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Groups > linux.kernel > #1214728
| From | Dave Hansen <dave@sr71.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 11/11] x86, fpu: check CPU-provided sizes against struct declarations |
| Date | 2015-08-27 19:20 +0200 |
| Message-ID | <q290g-2v7-41@gated-at.bofh.it> (permalink) |
| References | <q290d-2v7-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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 | 53 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 53 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 2015-08-27 10:08:05.023791536 -0700
+++ b/arch/x86/kernel/fpu/xstate.c 2015-08-27 10:08:05.027791718 -0700
@@ -409,6 +409,49 @@ 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 %ld 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_NR_YMM, struct ymmh_struct);
+ XCHECK_SZ(sz, nr, XFEATURE_NR_BNDREGS, struct mpx_bndreg_state);
+ XCHECK_SZ(sz, nr, XFEATURE_NR_BNDCSR, struct mpx_bndcsr_state);
+ XCHECK_SZ(sz, nr, XFEATURE_NR_OPMASK, struct avx_512_opmask_state);
+ XCHECK_SZ(sz, nr, XFEATURE_NR_ZMM_Hi256, struct avx_512_zmm_uppers_state);
+ XCHECK_SZ(sz, nr, XFEATURE_NR_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_NR_YMM) ||
+ (nr >= XFEATURES_NR_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
@@ -422,6 +465,8 @@ static void do_extra_xstate_size_checks(
for (i = FIRST_EXTENDED_XFEATURE_NR; i < XFEATURES_NR_MAX; i++) {
if (!xfeature_nr_enabled(i))
continue;
+
+ check_xstate_against_struct(i);
/*
* Supervisor state components can be managed only by
* XSAVES, which is compacted-format only.
@@ -447,6 +492,14 @@ static void do_extra_xstate_size_checks(
paranoid_xstate_size += xfeature_size(i);
}
XSTATE_WARN_ON(paranoid_xstate_size != xstate_size);
+ /*
+ * Basically, make sure that XSTATE_RESERVE has forced
+ * xregs_state to be large enough. This is not fatal
+ * because we reserve a *lot* of extra room in the init
+ * task struct, but we should at least know we got it
+ * wrong.
+ */
+ XSTATE_WARN_ON(xstate_size > sizeof(struct xregs_state));
}
/*
_
--
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[PATCH 00/11] [v2] x86, fpu: XSAVE cleanups and sanity checks Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
[PATCH 06/11] x86, fpu: rework MPX 'xstate' types Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
[PATCH 04/11] x86, fpu: remove xfeature_nr Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 04/11] x86, fpu: remove xfeature_nr Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:10 +0200
[PATCH 01/11] x86, fpu: kill LWP support Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 01/11] x86, fpu: kill LWP support Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:00 +0200
[PATCH 07/11] x86, fpu: rework YMM definition Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
[PATCH 09/11] x86, fpu: correct and check XSAVE xstate size calculations Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 09/11] x86, fpu: correct and check XSAVE xstate size calculations Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:00 +0200
Re: [PATCH 09/11] x86, fpu: correct and check XSAVE xstate size calculations Dave Hansen <dave@sr71.net> - 2015-08-28 16:40 +0200
Re: [PATCH 09/11] x86, fpu: correct and check XSAVE xstate size calculations Andi Kleen <andi@firstfloor.org> - 2015-08-28 18:50 +0200
[PATCH 10/11] x86, fpu: check to ensure increasing-offset xstate offsets Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
[PATCH 08/11] x86, fpu: add C structures for AVX-512 state components Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 08/11] x86, fpu: add C structures for AVX-512 state components Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:10 +0200
[PATCH 11/11] x86, fpu: check CPU-provided sizes against struct declarations Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 11/11] x86, fpu: check CPU-provided sizes against struct declarations Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:30 +0200
Re: [PATCH 11/11] x86, fpu: check CPU-provided sizes against struct declarations Dave Hansen <dave@sr71.net> - 2015-08-28 18:10 +0200
[PATCH 05/11] x86, fpu: add helper xfeature_nr_enabled() instead of test_bit() Dave Hansen <dave@sr71.net> - 2015-08-27 19:20 +0200
Re: [PATCH 05/11] x86, fpu: add helper xfeature_nr_enabled() instead of test_bit() Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:10 +0200
Re: [PATCH 00/11] [v2] x86, fpu: XSAVE cleanups and sanity checks Ingo Molnar <mingo@kernel.org> - 2015-08-28 07:20 +0200
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