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x86/split-lock: Avoid returning with interrupts enabled

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commit e14fd4ba8fb47fcf5f244366ec01ae94490cd86a upstream.

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: ca4c6a9858 ("x86/traps: Make interrupt enable/disable symmetric in C code")
Fixes: bce9b042ec ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andi Kleen
2020-12-22 09:40:10 -08:00
committed by Greg Kroah-Hartman
parent eadec7f537
commit 84bcbb0779
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kernel/traps.c
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@@ -299,11 +299,12 @@ 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();
}