blob: b25722876331792f5ac218fa4376f36318156f7f [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/objtool.h>
#include <linux/module.h>
#include <linux/sort.h>
#include <asm/exception.h>
#include <asm/orc_header.h>
#include <asm/orc_lookup.h>
#include <asm/orc_types.h>
#include <asm/ptrace.h>
#include <asm/setup.h>
#include <asm/stacktrace.h>
#include <asm/tlb.h>
#include <asm/unwind.h>
ORC_HEADER;
#define orc_warn(fmt, ...) \
printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__)
extern int __start_orc_unwind_ip[];
extern int __stop_orc_unwind_ip[];
extern struct orc_entry __start_orc_unwind[];
extern struct orc_entry __stop_orc_unwind[];
static bool orc_init __ro_after_init;
static unsigned int lookup_num_blocks __ro_after_init;
/* Fake frame pointer entry -- used as a fallback for generated code */
static struct orc_entry orc_fp_entry = {
.sp_reg = ORC_REG_FP,
.sp_offset = 16,
.fp_reg = ORC_REG_PREV_SP,
.fp_offset = -16,
.ra_reg = ORC_REG_PREV_SP,
.ra_offset = -8,
.type = ORC_TYPE_CALL
};
/*
* If we crash with IP==0, the last successfully executed instruction
* was probably an indirect function call with a NULL function pointer,
* and we don't have unwind information for NULL.
* This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function
* pointer into its parent and then continue normally from there.
*/
static struct orc_entry orc_null_entry = {
.sp_reg = ORC_REG_SP,
.sp_offset = sizeof(long),
.fp_reg = ORC_REG_UNDEFINED,
.type = ORC_TYPE_CALL
};
static inline unsigned long orc_ip(const int *ip)
{
return (unsigned long)ip + *ip;
}
static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
unsigned int num_entries, unsigned long ip)
{
int *first = ip_table;
int *mid = first, *found = first;
int *last = ip_table + num_entries - 1;
if (!num_entries)
return NULL;
/*
* Do a binary range search to find the rightmost duplicate of a given
* starting address. Some entries are section terminators which are
* "weak" entries for ensuring there are no gaps. They should be
* ignored when they conflict with a real entry.
*/
while (first <= last) {
mid = first + ((last - first) / 2);
if (orc_ip(mid) <= ip) {
found = mid;
first = mid + 1;
} else
last = mid - 1;
}
return u_table + (found - ip_table);
}
#ifdef CONFIG_MODULES
static struct orc_entry *orc_module_find(unsigned long ip)
{
struct module *mod;
mod = __module_address(ip);
if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
return NULL;
return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, mod->arch.num_orcs, ip);
}
#else
static struct orc_entry *orc_module_find(unsigned long ip)
{
return NULL;
}
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
static struct orc_entry *orc_find(unsigned long ip);
/*
* Ftrace dynamic trampolines do not have orc entries of their own.
* But they are copies of the ftrace entries that are static and
* defined in ftrace_*.S, which do have orc entries.
*
* If the unwinder comes across a ftrace trampoline, then find the
* ftrace function that was used to create it, and use that ftrace
* function's orc entry, as the placement of the return code in
* the stack will be identical.
