blob: 683749b80ae2829c0a3f56734c4e0da0bc3e4e0e [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
/*
* xsave/xrstor support.
*
* Author: Suresh Siddha <suresh.b.siddha@intel.com>
*/
#include <linux/compat.h>
#include <linux/cpu.h>
#include <linux/mman.h>
#include <linux/pkeys.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <asm/fpu/api.h>
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/xstate.h>
#include <asm/tlbflush.h>
#include <asm/cpufeature.h>
/*
* Although we spell it out in here, the Processor Trace
* xfeature is completely unused. We use other mechanisms
* to save/restore PT state in Linux.
*/
static const char *xfeature_names[] =
{
"x87 floating point registers" ,
"SSE registers" ,
"AVX registers" ,
"MPX bounds registers" ,
"MPX CSR" ,
"AVX-512 opmask" ,
"AVX-512 Hi256" ,
"AVX-512 ZMM_Hi256" ,
"Processor Trace (unused)" ,
"Protection Keys User registers",
"PASID state",
"unknown xstate feature" ,
};
static short xsave_cpuid_features[] __initdata = {
X86_FEATURE_FPU,
X86_FEATURE_XMM,
X86_FEATURE_AVX,
X86_FEATURE_MPX,
X86_FEATURE_MPX,
X86_FEATURE_AVX512F,
X86_FEATURE_AVX512F,
X86_FEATURE_AVX512F,
X86_FEATURE_INTEL_PT,
X86_FEATURE_PKU,
X86_FEATURE_ENQCMD,
};
/*
* This represents the full set of bits that should ever be set in a kernel
* XSAVE buffer, both supervisor and user xstates.
*/
u64 xfeatures_mask_all __read_mostly;
static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
/*
* The XSAVE area of kernel can be in standard or compacted format;
* it is always in standard format for user mode. This is the user
* mode standard format size used for signal and ptrace frames.
*/
unsigned int fpu_user_xstate_size;
/*
* Return whether the system supports a given xfeature.
*
* Also return the name of the (most advanced) feature that the caller requested:
*/
int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
{
u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask_all;
if (unlikely(feature_name)) {
long xfeature_idx, max_idx;
u64 xfeatures_print;
/*
* So we use FLS here to be able to print the most advanced
* feature that was requested but is missing. So if a driver
* asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
* missing AVX feature - this is the most informative message
* to users:
*/
if (xfeatures_missing)
xfeatures_print = xfeatures_missing;
else
xfeatures_print = xfeatures_needed;
xfeature_idx = fls64(xfeatures_print)-1;
max_idx = ARRAY_SIZE(xfeature_names)-1;
xfeature_idx = min(xfeature_idx, max_idx);
*feature_name = xfeature_names[xfeature_idx];
}
if (xfeatures_missing)
return 0;
return 1;
}
EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
static bool xfeature_is_supervisor(int xfeature_nr)
{
/*
* Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1)
* returns ECX[0] set to (1) for a supervisor state, and cleared (0)
* for a user state.
*/
u32 eax, ebx, ecx, edx;
cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
return ecx & 1;
}
/*
* When executing XSAVEOPT (or other optimized XSAVE instructions), if
* a processor implementation detects that an FPU state component is still
* (or is again) in its initialized state, it may clear the corresponding
* bit in the header.xfeatures field, and can skip the writeout of registers
* to the corresponding memory layout.
*
* This means that when the bit is zero, the state component might still contain
* some previous - non-initialized register state.
*
* Before writing xstate information to user-space we sanitize those components,
* to always ensure that the memory layout of a feature will be in the init state
* if the corresponding header bit is zero. This is to ensure that user-space doesn't
* see some stale state in the memory layout during signal handling, debugging etc.
*/
void fpstate_sanitize_xstate(struct fpu *fpu)
{
struct fxregs_state *fx = &fpu->state.fxsave;
int feature_bit;
u64 xfeatures;
if (!use_xsaveopt())
return;
xfeatures = fpu->state.xsave.header.xfeatures;
/*
* None of the feature bits are in init state. So nothing else
* to do for us, as the memory layout is up to date.
