Commit-ID: ef78f2a4bf84d8db9f36868decca2dc24e02a6af
Gitweb: http://git.kernel.org/tip/ef78f2a4bf84d8db9f36868decca2dc24e02a6af
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 2 Sep 2015 16:31:31 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 14 Sep 2015 12:22:02 +0200
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@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Cc: dave@xxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20150902233131.A8DB36DA@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/fpu/xstate.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index a8297f2..6454f27 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -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.
--
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