1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * arm64 callchain support 4 * 5 * Copyright (C) 2015 ARM Limited 6 */ 7 #include <linux/perf_event.h> 8 #include <linux/stacktrace.h> 9 #include <linux/uaccess.h> 10 11 #include <asm/pointer_auth.h> 12 13 struct frame_tail { 14 struct frame_tail __user *fp; 15 unsigned long lr; 16 } __attribute__((packed)); 17 18 /* 19 * Get the return address for a single stackframe and return a pointer to the 20 * next frame tail. 21 */ 22 static struct frame_tail __user * 23 user_backtrace(struct frame_tail __user *tail, 24 struct perf_callchain_entry_ctx *entry) 25 { 26 struct frame_tail buftail; 27 unsigned long err; 28 unsigned long lr; 29 30 /* Also check accessibility of one struct frame_tail beyond */ 31 if (!access_ok(tail, sizeof(buftail))) 32 return NULL; 33 34 pagefault_disable(); 35 err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); 36 pagefault_enable(); 37 38 if (err) 39 return NULL; 40 41 lr = ptrauth_strip_insn_pac(buftail.lr); 42 43 perf_callchain_store(entry, lr); 44 45 /* 46 * Frame pointers should strictly progress back up the stack 47 * (towards higher addresses). 48 */ 49 if (tail >= buftail.fp) 50 return NULL; 51 52 return buftail.fp; 53 } 54 55 #ifdef CONFIG_COMPAT 56 /* 57 * The registers we're interested in are at the end of the variable 58 * length saved register structure. The fp points at the end of this 59 * structure so the address of this struct is: 60 * (struct compat_frame_tail *)(xxx->fp)-1 61 * 62 * This code has been adapted from the ARM OProfile support. 63 */ 64 struct compat_frame_tail { 65 compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */ 66 u32 sp; 67 u32 lr; 68 } __attribute__((packed)); 69 70 static struct compat_frame_tail __user * 71 compat_user_backtrace(struct compat_frame_tail __user *tail, 72 struct perf_callchain_entry_ctx *entry) 73 { 74 struct compat_frame_tail buftail; 75 unsigned long err; 76 77 /* Also check accessibility of one struct frame_tail beyond */ 78 if (!access_ok(tail, sizeof(buftail))) 79 return NULL; 80 81 pagefault_disable(); 82 err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); 83 pagefault_enable(); 84 85 if (err) 86 return NULL; 87 88 perf_callchain_store(entry, buftail.lr); 89 90 /* 91 * Frame pointers should strictly progress back up the stack 92 * (towards higher addresses). 93 */ 94 if (tail + 1 >= (struct compat_frame_tail __user *) 95 compat_ptr(buftail.fp)) 96 return NULL; 97 98 return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1; 99 } 100 #endif /* CONFIG_COMPAT */ 101 102 void perf_callchain_user(struct perf_callchain_entry_ctx *entry, 103 struct pt_regs *regs) 104 { 105 if (perf_guest_state()) { 106 /* We don't support guest os callchain now */ 107 return; 108 } 109 110 perf_callchain_store(entry, regs->pc); 111 112 if (!compat_user_mode(regs)) { 113 /* AARCH64 mode */ 114 struct frame_tail __user *tail; 115 116 tail = (struct frame_tail __user *)regs->regs[29]; 117 118 while (entry->nr < entry->max_stack && 119 tail && !((unsigned long)tail & 0x7)) 120 tail = user_backtrace(tail, entry); 121 } else { 122 #ifdef CONFIG_COMPAT 123 /* AARCH32 compat mode */ 124 struct compat_frame_tail __user *tail; 125 126 tail = (struct compat_frame_tail __user *)regs->compat_fp - 1; 127 128 while ((entry->nr < entry->max_stack) && 129 tail && !((unsigned long)tail & 0x3)) 130 tail = compat_user_backtrace(tail, entry); 131 #endif 132 } 133 } 134 135 static bool callchain_trace(void *data, unsigned long pc) 136 { 137 struct perf_callchain_entry_ctx *entry = data; 138 return perf_callchain_store(entry, pc) == 0; 139 } 140 141 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, 142 struct pt_regs *regs) 143 { 144 if (perf_guest_state()) { 145 /* We don't support guest os callchain now */ 146 return; 147 } 148 149 arch_stack_walk(callchain_trace, entry, current, regs); 150 } 151 152 unsigned long perf_instruction_pointer(struct pt_regs *regs) 153 { 154 if (perf_guest_state()) 155 return perf_guest_get_ip(); 156 157 return instruction_pointer(regs); 158 } 159 160 unsigned long perf_misc_flags(struct pt_regs *regs) 161 { 162 unsigned int guest_state = perf_guest_state(); 163 int misc = 0; 164 165 if (guest_state) { 166 if (guest_state & PERF_GUEST_USER) 167 misc |= PERF_RECORD_MISC_GUEST_USER; 168 else 169 misc |= PERF_RECORD_MISC_GUEST_KERNEL; 170 } else { 171 if (user_mode(regs)) 172 misc |= PERF_RECORD_MISC_USER; 173 else 174 misc |= PERF_RECORD_MISC_KERNEL; 175 } 176 177 return misc; 178 } 179