[PATCH v5 01/17] arm64: stacktrace: Add shared header for common stack unwinding code

Kalesh Singh
2022-07-21T05:57:41Z

In order to reuse the arm64 stack unwinding logic for the nVHE
hypervisor stack, move the common code to a shared header
(arch/arm64/include/asm/stacktrace/common.h).

The nVHE hypervisor cannot safely link against kernel code, so we
make use of the shared header to avoid duplicated logic later in
this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Fuad Tabba <tabba@google.com>
---

Changes in v5:
- Add Reviewed-by tags from Mark Brown and Fuad

arch/arm64/include/asm/stacktrace.h | 35 +------
arch/arm64/include/asm/stacktrace/common.h | 105 +++++++++++++++++++++
arch/arm64/kernel/stacktrace.c | 57 -----------
3 files changed, 106 insertions(+), 91 deletions(-)
create mode 100644 arch/arm64/include/asm/stacktrace/common.h

diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index aec9315bf156..79f455b37c84 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -8,52 +8,19 @@
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
-#include <linux/types.h>
#include <linux/llist.h>

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

-enum stack_type {
- STACK_TYPE_UNKNOWN,
- STACK_TYPE_TASK,
- STACK_TYPE_IRQ,
- STACK_TYPE_OVERFLOW,
- STACK_TYPE_SDEI_NORMAL,
- STACK_TYPE_SDEI_CRITICAL,
- __NR_STACK_TYPES
-};
-
-struct stack_info {
- unsigned long low;
- unsigned long high;
- enum stack_type type;
-};
+#include <asm/stacktrace/common.h>

extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl);

DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);

-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)
-{
- if (!low)
- return false;
-
- if (sp < low || sp + size < sp || sp + size > high)
- return false;
-
- if (info) {
- info->low = low;
- info->high = high;
- info->type = type;
- }
- return true;
-}
-
static inline bool on_irq_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
new file mode 100644
index 000000000000..64ae4f6b06fe
--- /dev/null
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Common arm64 stack unwinder code.
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_STACKTRACE_COMMON_H
+#define __ASM_STACKTRACE_COMMON_H
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/types.h>
+
+enum stack_type {
+ STACK_TYPE_UNKNOWN,
+ STACK_TYPE_TASK,
+ STACK_TYPE_IRQ,
+ STACK_TYPE_OVERFLOW,
+ STACK_TYPE_SDEI_NORMAL,
+ STACK_TYPE_SDEI_CRITICAL,
+ __NR_STACK_TYPES
+};
+
+struct stack_info {
+ unsigned long low;
+ unsigned long high;
+ enum stack_type type;
+};
+
+/*
+ * A snapshot of a frame record or fp/lr register values, along with some
+ * accounting information necessary for robust unwinding.
+ *
+ * @fp: The fp value in the frame record (or the real fp)
+ * @pc: The lr value in the frame record (or the real lr)
+ *
+ * @stacks_done: Stacks which have been entirely unwound, for which it is no
+ * longer valid to unwind to.
+ *
+ * @prev_fp: The fp that pointed to this frame record, or a synthetic value
+ * of 0. This is used to ensure that within a stack, each
+ * subsequent frame record is at an increasing address.
+ * @prev_type: The type of stack this frame record was on, or a synthetic
+ * value of STACK_TYPE_UNKNOWN. This is used to detect a
+ * transition from one stack to another.
+ *
+ * @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;
+ unsigned long pc;
+ DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
+ unsigned long prev_fp;
+ enum stack_type prev_type;
+#ifdef CONFIG_KRETPROBES
+ struct llist_node *kr_cur;
+#endif
+ struct task_struct *task;
+};
+
+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)
+{
+ if (!low)
+ return false;
+
+ if (sp < low || sp + size < sp || sp + size > high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = type;
+ }
+ return true;
+}
+
+static inline void unwind_init_common(struct unwind_state *state,
+ struct task_struct *task)
+{
+ state->task = task;
+#ifdef CONFIG_KRETPROBES
+ state->kr_cur = NULL;
+#endif
+
+ /*
+ * Prime the first unwind.
+ *
+ * In unwind_next() we'll check that the FP points to a valid stack,
+ * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
+ * treated as a transition to whichever stack that happens to be. The
+ * prev_fp value won't be used, but we set it to 0 such that it is
+ * definitely not an accessible stack address.
+ */
+ bitmap_zero(state->stacks_done, __NR_STACK_TYPES);
+ state->prev_fp = 0;
+ state->prev_type = STACK_TYPE_UNKNOWN;
+}
+
+#endif /* __ASM_STACKTRACE_COMMON_H */
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index fcaa151b81f1..94a5dd2ab8fd 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -18,63 +18,6 @@
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>

-/*
- * A snapshot of a frame record or fp/lr register values, along with some
- * accounting information necessary for robust unwinding.
- *
- * @fp: The fp value in the frame record (or the real fp)
- * @pc: The lr value in the frame record (or the real lr)
- *
- * @stacks_done: Stacks which have been entirely unwound, for which it is no
- * longer valid to unwind to.
- *
- * @prev_fp: The fp that pointed to this frame record, or a synthetic value
- * of 0. This is used to ensure that within a stack, each
- * subsequent frame record is at an increasing address.
- * @prev_type: The type of stack this frame record was on, or a synthetic
- * value of STACK_TYPE_UNKNOWN. This is used to detect a
- * transition from one stack to another.
- *
- * @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;
- unsigned long pc;
- DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
- unsigned long prev_fp;
- enum stack_type prev_type;
-#ifdef CONFIG_KRETPROBES
- struct llist_node *kr_cur;
-#endif
- struct task_struct *task;
-};
-
-static void unwind_init_common(struct unwind_state *state,
- struct task_struct *task)
-{
- state->task = task;
-#ifdef CONFIG_KRETPROBES
- state->kr_cur = NULL;
-#endif
-
- /*
- * Prime the first unwind.
- *
- * In unwind_next() we'll check that the FP points to a valid stack,
- * which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
- * treated as a transition to whichever stack that happens to be. The
- * prev_fp value won't be used, but we set it to 0 such that it is
- * definitely not an accessible stack address.
- */
- bitmap_zero(state->stacks_done, __NR_STACK_TYPES);
- state->prev_fp = 0;
- state->prev_type = STACK_TYPE_UNKNOWN;
-}
-
/*
* Start an unwind from a pt_regs.
*
--
2.37.0.170.g444d1eabd0-goog