*/
if ((xfeatures & xfeatures_mask_all) == xfeatures_mask_all)
return;
/*
* FP is in init state
*/
if (!(xfeatures & XFEATURE_MASK_FP)) {
fx->cwd = 0x37f;
fx->swd = 0;
fx->twd = 0;
fx->fop = 0;
fx->rip = 0;
fx->rdp = 0;
memset(fx->st_space, 0, sizeof(fx->st_space));
}
/*
* SSE is in init state
*/
if (!(xfeatures & XFEATURE_MASK_SSE))
memset(fx->xmm_space, 0, sizeof(fx->xmm_space));
/*
* First two features are FPU and SSE, which above we handled
* in a special way already:
*/
feature_bit = 0x2;
xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
/*
* Update all the remaining memory layouts according to their
* standard xstate layout, if their header bit is in the init
* state:
*/
while (xfeatures) {
if (xfeatures & 0x1) {
int offset = xstate_comp_offsets[feature_bit];
int size = xstate_sizes[feature_bit];
memcpy((void *)fx + offset,
(void *)&init_fpstate.xsave + offset,
size);
}
xfeatures >>= 1;
feature_bit++;
}
}
/*
* Enable the extended processor state save/restore feature.
* Called once per CPU onlining.
*/
void fpu__init_cpu_xstate(void)
{
u64 unsup_bits;
if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_all)
return;
/*
* Unsupported supervisor xstates should not be found in
* the xfeatures mask.
*/
unsup_bits = xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
WARN_ONCE(unsup_bits, "x86/fpu: Found unsupported supervisor xstates: 0x%llx\n",
unsup_bits);
xfeatures_mask_all &= ~XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
cr4_set_bits(X86_CR4_OSXSAVE);
/*
* XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
* managed by XSAVE{C, OPT, S} and XRSTOR{S}. Only XSAVE user
* states can be set here.
*/
xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
/*
* MSR_IA32_XSS sets supervisor states managed by XSAVES.
*/
if (boot_cpu_has(X86_FEATURE_XSAVES)) {
wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
xfeatures_mask_dynamic());
}
}
static bool xfeature_enabled(enum xfeature xfeature)
{
return xfeatures_mask_all & BIT_ULL(xfeature);
}
/*
* Record the offsets and sizes of various xstates contained
* in the XSAVE state memory layout.
*/
static void __init setup_xstate_features(void)
{
u32 eax, ebx, ecx, edx, i;
/* start at the beginnning of the "extended state" */
unsigned int last_good_offset = offsetof(struct xregs_state,
extended_state_area);
/*
* The FP xstates and SSE xstates are legacy states. They are always
* in the fixed offsets in the xsave area in either compacted form
* or standard form.
*/
xstate_offsets[XFEATURE_FP] = 0;
xstate_sizes[XFEATURE_FP] = offsetof(struct fxregs_state,
xmm_space);
xstate_offsets[XFEATURE_SSE] = xstate_sizes[XFEATURE_FP];
xstate_sizes[XFEATURE_SSE] = sizeof_field(struct fxregs_state,
xmm_space);
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (!xfeature_enabled(i))
continue;
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
xstate_sizes[i] = eax;
/*
* If an xfeature is supervisor state, the offset in EBX is
* invalid, leave it to -1.
*/
if (xfeature_is_supervisor(i))
continue;
xstate_offsets[i] = ebx;
/*
* In our xstate size checks, we assume that the highest-numbered
* xstate feature has the highest offset in the buffer. Ensure
* it does.
*/
WARN_ONCE(last_good_offset > xstate_offsets[i],
"x86/fpu: misordered xstate at %d\n", last_good_offset);
last_good_offset = xstate_offsets[i];
}
}
static void __init print_xstate_feature(u64 xstate_mask)
{
const char *feature_name;
if (cpu_has_xfeatures(xstate_mask, &feature_name))
pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
}
/*
* Print out all the supported xstate features:
*/
static void __init print_xstate_features(void)
{
print_xstate_feature(XFEATURE_MASK_FP);
print_xstate_feature(XFEATURE_MASK_SSE);
print_xstate_feature(XFEATURE_MASK_YMM);
print_xstate_feature(XFEATURE_MASK_BNDREGS);
print_xstate_feature(XFEATURE_MASK_BNDCSR);
print_xstate_feature(XFEATURE_MASK_OPMASK);
print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
print_xstate_feature(XFEATURE_MASK_PKRU);
print_xstate_feature(XFEATURE_MASK_PASID);
}
/*
* This check is important because it is easy to get XSTATE_*
* confused with XSTATE_BIT_*.
*/
#define CHECK_XFEATURE(nr) do { \
WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \
WARN_ON(nr >= XFEATURE_MAX); \
} while (0)
/*
* We could cache this like xstate_size[], but we only use
* it here, so it would be a waste of space.
*/
static int xfeature_is_aligned(int xfeature_nr)
{
u32 eax, ebx, ecx, edx;
CHECK_XFEATURE(xfeature_nr);
if (!xfeature_enabled(xfeature_nr)) {
WARN_ONCE(1, "Checking alignment of disabled xfeature %d\n",
xfeature_nr);
return 0;
}
cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
/*
* The value returned by ECX[1] indicates the alignment
* of state component 'i' when the compacted format
* of the extended region of an XSAVE area is used:
*/
return !!(ecx & 2);
}
/*
* This function sets up offsets and sizes of all extended states in
* xsave area. This supports both standard format and compacted format
* of the xsave area.
