1 /* SPDX-License-Identifier: GPL-2.0 */
2 #include <linux/sched.h>
3 #include <linux/sched/task.h>
4 #include <linux/sched/task_stack.h>
5 #include <linux/interrupt.h>
6 #include <asm/sections.h>
7 #include <asm/ptrace.h>
8 #include <asm/bitops.h>
9 #include <asm/stacktrace.h>
10 #include <asm/unwind.h>
12 unsigned long unwind_get_return_address(struct unwind_state *state)
14 if (unwind_done(state))
16 return __kernel_text_address(state->ip) ? state->ip : 0;
18 EXPORT_SYMBOL_GPL(unwind_get_return_address);
20 static bool outside_of_stack(struct unwind_state *state, unsigned long sp)
22 return (sp <= state->sp) ||
23 (sp > state->stack_info.end - sizeof(struct stack_frame));
26 static bool update_stack_info(struct unwind_state *state, unsigned long sp)
28 struct stack_info *info = &state->stack_info;
29 unsigned long *mask = &state->stack_mask;
31 /* New stack pointer leaves the current stack */
32 if (get_stack_info(sp, state->task, info, mask) != 0 ||
33 !on_stack(info, sp, sizeof(struct stack_frame)))
34 /* 'sp' does not point to a valid stack */
39 bool unwind_next_frame(struct unwind_state *state)
41 struct stack_info *info = &state->stack_info;
42 struct stack_frame *sf;
49 if (state->reuse_sp) {
51 state->reuse_sp = false;
53 sp = READ_ONCE_NOCHECK(regs->gprs[15]);
54 if (unlikely(outside_of_stack(state, sp))) {
55 if (!update_stack_info(state, sp))
59 sf = (struct stack_frame *) sp;
60 ip = READ_ONCE_NOCHECK(sf->gprs[8]);
64 sf = (struct stack_frame *) state->sp;
65 sp = READ_ONCE_NOCHECK(sf->back_chain);
67 /* Non-zero back-chain points to the previous frame */
68 if (unlikely(outside_of_stack(state, sp))) {
69 if (!update_stack_info(state, sp))
72 sf = (struct stack_frame *) sp;
73 ip = READ_ONCE_NOCHECK(sf->gprs[8]);
76 /* No back-chain, look for a pt_regs structure */
77 sp = state->sp + STACK_FRAME_OVERHEAD;
78 if (!on_stack(info, sp, sizeof(struct pt_regs)))
80 regs = (struct pt_regs *) sp;
81 if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)
83 ip = READ_ONCE_NOCHECK(regs->psw.addr);
88 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
89 /* Decode any ftrace redirection */
90 if (ip == (unsigned long) return_to_handler)
91 ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
95 /* Update unwind state */
99 state->reliable = reliable;
105 state->stack_info.type = STACK_TYPE_UNKNOWN;
108 EXPORT_SYMBOL_GPL(unwind_next_frame);
110 void __unwind_start(struct unwind_state *state, struct task_struct *task,
111 struct pt_regs *regs, unsigned long sp)
113 struct stack_info *info = &state->stack_info;
114 unsigned long *mask = &state->stack_mask;
115 bool reliable, reuse_sp;
116 struct stack_frame *sf;
119 memset(state, 0, sizeof(*state));
123 /* Don't even attempt to start from user mode regs: */
124 if (regs && user_mode(regs)) {
125 info->type = STACK_TYPE_UNKNOWN;
129 /* Get current stack pointer and initialize stack info */
130 if (get_stack_info(sp, task, info, mask) != 0 ||
131 !on_stack(info, sp, sizeof(struct stack_frame))) {
132 /* Something is wrong with the stack pointer */
133 info->type = STACK_TYPE_UNKNOWN;
138 /* Get the instruction pointer from pt_regs or the stack frame */
140 ip = READ_ONCE_NOCHECK(regs->psw.addr);
144 sf = (struct stack_frame *) sp;
145 ip = READ_ONCE_NOCHECK(sf->gprs[8]);
150 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
151 /* Decode any ftrace redirection */
152 if (ip == (unsigned long) return_to_handler)
153 ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
157 /* Update unwind state */
160 state->reliable = reliable;
161 state->reuse_sp = reuse_sp;
163 EXPORT_SYMBOL_GPL(__unwind_start);