If a system call is made with a transaction active, the kernel
immediately aborts it and returns. scv system calls disable irqs even
earlier in their interrupt handler, and tabort_syscall does not fix this
up.
This can result in irq soft-mask state being messed up on the next
kernel entry, and crashing at BUG_ON(arch_irq_disabled_regs(regs)) in
the kernel exit handlers, or possibly worse.
Fix this by having tabort_syscall setting irq soft-mask back to enabled.
Reported-by: Eirik Fuller <eful...@redhat.com>
Fixes: 7fa95f9adaee7 ("powerpc/64s: system call support for scv/rfscv
instructions")
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/interrupt_64.S | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/interrupt_64.S
b/arch/powerpc/kernel/interrupt_64.S
index d4212d2ff0b5..44f99df36fb2 100644
--- a/arch/powerpc/kernel/interrupt_64.S
+++ b/arch/powerpc/kernel/interrupt_64.S
@@ -438,6 +438,10 @@ _ASM_NOKPROBE_SYMBOL(tabort_syscall)
li r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
TABORT(R9)
+ /* scv has disabled irqs so must re-enable. sc just remains enabled */
+ li r9,IRQS_ENABLED
+ stb r9,PACAIRQSOFTMASK(r13)
+
/*
* Return directly to userspace. We have corrupted user register state,
* but userspace will never see that register state. Execution will
--
2.23.0
