Messages in this thread Patch in this message | | | Subject | [PATCH 15/15] x86, fpu: check CPU-provided sizes against struct declarations | From | Dave Hansen <> | Date | Wed, 02 Sep 2015 16:31:31 -0700 |
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From: Dave Hansen <dave.hansen@linux.intel.com>
Changes from v2: * remove XSTATE_RESERVED check, since it is gone now
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From: Dave Hansen <dave.hansen@linux.intel.com>
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: Ingo Molnar <mingo@redhat.com> Cc: x86@kernel.org Cc: Borislav Petkov <bp@alien8.de> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: linux-kernel@vger.kernel.org ---
b/arch/x86/kernel/fpu/xstate.c | 45 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+)
diff -puN arch/x86/kernel/fpu/xstate.c~x86-fpu-check-against-struct-declarations arch/x86/kernel/fpu/xstate.c --- a/arch/x86/kernel/fpu/xstate.c~x86-fpu-check-against-struct-declarations 2015-09-02 16:26:46.232419598 -0700 +++ b/arch/x86/kernel/fpu/xstate.c 2015-09-02 16:26:46.236419780 -0700 @@ -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( 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. _
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