| Message ID | 20211026122531.3599918-1-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
On Tue, 26 Oct 2021 22:25:31 +1000, Nicholas Piggin wrote: > 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. > > [...] Applied to powerpc/next. [1/1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive https://git.kernel.org/powerpc/c/4a5cb51f3db4be547225a4bce7a43d41b231382b cheers
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index de10a2697258..835b626cd476 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -266,7 +266,7 @@ static void check_return_regs_valid(struct pt_regs *regs) 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;
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") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/interrupt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)