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arm64: Split unwind_init()

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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: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220617180219.20352-2-madvenka@linux.microsoft.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Madhavan T. Venkataraman
2022-06-17 13:02:14 -05:00
committed by Will Deacon
parent 446297b28a
commit a019d8a2cc
1 changed files with 55 additions and 11 deletions
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66
arch/arm64/kernel/stacktrace.c
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@@ -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);
}