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Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fpu updates from Ingo Molnar:
 "Misc changes:

   - add a pkey sanity check

   - three commits to improve and future-proof xstate/xfeature handling
     some more"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pkeys: Add check for pkey "overflow"
  x86/fpu/xstate: Warn when checking alignment of disabled xfeatures
  x86/fpu/xstate: Fix XSAVES offsets in setup_xstate_comp()
  x86/fpu/xstate: Fix last_good_offset in setup_xstate_features()
This commit is contained in:
Linus Torvalds 2020-03-31 11:26:22 -07:00
parent fdf5563a72 16171bffc8
commit d0be2d53c7
2 changed files with 46 additions and 38 deletions
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5
arch/x86/include/asm/pkeys.h
View File

@ -4,6 +4,11 @@
#define ARCH_DEFAULT_PKEY 0
/*
* If more than 16 keys are ever supported, a thorough audit
* will be necessary to ensure that the types that store key
* numbers and masks have sufficient capacity.
*/
#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,

79
arch/x86/kernel/fpu/xstate.c
View File

@ -120,11 +120,6 @@ static bool xfeature_is_supervisor(int xfeature_nr)
return ecx & 1;
}
static bool xfeature_is_user(int xfeature_nr)
{
return !xfeature_is_supervisor(xfeature_nr);
}
/*
* When executing XSAVEOPT (or other optimized XSAVE instructions), if
* a processor implementation detects that an FPU state component is still
@ -265,21 +260,25 @@ static void __init setup_xstate_features(void)
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
/*
* If an xfeature is supervisor state, the offset
* in EBX is invalid. We leave it to -1.
*/
if (xfeature_is_user(i))
xstate_offsets[i] = ebx;
xstate_sizes[i] = eax;
/*
* In our xstate size checks, we assume that the
* highest-numbered xstate feature has the
* highest offset in the buffer. Ensure it does.
* 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);
"x86/fpu: misordered xstate at %d\n", last_good_offset);
last_good_offset = xstate_offsets[i];
}
}
@ -326,6 +325,13 @@ 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
@ -338,11 +344,11 @@ static int xfeature_is_aligned(int xfeature_nr)
/*
* 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 aread.
* of the xsave area.
*/
static void __init setup_xstate_comp(void)
static void __init setup_xstate_comp_offsets(void)
{
unsigned int xstate_comp_sizes[XFEATURE_MAX];
unsigned int next_offset;
int i;
/*
@ -356,31 +362,23 @@ static void __init setup_xstate_comp(void)
if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (xfeature_enabled(i)) {
if (xfeature_enabled(i))
xstate_comp_offsets[i] = xstate_offsets[i];
xstate_comp_sizes[i] = xstate_sizes[i];
}
}
return;
}
xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
FXSAVE_SIZE + XSAVE_HDR_SIZE;
next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
if (xfeature_enabled(i))
xstate_comp_sizes[i] = xstate_sizes[i];
else
xstate_comp_sizes[i] = 0;
if (!xfeature_enabled(i))
continue;
if (i > FIRST_EXTENDED_XFEATURE) {
xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
+ xstate_comp_sizes[i-1];
if (xfeature_is_aligned(i))
next_offset = ALIGN(next_offset, 64);
if (xfeature_is_aligned(i))
xstate_comp_offsets[i] =
ALIGN(xstate_comp_offsets[i], 64);
}
xstate_comp_offsets[i] = next_offset;
next_offset += xstate_sizes[i];
}
}
@ -774,7 +772,7 @@ void __init fpu__init_system_xstate(void)
fpu__init_prepare_fx_sw_frame();
setup_init_fpu_buf();
setup_xstate_comp();
setup_xstate_comp_offsets();
print_xstate_offset_size();
pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
@ -897,8 +895,6 @@ const void *get_xsave_field_ptr(int xfeature_nr)
#ifdef CONFIG_ARCH_HAS_PKEYS
#define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2)
#define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1)
/*
* This will go out and modify PKRU register to set the access
* rights for @pkey to @init_val.
@ -917,6 +913,13 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
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;