From a80a0eb70c358f8c7dda4bb62b2278dc6285217b Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Thu, 11 Feb 2016 13:53:10 -0800 Subject: arm64: make irq_stack_ptr more robust Switching between stacks is only valid if we are tracing ourselves while on the irq_stack, so it is only valid when in current and non-preemptible context, otherwise is is just zeroed off. Fixes: 132cd887b5c5 ("arm64: Modify stack trace and dump for use with irq_stack") Acked-by: James Morse Tested-by: James Morse Signed-off-by: Yang Shi Signed-off-by: Will Deacon --- arch/arm64/kernel/traps.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'arch/arm64/kernel/traps.c') diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index cbedd724f48e..c5392081b49b 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -146,9 +146,18 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) { struct stackframe frame; - unsigned long irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id()); + unsigned long irq_stack_ptr; int skip; + /* + * Switching between stacks is valid when tracing current and in + * non-preemptible context. + */ + if (tsk == current && !preemptible()) + irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id()); + else + irq_stack_ptr = 0; + pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); if (!tsk) -- cgit v1.2.3