stacktrace.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Stack trace management functions
  4 *
  5 * Copyright (C) 2022 Loongson Technology Corporation Limited
  6 */
  7#include <linux/sched.h>
  8#include <linux/stacktrace.h>
  9#include <linux/uaccess.h>
 10
 11#include <asm/stacktrace.h>
 12#include <asm/unwind.h>
 13
 14void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 15		     struct task_struct *task, struct pt_regs *regs)
 16{
 17	unsigned long addr;
 18	struct pt_regs dummyregs;
 19	struct unwind_state state;
 20
 21	if (!regs) {
 22		regs = &dummyregs;
 23
 24		if (task == current) {
 25			regs->regs[3] = (unsigned long)__builtin_frame_address(0);
 26			regs->csr_era = (unsigned long)__builtin_return_address(0);
 27		} else {
 28			regs->regs[3] = thread_saved_fp(task);
 29			regs->csr_era = thread_saved_ra(task);
 30		}
 31		regs->regs[1] = 0;
 32		regs->regs[22] = 0;
 33	}
 34
 35	for (unwind_start(&state, task, regs);
 36	     !unwind_done(&state); unwind_next_frame(&state)) {
 37		addr = unwind_get_return_address(&state);
 38		if (!addr || !consume_entry(cookie, addr))
 39			break;
 40	}
 41}
 42
 43int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
 44			     void *cookie, struct task_struct *task)
 45{
 46	unsigned long addr;
 47	struct pt_regs dummyregs;
 48	struct pt_regs *regs = &dummyregs;
 49	struct unwind_state state;
 50
 51	if (task == current) {
 52		regs->regs[3] = (unsigned long)__builtin_frame_address(0);
 53		regs->csr_era = (unsigned long)__builtin_return_address(0);
 54		regs->regs[22] = 0;
 55	} else {
 56		regs->regs[3] = thread_saved_fp(task);
 57		regs->csr_era = thread_saved_ra(task);
 58		regs->regs[22] = task->thread.reg22;
 59	}
 60	regs->regs[1] = 0;
 61
 62	for (unwind_start(&state, task, regs);
 63	     !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
 64		addr = unwind_get_return_address(&state);
 65
 66		/*
 67		 * A NULL or invalid return address probably means there's some
 68		 * generated code which __kernel_text_address() doesn't know about.
 69		 */
 70		if (!addr)
 71			return -EINVAL;
 72
 73		if (!consume_entry(cookie, addr))
 74			return -EINVAL;
 75	}
 76
 77	/* Check for stack corruption */
 78	if (unwind_error(&state))
 79		return -EINVAL;
 80
 81	return 0;
 82}
 83
 84static int
 85copy_stack_frame(unsigned long fp, struct stack_frame *frame)
 86{
 87	int ret = 1;
 88	unsigned long err;
 89	unsigned long __user *user_frame_tail;
 90
 91	user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
 92	if (!access_ok(user_frame_tail, sizeof(*frame)))
 93		return 0;
 94
 95	pagefault_disable();
 96	err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
 97	if (err || (unsigned long)user_frame_tail >= frame->fp)
 98		ret = 0;
 99	pagefault_enable();
100
101	return ret;
102}
103
104void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
105			  const struct pt_regs *regs)
106{
107	unsigned long fp = regs->regs[22];
108
109	while (fp && !((unsigned long)fp & 0xf)) {
110		struct stack_frame frame;
111
112		frame.fp = 0;
113		frame.ra = 0;
114		if (!copy_stack_frame(fp, &frame))
115			break;
116		if (!frame.ra)
117			break;
118		if (!consume_entry(cookie, frame.ra))
119			break;
120		fp = frame.fp;
121	}
122}