xtensa: always use correct stack pointer for stack traces (586411dc) · Commits · 戴 / test

Commit ' xtensa: use correct stack pointer for stack traces' changed the stack tracer from always reading the stack pointer register to always using the saved value in the task descriptor. The author was too dense to consider the fact that the saved stack value is stale for a running process und thus unusable for 'current'. What we do now is to use the stack pointer register (a1) for when the task is unknown - we can't help it then - or when the task is 'current'. For everything else use the saved stack pointer value contained in the task descriptor. Signed-off-by:

Johannes Weiner <jw@emlix.com> Signed-off-by:

Chris Zankel <chris@zankel.net>

arch/xtensa/kernel/traps.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -369,6 +369,18 @@ void show_regs(struct pt_regs * regs)
		regs->syscall);
		}

		static __always_inline unsigned long stack_pointer(struct task_struct task)
		{
		unsigned long *sp;

		if (!task \|\| task == current)
		__asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
		else
		sp = (unsigned long *)task->thread.sp;

		return sp;
		}

		void show_trace(struct task_struct task, unsigned long sp)
		{
		unsigned long a0, a1, pc;
		@@ -377,7 +389,7 @@ void show_trace(struct task_struct task, unsigned long sp)
		if (sp)
		a1 = (unsigned long)sp;
		else
		a1 = task->thread.sp;
		a1 = (unsigned long)stack_pointer(task);

		sp_start = a1 & ~(THREAD_SIZE-1);
		sp_end = sp_start + THREAD_SIZE;
		@@ -420,7 +432,7 @@ void show_stack(struct task_struct task, unsigned long sp)
		unsigned long *stack;

		if (!sp)
		sp = (unsigned long *)task->thread.sp;
		sp = stack_pointer(task);
		stack = sp;

		printk("\nStack: ");

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