Commit 5bb8d344 authored by Jinyang He's avatar Jinyang He Committed by Huacai Chen
Browse files

LoongArch: Use correct sp value to get graph addr in stack unwinders 



The stack frame when function_graph enable like follows,

---------  <- function sp_on_entry
    |
    |
    |
 FAKE_RA   <- sp_on_entry - sizeof(pt_regs) + PT_R1
    |
---------  <- sp_on_entry - sizeof(pt_regs)

So if we want to get the &FAKE_RA we should get sp_on_entry first. In
the unwinder_prologue case, we can get the sp_on_entry as state->sp,
because we try to calculate each CFA and the ra saved address. But in
the unwinder_guess case, we cannot get it because we do not try to
calculate the CFA. Although LoongArch have not fixed frame, the $ra is
saved at CFA - 8 in most cases, we can try guess, too. As we store the
pc in state, we not need to dereference state->sp, too.

Signed-off-by: default avatarJinyang He <hejinyang@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 429a9671

arch/loongarch/include/asm/ftrace.h

+0 −2
Original line number Diff line number Diff line
@@ -10,8 +10,6 @@ 
#define FTRACE_REGS_PLT_IDX	1

#define NR_FTRACE_PLTS		2



#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))



#ifdef CONFIG_FUNCTION_TRACER



#define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */

arch/loongarch/include/asm/unwind.h

+10 −0
Original line number Diff line number Diff line
@@ -8,7 +8,9 @@ 
#define _ASM_UNWIND_H



#include <linux/sched.h>

#include <linux/ftrace.h>



#include <asm/ptrace.h>

#include <asm/stacktrace.h>



enum unwinder_type {
@@ -40,4 +42,12 @@ static inline bool unwind_error(struct unwind_state *state) 
	return state->error;

}



#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))



static inline unsigned long unwind_graph_addr(struct unwind_state *state,

					unsigned long pc, unsigned long cfa)

{

	return ftrace_graph_ret_addr(state->task, &state->graph_idx,

				     pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));

}

#endif /* _ASM_UNWIND_H */

arch/loongarch/kernel/unwind_guess.c

+4 −7
Original line number Diff line number Diff line
@@ -11,10 +11,8 @@ unsigned long unwind_get_return_address(struct unwind_state *state) 
{

	if (unwind_done(state))

		return 0;

	else if (state->first)

		return state->pc;



	return *(unsigned long *)(state->sp);

	return state->pc;

}

EXPORT_SYMBOL_GPL(unwind_get_return_address);
@@ -36,7 +34,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task, 


	state->task = task;

	state->first = true;



	state->pc = unwind_graph_addr(state, state->pc, state->sp);

	get_stack_info(state->sp, state->task, &state->stack_info);



	if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -60,9 +58,8 @@ bool unwind_next_frame(struct unwind_state *state) 
		     state->sp < info->end;

		     state->sp += sizeof(unsigned long)) {

			addr = *(unsigned long *)(state->sp);

			state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,

					addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));

			if (__kernel_text_address(addr))

			state->pc = unwind_graph_addr(state, addr, state->sp + 8);

			if (__kernel_text_address(state->pc))

				return true;

		}

arch/loongarch/kernel/unwind_prologue.c

+6 −15
Original line number Diff line number Diff line
@@ -21,16 +21,10 @@ static inline void unwind_state_fixup(struct unwind_state *state) 


unsigned long unwind_get_return_address(struct unwind_state *state)

{



	if (unwind_done(state))

		return 0;

	else if (state->type)

		return state->pc;

	else if (state->first)

		return state->pc;



	return *(unsigned long *)(state->sp);



	return state->pc;

}

EXPORT_SYMBOL_GPL(unwind_get_return_address);
@@ -43,9 +37,8 @@ static bool unwind_by_guess(struct unwind_state *state) 
	     state->sp < info->end;

	     state->sp += sizeof(unsigned long)) {

		addr = *(unsigned long *)(state->sp);

		state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,

				addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));

		if (__kernel_text_address(addr))

		state->pc = unwind_graph_addr(state, addr, state->sp + 8);

		if (__kernel_text_address(state->pc))

			return true;

	}
@@ -166,7 +159,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task, 


	state->task = task;

	state->first = true;



	state->pc = unwind_graph_addr(state, state->pc, state->sp);

	get_stack_info(state->sp, state->task, &state->stack_info);



	if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -193,8 +186,7 @@ bool unwind_next_frame(struct unwind_state *state) 


		case UNWINDER_PROLOGUE:

			if (unwind_by_prologue(state)) {

				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,

						state->pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));

				state->pc = unwind_graph_addr(state, state->pc, state->sp);

				return true;

			}
@@ -209,8 +201,7 @@ bool unwind_next_frame(struct unwind_state *state) 
				state->first = true;

				state->ra = regs->regs[1];

				state->sp = regs->regs[3];

				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,

						pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));

				state->pc = pc;

				get_stack_info(state->sp, state->task, info);



				return true;