[PATCH v2 1/2] arm64/traps: Replace this_cpu_* with raw_cpu_* in panic_bad_stack()

Zhen Lei
2022-08-26T09:57:15Z

The hardware automatically disable the IRQ interrupt before jumping to the
interrupt or exception vector. Therefore, the preempt_disable() operation
in this_cpu_read() after macro expansion is unnecessary for exception
handler. Use raw_cpu_* instead of this_cpu_* can reduce a few lines of
assembly code. To be honest, the fewer unnecessary operations in exception
handler, the better.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
arch/arm64/kernel/traps.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index b7fed33981f7b76..e6b6f4650e3d895 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -871,8 +871,8 @@ DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
void panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far)
{
unsigned long tsk_stk = (unsigned long)current->stack;
- unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
- unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack);
+ unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
+ unsigned long ovf_stk = (unsigned long)raw_cpu_ptr(overflow_stack);

console_verbose();
pr_emerg("Insufficient stack space to handle exception!");
--
2.25.1