1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Stack trace management functions 4 * 5 * Copyright IBM Corp. 2006 6 */ 7 8 #include <linux/perf_event.h> 9 #include <linux/stacktrace.h> 10 #include <linux/uaccess.h> 11 #include <asm/asm-offsets.h> 12 #include <asm/stacktrace.h> 13 #include <asm/unwind.h> 14 #include <asm/kprobes.h> 15 #include <asm/ptrace.h> 16 17 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 18 struct task_struct *task, struct pt_regs *regs) 19 { 20 struct unwind_state state; 21 unsigned long addr; 22 23 unwind_for_each_frame(&state, task, regs, 0) { 24 addr = unwind_get_return_address(&state); 25 if (!addr || !consume_entry(cookie, addr)) 26 break; 27 } 28 } 29 30 int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, 31 void *cookie, struct task_struct *task) 32 { 33 struct unwind_state state; 34 unsigned long addr; 35 36 unwind_for_each_frame(&state, task, NULL, 0) { 37 if (state.stack_info.type != STACK_TYPE_TASK) 38 return -EINVAL; 39 40 if (state.regs) 41 return -EINVAL; 42 43 addr = unwind_get_return_address(&state); 44 if (!addr) 45 return -EINVAL; 46 47 #ifdef CONFIG_RETHOOK 48 /* 49 * Mark stacktraces with krethook functions on them 50 * as unreliable. 51 */ 52 if (state.ip == (unsigned long)arch_rethook_trampoline) 53 return -EINVAL; 54 #endif 55 56 if (!consume_entry(cookie, addr)) 57 return -EINVAL; 58 } 59 60 /* Check for stack corruption */ 61 if (unwind_error(&state)) 62 return -EINVAL; 63 return 0; 64 } 65 66 static inline bool store_ip(stack_trace_consume_fn consume_entry, void *cookie, 67 struct perf_callchain_entry_ctx *entry, bool perf, 68 unsigned long ip) 69 { 70 #ifdef CONFIG_PERF_EVENTS 71 if (perf) { 72 if (perf_callchain_store(entry, ip)) 73 return false; 74 return true; 75 } 76 #endif 77 return consume_entry(cookie, ip); 78 } 79 80 static inline bool ip_invalid(unsigned long ip) 81 { 82 /* 83 * Perform some basic checks if an instruction address taken 84 * from unreliable source is invalid. 85 */ 86 if (ip & 1) 87 return true; 88 if (ip < mmap_min_addr) 89 return true; 90 if (ip >= current->mm->context.asce_limit) 91 return true; 92 return false; 93 } 94 95 static inline bool ip_within_vdso(unsigned long ip) 96 { 97 return in_range(ip, current->mm->context.vdso_base, vdso_text_size()); 98 } 99 100 void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie, 101 struct perf_callchain_entry_ctx *entry, 102 const struct pt_regs *regs, bool perf) 103 { 104 struct stack_frame_vdso_wrapper __user *sf_vdso; 105 struct stack_frame_user __user *sf; 106 unsigned long ip, sp; 107 bool first = true; 108 109 if (!current->mm) 110 return; 111 ip = instruction_pointer(regs); 112 if (!store_ip(consume_entry, cookie, entry, perf, ip)) 113 return; 114 sf = (void __user *)user_stack_pointer(regs); 115 pagefault_disable(); 116 while (1) { 117 if (__get_user(sp, &sf->back_chain)) 118 break; 119 /* 120 * VDSO entry code has a non-standard stack frame layout. 121 * See VDSO user wrapper code for details. 122 */ 123 if (!sp && ip_within_vdso(ip)) { 124 sf_vdso = (void __user *)sf; 125 if (__get_user(ip, &sf_vdso->return_address)) 126 break; 127 sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD; 128 sf = (void __user *)sp; 129 if (__get_user(sp, &sf->back_chain)) 130 break; 131 } else { 132 sf = (void __user *)sp; 133 if (__get_user(ip, &sf->gprs[8])) 134 break; 135 } 136 /* Sanity check: ABI requires SP to be 8 byte aligned. */ 137 if (sp & 0x7) 138 break; 139 if (ip_invalid(ip)) { 140 /* 141 * If the instruction address is invalid, and this 142 * is the first stack frame, assume r14 has not 143 * been written to the stack yet. Otherwise exit. 144 */ 145 if (!first) 146 break; 147 ip = regs->gprs[14]; 148 if (ip_invalid(ip)) 149 break; 150 } 151 if (!store_ip(consume_entry, cookie, entry, perf, ip)) 152 break; 153 first = false; 154 } 155 pagefault_enable(); 156 } 157 158 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie, 159 const struct pt_regs *regs) 160 { 161 arch_stack_walk_user_common(consume_entry, cookie, NULL, regs, false); 162 } 163