prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_jiffies64) {
struct bpf_insn ld_jiffies_addr[2] = {
BPF_LD_IMM64(BPF_REG_0,
(unsigned long)&jiffies),
};
insn_buf[0] = ld_jiffies_addr[0];
insn_buf[1] = ld_jiffies_addr[1];
insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,
BPF_REG_0, 0);
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
/* Implement bpf_get_smp_processor_id() inline. */
if (insn->imm == BPF_FUNC_get_smp_processor_id &&
bpf_verifier_inlines_helper_call(env, insn->imm)) {
/* BPF_FUNC_get_smp_processor_id inlining is an
* optimization, so if cpu_number is ever
* changed in some incompatible and hard to support
* way, it's fine to back out this inlining logic
*/
#ifdef CONFIG_SMP
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, (u32)(unsigned long)&cpu_number);
insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
cnt = 3;
#else
insn_buf[0] = BPF_ALU32_REG(BPF_XOR, BPF_REG_0, BPF_REG_0);
cnt = 1;
#endif
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_current_task() and bpf_get_current_task_btf() inline. */
if ((insn->imm == BPF_FUNC_get_current_task || insn->imm == BPF_FUNC_get_current_task_btf) &&
bpf_verifier_inlines_helper_call(env, insn->imm)) {
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, (u32)(unsigned long)&current_task);
insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
#endif
/* Implement bpf_get_func_arg inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_arg) {
if (eatype == BPF_TRACE_RAW_TP) {
int nr_args = btf_type_vlen(prog->aux->attach_func_proto);
/* skip 'void *__data' in btf_trace_##name() and save to reg0 */
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args - 1);
cnt = 1;
} else {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
insn_buf[1] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xFF);
cnt = 2;
}
insn_buf[cnt++] = BPF_JMP32_REG(BPF_JGE, BPF_REG_2, BPF_REG_0, 6);
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 3);
insn_buf[cnt++] = BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_1);
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0);
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
insn_buf[cnt++] = BPF_MOV64_IMM(BPF_REG_0, 0);
insn_buf[cnt++] = BPF_JMP_A(1);
insn_buf[cnt++] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_func_ret inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ret) {
if (eatype == BPF_TRACE_FEXIT ||
eatype == BPF_TRACE_FSESSION ||
eatype == BPF_TRACE_FEXIT_MULTI ||
eatype == BPF_TRACE_FSESSION_MULTI ||
eatype == BPF_MODIFY_RETURN) {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
insn_buf[1] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xFF);
insn_buf[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);
insn_buf[3] = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);
insn_buf[4] = BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_0, 0);
insn_buf[5] = BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_3, 0);
insn_buf[6] = BPF_MOV64_IMM(BPF_REG_0, 0);
cnt = 7;
} else {
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, -EOPNOTSUPP);
cnt = 1;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement get_func_arg_cnt inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_arg_cnt) {
if (eatype == BPF_TRACE_RAW_TP) {
int nr_args = btf_type_vlen(prog->aux->attach_func_proto);
/* skip 'void *__data' in btf_trace_##name() and save to reg0 */
insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args - 1);
cnt = 1;
} else {
/* Load nr_args from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
insn_buf[1] = BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xFF);
cnt = 2;
}
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx - 16 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -16);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_get_branch_snapshot inline. */
if (IS_ENABLED(CONFIG_PERF_EVENTS) &&
prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_get_branch_snapshot) {
/* We are dealing with the following func protos:
* u64 bpf_get_branch_snapshot(void *buf, u32 size, u64 flags);
* int perf_snapshot_branch_stack(struct perf_branch_entry *entries, u32 cnt);
*/
const u32 br_entry_size = sizeof(struct perf_branch_entry);
/* struct perf_branch_entry is part of UAPI and is
* used as an array element, so extremely unlikely to
* ever grow or shrink
*/
BUILD_BUG_ON(br_entry_size != 24);
/* if (unlikely(flags)) return -EINVAL */
insn_buf[0] = BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 0, 7);
/* Transform size (bytes) into number of entries (cnt = size / 24).
* But to avoid expensive division instruction, we implement
* divide-by-3 through multiplication, followed by further
* division by 8 through 3-bit right shift.
* Refer to book "Hacker's Delight, 2nd ed." by Henry S. Warren, Jr.,
* p. 227, chapter "Unsigned Division by 3" for details and proofs.
*
* N / 3 <=> M * N / 2^33, where M = (2^33 + 1) / 3 = 0xaaaaaaab.
