[PATCH 4.9 3/8] arm64: fix for bad_mode() handler to always result in panic

Lee Jones
2019-11-22T10:53:32Z

From: Hari Vyas <hari.vyas@broadcom.com>

[ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ]

The bad_mode() handler is called if we encounter an uunknown exception,
with the expectation that the subsequent call to panic() will halt the
system. Unfortunately, if the exception calling bad_mode() is taken from
EL0, then the call to die() can end up killing the current user task and
calling schedule() instead of falling through to panic().

Remove the die() call altogether, since we really want to bring down the
machine in this "impossible" case.

Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
arch/arm64/kernel/traps.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 28bef94cf792..5962badb3346 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -611,7 +611,6 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
handler[reason], smp_processor_id(), esr,
esr_get_class_string(esr));

- die("Oops - bad mode", regs, 0);
local_irq_disable();
panic("bad mode");
}
--
2.24.0