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authorPeter Zijlstra <peterz@infradead.org>2020-09-02 16:25:50 +0300
committerThomas Gleixner <tglx@linutronix.de>2020-09-04 16:09:29 +0300
commit662a0221893a3d58aa72719671844264306f6e4b (patch)
tree8e261b7b2011e4e669c066528dc8aba50a715960 /arch
parent2356bb4b8221d7dc8c7beb810418122ed90254c9 (diff)
downloadlinux-662a0221893a3d58aa72719671844264306f6e4b.tar.xz
x86/entry: Fix AC assertion
The WARN added in commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") unconditionally triggers on a IVB machine because it does not support SMAP. For !SMAP hardware the CLAC/STAC instructions are patched out and thus if userspace sets AC, it is still have set after entry. Fixes: 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Daniel Thompson <daniel.thompson@linaro.org> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200902133200.666781610@infradead.org
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/entry-common.h12
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86/include/asm/entry-common.h b/arch/x86/include/asm/entry-common.h
index a8f9315b9eae..6fe54b2813c1 100644
--- a/arch/x86/include/asm/entry-common.h
+++ b/arch/x86/include/asm/entry-common.h
@@ -18,8 +18,16 @@ static __always_inline void arch_check_user_regs(struct pt_regs *regs)
* state, not the interrupt state as imagined by Xen.
*/
unsigned long flags = native_save_fl();
- WARN_ON_ONCE(flags & (X86_EFLAGS_AC | X86_EFLAGS_DF |
- X86_EFLAGS_NT));
+ unsigned long mask = X86_EFLAGS_DF | X86_EFLAGS_NT;
+
+ /*
+ * For !SMAP hardware we patch out CLAC on entry.
+ */
+ if (boot_cpu_has(X86_FEATURE_SMAP) ||
+ (IS_ENABLED(CONFIG_64_BIT) && boot_cpu_has(X86_FEATURE_XENPV)))
+ mask |= X86_EFLAGS_AC;
+
+ WARN_ON_ONCE(flags & mask);
/* We think we came from user mode. Make sure pt_regs agrees. */
WARN_ON_ONCE(!user_mode(regs));