Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a80a0eb7 authored by Yang Shi's avatar Yang Shi Committed by Will Deacon
Browse files

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: 132cd887 ("arm64: Modify stack trace and dump for use with irq_stack")
Acked-by: default avatarJames Morse <james.morse@arm.com>
Tested-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarYang Shi <yang.shi@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent e04a28d4

arch/arm64/kernel/stacktrace.c

+6 −7
Original line number Diff line number Diff line
@@ -44,14 +44,13 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) 
	unsigned long irq_stack_ptr;



	/*

	 * Use raw_smp_processor_id() to avoid false-positives from

	 * CONFIG_DEBUG_PREEMPT. get_wchan() calls unwind_frame() on sleeping

	 * task stacks, we can be pre-empted in this case, so

	 * {raw_,}smp_processor_id() may give us the wrong value. Sleeping

	 * tasks can't ever be on an interrupt stack, so regardless of cpu,

	 * the checks will always fail.

	 * Switching between stacks is valid when tracing current and in

	 * non-preemptible context.

	 */

	irq_stack_ptr = IRQ_STACK_PTR(raw_smp_processor_id());

	if (tsk == current && !preemptible())

		irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());

	else

		irq_stack_ptr = 0;



	low  = frame->sp;

	/* irq stacks are not THREAD_SIZE aligned */

arch/arm64/kernel/traps.c

+10 −1
Original line number Diff line number Diff line
@@ -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)