*/
static struct orc_entry *orc_ftrace_find(unsigned long ip)
{
struct ftrace_ops *ops;
unsigned long tramp_addr, offset;
ops = ftrace_ops_trampoline(ip);
if (!ops)
return NULL;
/* Set tramp_addr to the start of the code copied by the trampoline */
if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
tramp_addr = (unsigned long)ftrace_regs_caller;
else
tramp_addr = (unsigned long)ftrace_caller;
/* Now place tramp_addr to the location within the trampoline ip is at */
offset = ip - ops->trampoline;
tramp_addr += offset;
/* Prevent unlikely recursion */
if (ip == tramp_addr)
return NULL;
return orc_find(tramp_addr);
}
#else
static struct orc_entry *orc_ftrace_find(unsigned long ip)
{
return NULL;
}
#endif
static struct orc_entry *orc_find(unsigned long ip)
{
static struct orc_entry *orc;
if (ip == 0)
return &orc_null_entry;
/* For non-init vmlinux addresses, use the fast lookup table: */
if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
unsigned int idx, start, stop;
idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
if (unlikely((idx >= lookup_num_blocks-1))) {
orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
idx, lookup_num_blocks, (void *)ip);
return NULL;
}
start = orc_lookup[idx];
stop = orc_lookup[idx + 1] + 1;
if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
(__start_orc_unwind + stop > __stop_orc_unwind))) {
orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
idx, lookup_num_blocks, start, stop, (void *)ip);
return NULL;
}
return __orc_find(__start_orc_unwind_ip + start,
__start_orc_unwind + start, stop - start, ip);
}
/* vmlinux .init slow lookup: */
if (is_kernel_inittext(ip))
return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
__stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
/* Module lookup: */
orc = orc_module_find(ip);
if (orc)
return orc;
return orc_ftrace_find(ip);
}
#ifdef CONFIG_MODULES
static DEFINE_MUTEX(sort_mutex);
static int *cur_orc_ip_table = __start_orc_unwind_ip;
static struct orc_entry *cur_orc_table = __start_orc_unwind;
static void orc_sort_swap(void *_a, void *_b, int size)
{
int delta = _b - _a;
int *a = _a, *b = _b, tmp;
struct orc_entry *orc_a, *orc_b;
/* Swap the .orc_unwind_ip entries: */
tmp = *a;
*a = *b + delta;
*b = tmp - delta;
/* Swap the corresponding .orc_unwind entries: */
orc_a = cur_orc_table + (a - cur_orc_ip_table);
orc_b = cur_orc_table + (b - cur_orc_ip_table);
swap(*orc_a, *orc_b);
}
static int orc_sort_cmp(const void *_a, const void *_b)
{
const int *a = _a, *b = _b;
unsigned long a_val = orc_ip(a);
unsigned long b_val = orc_ip(b);
struct orc_entry *orc_a;
if (a_val > b_val)
return 1;
if (a_val < b_val)
return -1;
/*
* The "weak" section terminator entries need to always be first
* to ensure the lookup code skips them in favor of real entries.
* These terminator entries exist to handle any gaps created by
* whitelisted .o files which didn't get objtool generation.
*/
orc_a = cur_orc_table + (a - cur_orc_ip_table);
return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
}
void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
void *_orc, size_t orc_size)
{
int *orc_ip = _orc_ip;
struct orc_entry *orc = _orc;
unsigned int num_entries = orc_ip_size / sizeof(int);
WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
orc_size % sizeof(*orc) != 0 ||
num_entries != orc_size / sizeof(*orc));
/*
* The 'cur_orc_*' globals allow the orc_sort_swap() callback to
* associate an .orc_unwind_ip table entry with its corresponding
* .orc_unwind entry so they can both be swapped.
*/
mutex_lock(&sort_mutex);
cur_orc_ip_table = orc_ip;
cur_orc_table = orc;
sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
mutex_unlock(&sort_mutex);
mod->arch.orc_unwind_ip = orc_ip;
mod->arch.orc_unwind = orc;
mod->arch.num_orcs = num_entries;
}
#endif
void __init unwind_init(void)
{
int i;
size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
size_t num_entries = orc_ip_size / sizeof(int);
struct orc_entry *orc;
if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
orc_size % sizeof(struct orc_entry) != 0 ||
num_entries != orc_size / sizeof(struct orc_entry)) {
orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n");
return;
}
/*
* Note, the orc_unwind and orc_unwind_ip tables were already
* sorted at build time via the 'sorttable' tool.
* It's ready for binary search straight away, no need to sort it.
