1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Stack trace management functions 4 * 5 * Copyright (C) 2022 Loongson Technology Corporation Limited 6 */ 7 #include <linux/sched.h> 8 #include <linux/stacktrace.h> 9 #include <linux/uaccess.h> 10 11 #include <asm/stacktrace.h> 12 #include <asm/unwind.h> 13 14 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 15 struct task_struct *task, struct pt_regs *regs) 16 { 17 unsigned long addr; 18 struct pt_regs dummyregs; 19 struct unwind_state state; 20 21 if (!regs) { 22 regs = &dummyregs; 23 24 if (task == current) { 25 regs->regs[3] = (unsigned long)__builtin_frame_address(0); 26 regs->csr_era = (unsigned long)__builtin_return_address(0); 27 } else { 28 regs->regs[3] = thread_saved_fp(task); 29 regs->csr_era = thread_saved_ra(task); 30 } 31 regs->regs[1] = 0; 32 regs->regs[22] = 0; 33 } 34 35 for (unwind_start(&state, task, regs); 36 !unwind_done(&state); unwind_next_frame(&state)) { 37 addr = unwind_get_return_address(&state); 38 if (!addr || !consume_entry(cookie, addr)) 39 break; 40 } 41 } 42 43 int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, 44 void *cookie, struct task_struct *task) 45 { 46 unsigned long addr; 47 struct pt_regs dummyregs; 48 struct pt_regs *regs = &dummyregs; 49 struct unwind_state state; 50 51 if (task == current) { 52 regs->regs[3] = (unsigned long)__builtin_frame_address(0); 53 regs->csr_era = (unsigned long)__builtin_return_address(0); 54 regs->regs[22] = 0; 55 } else { 56 regs->regs[3] = thread_saved_fp(task); 57 regs->csr_era = thread_saved_ra(task); 58 regs->regs[22] = task->thread.reg22; 59 } 60 regs->regs[1] = 0; 61 62 for (unwind_start(&state, task, regs); 63 !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) { 64 addr = unwind_get_return_address(&state); 65 66 /* 67 * A NULL or invalid return address probably means there's some 68 * generated code which __kernel_text_address() doesn't know about. 69 */ 70 if (!addr) 71 return -EINVAL; 72 73 if (!consume_entry(cookie, addr)) 74 return -EINVAL; 75 } 76 77 /* Check for stack corruption */ 78 if (unwind_error(&state)) 79 return -EINVAL; 80 81 return 0; 82 } 83 84 static int 85 copy_stack_frame(unsigned long fp, struct stack_frame *frame) 86 { 87 int ret = 1; 88 unsigned long err; 89 unsigned long __user *user_frame_tail; 90 91 user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame)); 92 if (!access_ok(user_frame_tail, sizeof(*frame))) 93 return 0; 94 95 pagefault_disable(); 96 err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame))); 97 if (err || (unsigned long)user_frame_tail >= frame->fp) 98 ret = 0; 99 pagefault_enable(); 100 101 return ret; 102 } 103 104 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie, 105 const struct pt_regs *regs) 106 { 107 unsigned long fp = regs->regs[22]; 108 109 while (fp && !((unsigned long)fp & 0xf)) { 110 struct stack_frame frame; 111 112 frame.fp = 0; 113 frame.ra = 0; 114 if (!copy_stack_frame(fp, &frame)) 115 break; 116 if (!frame.ra) 117 break; 118 if (!consume_entry(cookie, frame.ra)) 119 break; 120 fp = frame.fp; 121 } 122 } 123