From: Nicholas Piggin npiggin@gmail.com
commit 4a5cb51f3db4be547225a4bce7a43d41b231382b upstream.
The check_return_regs_valid() can cause a false positive if the return regs are marked as norestart and they are an HSRR type interrupt, because the low bit in the bottom of regs->trap causes interrupt type matching to fail.
This can occcur for example on bare metal with a HV privileged doorbell interrupt that causes a signal, but do_signal returns early because get_signal() fails, and takes the "No signal to deliver" path. In this case no signal was delivered so the return location is not changed so return SRRs are not invalidated, yet set_trap_norestart is called, which messes up the match. Building go-1.16.6 is known to reproduce this.
Fix it by using the TRAP() accessor which masks out the low bit.
Fixes: 6eaaf9de3599 ("powerpc/64s/interrupt: Check and fix srr_valid without crashing") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20211026122531.3599918-1-npiggin@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kernel/interrupt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -268,7 +268,7 @@ static void check_return_regs_valid(stru if (trap_is_scv(regs)) return;
- trap = regs->trap; + trap = TRAP(regs); // EE in HV mode sets HSRRs like 0xea0 if (cpu_has_feature(CPU_FTR_HVMODE) && trap == INTERRUPT_EXTERNAL) trap = 0xea0;