1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Most of this ideas comes from x86. 4 * 5 * Copyright (C) 2022 Loongson Technology Corporation Limited 6 */ 7 #ifndef _ASM_UNWIND_H 8 #define _ASM_UNWIND_H 9 10 #include <linux/sched.h> 11 #include <linux/ftrace.h> 12 13 #include <asm/ptrace.h> 14 #include <asm/stacktrace.h> 15 16 enum unwinder_type { 17 UNWINDER_GUESS, 18 UNWINDER_PROLOGUE, 19 }; 20 21 struct unwind_state { 22 char type; /* UNWINDER_XXX */ 23 struct stack_info stack_info; 24 struct task_struct *task; 25 bool first, error, reset; 26 int graph_idx; 27 unsigned long sp, pc, ra; 28 }; 29 30 bool default_next_frame(struct unwind_state *state); 31 32 void unwind_start(struct unwind_state *state, 33 struct task_struct *task, struct pt_regs *regs); 34 bool unwind_next_frame(struct unwind_state *state); 35 unsigned long unwind_get_return_address(struct unwind_state *state); 36 37 static inline bool unwind_done(struct unwind_state *state) 38 { 39 return state->stack_info.type == STACK_TYPE_UNKNOWN; 40 } 41 42 static inline bool unwind_error(struct unwind_state *state) 43 { 44 return state->error; 45 } 46 47 #define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1])) 48 49 static inline unsigned long unwind_graph_addr(struct unwind_state *state, 50 unsigned long pc, unsigned long cfa) 51 { 52 return ftrace_graph_ret_addr(state->task, &state->graph_idx, 53 pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET)); 54 } 55 56 static __always_inline void __unwind_start(struct unwind_state *state, 57 struct task_struct *task, struct pt_regs *regs) 58 { 59 memset(state, 0, sizeof(*state)); 60 if (regs) { 61 state->sp = regs->regs[3]; 62 state->pc = regs->csr_era; 63 state->ra = regs->regs[1]; 64 } else if (task && task != current) { 65 state->sp = thread_saved_fp(task); 66 state->pc = thread_saved_ra(task); 67 state->ra = 0; 68 } else { 69 state->sp = (unsigned long)__builtin_frame_address(0); 70 state->pc = (unsigned long)__builtin_return_address(0); 71 state->ra = 0; 72 } 73 state->task = task; 74 get_stack_info(state->sp, state->task, &state->stack_info); 75 state->pc = unwind_graph_addr(state, state->pc, state->sp); 76 } 77 78 static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state) 79 { 80 return unwind_done(state) ? 0 : state->pc; 81 } 82 #endif /* _ASM_UNWIND_H */ 83