Commit f51e7146 authored by Kalesh Singh's avatar Kalesh Singh Committed by Marc Zyngier
Browse files

arm64: stacktrace: Factor out common unwind() 



Move unwind() to stacktrace/common.h, and as a result
the kernel unwind_next() to asm/stacktrace.h. This allow
reusing unwind() in the implementation of the nVHE HYP
stack unwinder, later in the series.

Signed-off-by: default avatarKalesh Singh <kaleshsingh@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-6-kaleshsingh@google.com
parent 5b1b0861

arch/arm64/include/asm/stacktrace.h

+51 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/llist.h>



#include <asm/memory.h>

#include <asm/pointer_auth.h>

#include <asm/ptrace.h>

#include <asm/sdei.h>
@@ -80,4 +81,54 @@ static inline bool on_accessible_stack(const struct task_struct *tsk, 
	return false;

}



/*

 * Unwind from one frame record (A) to the next frame record (B).

 *

 * We terminate early if the location of B indicates a malformed chain of frame

 * records (e.g. a cycle), determined based on the location and fp value of A

 * and the location (but not the fp value) of B.

 */

static inline int notrace unwind_next(struct unwind_state *state)

{

	struct task_struct *tsk = state->task;

	unsigned long fp = state->fp;

	struct stack_info info;

	int err;



	/* Final frame; nothing to unwind */

	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)

		return -ENOENT;



	err = unwind_next_common(state, &info, NULL);

	if (err)

		return err;



	state->pc = ptrauth_strip_insn_pac(state->pc);



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	if (tsk->ret_stack &&

		(state->pc == (unsigned long)return_to_handler)) {

		unsigned long orig_pc;

		/*

		 * This is a case where function graph tracer has

		 * modified a return address (LR) in a stack frame

		 * to hook a function return.

		 * So replace it to an original value.

		 */

		orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,

						(void *)state->fp);

		if (WARN_ON_ONCE(state->pc == orig_pc))

			return -EINVAL;

		state->pc = orig_pc;

	}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifdef CONFIG_KRETPROBES

	if (is_kretprobe_trampoline(state->pc))

		state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);

#endif



	return 0;

}

NOKPROBE_SYMBOL(unwind_next);



#endif	/* __ASM_STACKTRACE_H */

arch/arm64/include/asm/stacktrace/common.h

+19 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 


#include <linux/bitmap.h>

#include <linux/bitops.h>

#include <linux/kprobes.h>

#include <linux/types.h>



enum stack_type {
@@ -69,6 +70,8 @@ static inline bool on_accessible_stack(const struct task_struct *tsk, 
				       unsigned long sp, unsigned long size,

				       struct stack_info *info);



static inline int unwind_next(struct unwind_state *state);



static inline bool on_stack(unsigned long sp, unsigned long size,

			    unsigned long low, unsigned long high,

			    enum stack_type type, struct stack_info *info)
@@ -191,4 +194,20 @@ static inline int unwind_next_common(struct unwind_state *state, 


	return 0;

}



static inline void notrace unwind(struct unwind_state *state,

				  stack_trace_consume_fn consume_entry,

				  void *cookie)

{

	while (1) {

		int ret;



		if (!consume_entry(cookie, state->pc))

			break;

		ret = unwind_next(state);

		if (ret < 0)

			break;

	}

}

NOKPROBE_SYMBOL(unwind);

#endif	/* __ASM_STACKTRACE_COMMON_H */

arch/arm64/kernel/stacktrace.c

+0 −67
Original line number Diff line number Diff line
@@ -7,14 +7,12 @@ 
#include <linux/kernel.h>

#include <linux/export.h>

#include <linux/ftrace.h>

#include <linux/kprobes.h>

#include <linux/sched.h>

#include <linux/sched/debug.h>

#include <linux/sched/task_stack.h>

#include <linux/stacktrace.h>



#include <asm/irq.h>

#include <asm/pointer_auth.h>

#include <asm/stack_pointer.h>

#include <asm/stacktrace.h>
@@ -69,71 +67,6 @@ static inline void unwind_init_from_task(struct unwind_state *state, 
	state->pc = thread_saved_pc(task);

}



/*

 * Unwind from one frame record (A) to the next frame record (B).

 *

 * We terminate early if the location of B indicates a malformed chain of frame

 * records (e.g. a cycle), determined based on the location and fp value of A

 * and the location (but not the fp value) of B.

 */

static int notrace unwind_next(struct unwind_state *state)

{

	struct task_struct *tsk = state->task;

	unsigned long fp = state->fp;

	struct stack_info info;

	int err;



	/* Final frame; nothing to unwind */

	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)

		return -ENOENT;



	err = unwind_next_common(state, &info, NULL);

	if (err)

		return err;



	state->pc = ptrauth_strip_insn_pac(state->pc);



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	if (tsk->ret_stack &&

		(state->pc == (unsigned long)return_to_handler)) {

		unsigned long orig_pc;

		/*

		 * This is a case where function graph tracer has

		 * modified a return address (LR) in a stack frame

		 * to hook a function return.

		 * So replace it to an original value.

		 */

		orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,

						(void *)state->fp);

		if (WARN_ON_ONCE(state->pc == orig_pc))

			return -EINVAL;

		state->pc = orig_pc;

	}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#ifdef CONFIG_KRETPROBES

	if (is_kretprobe_trampoline(state->pc))

		state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);

#endif



	return 0;

}

NOKPROBE_SYMBOL(unwind_next);



static void notrace unwind(struct unwind_state *state,

			   stack_trace_consume_fn consume_entry, void *cookie)

{

	while (1) {

		int ret;



		if (!consume_entry(cookie, state->pc))

			break;

		ret = unwind_next(state);

		if (ret < 0)

			break;

	}

}

NOKPROBE_SYMBOL(unwind);



static bool dump_backtrace_entry(void *arg, unsigned long where)

{

	char *loglvl = arg;