*/
static void __init setup_xstate_comp_offsets(void)
{
unsigned int next_offset;
int i;
/*
* The FP xstates and SSE xstates are legacy states. They are always
* in the fixed offsets in the xsave area in either compacted form
* or standard form.
*/
xstate_comp_offsets[XFEATURE_FP] = 0;
xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
xmm_space);
if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (xfeature_enabled(i))
xstate_comp_offsets[i] = xstate_offsets[i];
}
return;
}
next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (!xfeature_enabled(i))
continue;
if (xfeature_is_aligned(i))
next_offset = ALIGN(next_offset, 64);
xstate_comp_offsets[i] = next_offset;
next_offset += xstate_sizes[i];
}
}
/*
* Setup offsets of a supervisor-state-only XSAVES buffer:
*
* The offsets stored in xstate_comp_offsets[] only work for one specific
* value of the Requested Feature BitMap (RFBM). In cases where a different
* RFBM value is used, a different set of offsets is required. This set of
* offsets is for when RFBM=xfeatures_mask_supervisor().
*/
static void __init setup_supervisor_only_offsets(void)
{
unsigned int next_offset;
int i;
next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (!xfeature_enabled(i) || !xfeature_is_supervisor(i))
continue;
if (xfeature_is_aligned(i))
next_offset = ALIGN(next_offset, 64);
xstate_supervisor_only_offsets[i] = next_offset;
next_offset += xstate_sizes[i];
}
}
/*
* Print out xstate component offsets and sizes
*/
static void __init print_xstate_offset_size(void)
{
int i;
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (!xfeature_enabled(i))
continue;
pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
i, xstate_comp_offsets[i], i, xstate_sizes[i]);
}
}
/*
* setup the xstate image representing the init state
*/
static void __init setup_init_fpu_buf(void)
{
static int on_boot_cpu __initdata = 1;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
if (!boot_cpu_has(X86_FEATURE_XSAVE))
return;
setup_xstate_features();
print_xstate_features();
if (boot_cpu_has(X86_FEATURE_XSAVES))
init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
xfeatures_mask_all;
/*
* Init all the features state with header.xfeatures being 0x0
*/
copy_kernel_to_xregs_booting(&init_fpstate.xsave);
/*
* Dump the init state again. This is to identify the init state
* of any feature which is not represented by all zero's.
*/
copy_xregs_to_kernel_booting(&init_fpstate.xsave);
}
static int xfeature_uncompacted_offset(int xfeature_nr)
{
u32 eax, ebx, ecx, edx;
/*
* Only XSAVES supports supervisor states and it uses compacted
* format. Checking a supervisor state's uncompacted offset is
* an error.
*/
if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {
WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
return -1;
}
CHECK_XFEATURE(xfeature_nr);
cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
return ebx;
}
int xfeature_size(int xfeature_nr)
{
u32 eax, ebx, ecx, edx;
CHECK_XFEATURE(xfeature_nr);
cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
return eax;
}
/*
* 'XSAVES' implies two different things:
* 1. saving of supervisor/system state
* 2. using the compacted format
*
* Use this function when dealing with the compacted format so
* that it is obvious which aspect of 'XSAVES' is being handled
* by the calling code.
*/
int using_compacted_format(void)
{
return boot_cpu_has(X86_FEATURE_XSAVES);
}
/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
int validate_user_xstate_header(const struct xstate_header *hdr)
{
/* No unknown or supervisor features may be set */
if (hdr->xfeatures & ~xfeatures_mask_user())
return -EINVAL;
/* Userspace must use the uncompacted format */
if (hdr->xcomp_bv)
return -EINVAL;
/*
* If 'reserved' is shrunken to add a new field, make sure to validate
* that new field here!
*/
BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
/* No reserved bits may be set */
if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
return -EINVAL;
return 0;
}
static void __xstate_dump_leaves(void)
{
int i;
u32 eax, ebx, ecx, edx;
static int should_dump = 1;
if (!should_dump)
return;
should_dump = 0;
/*
* Dump out a few leaves past the ones that we support
* just in case there are some goodies up there
*/
for (i = 0; i < XFEATURE_MAX + 10; i++) {
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
XSTATE_CPUID, i, eax, ebx, ecx, edx);
}
}
#define XSTATE_WARN_ON(x) do { \
if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) { \
__xstate_dump_leaves(); \
} \
} while (0)
#define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \
if ((nr == nr_macro) && \
WARN_ONCE(sz != sizeof(__struct), \
"%s: struct is %zu bytes, cpu state %d bytes\n", \
__stringify(nr_macro), sizeof(__struct), sz)) { \
__xstate_dump_leaves(); \
} \
} while (0)
/*
* We have a C struct for each 'xstate'. We need to ensure
* that our software representation matches what the CPU
* tells us about the state's size.
