linux-kernel - [PATCH AUTOSEL 6.6 46/47] LoongArch: Set unwind stack type to unknown rather than set error flag

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Date:   Mon, 11 Dec 2023 08:50:47 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jinyang He <hejinyang@...ngson.cn>,
        Hengqi Chen <hengqi.chen@...il.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        Sasha Levin <sashal@...nel.org>, chenhuacai@...nel.org,
        lienze@...inos.cn, yangtiezhu@...ngson.cn, zhangqing@...ngson.cn,
        loongarch@...ts.linux.dev
Subject: [PATCH AUTOSEL 6.6 46/47] LoongArch: Set unwind stack type to unknown rather than set error flag

From: Jinyang He <hejinyang@...ngson.cn>

[ Upstream commit 97ceddbc9404a7d1e2c4049435bff29427d762cc ]

During unwinding, unwind_done() is used as an end condition. Normally it
unwind to the user stack and then set the stack type to unknown, which
is a normal exit. When something unexpected happens in unwind process
and we cannot unwind anymore, we should set the error flag, and also set
the stack type to unknown to indicate that the unwind process can not
continue. The error flag emphasizes that the unwind process produce an
unexpected error. There is no unexpected things when we unwind the PT_REGS
in the top of IRQ stack and find out that is an user mode PT_REGS. Thus,
we should not set error flag and just set stack type to unknown.

Reported-by: Hengqi Chen <hengqi.chen@...il.com>
Acked-by: Hengqi Chen <hengqi.chen@...il.com>
Signed-off-by: Jinyang He <hejinyang@...ngson.cn>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/loongarch/kernel/stacktrace.c      | 2 +-
 arch/loongarch/kernel/unwind.c          | 1 -
 arch/loongarch/kernel/unwind_prologue.c | 2 +-
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/loongarch/kernel/stacktrace.c b/arch/loongarch/kernel/stacktrace.c
index 92270f14db948..f623feb2129f1 100644
--- a/arch/loongarch/kernel/stacktrace.c
+++ b/arch/loongarch/kernel/stacktrace.c
@@ -32,7 +32,7 @@ void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 	}
 
 	for (unwind_start(&state, task, regs);
-	     !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
+	     !unwind_done(&state); unwind_next_frame(&state)) {
 		addr = unwind_get_return_address(&state);
 		if (!addr || !consume_entry(cookie, addr))
 			break;
diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
index ba324ba76fa15..a463d6961344c 100644
--- a/arch/loongarch/kernel/unwind.c
+++ b/arch/loongarch/kernel/unwind.c
@@ -28,6 +28,5 @@ bool default_next_frame(struct unwind_state *state)
 
 	} while (!get_stack_info(state->sp, state->task, info));
 
-	state->error = true;
 	return false;
 }
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 55afc27320e12..929ae240280a5 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -227,7 +227,7 @@ static bool next_frame(struct unwind_state *state)
 	} while (!get_stack_info(state->sp, state->task, info));
 
 out:
-	state->error = true;
+	state->stack_info.type = STACK_TYPE_UNKNOWN;
 	return false;
 }
 
-- 
2.42.0