*/
/* Initialize the fast lookup table: */
lookup_num_blocks = orc_lookup_end - orc_lookup;
for (i = 0; i < lookup_num_blocks-1; i++) {
orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
num_entries, LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
if (!orc) {
orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
return;
}
orc_lookup[i] = orc - __start_orc_unwind;
}
/* Initialize the ending block: */
orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, LOOKUP_STOP_IP);
if (!orc) {
orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
return;
}
orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
orc_init = true;
}
static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
{
unsigned long begin = info->begin;
unsigned long end = info->end;
return (info->type != STACK_TYPE_UNKNOWN &&
addr >= begin && addr < end && addr + len > begin && addr + len <= end);
}
static bool stack_access_ok(struct unwind_state *state, unsigned long addr, size_t len)
{
struct stack_info *info = &state->stack_info;
if (on_stack(info, addr, len))
return true;
return !get_stack_info(addr, state->task, info) && on_stack(info, addr, len);
}
unsigned long unwind_get_return_address(struct unwind_state *state)
{
return __unwind_get_return_address(state);
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);
void unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs)
{
__unwind_start(state, task, regs);
state->type = UNWINDER_ORC;
if (!unwind_done(state) && !__kernel_text_address(state->pc))
unwind_next_frame(state);
}
EXPORT_SYMBOL_GPL(unwind_start);
static bool is_entry_func(unsigned long addr)
{
extern u32 kernel_entry;
extern u32 kernel_entry_end;
return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
}
static inline unsigned long bt_address(unsigned long ra)
{
extern unsigned long eentry;
if (__kernel_text_address(ra))
return ra;
if (__module_text_address(ra))
return ra;
if (ra >= eentry && ra < eentry + EXCCODE_INT_END * VECSIZE) {
unsigned long func;
unsigned long type = (ra - eentry) / VECSIZE;
unsigned long offset = (ra - eentry) % VECSIZE;
switch (type) {
case 0 ... EXCCODE_INT_START - 1:
func = (unsigned long)exception_table[type];
break;
case EXCCODE_INT_START ... EXCCODE_INT_END:
func = (unsigned long)handle_vint;
break;
default:
func = (unsigned long)handle_reserved;
break;
}
return func + offset;
}
return ra;
}
bool unwind_next_frame(struct unwind_state *state)
{
unsigned long *p, pc;
struct pt_regs *regs;
struct orc_entry *orc;
struct stack_info *info = &state->stack_info;
if (unwind_done(state))
return false;
/* Don't let modules unload while we're reading their ORC data. */
preempt_disable();
if (is_entry_func(state->pc))
goto end;
orc = orc_find(state->pc);
if (!orc) {
/*
* As a fallback, try to assume this code uses a frame pointer.
* This is useful for generated code, like BPF, which ORC
* doesn't know about. This is just a guess, so the rest of
* the unwind is no longer considered reliable.
*/
orc = &orc_fp_entry;
state->error = true;
} else {
if (orc->type == ORC_TYPE_UNDEFINED)
goto err;
if (orc->type == ORC_TYPE_END_OF_STACK)
goto end;
}
switch (orc->sp_reg) {
case ORC_REG_SP:
if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
orc->type = ORC_TYPE_REGS;
else
state->sp = state->sp + orc->sp_offset;
break;
case ORC_REG_FP:
state->sp = state->fp;
break;
default:
orc_warn("unknown SP base reg %d at %pB\n", orc->sp_reg, (void *)state->pc);
goto err;
}
switch (orc->fp_reg) {
case ORC_REG_PREV_SP:
p = (unsigned long *)(state->sp + orc->fp_offset);
if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
goto err;
state->fp = *p;
break;
case ORC_REG_UNDEFINED:
/* Nothing. */
break;
default:
orc_warn("unknown FP base reg %d at %pB\n", orc->fp_reg, (void *)state->pc);
goto err;
}
switch (orc->type) {
case ORC_TYPE_CALL:
if (orc->ra_reg == ORC_REG_PREV_SP) {
p = (unsigned long *)(state->sp + orc->ra_offset);
if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
goto err;
pc = unwind_graph_addr(state, *p, state->sp);
pc -= LOONGARCH_INSN_SIZE;
} else if (orc->ra_reg == ORC_REG_UNDEFINED) {
if (!state->ra || state->ra == state->pc)
goto err;
pc = unwind_graph_addr(state, state->ra, state->sp);
pc -= LOONGARCH_INSN_SIZE;
state->ra = 0;
} else {
orc_warn("unknown ra base reg %d at %pB\n", orc->ra_reg, (void *)state->pc);
goto err;
}
break;
case ORC_TYPE_REGS:
if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
regs = (struct pt_regs *)info->next_sp;
else
regs = (struct pt_regs *)state->sp;
if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
goto err;
if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
!regs->regs[3] && !regs->regs[1])
goto end;
if (user_mode(regs))
goto end;
pc = regs->csr_era;
if (!__kernel_text_address(pc))
goto err;
state->sp = regs->regs[3];
state->ra = regs->regs[1];
state->fp = regs->regs[22];
get_stack_info(state->sp, state->task, info);
break;
default:
orc_warn("unknown .orc_unwind entry type %d at %pB\n", orc->type, (void *)state->pc);
goto err;
}
state->pc = bt_address(pc);
if (!state->pc) {
pr_err("cannot find unwind pc at %pK\n", (void *)pc);
goto err;
}
if (!__kernel_text_address(state->pc))
goto err;
preempt_enable();
return true;
err:
state->error = true;
end:
preempt_enable();
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;
}
EXPORT_SYMBOL_GPL(unwind_next_frame);