*/
static void check_xstate_against_struct(int nr)
{
/*
* Ask the CPU for the size of the state.
*/
int sz = xfeature_size(nr);
/*
* Match each CPU state with the corresponding software
* structure.
*/
XCHECK_SZ(sz, nr, XFEATURE_YMM, struct ymmh_struct);
XCHECK_SZ(sz, nr, XFEATURE_BNDREGS, struct mpx_bndreg_state);
XCHECK_SZ(sz, nr, XFEATURE_BNDCSR, struct mpx_bndcsr_state);
XCHECK_SZ(sz, nr, XFEATURE_OPMASK, struct avx_512_opmask_state);
XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state);
XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state);
XCHECK_SZ(sz, nr, XFEATURE_PASID, struct ia32_pasid_state);
/*
* Make *SURE* to add any feature numbers in below if
* there are "holes" in the xsave state component
* numbers.
*/
if ((nr < XFEATURE_YMM) ||
(nr >= XFEATURE_MAX) ||
(nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) {
WARN_ONCE(1, "no structure for xstate: %d\n", nr);
XSTATE_WARN_ON(1);
}
}
/*
* This essentially double-checks what the cpu told us about
* how large the XSAVE buffer needs to be. We are recalculating
* it to be safe.
*
* Dynamic XSAVE features allocate their own buffers and are not
* covered by these checks. Only the size of the buffer for task->fpu
* is checked here.
*/
static void do_extra_xstate_size_checks(void)
{
int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
int i;
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (!xfeature_enabled(i))
continue;
check_xstate_against_struct(i);
/*
* Supervisor state components can be managed only by
* XSAVES, which is compacted-format only.
*/
if (!using_compacted_format())
XSTATE_WARN_ON(xfeature_is_supervisor(i));
/* Align from the end of the previous feature */
if (xfeature_is_aligned(i))
paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64);
/*
* The offset of a given state in the non-compacted
* format is given to us in a CPUID leaf. We check
* them for being ordered (increasing offsets) in
* setup_xstate_features().
*/
if (!using_compacted_format())
paranoid_xstate_size = xfeature_uncompacted_offset(i);
/*
* The compacted-format offset always depends on where
* the previous state ended.
*/
paranoid_xstate_size += xfeature_size(i);
}
XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
}
/*
* Get total size of enabled xstates in XCR0 | IA32_XSS.
*
* Note the SDM's wording here. "sub-function 0" only enumerates
* the size of the *user* states. If we use it to size a buffer
* that we use 'XSAVES' on, we could potentially overflow the
* buffer because 'XSAVES' saves system states too.
*/
static unsigned int __init get_xsaves_size(void)
{
unsigned int eax, ebx, ecx, edx;
/*
* - CPUID function 0DH, sub-function 1:
* EBX enumerates the size (in bytes) required by
* the XSAVES instruction for an XSAVE area
* containing all the state components
* corresponding to bits currently set in
* XCR0 | IA32_XSS.
*/
cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
return ebx;
}
/*
* Get the total size of the enabled xstates without the dynamic supervisor
* features.
*/
static unsigned int __init get_xsaves_size_no_dynamic(void)
{
u64 mask = xfeatures_mask_dynamic();
unsigned int size;
if (!mask)
return get_xsaves_size();
/* Disable dynamic features. */
wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
/*
* Ask the hardware what size is required of the buffer.
* This is the size required for the task->fpu buffer.
*/
size = get_xsaves_size();
/* Re-enable dynamic features so XSAVES will work on them again. */
wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
return size;
}
static unsigned int __init get_xsave_size(void)
{
unsigned int eax, ebx, ecx, edx;
/*
* - CPUID function 0DH, sub-function 0:
* EBX enumerates the size (in bytes) required by
* the XSAVE instruction for an XSAVE area
* containing all the *user* state components
* corresponding to bits currently set in XCR0.
*/
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
return ebx;
}
/*
* Will the runtime-enumerated 'xstate_size' fit in the init
* task's statically-allocated buffer?
