Commit 12964443 authored by Mark Rutland's avatar Mark Rutland
Browse files

arm64: add on_accessible_stack() 



Both unwind_frame() and dump_backtrace() try to check whether a stack
address is sane to access, with very similar logic. Both will need
updating in order to handle overflow stacks.

Factor out this logic into a helper, so that we can avoid further
duplication when we add overflow stacks.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
parent e3067861

arch/arm64/include/asm/stacktrace.h

+16 −0
Original line number Diff line number Diff line
@@ -57,4 +57,20 @@ static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp) 
	return (low <= sp && sp < high);

}



/*

 * We can only safely access per-cpu stacks from current in a non-preemptible

 * context.

 */

static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp)

{

	if (on_task_stack(tsk, sp))

		return true;

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

		return false;

	if (on_irq_stack(sp))

		return true;



	return false;

}



#endif	/* __ASM_STACKTRACE_H */

arch/arm64/kernel/stacktrace.c

+1 −6
Original line number Diff line number Diff line
@@ -50,12 +50,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) 
	if (!tsk)

		tsk = current;



	/*

	 * Switching between stacks is valid when tracing current and in

	 * non-preemptible context.

	 */

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

	    !on_task_stack(tsk, fp))

	if (!on_accessible_stack(tsk, fp))

		return -EINVAL;



	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));

arch/arm64/kernel/traps.c

+1 −2
Original line number Diff line number Diff line
@@ -193,8 +193,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 
		if (in_entry_text(frame.pc)) {

			stack = frame.fp - offsetof(struct pt_regs, stackframe);



			if (on_task_stack(tsk, stack) ||

			    (tsk == current && !preemptible() && on_irq_stack(stack)))

			if (on_accessible_stack(tsk, stack))

				dump_mem("", "Exception stack", stack,

					 stack + sizeof(struct pt_regs));

		}

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