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authorVincent Chen <vincent.chen@sifive.com>2019-09-16 11:47:41 +0300
committerPaul Walmsley <paul.walmsley@sifive.com>2019-09-20 18:42:34 +0300
commitc82dd6d078a2bb29d41eda032bb96d05699a524d (patch)
tree8d923bcab717fdd68ed371707b9c0ac58c7e5898
parentc81007116bd23e9e2103c267184dc38d3acc1099 (diff)
downloadlinux-c82dd6d078a2bb29d41eda032bb96d05699a524d.tar.xz
riscv: Avoid interrupts being erroneously enabled in handle_exception()
When the handle_exception function addresses an exception, the interrupts will be unconditionally enabled after finishing the context save. However, It may erroneously enable the interrupts if the interrupts are disabled before entering the handle_exception. For example, one of the WARN_ON() condition is satisfied in the scheduling where the interrupt is disabled and rq.lock is locked. The WARN_ON will trigger a break exception and the handle_exception function will enable the interrupts before entering do_trap_break function. During the procedure, if a timer interrupt is pending, it will be taken when interrupts are enabled. In this case, it may cause a deadlock problem if the rq.lock is locked again in the timer ISR. Hence, the handle_exception() can only enable interrupts when the state of sstatus.SPIE is 1. This patch is tested on HiFive Unleashed board. Signed-off-by: Vincent Chen <vincent.chen@sifive.com> Reviewed-by: Palmer Dabbelt <palmer@sifive.com> [paul.walmsley@sifive.com: updated to apply] Fixes: bcae803a21317 ("RISC-V: Enable IRQ during exception handling") Cc: David Abdurachmanov <david.abdurachmanov@sifive.com> Cc: stable@vger.kernel.org Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
-rw-r--r--arch/riscv/kernel/entry.S6
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 74ccfd464071..da7aa88113c2 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -166,9 +166,13 @@ ENTRY(handle_exception)
move a0, sp /* pt_regs */
tail do_IRQ
1:
- /* Exceptions run with interrupts enabled */
+ /* Exceptions run with interrupts enabled or disabled
+ depending on the state of sstatus.SR_SPIE */
+ andi t0, s1, SR_SPIE
+ beqz t0, 1f
csrs CSR_SSTATUS, SR_SIE
+1:
/* Handle syscalls */
li t0, EXC_SYSCALL
beq s4, t0, handle_syscall