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, false))
  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, false))
  28                        break;
  29        }
  30}
  31
  32/*
  33 * This function returns an error if it detects any unreliable features of the
  34 * stack.  Otherwise it guarantees that the stack trace is reliable.
  35 *
  36 * If the task is not 'current', the caller *must* ensure the task is inactive.
  37 */
  38int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
  39                             void *cookie, struct task_struct *task)
  40{
  41        struct unwind_state state;
  42        struct pt_regs *regs;
  43        unsigned long addr;
  44
  45        for (unwind_start(&state, task, NULL, NULL);
  46             !unwind_done(&state) && !unwind_error(&state);
  47             unwind_next_frame(&state)) {
  48
  49                regs = unwind_get_entry_regs(&state, NULL);
  50                if (regs) {
  51                        /* Success path for user tasks */
  52                        if (user_mode(regs))
  53                                return 0;
  54
  55                        /*
  56                         * Kernel mode registers on the stack indicate an
  57                         * in-kernel interrupt or exception (e.g., preemption
  58                         * or a page fault), which can make frame pointers
  59                         * unreliable.
  60                         */
  61
  62                        if (IS_ENABLED(CONFIG_FRAME_POINTER))
  63                                return -EINVAL;
  64                }
  65
  66                addr = unwind_get_return_address(&state);
  67
  68                /*
  69                 * A NULL or invalid return address probably means there's some
  70                 * generated code which __kernel_text_address() doesn't know
  71                 * about.
  72                 */
  73                if (!addr)
  74                        return -EINVAL;
  75
  76                if (!consume_entry(cookie, addr, false))
  77                        return -EINVAL;
  78        }
  79
  80        /* Check for stack corruption */
  81        if (unwind_error(&state))
  82                return -EINVAL;
  83
  84        /* Success path for non-user tasks, i.e. kthreads and idle tasks */
  85        if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
  86                return -EINVAL;
  87
  88        return 0;
  89}
  90
  91/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  92
  93struct stack_frame_user {
  94        const void __user       *next_fp;
  95        unsigned long           ret_addr;
  96};
  97
  98static int
  99copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
 100{
 101        int ret;
 102
 103        if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
 104                return 0;
 105
 106        ret = 1;
 107        pagefault_disable();
 108        if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
 109                ret = 0;
 110        pagefault_enable();
 111
 112        return ret;
 113}
 114
 115void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
 116                          const struct pt_regs *regs)
 117{
 118        const void __user *fp = (const void __user *)regs->bp;
 119
 120        if (!consume_entry(cookie, regs->ip, false))
 121                return;
 122
 123        while (1) {
 124                struct stack_frame_user frame;
 125
 126                frame.next_fp = NULL;
 127                frame.ret_addr = 0;
 128                if (!copy_stack_frame(fp, &frame))
 129                        break;
 130                if ((unsigned long)fp < regs->sp)
 131                        break;
 132                if (!frame.ret_addr)
 133                        break;
 134                if (!consume_entry(cookie, frame.ret_addr, false))
 135                        break;
 136                fp = frame.next_fp;
 137        }
 138}
 139
 140#include "rh_stacktrace.c"
 141