[PATCH v2 2/8] arm64: stacktrace: rename unwind_next_common() -> unwind_next_frame_record()

Mark Rutland
2022-08-05T12:47:11Z

The unwind_next_common() function unwinds a single frame record. There
are other unwind steps (e.g. unwinding through trampolines) which are
handled in the regular kernel unwinder, and in future there may be other
common unwind helpers.

Clarify the purpose of unwind_next_common() by renaming it to
unwind_next_frame_record(). At the same time, add commentary, and delete
the redundant comment at the top of asm/stacktrace/common.h.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: Fuad Tabba <tabba@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/stacktrace/common.h | 22 ++++++++++++----------
arch/arm64/kernel/stacktrace.c | 2 +-
arch/arm64/kvm/hyp/nvhe/stacktrace.c | 2 +-
arch/arm64/kvm/stacktrace.c | 4 ++--
4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
index 01dc9f44a24a7..676002d7d333c 100644
--- a/arch/arm64/include/asm/stacktrace/common.h
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -2,13 +2,6 @@
/*
* Common arm64 stack unwinder code.
*
- * To implement a new arm64 stack unwinder:
- * 1) Include this header
- *
- * 2) Call into unwind_next_common() from your top level unwind
- * function, passing it the validation and translation callbacks
- * (though the later can be NULL if no translation is required).
- *
* See: arch/arm64/kernel/stacktrace.c for the reference implementation.
*
* Copyright (C) 2012 ARM Ltd.
@@ -139,9 +132,18 @@ typedef bool (*on_accessible_stack_fn)(const struct task_struct *tsk,
unsigned long sp, unsigned long size,
struct stack_info *info);

-static inline int unwind_next_common(struct unwind_state *state,
- on_accessible_stack_fn accessible,
- stack_trace_translate_fp_fn translate_fp)
+/*
+ * unwind_next_frame_record() - Unwind to the next frame record indicated by
+ * @state->fp.
+ *
+ * @state: the current unwind state.
+ * @accessible: determines whether the frame record is accessible
+ * @translate_fp: translates the fp prior to access (may be NULL)
+ */
+static inline int
+unwind_next_frame_record(struct unwind_state *state,
+ on_accessible_stack_fn accessible,
+ stack_trace_translate_fp_fn translate_fp)
{
struct stack_info info;
unsigned long fp = state->fp, kern_fp = fp;
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 056fb045d0e0c..4c8865e495fea 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -109,7 +109,7 @@ static int notrace unwind_next(struct unwind_state *state)
if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
return -ENOENT;

- err = unwind_next_common(state, on_accessible_stack, NULL);
+ err = unwind_next_frame_record(state, on_accessible_stack, NULL);
if (err)
return err;

diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
index 50a1fa6b5c044..579b46aa9a553 100644
--- a/arch/arm64/kvm/hyp/nvhe/stacktrace.c
+++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
@@ -71,7 +71,7 @@ static bool on_accessible_stack(const struct task_struct *tsk,

static int unwind_next(struct unwind_state *state)
{
- return unwind_next_common(state, on_accessible_stack, NULL);
+ return unwind_next_frame_record(state, on_accessible_stack, NULL);
}

static void notrace unwind(struct unwind_state *state,
diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c
index b9cf551d9d31d..b69c18a26567d 100644
--- a/arch/arm64/kvm/stacktrace.c
+++ b/arch/arm64/kvm/stacktrace.c
@@ -97,8 +97,8 @@ static bool on_accessible_stack(const struct task_struct *tsk,

static int unwind_next(struct unwind_state *state)
{
- return unwind_next_common(state, on_accessible_stack,
- kvm_nvhe_stack_kern_va);
+ return unwind_next_frame_record(state, on_accessible_stack,
+ kvm_nvhe_stack_kern_va);
}

static void unwind(struct unwind_state *state,
--
2.30.2