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Subject[PATCH v15 2/6] arm64: Copy the task argument to unwind_state
Date
From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>

Copy the task argument passed to arch_stack_walk() to unwind_state so that
it can be passed to unwind functions via unwind_state rather than as a
separate argument. The task is a fundamental part of the unwind state.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/kernel/stacktrace.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index e44f93ff25f0..8e43444d50e2 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -38,6 +38,8 @@
* @kr_cur: When KRETPROBES is selected, holds the kretprobe instance
* associated with the most recently encountered replacement lr
* value.
+ *
+ * @task: The task being unwound.
*/
struct unwind_state {
unsigned long fp;
@@ -48,10 +50,13 @@ struct unwind_state {
#ifdef CONFIG_KRETPROBES
struct llist_node *kr_cur;
#endif
+ struct task_struct *task;
};

-static void unwind_init_common(struct unwind_state *state)
+static void unwind_init_common(struct unwind_state *state,
+ struct task_struct *task)
{
+ state->task = task;
#ifdef CONFIG_KRETPROBES
state->kr_cur = NULL;
#endif
@@ -80,7 +85,7 @@ static void unwind_init_common(struct unwind_state *state)
static inline void unwind_init_from_regs(struct unwind_state *state,
struct pt_regs *regs)
{
- unwind_init_common(state);
+ unwind_init_common(state, current);

state->fp = regs->regs[29];
state->pc = regs->pc;
@@ -96,7 +101,7 @@ static inline void unwind_init_from_regs(struct unwind_state *state,
*/
static __always_inline void unwind_init_from_caller(struct unwind_state *state)
{
- unwind_init_common(state);
+ unwind_init_common(state, current);

state->fp = (unsigned long)__builtin_frame_address(1);
state->pc = (unsigned long)__builtin_return_address(0);
@@ -115,7 +120,7 @@ static __always_inline void unwind_init_from_caller(struct unwind_state *state)
static inline void unwind_init_from_task(struct unwind_state *state,
struct task_struct *task)
{
- unwind_init_common(state);
+ unwind_init_common(state, task);

state->fp = thread_saved_fp(task);
state->pc = thread_saved_pc(task);
@@ -128,9 +133,9 @@ static inline void unwind_init_from_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;

@@ -204,8 +209,7 @@ 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,
+static void notrace unwind(struct unwind_state *state,
stack_trace_consume_fn consume_entry, void *cookie)
{
while (1) {
@@ -213,7 +217,7 @@ static void notrace unwind(struct task_struct *tsk,

if (!consume_entry(cookie, state->pc))
break;
- ret = unwind_next(tsk, state);
+ ret = unwind_next(state);
if (ret < 0)
break;
}
@@ -259,12 +263,15 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
{
struct unwind_state state;

- if (regs)
+ if (regs) {
+ if (task != current)
+ return;
unwind_init_from_regs(&state, regs);
- else if (task == current)
+ } else if (task == current) {
unwind_init_from_caller(&state);
- else
+ } else {
unwind_init_from_task(&state, task);
+ }

- unwind(task, &state, consume_entry, cookie);
+ unwind(&state, consume_entry, cookie);
}
--
2.25.1
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