Commit-ID: ef78f2a4bf84d8db9f36868decca2dc24e02a6af Gitweb: http://git.kernel.org/tip/ef78f2a4bf84d8db9f36868decca2dc24e02a6af Author: Dave Hansen <dave.han...@linux.intel.com> AuthorDate: Wed, 2 Sep 2015 16:31:31 -0700 Committer: Ingo Molnar <mi...@kernel.org> 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.han...@linux.intel.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Fenghua Yu <fenghua...@intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Tim Chen <tim.c.c...@linux.intel.com> Cc: d...@sr71.net Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20150902233131.a8db3...@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/