1 files changed, 29 insertions, 96 deletions

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index fcaa151b81f1..ce190ee18a20 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -7,75 +7,16 @@
 #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>
 
 /*
- * 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.
  *
  * The unwind will begin at the PC within the regs.
@@ -127,6 +68,31 @@ static inline void unwind_init_from_task(struct unwind_state *state,
 }
 
 /*
+ * We can only safely access per-cpu stacks from current in a non-preemptible
+ * context.
+ */
+static bool on_accessible_stack(const struct task_struct *tsk,
+				unsigned long sp, unsigned long size,
+				struct stack_info *info)
+{
+	if (info)
+		info->type = STACK_TYPE_UNKNOWN;
+
+	if (on_task_stack(tsk, sp, size, info))
+		return true;
+	if (tsk != current || preemptible())
+		return false;
+	if (on_irq_stack(sp, size, info))
+		return true;
+	if (on_overflow_stack(sp, size, info))
+		return true;
+	if (on_sdei_stack(sp, size, info))
+		return true;
+
+	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
@@ -138,48 +104,15 @@ 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;
 
-	if (fp & 0x7)
-		return -EINVAL;
-
-	if (!on_accessible_stack(tsk, fp, 16, &info))
-		return -EINVAL;
-
-	if (test_bit(info.type, state->stacks_done))
-		return -EINVAL;
-
-	/*
-	 * As stacks grow downward, any valid record on the same stack must be
-	 * at a strictly higher address than the prior record.
-	 *
-	 * Stacks can nest in several valid orders, e.g.
-	 *
-	 * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
-	 * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
-	 *
-	 * ... but the nesting itself is strict. Once we transition from one
-	 * stack to another, it's never valid to unwind back to that first
-	 * stack.
-	 */
-	if (info.type == state->prev_type) {
-		if (fp <= state->prev_fp)
-			return -EINVAL;
-	} else {
-		__set_bit(state->prev_type, state->stacks_done);
-	}
-
-	/*
-	 * Record this frame record's values and location. The prev_fp and
-	 * prev_type are only meaningful to the next unwind_next() invocation.
-	 */
-	state->fp = READ_ONCE(*(unsigned long *)(fp));
-	state->pc = READ_ONCE(*(unsigned long *)(fp + 8));
-	state->prev_fp = fp;
-	state->prev_type = info.type;
+	err = unwind_next_common(state, &info, on_accessible_stack, NULL);
+	if (err)
+		return err;
 
 	state->pc = ptrauth_strip_insn_pac(state->pc);