| From dffba9a31c7769be3231c420d4b364c92ba3f1ac Mon Sep 17 00:00:00 2001 |
| From: Yu-cheng Yu <yu-cheng.yu@intel.com> |
| Date: Mon, 23 Jan 2017 14:54:44 -0800 |
| Subject: [PATCH] x86/fpu/xstate: Fix xcomp_bv in XSAVES header |
| |
| commit dffba9a31c7769be3231c420d4b364c92ba3f1ac upstream. |
| |
| The compacted-format XSAVES area is determined at boot time and |
| never changed after. The field xsave.header.xcomp_bv indicates |
| which components are in the fixed XSAVES format. |
| |
| In fpstate_init() we did not set xcomp_bv to reflect the XSAVES |
| format since at the time there is no valid data. |
| |
| However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(), |
| as in commit: |
| |
| b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve() |
| |
| and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode |
| app, a #GP occurs. This can be easily triggered by doing valgrind on |
| a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and |
| others: |
| |
| https://bugzilla.kernel.org/show_bug.cgi?id=190061 |
| |
| Fix it by setting xcomp_bv correctly. |
| |
| This patch also moves the xcomp_bv initialization to the proper |
| place, which was in copyin_to_xsaves() as of: |
| |
| 4c833368f0bf x86/fpu: Set the xcomp_bv when we fake up a XSAVES area |
| |
| which fixed the bug too, but it's more efficient and cleaner to |
| initialize things once per boot, not for every signal handling |
| operation. |
| |
| Reported-by: Kevin Hao <haokexin@gmail.com> |
| Reported-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com> |
| Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> |
| Cc: Andy Lutomirski <luto@kernel.org> |
| Cc: Borislav Petkov <bp@suse.de> |
| Cc: Dave Hansen <dave.hansen@linux.intel.com> |
| Cc: Fenghua Yu <fenghua.yu@intel.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: haokexin@gmail.com |
| Link: http://lkml.kernel.org/r/1485212084-4418-1-git-send-email-yu-cheng.yu@intel.com |
| [ Combined it with 4c833368f0bf. ] |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| |
| diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c |
| index e4e97a5355ce..de7234401275 100644 |
| --- a/arch/x86/kernel/fpu/core.c |
| +++ b/arch/x86/kernel/fpu/core.c |
| @@ -9,6 +9,7 @@ |
| #include <asm/fpu/regset.h> |
| #include <asm/fpu/signal.h> |
| #include <asm/fpu/types.h> |
| +#include <asm/fpu/xstate.h> |
| #include <asm/traps.h> |
| |
| #include <linux/hardirq.h> |
| @@ -183,7 +184,8 @@ void fpstate_init(union fpregs_state *state) |
| * it will #GP. Make sure it is replaced after the memset(). |
| */ |
| if (static_cpu_has(X86_FEATURE_XSAVES)) |
| - state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT; |
| + state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | |
| + xfeatures_mask; |
| |
| if (static_cpu_has(X86_FEATURE_FXSR)) |
| fpstate_init_fxstate(&state->fxsave); |
| diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c |
| index e287b9075527..1d7770447b3e 100644 |
| --- a/arch/x86/kernel/fpu/xstate.c |
| +++ b/arch/x86/kernel/fpu/xstate.c |
| @@ -1070,7 +1070,6 @@ int copyin_to_xsaves(const void *kbuf, const void __user *ubuf, |
| * Add back in the features that came in from userspace: |
| */ |
| xsave->header.xfeatures |= xfeatures; |
| - xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xsave->header.xfeatures; |
| |
| return 0; |
| } |
| -- |
| 2.12.0 |
| |