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ARM: 9232/1: Replace this_cpu_* with raw_cpu_* in handle_bad_stack()

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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. In fact, function
this_cpu_read() may trigger scheduling, see pseudocode below.

Pseudocode of this_cpu_read(xx):
preempt_disable_notrace();
raw_cpu_read(xx);
if (unlikely(__preempt_count_dec_and_test()))
	__preempt_schedule_notrace();

Therefore, use raw_cpu_* instead of this_cpu_* to eliminate potential
hazards. At the very least, it reduces a few lines of assembly code.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Zhen Lei 2022-08-25 07:31:54 +01:00 committed by Russell King (Oracle)
parent edd61fc1ca
commit 370d51c842
1 changed files with 2 additions and 2 deletions
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4
arch/arm/kernel/traps.c
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@ -920,9 +920,9 @@ asmlinkage void handle_bad_stack(struct pt_regs *regs)
{
unsigned long tsk_stk = (unsigned long)current->stack;
#ifdef CONFIG_IRQSTACKS
unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
#endif
unsigned long ovf_stk = (unsigned long)this_cpu_read(overflow_stack_ptr);
unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
console_verbose();
pr_emerg("Insufficient stack space to handle exception!");