*/
insn_buf[1] = BPF_MOV32_IMM(BPF_REG_0, 0xaaaaaaab);
insn_buf[2] = BPF_ALU64_REG(BPF_MUL, BPF_REG_2, BPF_REG_0);
insn_buf[3] = BPF_ALU64_IMM(BPF_RSH, BPF_REG_2, 36);
/* call perf_snapshot_branch_stack implementation */
insn_buf[4] = BPF_EMIT_CALL(static_call_query(perf_snapshot_branch_stack));
/* if (entry_cnt == 0) return -ENOENT */
insn_buf[5] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4);
/* return entry_cnt * sizeof(struct perf_branch_entry) */
insn_buf[6] = BPF_ALU32_IMM(BPF_MUL, BPF_REG_0, br_entry_size);
insn_buf[7] = BPF_JMP_A(3);
/* return -EINVAL; */
insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, -EINVAL);
insn_buf[9] = BPF_JMP_A(1);
/* return -ENOENT; */
insn_buf[10] = BPF_MOV64_IMM(BPF_REG_0, -ENOENT);
cnt = 11;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
/* Implement bpf_kptr_xchg inline */
if (prog->jit_requested && BITS_PER_LONG == 64 &&
insn->imm == BPF_FUNC_kptr_xchg &&
bpf_jit_supports_ptr_xchg()) {
insn_buf[0] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_2);
insn_buf[1] = BPF_ATOMIC_OP(BPF_DW, BPF_XCHG, BPF_REG_1, BPF_REG_0, 0);
cnt = 2;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog);
/* all functions that have prototype and verifier allowed
* programs to call them, must be real in-kernel functions
*/
if (!fn->func) {
verifier_bug(env,
"not inlined functions %s#%d is missing func",
func_id_name(insn->imm), insn->imm);
return -EFAULT;
}
insn->imm = fn->func - __bpf_call_base;
next_insn:
if (subprogs[cur_subprog + 1].start == i + delta + 1) {
subprogs[cur_subprog].stack_depth += stack_depth_extra;
subprogs[cur_subprog].stack_extra = stack_depth_extra;
stack_depth = subprogs[cur_subprog].stack_depth;
if (stack_depth > MAX_BPF_STACK && !prog->jit_requested) {
verbose(env, "stack size %d(extra %d) is too large\n",
stack_depth, stack_depth_extra);
return -EINVAL;
}
cur_subprog++;
stack_depth = subprogs[cur_subprog].stack_depth;
stack_depth_extra = 0;
}
i++;
insn++;
}
env->prog->aux->stack_depth = subprogs[0].stack_depth;
for (i = 0; i < env->subprog_cnt; i++) {
int delta = bpf_jit_supports_timed_may_goto() ? 2 : 1;
int subprog_start = subprogs[i].start;
int stack_slots = subprogs[i].stack_extra / 8;
int slots = delta, cnt = 0;
if (!stack_slots)
continue;
/* We need two slots in case timed may_goto is supported. */
if (stack_slots > slots) {
verifier_bug(env, "stack_slots supports may_goto only");
return -EFAULT;
}
stack_depth = subprogs[i].stack_depth;
if (bpf_jit_supports_timed_may_goto()) {
insn_buf[cnt++] = BPF_ST_MEM(BPF_DW, BPF_REG_FP, -stack_depth,
BPF_MAX_TIMED_LOOPS);
insn_buf[cnt++] = BPF_ST_MEM(BPF_DW, BPF_REG_FP, -stack_depth + 8, 0);
} else {
/* Add ST insn to subprog prologue to init extra stack */
insn_buf[cnt++] = BPF_ST_MEM(BPF_DW, BPF_REG_FP, -stack_depth,
BPF_MAX_LOOPS);
}
/* Copy first actual insn to preserve it */
insn_buf[cnt++] = env->prog->insnsi[subprog_start];
new_prog = bpf_patch_insn_data(env, subprog_start, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
/*
* If may_goto is a first insn of a prog there could be a jmp
* insn that points to it, hence adjust all such jmps to point
* to insn after BPF_ST that inits may_goto count.
* Adjustment will succeed because bpf_patch_insn_data() didn't fail.
*/
WARN_ON(adjust_jmp_off(env->prog, subprog_start, delta));
}
/* Since poke tab is now finalized, publish aux to tracker. */
for (i = 0; i < prog->aux->size_poke_tab; i++) {
map_ptr = prog->aux->poke_tab[i].tail_call.map;
if (!map_ptr->ops->map_poke_track ||
!map_ptr->ops->map_poke_untrack ||
!map_ptr->ops->map_poke_run) {
verifier_bug(env, "poke tab is misconfigured");
return -EFAULT;
}
ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
if (ret < 0) {
verbose(env, "tracking tail call prog failed\n");
return ret;
}
}
ret = sort_kfunc_descs_by_imm_off(env);
if (ret)
return ret;
return 0;
}
static struct bpf_prog *inline_bpf_loop(struct bpf_verifier_env *env,
int position,
s32 stack_base,
u32 callback_subprogno,
u32 *total_cnt)
{
s32 r6_offset = stack_base + 0 * BPF_REG_SIZE;
s32 r7_offset = stack_base + 1 * BPF_REG_SIZE;
s32 r8_offset = stack_base + 2 * BPF_REG_SIZE;
int reg_loop_max = BPF_REG_6;
int reg_loop_cnt = BPF_REG_7;
int reg_loop_ctx = BPF_REG_8;
struct bpf_insn *insn_buf = env->insn_buf;
struct bpf_prog *new_prog;
u32 callback_start;
u32 call_insn_offset;
s32 callback_offset;
u32 cnt = 0;
/* This represents an inlined version of bpf_iter.c:bpf_loop,
* be careful to modify this code in sync.
