LXR linux/arch/x86/kernel/unwind

   1#include <linux/sched.h>
   2#include <asm/ptrace.h>
   3#include <asm/bitops.h>
   4#include <asm/stacktrace.h>
   5#include <asm/unwind.h>
   6
   7#define FRAME_HEADER_SIZE (sizeof(long) * 2)
   8
   9unsigned long unwind_get_return_address(struct unwind_state *state)
  10{
  11        unsigned long addr;
  12        unsigned long *addr_p = unwind_get_return_address_ptr(state);
  13
  14        if (unwind_done(state))
  15                return 0;
  16
  17        addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p,
  18                                     addr_p);
  19
  20        return __kernel_text_address(addr) ? addr : 0;
  21}
  22EXPORT_SYMBOL_GPL(unwind_get_return_address);
  23
  24static bool update_stack_state(struct unwind_state *state, void *addr,
  25                               size_t len)
  26{
  27        struct stack_info *info = &state->stack_info;
  28
  29        /*
  30         * If addr isn't on the current stack, switch to the next one.
  31         *
  32         * We may have to traverse multiple stacks to deal with the possibility
  33         * that 'info->next_sp' could point to an empty stack and 'addr' could
  34         * be on a subsequent stack.
  35         */
  36        while (!on_stack(info, addr, len))
  37                if (get_stack_info(info->next_sp, state->task, info,
  38                                   &state->stack_mask))
  39                        return false;
  40
  41        return true;
  42}
  43
  44bool unwind_next_frame(struct unwind_state *state)
  45{
  46        unsigned long *next_bp;
  47
  48        if (unwind_done(state))
  49                return false;
  50
  51        next_bp = (unsigned long *)*state->bp;
  52
  53        /* make sure the next frame's data is accessible */
  54        if (!update_stack_state(state, next_bp, FRAME_HEADER_SIZE))
  55                return false;
  56
  57        /* move to the next frame */
  58        state->bp = next_bp;
  59        return true;
  60}
  61EXPORT_SYMBOL_GPL(unwind_next_frame);
  62
  63void __unwind_start(struct unwind_state *state, struct task_struct *task,
  64                    struct pt_regs *regs, unsigned long *first_frame)
  65{
  66        memset(state, 0, sizeof(*state));
  67        state->task = task;
  68
  69        /* don't even attempt to start from user mode regs */
  70        if (regs && user_mode(regs)) {
  71                state->stack_info.type = STACK_TYPE_UNKNOWN;
  72                return;
  73        }
  74
  75        /* set up the starting stack frame */
  76        state->bp = get_frame_pointer(task, regs);
  77
  78        /* initialize stack info and make sure the frame data is accessible */
  79        get_stack_info(state->bp, state->task, &state->stack_info,
  80                       &state->stack_mask);
  81        update_stack_state(state, state->bp, FRAME_HEADER_SIZE);
  82
  83        /*
  84         * The caller can provide the address of the first frame directly
  85         * (first_frame) or indirectly (regs->sp) to indicate which stack frame
  86         * to start unwinding at.  Skip ahead until we reach it.
  87         */
  88        while (!unwind_done(state) &&
  89               (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
  90                        state->bp < first_frame))
  91                unwind_next_frame(state);
  92}
  93EXPORT_SYMBOL_GPL(__unwind_start);
  94