LXR linux/arch/x86/kernel/stacktrace.c

   1/*
   2 * Stack trace management functions
   3 *
   4 *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   5 */
   6#include <linux/sched.h>
   7#include <linux/sched/debug.h>
   8#include <linux/sched/task_stack.h>
   9#include <linux/stacktrace.h>
  10#include <linux/export.h>
  11#include <linux/uaccess.h>
  12#include <asm/stacktrace.h>
  13#include <asm/unwind.h>
  14
  15void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
  16                     struct task_struct *task, struct pt_regs *regs)
  17{
  18        struct unwind_state state;
  19        unsigned long addr;
  20
  21        if (regs && !consume_entry(cookie, regs->ip))
  22                return;
  23
  24        for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
  25             unwind_next_frame(&state)) {
  26                addr = unwind_get_return_address(&state);
  27                if (!addr || !consume_entry(cookie, addr))
  28                        break;
  29        }
  30}
  31
  32int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
  33                             void *cookie, struct task_struct *task)
  34{
  35        struct unwind_state state;
  36        struct pt_regs *regs;
  37        unsigned long addr;
  38
  39        for (unwind_start(&state, task, NULL, NULL);
  40             !unwind_done(&state) && !unwind_error(&state);
  41             unwind_next_frame(&state)) {
  42
  43                regs = unwind_get_entry_regs(&state, NULL);
  44                if (regs) {
  45                        /* Success path for user tasks */
  46                        if (user_mode(regs))
  47                                return 0;
  48
  49                        /*
  50                         * Kernel mode registers on the stack indicate an
  51                         * in-kernel interrupt or exception (e.g., preemption
  52                         * or a page fault), which can make frame pointers
  53                         * unreliable.
  54                         */
  55                        if (IS_ENABLED(CONFIG_FRAME_POINTER))
  56                                return -EINVAL;
  57                }
  58
  59                addr = unwind_get_return_address(&state);
  60
  61                /*
  62                 * A NULL or invalid return address probably means there's some
  63                 * generated code which __kernel_text_address() doesn't know
  64                 * about.
  65                 */
  66                if (!addr)
  67                        return -EINVAL;
  68
  69                if (!consume_entry(cookie, addr))
  70                        return -EINVAL;
  71        }
  72
  73        /* Check for stack corruption */
  74        if (unwind_error(&state))
  75                return -EINVAL;
  76
  77        return 0;
  78}
  79
  80/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  81
  82struct stack_frame_user {
  83        const void __user       *next_fp;
  84        unsigned long           ret_addr;
  85};
  86
  87static int
  88copy_stack_frame(const struct stack_frame_user __user *fp,
  89                 struct stack_frame_user *frame)
  90{
  91        int ret;
  92
  93        if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
  94                return 0;
  95
  96        ret = 1;
  97        pagefault_disable();
  98        if (__get_user(frame->next_fp, &fp->next_fp) ||
  99            __get_user(frame->ret_addr, &fp->ret_addr))
 100                ret = 0;
 101        pagefault_enable();
 102
 103        return ret;
 104}
 105
 106void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
 107                          const struct pt_regs *regs)
 108{
 109        const void __user *fp = (const void __user *)regs->bp;
 110
 111        if (!consume_entry(cookie, regs->ip))
 112                return;
 113
 114        while (1) {
 115                struct stack_frame_user frame;
 116
 117                frame.next_fp = NULL;
 118                frame.ret_addr = 0;
 119                if (!copy_stack_frame(fp, &frame))
 120                        break;
 121                if ((unsigned long)fp < regs->sp)
 122                        break;
 123                if (!frame.ret_addr)
 124                        break;
 125                if (!consume_entry(cookie, frame.ret_addr))
 126                        break;
 127                fp = frame.next_fp;
 128        }
 129}
 130
 131