From: Andi Kleen <[email protected]>
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: 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 <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Tony Luck <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kernel/traps.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -299,11 +299,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_
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();
}