*/
static bool is_supported_xstate_size(unsigned int test_xstate_size)
{
if (test_xstate_size <= sizeof(union fpregs_state))
return true;
pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
sizeof(union fpregs_state), test_xstate_size);
return false;
}
static int __init init_xstate_size(void)
{
/* Recompute the context size for enabled features: */
unsigned int possible_xstate_size;
unsigned int xsave_size;
xsave_size = get_xsave_size();
if (boot_cpu_has(X86_FEATURE_XSAVES))
possible_xstate_size = get_xsaves_size_no_dynamic();
else
possible_xstate_size = xsave_size;
/* Ensure we have the space to store all enabled: */
if (!is_supported_xstate_size(possible_xstate_size))
return -EINVAL;
/*
* The size is OK, we are definitely going to use xsave,
* make it known to the world that we need more space.
*/
fpu_kernel_xstate_size = possible_xstate_size;
do_extra_xstate_size_checks();
/*
* User space is always in standard format.
*/
fpu_user_xstate_size = xsave_size;
return 0;
}
/*
* We enabled the XSAVE hardware, but something went wrong and
* we can not use it. Disable it.
*/
static void fpu__init_disable_system_xstate(void)
{
xfeatures_mask_all = 0;
cr4_clear_bits(X86_CR4_OSXSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
}
/*
* Enable and initialize the xsave feature.
* Called once per system bootup.
*/
void __init fpu__init_system_xstate(void)
{
unsigned int eax, ebx, ecx, edx;
static int on_boot_cpu __initdata = 1;
int err;
int i;
WARN_ON_FPU(!on_boot_cpu);
on_boot_cpu = 0;
if (!boot_cpu_has(X86_FEATURE_FPU)) {
pr_info("x86/fpu: No FPU detected\n");
return;
}
if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
pr_info("x86/fpu: x87 FPU will use %s\n",
boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
return;
}
if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
WARN_ON_FPU(1);
return;
}
/*
* Find user xstates supported by the processor.
*/
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
xfeatures_mask_all = eax + ((u64)edx << 32);
/*
* Find supervisor xstates supported by the processor.
*/
cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
xfeatures_mask_all |= ecx + ((u64)edx << 32);
if ((xfeatures_mask_user() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
/*
* This indicates that something really unexpected happened
* with the enumeration. Disable XSAVE and try to continue
* booting without it. This is too early to BUG().
*/
pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
xfeatures_mask_all);
goto out_disable;
}
/*
* Clear XSAVE features that are disabled in the normal CPUID.
*/
for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
if (!boot_cpu_has(xsave_cpuid_features[i]))
xfeatures_mask_all &= ~BIT_ULL(i);
}
xfeatures_mask_all &= fpu__get_supported_xfeatures_mask();
/* Enable xstate instructions to be able to continue with initialization: */
fpu__init_cpu_xstate();
err = init_xstate_size();
if (err)
goto out_disable;
/*
* Update info used for ptrace frames; use standard-format size and no
* supervisor xstates:
*/
update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_user());
fpu__init_prepare_fx_sw_frame();
setup_init_fpu_buf();
setup_xstate_comp_offsets();
setup_supervisor_only_offsets();
print_xstate_offset_size();
pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
xfeatures_mask_all,
fpu_kernel_xstate_size,
boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
return;
out_disable:
/* something went wrong, try to boot without any XSAVE support */
fpu__init_disable_system_xstate();
}
/*
* Restore minimal FPU state after suspend:
*/
void fpu__resume_cpu(void)
{
/*
* Restore XCR0 on xsave capable CPUs:
*/
if (boot_cpu_has(X86_FEATURE_XSAVE))
xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
/*
* Restore IA32_XSS. The same CPUID bit enumerates support
* of XSAVES and MSR_IA32_XSS.
*/
if (boot_cpu_has(X86_FEATURE_XSAVES)) {
wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
xfeatures_mask_dynamic());
}
}
/*
* Given an xstate feature nr, calculate where in the xsave
* buffer the state is. Callers should ensure that the buffer
* is valid.
*/
static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
{
if (!xfeature_enabled(xfeature_nr)) {
WARN_ON_FPU(1);
return NULL;
}
return (void *)xsave + xstate_comp_offsets[xfeature_nr];
}
/*
* Given the xsave area and a state inside, this function returns the
* address of the state.
*
* This is the API that is called to get xstate address in either
* standard format or compacted format of xsave area.
*
* Note that if there is no data for the field in the xsave buffer
* this will return NULL.
*
* Inputs:
* xstate: the thread's storage area for all FPU data
* xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
* XFEATURE_SSE, etc...)
* Output:
* address of the state in the xsave area, or NULL if the
* field is not present in the xsave buffer.
*/
void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
{
/*
* Do we even *have* xsave state?
