[PATCH v5 05/17] arm64: stacktrace: Factor out common unwind()

Kalesh Singh
2022-07-21T05:57:59Z

Move unwind() to stacktrace/common.h, and as a result
the kernel unwind_next() to asm/stacktrace.h. This allow
reusing unwind() in the implementation of the nVHE HYP
stack unwinder, later in the series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
---

Changes in v5:
- Add Reviewed-by tag from Fuad

arch/arm64/include/asm/stacktrace.h | 51 ++++++++++++++++
arch/arm64/include/asm/stacktrace/common.h | 19 ++++++
arch/arm64/kernel/stacktrace.c | 67 ----------------------
3 files changed, 70 insertions(+), 67 deletions(-)

diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index 43f4b4a6d383..ea828579a98b 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -11,6 +11,7 @@
#include <linux/llist.h>

#include <asm/memory.h>
+#include <asm/pointer_auth.h>
#include <asm/ptrace.h>
#include <asm/sdei.h>

@@ -80,4 +81,54 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
return false;
}

+/*
+ * Unwind from one frame record (A) to the next frame record (B).
+ *
+ * We terminate early if the location of B indicates a malformed chain of frame
+ * 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 inline int notrace unwind_next(struct unwind_state *state)
+{
+ struct task_struct *tsk = state->task;
+ unsigned long fp = state->fp;
+ struct stack_info info;
+ int err;
+
+ /* Final frame; nothing to unwind */
+ if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
+ return -ENOENT;
+
+ err = unwind_next_common(state, &info, NULL);
+ if (err)
+ return err;
+
+ state->pc = ptrauth_strip_insn_pac(state->pc);
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ if (tsk->ret_stack &&
+ (state->pc == (unsigned long)return_to_handler)) {
+ unsigned long orig_pc;
+ /*
+ * This is a case where function graph tracer has
+ * modified a return address (LR) in a stack frame
+ * to hook a function return.
+ * So replace it to an original value.
+ */
+ orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,
+ (void *)state->fp);
+ if (WARN_ON_ONCE(state->pc == orig_pc))
+ return -EINVAL;
+ state->pc = orig_pc;
+ }
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+#ifdef CONFIG_KRETPROBES
+ if (is_kretprobe_trampoline(state->pc))
+ state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);
+#endif
+
+ return 0;
+}
+NOKPROBE_SYMBOL(unwind_next);
+
#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
index e89c8c39858d..7807752aaab1 100644
--- a/arch/arm64/include/asm/stacktrace/common.h
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -9,6 +9,7 @@

#include <linux/bitmap.h>
#include <linux/bitops.h>
+#include <linux/kprobes.h>
#include <linux/types.h>

enum stack_type {
@@ -69,6 +70,8 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
unsigned long sp, unsigned long size,
struct stack_info *info);

+static inline int unwind_next(struct unwind_state *state);
+
static inline bool on_stack(unsigned long sp, unsigned long size,
unsigned long low, unsigned long high,
enum stack_type type, struct stack_info *info)
@@ -191,4 +194,20 @@ static inline int unwind_next_common(struct unwind_state *state,

return 0;
}
+
+static inline void notrace unwind(struct unwind_state *state,
+ stack_trace_consume_fn consume_entry,
+ void *cookie)
+{
+ while (1) {
+ int ret;
+
+ if (!consume_entry(cookie, state->pc))
+ break;
+ ret = unwind_next(state);
+ if (ret < 0)
+ break;
+ }
+}
+NOKPROBE_SYMBOL(unwind);
#endif /* __ASM_STACKTRACE_COMMON_H */
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index eef3cf6bf2d7..9fa60ee48499 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -7,14 +7,12 @@
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/ftrace.h>
-#include <linux/kprobes.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>

#include <asm/irq.h>
-#include <asm/pointer_auth.h>
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>

@@ -69,71 +67,6 @@ static inline void unwind_init_from_task(struct unwind_state *state,
state->pc = thread_saved_pc(task);
}

-/*
- * Unwind from one frame record (A) to the next frame record (B).
- *
- * We terminate early if the location of B indicates a malformed chain of frame
- * 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 unwind_state *state)
-{
- struct task_struct *tsk = state->task;
- unsigned long fp = state->fp;
- struct stack_info info;
- int err;
-
- /* Final frame; nothing to unwind */
- if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
- return -ENOENT;
-
- err = unwind_next_common(state, &info, NULL);
- if (err)
- return err;
-
- state->pc = ptrauth_strip_insn_pac(state->pc);
-
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- if (tsk->ret_stack &&
- (state->pc == (unsigned long)return_to_handler)) {
- unsigned long orig_pc;
- /*
- * This is a case where function graph tracer has
- * modified a return address (LR) in a stack frame
- * to hook a function return.
- * So replace it to an original value.
- */
- orig_pc = ftrace_graph_ret_addr(tsk, NULL, state->pc,
- (void *)state->fp);
- if (WARN_ON_ONCE(state->pc == orig_pc))
- return -EINVAL;
- state->pc = orig_pc;
- }
-#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-#ifdef CONFIG_KRETPROBES
- if (is_kretprobe_trampoline(state->pc))
- state->pc = kretprobe_find_ret_addr(tsk, (void *)state->fp, &state->kr_cur);
-#endif
-
- return 0;
-}
-NOKPROBE_SYMBOL(unwind_next);
-
-static void notrace unwind(struct unwind_state *state,
- stack_trace_consume_fn consume_entry, void *cookie)
-{
- while (1) {
- int ret;
-
- if (!consume_entry(cookie, state->pc))
- break;
- ret = unwind_next(state);
- if (ret < 0)
- break;
- }
-}
-NOKPROBE_SYMBOL(unwind);
-
static bool dump_backtrace_entry(void *arg, unsigned long where)
{
char *loglvl = arg;
--
2.37.0.170.g444d1eabd0-goog