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 9 unsigned 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 } 22 EXPORT_SYMBOL_GPL(unwind_get_return_address); 23 24 static 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 44 bool 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 } 61 EXPORT_SYMBOL_GPL(unwind_next_frame); 62 63 void __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 } 93 EXPORT_SYMBOL_GPL(__unwind_start); 94