*/
if (!boot_cpu_has(X86_FEATURE_XSAVE))
return NULL;
/*
* We should not ever be requesting features that we
* have not enabled.
*/
WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
"get of unsupported state");
/*
* This assumes the last 'xsave*' instruction to
* have requested that 'xfeature_nr' be saved.
* If it did not, we might be seeing and old value
* of the field in the buffer.
*
* This can happen because the last 'xsave' did not
* request that this feature be saved (unlikely)
* or because the "init optimization" caused it
* to not be saved.
*/
if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
return NULL;
return __raw_xsave_addr(xsave, xfeature_nr);
}
EXPORT_SYMBOL_GPL(get_xsave_addr);
/*
* This wraps up the common operations that need to occur when retrieving
* data from xsave state. It first ensures that the current task was
* using the FPU and retrieves the data in to a buffer. It then calculates
* the offset of the requested field in the buffer.
*
* This function is safe to call whether the FPU is in use or not.
*
* Note that this only works on the current task.
*
* Inputs:
* @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
* XFEATURE_SSE, etc...)
* Output:
* address of the state in the xsave area or NULL if the state
* is not present or is in its 'init state'.
*/
const void *get_xsave_field_ptr(int xfeature_nr)
{
struct fpu *fpu = &current->thread.fpu;
/*
* fpu__save() takes the CPU's xstate registers
* and saves them off to the 'fpu memory buffer.
*/
fpu__save(fpu);
return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
}
#ifdef CONFIG_ARCH_HAS_PKEYS
/*
* This will go out and modify PKRU register to set the access
* rights for @pkey to @init_val.
*/
int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val)
{
u32 old_pkru;
int pkey_shift = (pkey * PKRU_BITS_PER_PKEY);
u32 new_pkru_bits = 0;
/*
* This check implies XSAVE support. OSPKE only gets
* set if we enable XSAVE and we enable PKU in XCR0.
*/
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return -EINVAL;
/*
* This code should only be called with valid 'pkey'
* values originating from in-kernel users. Complain
* if a bad value is observed.
*/
WARN_ON_ONCE(pkey >= arch_max_pkey());
/* Set the bits we need in PKRU: */
if (init_val & PKEY_DISABLE_ACCESS)
new_pkru_bits |= PKRU_AD_BIT;
if (init_val & PKEY_DISABLE_WRITE)
new_pkru_bits |= PKRU_WD_BIT;
/* Shift the bits in to the correct place in PKRU for pkey: */
new_pkru_bits <<= pkey_shift;
/* Get old PKRU and mask off any old bits in place: */
old_pkru = read_pkru();
old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
/* Write old part along with new part: */
write_pkru(old_pkru | new_pkru_bits);
return 0;
}
#endif /* ! CONFIG_ARCH_HAS_PKEYS */
/*
* Weird legacy quirk: SSE and YMM states store information in the
* MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
* area is marked as unused in the xfeatures header, we need to copy
* MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
*/
static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
{
if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
return false;
if (xfeatures & XFEATURE_MASK_FP)
return false;
return true;
}
static void fill_gap(struct membuf *to, unsigned *last, unsigned offset)
{
if (*last >= offset)
return;
membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
*last = offset;
}
static void copy_part(struct membuf *to, unsigned *last, unsigned offset,
unsigned size, void *from)
{
fill_gap(to, last, offset);
membuf_write(to, from, size);
*last = offset + size;
}
/*
* Convert from kernel XSAVES compacted format to standard format and copy
* to a kernel-space ptrace buffer.
*
* It supports partial copy but pos always starts from zero. This is called
* from xstateregs_get() and there we check the CPU has XSAVES.
*/
void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave)
{
struct xstate_header header;
const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
unsigned size = to.left;
unsigned last = 0;
int i;
/*
* The destination is a ptrace buffer; we put in only user xstates:
*/
memset(&header, 0, sizeof(header));
header.xfeatures = xsave->header.xfeatures;
header.xfeatures &= xfeatures_mask_user();
if (header.xfeatures & XFEATURE_MASK_FP)
copy_part(&to, &last, 0, off_mxcsr, &xsave->i387);
if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
copy_part(&to, &last, off_mxcsr,
MXCSR_AND_FLAGS_SIZE, &xsave->i387.mxcsr);
if (header.xfeatures & XFEATURE_MASK_FP)
copy_part(&to, &last, offsetof(struct fxregs_state, st_space),
128, &xsave->i387.st_space);
if (header.xfeatures & XFEATURE_MASK_SSE)
copy_part(&to, &last, xstate_offsets[XFEATURE_SSE],
256, &xsave->i387.xmm_space);
/*
* Fill xsave->i387.sw_reserved value for ptrace frame:
*/
copy_part(&to, &last, offsetof(struct fxregs_state, sw_reserved),
48, xstate_fx_sw_bytes);
/*
* Copy xregs_state->header:
*/
copy_part(&to, &last, offsetof(struct xregs_state, header),
sizeof(header), &header);
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
/*
* Copy only in-use xstates:
*/
if ((header.xfeatures >> i) & 1) {
void *src = __raw_xsave_addr(xsave, i);
copy_part(&to, &last, xstate_offsets[i],
xstate_sizes[i], src);
}
}
fill_gap(&to, &last, size);
}
/*
* Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
* and copy to the target thread. This is called from xstateregs_set().
