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: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 4 insertions, 7 deletions

diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index 9ef5f2a47f88..e7e637bdba17 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -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;
 		}