linux-kernel - [PATCH v12 05/10] arm64: Copy unwind arguments to unwind

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Message-Id: <20220103165212.9303-6-madvenka@linux.microsoft.com>
Date:   Mon,  3 Jan 2022 10:52:07 -0600
From:   madvenka@...ux.microsoft.com
To:     mark.rutland@....com, broonie@...nel.org, jpoimboe@...hat.com,
        ardb@...nel.org, nobuta.keiya@...itsu.com,
        sjitindarsingh@...il.com, catalin.marinas@....com, will@...nel.org,
        jmorris@...ei.org, linux-arm-kernel@...ts.infradead.org,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        madvenka@...ux.microsoft.com
Subject: [PATCH v12 05/10] arm64: Copy unwind arguments to unwind_state

From: "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>

Copy the following arguments passed to arch_stack_walk() to unwind_state
so that they can be passed to unwind functions via unwind_state rather
than as separate arguments:

	- task
	- regs
	- consume_entry
	- cookie

Signed-off-by: Madhavan T. Venkataraman <madvenka@...ux.microsoft.com>
---
 arch/arm64/include/asm/stacktrace.h | 12 ++++++++
 arch/arm64/kernel/stacktrace.c      | 45 ++++++++++++++++-------------
 2 files changed, 37 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index fc828c3c5dfd..322817d40a75 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -51,6 +51,14 @@ struct stack_info {
  * @kr_cur:      When KRETPOLINES is selected, holds the kretprobe instance
  *               associated with the most recently encountered replacement lr
  *               value.
+ *
+ * @task:        Pointer to the task structure.
+ *
+ * @regs:        Registers, if any.
+ *
+ * @consume_pc   Consume PC function pointer.
+ *
+ * @cookie       Argument to consume_pc().
  */
 struct unwind_state {
 	unsigned long fp;
@@ -61,6 +69,10 @@ struct unwind_state {
 #ifdef CONFIG_KRETPROBES
 	struct llist_node *kr_cur;
 #endif
+	struct task_struct *task;
+	struct pt_regs *regs;
+	stack_trace_consume_fn consume_pc;
+	void *cookie;
 };
 
 extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index bd797e3f7789..3ecb8242caa5 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -33,8 +33,17 @@
  */
 
 
-static void unwind_init_common(struct unwind_state *state)
+static void unwind_init_common(struct unwind_state *state,
+			       struct task_struct *task,
+			       struct pt_regs *regs,
+			       stack_trace_consume_fn consume_pc,
+			       void *cookie)
 {
+	state->task = task;
+	state->regs = regs;
+	state->consume_pc = consume_pc;
+	state->cookie = cookie;
+
 #ifdef CONFIG_KRETPROBES
 	state->kr_cur = NULL;
 #endif
@@ -56,11 +65,10 @@ static void unwind_init_common(struct unwind_state *state)
 /*
  * TODO: document requirements here.
  */
-static inline void unwind_init_regs(struct unwind_state *state,
-				    struct pt_regs *regs)
+static inline void unwind_init_regs(struct unwind_state *state)
 {
-	state->fp = regs->regs[29];
-	state->pc = regs->pc;
+	state->fp = state->regs->regs[29];
+	state->pc = state->regs->pc;
 }
 
 /*
@@ -80,11 +88,10 @@ static __always_inline void unwind_init_current(struct unwind_state *state)
  *
  * The caller guarantees that the task is not running.
  */
-static inline void unwind_init_task(struct unwind_state *state,
-				    struct task_struct *task)
+static inline void unwind_init_task(struct unwind_state *state)
 {
-	state->fp = thread_saved_fp(task);
-	state->pc = thread_saved_pc(task);
+	state->fp = thread_saved_fp(state->task);
+	state->pc = thread_saved_pc(state->task);
 }
 
 /*
@@ -94,9 +101,9 @@ static inline void unwind_init_task(struct unwind_state *state,
  * 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 task_struct *tsk,
-			       struct unwind_state *state)
+static int notrace unwind_next(struct unwind_state *state)
 {
+	struct task_struct *tsk = state->task;
 	unsigned long fp = state->fp;
 	struct stack_info info;
 
@@ -170,16 +177,14 @@ static int notrace unwind_next(struct task_struct *tsk,
 }
 NOKPROBE_SYMBOL(unwind_next);
 
-static void notrace unwind(struct task_struct *tsk,
-			   struct unwind_state *state,
-			   bool (*fn)(void *, unsigned long), void *data)
+static void notrace unwind(struct unwind_state *state)
 {
 	while (1) {
 		int ret;
 
-		if (!fn(data, state->pc))
+		if (!state->consume_pc(state->cookie, state->pc))
 			break;
-		ret = unwind_next(tsk, state);
+		ret = unwind_next(state);
 		if (ret < 0)
 			break;
 	}
@@ -225,14 +230,14 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
 {
 	struct unwind_state state;
 
-	unwind_init_common(&state);
+	unwind_init_common(&state, task, regs, consume_entry, cookie);
 
 	if (regs)
-		unwind_init_regs(&state, regs);
+		unwind_init_regs(&state);
 	else if (task == current)
 		unwind_init_current(&state);
 	else
-		unwind_init_task(&state, task);
+		unwind_init_task(&state);
 
-	unwind(task, &state, consume_entry, cookie);
+	unwind(&state);
 }
-- 
2.25.1