*/
int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
{
unsigned int offset, size;
int i;
struct xstate_header hdr;
offset = offsetof(struct xregs_state, header);
size = sizeof(hdr);
memcpy(&hdr, kbuf + offset, size);
if (validate_user_xstate_header(&hdr))
return -EINVAL;
for (i = 0; i < XFEATURE_MAX; i++) {
u64 mask = ((u64)1 << i);
if (hdr.xfeatures & mask) {
void *dst = __raw_xsave_addr(xsave, i);
offset = xstate_offsets[i];
size = xstate_sizes[i];
memcpy(dst, kbuf + offset, size);
}
}
if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
offset = offsetof(struct fxregs_state, mxcsr);
size = MXCSR_AND_FLAGS_SIZE;
memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
}
/*
* The state that came in from userspace was user-state only.
* Mask all the user states out of 'xfeatures':
*/
xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
/*
* Add back in the features that came in from userspace:
*/
xsave->header.xfeatures |= hdr.xfeatures;
return 0;
}
/*
* Convert from a ptrace or sigreturn standard-format user-space buffer to
* kernel XSAVES format and copy to the target thread. This is called from
* xstateregs_set(), as well as potentially from the sigreturn() and
* rt_sigreturn() system calls.
*/
int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
{
unsigned int offset, size;
int i;
struct xstate_header hdr;
offset = offsetof(struct xregs_state, header);
size = sizeof(hdr);
if (__copy_from_user(&hdr, ubuf + offset, size))
return -EFAULT;
if (validate_user_xstate_header(&hdr))
return -EINVAL;
for (i = 0; i < XFEATURE_MAX; i++) {
u64 mask = ((u64)1 << i);
if (hdr.xfeatures & mask) {
void *dst = __raw_xsave_addr(xsave, i);
offset = xstate_offsets[i];
size = xstate_sizes[i];
if (__copy_from_user(dst, ubuf + offset, size))
return -EFAULT;
}
}
if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
offset = offsetof(struct fxregs_state, mxcsr);
size = MXCSR_AND_FLAGS_SIZE;
if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
return -EFAULT;
}
/*
* The state that came in from userspace was user-state only.
* Mask all the user states out of 'xfeatures':
*/
xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
/*
* Add back in the features that came in from userspace:
*/
xsave->header.xfeatures |= hdr.xfeatures;
return 0;
}
/*
* Save only supervisor states to the kernel buffer. This blows away all
* old states, and is intended to be used only in __fpu__restore_sig(), where
* user states are restored from the user buffer.
*/
void copy_supervisor_to_kernel(struct xregs_state *xstate)
{
struct xstate_header *header;
u64 max_bit, min_bit;
u32 lmask, hmask;
int err, i;
if (WARN_ON(!boot_cpu_has(X86_FEATURE_XSAVES)))
return;
if (!xfeatures_mask_supervisor())
return;
max_bit = __fls(xfeatures_mask_supervisor());
min_bit = __ffs(xfeatures_mask_supervisor());
lmask = xfeatures_mask_supervisor();
hmask = xfeatures_mask_supervisor() >> 32;
XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
/* We should never fault when copying to a kernel buffer: */
if (WARN_ON_FPU(err))
return;
/*
* At this point, the buffer has only supervisor states and must be
* converted back to normal kernel format.
*/
header = &xstate->header;
header->xcomp_bv |= xfeatures_mask_all;
/*
* This only moves states up in the buffer. Start with
* the last state and move backwards so that states are
* not overwritten until after they are moved. Note:
* memmove() allows overlapping src/dst buffers.
