From: Andi Kleen ak@linux.intel.com
stable inclusion from stable-5.10.3 commit 84bcbb0779c6a062e51c84abaca356f79be1abeb bugzilla: 46871
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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: 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Signed-off-by: Chen Jun chenjun102@huawei.com --- arch/x86/kernel/traps.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e19df6cde35d..170c94ec0068 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -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(); }