* [PATCH v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive
@ 2021-10-26 12:25 Nicholas Piggin
2021-11-02 10:11 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Nicholas Piggin @ 2021-10-26 12:25 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Nicholas Piggin
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(-)
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;
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive
2021-10-26 12:25 [PATCH v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive Nicholas Piggin
@ 2021-11-02 10:11 ` Michael Ellerman
0 siblings, 0 replies; 2+ messages in thread
From: Michael Ellerman @ 2021-11-02 10:11 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
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
^ permalink raw reply [flat|nested] 2+ messages in thread
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