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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:
 "Three changes: fix a race that can result in FPU corruption, plus two
  cleanups"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Deactivate FPU state after failure during state load
  x86/fpu/xstate: Make xfeature_is_supervisor()/xfeature_is_user() return bool
  x86/fpu/xstate: Fix small issues
This commit is contained in:
Linus Torvalds 2020-01-28 13:04:38 -08:00
parent c0275ae758 bbc55341b9
commit 4d6245ce8c
2 changed files with 11 additions and 10 deletions
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3
arch/x86/kernel/fpu/signal.c
View File

@ -352,6 +352,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
fpregs_unlock();
return 0;
}
fpregs_deactivate(fpu);
fpregs_unlock();
}
@ -403,6 +404,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
}
if (!ret)
fpregs_mark_activate();
else
fpregs_deactivate(fpu);
fpregs_unlock();
err_out:

18
arch/x86/kernel/fpu/xstate.c
View File

@ -107,23 +107,20 @@ int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
}
EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
static int xfeature_is_supervisor(int xfeature_nr)
static bool xfeature_is_supervisor(int xfeature_nr)
{
/*
* We currently do not support supervisor states, but if
* we did, we could find out like this.
*
* SDM says: If state component 'i' is a user state component,
* ECX[0] return 0; if state component i is a supervisor
* state component, ECX[0] returns 1.
* 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);
return ecx & 1;
}
static int xfeature_is_user(int xfeature_nr)
static bool xfeature_is_user(int xfeature_nr)
{
return !xfeature_is_supervisor(xfeature_nr);
}
@ -419,7 +416,8 @@ static void __init setup_init_fpu_buf(void)
print_xstate_features();
if (boot_cpu_has(X86_FEATURE_XSAVES))
init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask;
init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
xfeatures_mask;
/*
* Init all the features state with header.xfeatures being 0x0