*/
/* Return error and jump to the end of the patch if
* expected number of iterations is too big.
*/
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JLE, BPF_REG_1, BPF_MAX_LOOPS, 2);
insn_buf[cnt++] = BPF_MOV32_IMM(BPF_REG_0, -E2BIG);
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JA, 0, 0, 16);
/* spill R6, R7, R8 to use these as loop vars */
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, r6_offset);
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_7, r7_offset);
insn_buf[cnt++] = BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_8, r8_offset);
/* initialize loop vars */
insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_max, BPF_REG_1);
insn_buf[cnt++] = BPF_MOV32_IMM(reg_loop_cnt, 0);
insn_buf[cnt++] = BPF_MOV64_REG(reg_loop_ctx, BPF_REG_3);
/* loop header,
* if reg_loop_cnt >= reg_loop_max skip the loop body
*/
insn_buf[cnt++] = BPF_JMP_REG(BPF_JGE, reg_loop_cnt, reg_loop_max, 5);
/* callback call,
* correct callback offset would be set after patching
*/
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_1, reg_loop_cnt);
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_2, reg_loop_ctx);
insn_buf[cnt++] = BPF_CALL_REL(0);
/* increment loop counter */
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_ADD, reg_loop_cnt, 1);
/* jump to loop header if callback returned 0 */
insn_buf[cnt++] = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, -6);
/* return value of bpf_loop,
* set R0 to the number of iterations
*/
insn_buf[cnt++] = BPF_MOV64_REG(BPF_REG_0, reg_loop_cnt);
/* restore original values of R6, R7, R8 */
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, r6_offset);
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, r7_offset);
insn_buf[cnt++] = BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_10, r8_offset);
*total_cnt = cnt;
new_prog = bpf_patch_insn_data(env, position, insn_buf, cnt);
if (!new_prog)
return new_prog;
/* callback start is known only after patching */
callback_start = env->subprog_info[callback_subprogno].start;
/* Note: insn_buf[12] is an offset of BPF_CALL_REL instruction */
call_insn_offset = position + 12;
callback_offset = callback_start - call_insn_offset - 1;
new_prog->insnsi[call_insn_offset].imm = callback_offset;
return new_prog;
}
static bool is_bpf_loop_call(struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL) &&
insn->src_reg == 0 &&
insn->imm == BPF_FUNC_loop;
}
/* For all sub-programs in the program (including main) check
* insn_aux_data to see if there are bpf_loop calls that require
* inlining. If such calls are found the calls are replaced with a
* sequence of instructions produced by `inline_bpf_loop` function and
* subprog stack_depth is increased by the size of 3 registers.
* This stack space is used to spill values of the R6, R7, R8. These
* registers are used to store the loop bound, counter and context
* variables.
*/
int bpf_optimize_bpf_loop(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprogs = env->subprog_info;
int i, cur_subprog = 0, cnt, delta = 0;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
u16 stack_depth = subprogs[cur_subprog].stack_depth;
u16 stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
u16 stack_depth_extra = 0;
for (i = 0; i < insn_cnt; i++, insn++) {
struct bpf_loop_inline_state *inline_state =
&env->insn_aux_data[i + delta].loop_inline_state;
if (is_bpf_loop_call(insn) && inline_state->fit_for_inline) {
struct bpf_prog *new_prog;
stack_depth_extra = BPF_REG_SIZE * 3 + stack_depth_roundup;
new_prog = inline_bpf_loop(env,
i + delta,
-(stack_depth + stack_depth_extra),
inline_state->callback_subprogno,
&cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = new_prog;
insn = new_prog->insnsi + i + delta;
}
if (subprogs[cur_subprog + 1].start == i + delta + 1) {
subprogs[cur_subprog].stack_depth += stack_depth_extra;
cur_subprog++;
stack_depth = subprogs[cur_subprog].stack_depth;
stack_depth_roundup = round_up(stack_depth, 8) - stack_depth;
stack_depth_extra = 0;
}
}
env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
return 0;
}
/* Remove unnecessary spill/fill pairs, members of fastcall pattern,
* adjust subprograms stack depth when possible.
*/
int bpf_remove_fastcall_spills_fills(struct bpf_verifier_env *env)
{
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn_aux_data *aux = env->insn_aux_data;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
u32 spills_num;
bool modified = false;
int i, j;
for (i = 0; i < insn_cnt; i++, insn++) {
if (aux[i].fastcall_spills_num > 0) {
spills_num = aux[i].fastcall_spills_num;
/* NOPs would be removed by opt_remove_nops() */
for (j = 1; j <= spills_num; ++j) {
*(insn - j) = NOP;
*(insn + j) = NOP;
}
modified = true;
}
if ((subprog + 1)->start == i + 1) {
if (modified && !subprog->keep_fastcall_stack)
subprog->stack_depth = -subprog->fastcall_stack_off;
subprog++;
modified = false;
}
}
return 0;
}