Commit a019d8a2 authored by Madhavan T. Venkataraman's avatar Madhavan T. Venkataraman Committed by Will Deacon
Browse files

arm64: Split unwind_init() 



unwind_init() is currently a single function that initializes all of the
unwind state. Split it into the following functions and call them
appropriately:

	- unwind_init_from_regs() - initialize from regs passed by caller.

	- unwind_init_from_caller() - initialize for the current task
	  from the caller of arch_stack_walk().

	- unwind_init_from_task() - initialize from the saved state of a
	  task other than the current task. In this case, the other
	  task must not be running.

This is done for two reasons:

	- the different ways of initializing are clear

	- specialized code can be added to each initializer in the future.

Signed-off-by: default avatarMadhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220617180219.20352-2-madvenka@linux.microsoft.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 446297b2

arch/arm64/kernel/stacktrace.c

+55 −11
Original line number Diff line number Diff line
@@ -50,11 +50,8 @@ struct unwind_state { 
#endif

};



static notrace void unwind_init(struct unwind_state *state, unsigned long fp,

				unsigned long pc)

static void unwind_init_common(struct unwind_state *state)

{

	state->fp = fp;

	state->pc = pc;

#ifdef CONFIG_KRETPROBES

	state->kr_cur = NULL;

#endif
@@ -72,7 +69,57 @@ static notrace void unwind_init(struct unwind_state *state, unsigned long fp, 
	state->prev_fp = 0;

	state->prev_type = STACK_TYPE_UNKNOWN;

}

NOKPROBE_SYMBOL(unwind_init);



/*

 * Start an unwind from a pt_regs.

 *

 * The unwind will begin at the PC within the regs.

 *

 * The regs must be on a stack currently owned by the calling task.

 */

static inline void unwind_init_from_regs(struct unwind_state *state,

					 struct pt_regs *regs)

{

	unwind_init_common(state);



	state->fp = regs->regs[29];

	state->pc = regs->pc;

}



/*

 * Start an unwind from a caller.

 *

 * The unwind will begin at the caller of whichever function this is inlined

 * into.

 *

 * The function which invokes this must be noinline.

 */

static __always_inline void unwind_init_from_caller(struct unwind_state *state)

{

	unwind_init_common(state);



	state->fp = (unsigned long)__builtin_frame_address(1);

	state->pc = (unsigned long)__builtin_return_address(0);

}



/*

 * Start an unwind from a blocked task.

 *

 * The unwind will begin at the blocked tasks saved PC (i.e. the caller of

 * cpu_switch_to()).

 *

 * The caller should ensure the task is blocked in cpu_switch_to() for the

 * duration of the unwind, or the unwind will be bogus. It is never valid to

 * call this for the current task.

 */

static inline void unwind_init_from_task(struct unwind_state *state,

					 struct task_struct *task)

{

	unwind_init_common(state);



	state->fp = thread_saved_fp(task);

	state->pc = thread_saved_pc(task);

}



/*

 * Unwind from one frame record (A) to the next frame record (B).
@@ -213,14 +260,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, 
	struct unwind_state state;



	if (regs)

		unwind_init(&state, regs->regs[29], regs->pc);

		unwind_init_from_regs(&state, regs);

	else if (task == current)

		unwind_init(&state,

				(unsigned long)__builtin_frame_address(1),

				(unsigned long)__builtin_return_address(0));

		unwind_init_from_caller(&state);

	else

		unwind_init(&state, thread_saved_fp(task),

				thread_saved_pc(task));

		unwind_init_from_task(&state, task);



	unwind(task, &state, consume_entry, cookie);

}