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x86/fpu: Check CPU-provided sizes against struct declarations 

We now have C structures defined for each of the XSAVE state
components that we support.  This patch adds checks during our
verification pass to ensure that the CPU-provided data
enumerated in CPUID leaves matches our C structures.

If not, we warn and dump all the XSAVE CPUID leaves.

Note: this *actually* found an inconsistency with the MPX
'bndcsr' state.  The hardware pads it out differently from
our C structures.  This patch caught it and warned.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: dave@sr71.net
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150902233131.A8DB36DA@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dave Hansen 2015-09-02 16:31:31 -07:00 committed by Ingo Molnar
parent e6e888f96b
commit ef78f2a4bf
1 changed files with 45 additions and 0 deletions
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45
arch/x86/kernel/fpu/xstate.c
View File

@ -432,6 +432,49 @@ static void __xstate_dump_leaves(void)
} \
} 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);
/*
* 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)) {
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
@ -445,6 +488,8 @@ static void do_extra_xstate_size_checks(void)
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.