riscv: Avoid enabling interrupts in die()

[ Upstream commit 130aee3fd9981297ff9354e5d5609cd59aafbbea ]

While working on something else, I noticed that the kernel would start
accepting interrupts again after crashing in an interrupt handler. Since
the kernel is already in inconsistent state, enabling interrupts is
dangerous and opens up risk of kernel state deteriorating further.
Interrupts do get enabled via what looks like an unintended side effect of
spin_unlock_irq, so switch to the more cautious
spin_lock_irqsave/spin_unlock_irqrestore instead.

Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code")
Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20230215144828.3370316-1-mnissler@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 502cba5029ca4b4f38e310e1437fb47e4ca6b742..4f38b3c47e6d53fea9ad90ec89c17a3c8d5844c4 100644 (file)
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -34,10 +34,11 @@ void die(struct pt_regs *regs, const char *str)
        static int die_counter;
        int ret;
        long cause;
+       unsigned long flags;
 
        oops_enter();
 
-       spin_lock_irq(&die_lock);
+       spin_lock_irqsave(&die_lock, flags);
        console_verbose();
        bust_spinlocks(1);
 
@@ -54,7 +55,7 @@ void die(struct pt_regs *regs, const char *str)
 
        bust_spinlocks(0);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-       spin_unlock_irq(&die_lock);
+       spin_unlock_irqrestore(&die_lock, flags);
        oops_exit();
 
        if (in_interrupt())