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authorAndi Kleen <ak@linux.intel.com>2020-12-22 20:40:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-23 00:06:10 +0300
commite14fd4ba8fb47fcf5f244366ec01ae94490cd86a (patch)
treea80fd68c5097cb09c264c13515655362b40da9c5
parent8653b778e454a7708847aeafe689bce07aeeb94e (diff)
downloadlinux-e14fd4ba8fb47fcf5f244366ec01ae94490cd86a.tar.xz
x86/split-lock: Avoid returning with interrupts enabled
When a split lock is detected always make sure to disable interrupts before returning from the trap handler. The kernel exit code assumes that all exits run with interrupts disabled, otherwise the SWAPGS sequence can race against interrupts and cause recursing page faults and later panics. The problem will only happen on CPUs with split lock disable functionality, so Icelake Server, Tiger Lake, Snow Ridge, Jacobsville. Fixes: ca4c6a9858c2 ("x86/traps: Make interrupt enable/disable symmetric in C code") Fixes: bce9b042ec73 ("x86/traps: Disable interrupts in exc_aligment_check()") # v5.8+ Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/kernel/traps.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index fb55981f2a0d..7f5aec758f0e 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -303,11 +303,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check)
local_irq_enable();
if (handle_user_split_lock(regs, error_code))
- return;
+ goto out;
do_trap(X86_TRAP_AC, SIGBUS, "alignment check", regs,
error_code, BUS_ADRALN, NULL);
+out:
local_irq_disable();
}