From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive
Date: Tue, 26 Oct 2021 22:25:31 +1000 [thread overview]
Message-ID: <20211026122531.3599918-1-npiggin@gmail.com> (raw)
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
next reply other threads:[~2021-10-26 12:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 12:25 Nicholas Piggin [this message]
2021-11-02 10:11 ` [PATCH v1] powerpc/64s/interrupt: Fix check_return_regs_valid false positive Michael Ellerman
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