1 files changed, 229 insertions, 0 deletions
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
new file mode 100644
index 000000000..762745504
--- /dev/null
+++ b/arch/x86/kernel/stacktrace.c
@@ -0,0 +1,229 @@
+/*
+ * Stack trace management functions
+ *
+ *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ */
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <linux/export.h>
+#include <linux/uaccess.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+static int save_stack_address(struct stack_trace *trace, unsigned long addr,
+			      bool nosched)
+{
+	if (nosched && in_sched_functions(addr))
+		return 0;
+
+	if (trace->skip > 0) {
+		trace->skip--;
+		return 0;
+	}
+
+	if (trace->nr_entries >= trace->max_entries)
+		return -1;
+
+	trace->entries[trace->nr_entries++] = addr;
+	return 0;
+}
+
+static void noinline __save_stack_trace(struct stack_trace *trace,
+			       struct task_struct *task, struct pt_regs *regs,
+			       bool nosched)
+{
+	struct unwind_state state;
+	unsigned long addr;
+
+	if (regs)
+		save_stack_address(trace, regs->ip, nosched);
+
+	for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
+	     unwind_next_frame(&state)) {
+		addr = unwind_get_return_address(&state);
+		if (!addr || save_stack_address(trace, addr, nosched))
+			break;
+	}
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+	trace->skip++;
+	__save_stack_trace(trace, current, NULL, false);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+	__save_stack_trace(trace, current, regs, false);
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+	if (!try_get_task_stack(tsk))
+		return;
+
+	if (tsk == current)
+		trace->skip++;
+	__save_stack_trace(trace, tsk, NULL, true);
+
+	put_task_stack(tsk);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
+
+static int __always_inline
+__save_stack_trace_reliable(struct stack_trace *trace,
+			    struct task_struct *task)
+{
+	struct unwind_state state;
+	struct pt_regs *regs;
+	unsigned long addr;
+
+	for (unwind_start(&state, task, NULL, NULL);
+	     !unwind_done(&state) && !unwind_error(&state);
+	     unwind_next_frame(&state)) {
+
+		regs = unwind_get_entry_regs(&state, NULL);
+		if (regs) {
+			/* Success path for user tasks */
+			if (user_mode(regs))
+				goto success;
+
+			/*
+			 * Kernel mode registers on the stack indicate an
+			 * in-kernel interrupt or exception (e.g., preemption
+			 * or a page fault), which can make frame pointers
+			 * unreliable.
+			 */
+
+			if (IS_ENABLED(CONFIG_FRAME_POINTER))
+				return -EINVAL;
+		}
+
+		addr = unwind_get_return_address(&state);
+
+		/*
+		 * A NULL or invalid return address probably means there's some
+		 * generated code which __kernel_text_address() doesn't know
+		 * about.
+		 */
+		if (!addr)
+			return -EINVAL;
+
+		if (save_stack_address(trace, addr, false))
+			return -EINVAL;
+	}
+
+	/* Check for stack corruption */
+	if (unwind_error(&state))
+		return -EINVAL;
+
+	/* Success path for non-user tasks, i.e. kthreads and idle tasks */
+	if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
+		return -EINVAL;
+
+success:
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+	return 0;
+}
+
+/*
+ * This function returns an error if it detects any unreliable features of the
+ * stack.  Otherwise it guarantees that the stack trace is reliable.
+ *
+ * If the task is not 'current', the caller *must* ensure the task is inactive.
+ */
+int save_stack_trace_tsk_reliable(struct task_struct *tsk,
+				  struct stack_trace *trace)
+{
+	int ret;
+
+	/*
+	 * If the task doesn't have a stack (e.g., a zombie), the stack is
+	 * "reliably" empty.
+	 */
+	if (!try_get_task_stack(tsk))
+		return 0;
+
+	ret = __save_stack_trace_reliable(trace, tsk);
+
+	put_task_stack(tsk);
+
+	return ret;
+}
+#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
+
+/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
+
+struct stack_frame_user {
+	const void __user	*next_fp;
+	unsigned long		ret_addr;
+};
+
+static int
+copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
+{
+	int ret;
+
+	if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
+		return 0;
+
+	ret = 1;
+	pagefault_disable();
+	if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
+		ret = 0;
+	pagefault_enable();
+
+	return ret;
+}
+
+static inline void __save_stack_trace_user(struct stack_trace *trace)
+{
+	const struct pt_regs *regs = task_pt_regs(current);
+	const void __user *fp = (const void __user *)regs->bp;
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = regs->ip;
+
+	while (trace->nr_entries < trace->max_entries) {
+		struct stack_frame_user frame;
+
+		frame.next_fp = NULL;
+		frame.ret_addr = 0;
+		if (!copy_stack_frame(fp, &frame))
+			break;
+		if ((unsigned long)fp < regs->sp)
+			break;
+		if (frame.ret_addr) {
+			trace->entries[trace->nr_entries++] =
+				frame.ret_addr;
+		}
+		if (fp == frame.next_fp)
+			break;
+		fp = frame.next_fp;
+	}
+}
+
+void save_stack_trace_user(struct stack_trace *trace)
+{
+	/*
+	 * Trace user stack if we are not a kernel thread
+	 */
+	if (current->mm) {
+		__save_stack_trace_user(trace);
+	}
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}