1 /* 2 * arm64 callchain support 3 * 4 * Copyright (C) 2015 ARM Limited 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 #include <linux/perf_event.h> 19 #include <linux/uaccess.h> 20 21 #include <asm/stacktrace.h> 22 23 struct frame_tail { 24 struct frame_tail __user *fp; 25 unsigned long lr; 26 } __attribute__((packed)); 27 28 /* 29 * Get the return address for a single stackframe and return a pointer to the 30 * next frame tail. 31 */ 32 static struct frame_tail __user * 33 user_backtrace(struct frame_tail __user *tail, 34 struct perf_callchain_entry *entry) 35 { 36 struct frame_tail buftail; 37 unsigned long err; 38 39 /* Also check accessibility of one struct frame_tail beyond */ 40 if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) 41 return NULL; 42 43 pagefault_disable(); 44 err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); 45 pagefault_enable(); 46 47 if (err) 48 return NULL; 49 50 perf_callchain_store(entry, buftail.lr); 51 52 /* 53 * Frame pointers should strictly progress back up the stack 54 * (towards higher addresses). 55 */ 56 if (tail >= buftail.fp) 57 return NULL; 58 59 return buftail.fp; 60 } 61 62 #ifdef CONFIG_COMPAT 63 /* 64 * The registers we're interested in are at the end of the variable 65 * length saved register structure. The fp points at the end of this 66 * structure so the address of this struct is: 67 * (struct compat_frame_tail *)(xxx->fp)-1 68 * 69 * This code has been adapted from the ARM OProfile support. 70 */ 71 struct compat_frame_tail { 72 compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */ 73 u32 sp; 74 u32 lr; 75 } __attribute__((packed)); 76 77 static struct compat_frame_tail __user * 78 compat_user_backtrace(struct compat_frame_tail __user *tail, 79 struct perf_callchain_entry *entry) 80 { 81 struct compat_frame_tail buftail; 82 unsigned long err; 83 84 /* Also check accessibility of one struct frame_tail beyond */ 85 if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) 86 return NULL; 87 88 pagefault_disable(); 89 err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); 90 pagefault_enable(); 91 92 if (err) 93 return NULL; 94 95 perf_callchain_store(entry, buftail.lr); 96 97 /* 98 * Frame pointers should strictly progress back up the stack 99 * (towards higher addresses). 100 */ 101 if (tail + 1 >= (struct compat_frame_tail __user *) 102 compat_ptr(buftail.fp)) 103 return NULL; 104 105 return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1; 106 } 107 #endif /* CONFIG_COMPAT */ 108 109 void perf_callchain_user(struct perf_callchain_entry *entry, 110 struct pt_regs *regs) 111 { 112 if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { 113 /* We don't support guest os callchain now */ 114 return; 115 } 116 117 perf_callchain_store(entry, regs->pc); 118 119 if (!compat_user_mode(regs)) { 120 /* AARCH64 mode */ 121 struct frame_tail __user *tail; 122 123 tail = (struct frame_tail __user *)regs->regs[29]; 124 125 while (entry->nr < PERF_MAX_STACK_DEPTH && 126 tail && !((unsigned long)tail & 0xf)) 127 tail = user_backtrace(tail, entry); 128 } else { 129 #ifdef CONFIG_COMPAT 130 /* AARCH32 compat mode */ 131 struct compat_frame_tail __user *tail; 132 133 tail = (struct compat_frame_tail __user *)regs->compat_fp - 1; 134 135 while ((entry->nr < PERF_MAX_STACK_DEPTH) && 136 tail && !((unsigned long)tail & 0x3)) 137 tail = compat_user_backtrace(tail, entry); 138 #endif 139 } 140 } 141 142 /* 143 * Gets called by walk_stackframe() for every stackframe. This will be called 144 * whist unwinding the stackframe and is like a subroutine return so we use 145 * the PC. 146 */ 147 static int callchain_trace(struct stackframe *frame, void *data) 148 { 149 struct perf_callchain_entry *entry = data; 150 perf_callchain_store(entry, frame->pc); 151 return 0; 152 } 153 154 void perf_callchain_kernel(struct perf_callchain_entry *entry, 155 struct pt_regs *regs) 156 { 157 struct stackframe frame; 158 159 if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { 160 /* We don't support guest os callchain now */ 161 return; 162 } 163 164 frame.fp = regs->regs[29]; 165 frame.sp = regs->sp; 166 frame.pc = regs->pc; 167 168 walk_stackframe(&frame, callchain_trace, entry); 169 } 170 171 unsigned long perf_instruction_pointer(struct pt_regs *regs) 172 { 173 if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) 174 return perf_guest_cbs->get_guest_ip(); 175 176 return instruction_pointer(regs); 177 } 178 179 unsigned long perf_misc_flags(struct pt_regs *regs) 180 { 181 int misc = 0; 182 183 if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { 184 if (perf_guest_cbs->is_user_mode()) 185 misc |= PERF_RECORD_MISC_GUEST_USER; 186 else 187 misc |= PERF_RECORD_MISC_GUEST_KERNEL; 188 } else { 189 if (user_mode(regs)) 190 misc |= PERF_RECORD_MISC_USER; 191 else 192 misc |= PERF_RECORD_MISC_KERNEL; 193 } 194 195 return misc; 196 } 197