*/
for (i = max_bit; i >= min_bit; i--) {
u8 *xbuf = (u8 *)xstate;
if (!((header->xfeatures >> i) & 1))
continue;
/* Move xfeature 'i' into its normal location */
memmove(xbuf + xstate_comp_offsets[i],
xbuf + xstate_supervisor_only_offsets[i],
xstate_sizes[i]);
}
}
/**
* copy_dynamic_supervisor_to_kernel() - Save dynamic supervisor states to
* an xsave area
* @xstate: A pointer to an xsave area
* @mask: Represent the dynamic supervisor features saved into the xsave area
*
* Only the dynamic supervisor states sets in the mask are saved into the xsave
* area (See the comment in XFEATURE_MASK_DYNAMIC for the details of dynamic
* supervisor feature). Besides the dynamic supervisor states, the legacy
* region and XSAVE header are also saved into the xsave area. The supervisor
* features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
* XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not saved.
*
* The xsave area must be 64-bytes aligned.
*/
void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask)
{
u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
u32 lmask, hmask;
int err;
if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES)))
return;
if (WARN_ON_FPU(!dynamic_mask))
return;
lmask = dynamic_mask;
hmask = dynamic_mask >> 32;
XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
/* Should never fault when copying to a kernel buffer */
WARN_ON_FPU(err);
}
/**
* copy_kernel_to_dynamic_supervisor() - Restore dynamic supervisor states from
* an xsave area
* @xstate: A pointer to an xsave area
* @mask: Represent the dynamic supervisor features restored from the xsave area
*
* Only the dynamic supervisor states sets in the mask are restored from the
* xsave area (See the comment in XFEATURE_MASK_DYNAMIC for the details of
* dynamic supervisor feature). Besides the dynamic supervisor states, the
* legacy region and XSAVE header are also restored from the xsave area. The
* supervisor features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
* XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not restored.
*
* The xsave area must be 64-bytes aligned.
*/
void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask)
{
u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
u32 lmask, hmask;
int err;
if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES)))
return;
if (WARN_ON_FPU(!dynamic_mask))
return;
lmask = dynamic_mask;
hmask = dynamic_mask >> 32;
XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
/* Should never fault when copying from a kernel buffer */
WARN_ON_FPU(err);
}
#ifdef CONFIG_PROC_PID_ARCH_STATUS
/*
* Report the amount of time elapsed in millisecond since last AVX512
* use in the task.
*/
static void avx512_status(struct seq_file *m, struct task_struct *task)
{
unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
long delta;
if (!timestamp) {
/*
* Report -1 if no AVX512 usage
*/
delta = -1;
} else {
delta = (long)(jiffies - timestamp);
/*
* Cap to LONG_MAX if time difference > LONG_MAX
*/
if (delta < 0)
delta = LONG_MAX;
delta = jiffies_to_msecs(delta);
}
seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
seq_putc(m, '\n');
}
/*
* Report architecture specific information
*/
int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
/*
* Report AVX512 state if the processor and build option supported.
*/
if (cpu_feature_enabled(X86_FEATURE_AVX512F))
avx512_status(m, task);
return 0;
}
#endif /* CONFIG_PROC_PID_ARCH_STATUS */
#ifdef CONFIG_IOMMU_SUPPORT
void update_pasid(void)
{
u64 pasid_state;
u32 pasid;
if (!cpu_feature_enabled(X86_FEATURE_ENQCMD))
return;
if (!current->mm)
return;
pasid = READ_ONCE(current->mm->pasid);
/* Set the valid bit in the PASID MSR/state only for valid pasid. */
pasid_state = pasid == PASID_DISABLED ?
pasid : pasid | MSR_IA32_PASID_VALID;
/*
* No need to hold fregs_lock() since the task's fpstate won't
* be changed by others (e.g. ptrace) while the task is being
* switched to or is in IPI.
*/
if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
/* The MSR is active and can be directly updated. */
wrmsrl(MSR_IA32_PASID, pasid_state);
} else {
struct fpu *fpu = &current->thread.fpu;
struct ia32_pasid_state *ppasid_state;
struct xregs_state *xsave;
/*
* The CPU's xstate registers are not currently active. Just
* update the PASID state in the memory buffer here. The
* PASID MSR will be loaded when returning to user mode.
*/
xsave = &fpu->state.xsave;
xsave->header.xfeatures |= XFEATURE_MASK_PASID;
ppasid_state = get_xsave_addr(xsave, XFEATURE_PASID);
/*
* Since XFEATURE_MASK_PASID is set in xfeatures, ppasid_state
* won't be NULL and no need to check its value.
*
* Only update the task's PASID state when it's different
* from the mm's pasid.
*/
if (ppasid_state->pasid != pasid_state) {
/*
* Invalid fpregs so that state restoring will pick up
* the PASID state.
*/
__fpu_invalidate_fpregs_state(fpu);
ppasid_state->pasid = pasid_state;
}
}
}
#endif /* CONFIG_IOMMU_SUPPORT */