Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Code for replacing ftrace calls with jumps. |
| 3 | * |
| 4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 5 | * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China |
Wu Zhangjin | f7a904d | 2010-01-04 17:16:51 +0800 | [diff] [blame] | 6 | * Author: Wu Zhangjin <wuzhangjin@gmail.com> |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 7 | * |
| 8 | * Thanks goes to Steven Rostedt for writing the original x86 version. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/uaccess.h> |
| 12 | #include <linux/init.h> |
| 13 | #include <linux/ftrace.h> |
| 14 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 15 | #include <asm/asm.h> |
| 16 | #include <asm/asm-offsets.h> |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 17 | #include <asm/cacheflush.h> |
| 18 | #include <asm/uasm.h> |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 19 | |
Wu Zhangjin | c9f8487 | 2010-05-14 19:08:34 +0800 | [diff] [blame] | 20 | /* |
| 21 | * If the Instruction Pointer is in module space (0xc0000000), return true; |
| 22 | * otherwise, it is in kernel space (0x80000000), return false. |
| 23 | * |
| 24 | * FIXME: This will not work when the kernel space and module space are the |
| 25 | * same. If they are the same, we need to modify scripts/recordmcount.pl, |
| 26 | * ftrace_make_nop/call() and the other related parts to ensure the |
| 27 | * enabling/disabling of the calling site to _mcount is right for both kernel |
| 28 | * and module. |
| 29 | */ |
| 30 | |
| 31 | static inline int in_module(unsigned long ip) |
| 32 | { |
| 33 | return ip & 0x40000000; |
| 34 | } |
| 35 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 36 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 37 | |
| 38 | #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ |
| 39 | #define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */ |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 40 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 41 | #define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */ |
| 42 | #define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */ |
| 43 | #define INSN_NOP 0x00000000 /* nop */ |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 44 | #define INSN_JAL(addr) \ |
| 45 | ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK))) |
| 46 | |
| 47 | static unsigned int insn_jal_ftrace_caller __read_mostly; |
| 48 | static unsigned int insn_lui_v1_hi16_mcount __read_mostly; |
| 49 | static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly; |
| 50 | |
| 51 | static inline void ftrace_dyn_arch_init_insns(void) |
| 52 | { |
| 53 | u32 *buf; |
| 54 | unsigned int v1; |
| 55 | |
| 56 | /* lui v1, hi16_mcount */ |
| 57 | v1 = 3; |
| 58 | buf = (u32 *)&insn_lui_v1_hi16_mcount; |
| 59 | UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR); |
| 60 | |
| 61 | /* jal (ftrace_caller + 8), jump over the first two instruction */ |
| 62 | buf = (u32 *)&insn_jal_ftrace_caller; |
| 63 | uasm_i_jal(&buf, (FTRACE_ADDR + 8)); |
| 64 | |
| 65 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 66 | /* j ftrace_graph_caller */ |
| 67 | buf = (u32 *)&insn_j_ftrace_graph_caller; |
| 68 | uasm_i_j(&buf, (unsigned long)ftrace_graph_caller); |
| 69 | #endif |
| 70 | } |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 71 | |
| 72 | static int ftrace_modify_code(unsigned long ip, unsigned int new_code) |
| 73 | { |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 74 | int faulted; |
| 75 | |
| 76 | /* *(unsigned int *)ip = new_code; */ |
| 77 | safe_store_code(new_code, ip, faulted); |
| 78 | |
| 79 | if (unlikely(faulted)) |
| 80 | return -EFAULT; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 81 | |
| 82 | flush_icache_range(ip, ip + 8); |
| 83 | |
| 84 | return 0; |
| 85 | } |
| 86 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 87 | int ftrace_make_nop(struct module *mod, |
| 88 | struct dyn_ftrace *rec, unsigned long addr) |
| 89 | { |
| 90 | unsigned int new; |
| 91 | unsigned long ip = rec->ip; |
| 92 | |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 93 | /* |
| 94 | * We have compiled module with -mlong-calls, but compiled the kernel |
| 95 | * without it, we need to cope with them respectively. |
| 96 | */ |
Wu Zhangjin | c9f8487 | 2010-05-14 19:08:34 +0800 | [diff] [blame] | 97 | if (in_module(ip)) { |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 98 | #if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT) |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 99 | /* |
| 100 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005) |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 101 | * addiu v1, v1, low_16bit_of_mcount |
| 102 | * move at, ra |
| 103 | * move $12, ra_address |
| 104 | * jalr v1 |
| 105 | * sub sp, sp, 8 |
| 106 | * 1: offset = 5 instructions |
| 107 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 108 | new = INSN_B_1F_5; |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 109 | #else |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 110 | /* |
| 111 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004) |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 112 | * addiu v1, v1, low_16bit_of_mcount |
| 113 | * move at, ra |
| 114 | * jalr v1 |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 115 | * nop | move $12, ra_address | sub sp, sp, 8 |
| 116 | * 1: offset = 4 instructions |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 117 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 118 | new = INSN_B_1F_4; |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 119 | #endif |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 120 | } else { |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 121 | /* |
| 122 | * move at, ra |
| 123 | * jal _mcount --> nop |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 124 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 125 | new = INSN_NOP; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 126 | } |
| 127 | return ftrace_modify_code(ip, new); |
| 128 | } |
| 129 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 130 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 131 | { |
| 132 | unsigned int new; |
| 133 | unsigned long ip = rec->ip; |
| 134 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 135 | /* ip, module: 0xc0000000, kernel: 0x80000000 */ |
Wu Zhangjin | c9f8487 | 2010-05-14 19:08:34 +0800 | [diff] [blame] | 136 | new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 137 | |
| 138 | return ftrace_modify_code(ip, new); |
| 139 | } |
| 140 | |
| 141 | #define FTRACE_CALL_IP ((unsigned long)(&ftrace_call)) |
| 142 | |
| 143 | int ftrace_update_ftrace_func(ftrace_func_t func) |
| 144 | { |
| 145 | unsigned int new; |
| 146 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 147 | new = INSN_JAL((unsigned long)func); |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 148 | |
| 149 | return ftrace_modify_code(FTRACE_CALL_IP, new); |
| 150 | } |
| 151 | |
| 152 | int __init ftrace_dyn_arch_init(void *data) |
| 153 | { |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 154 | /* Encode the instructions when booting */ |
| 155 | ftrace_dyn_arch_init_insns(); |
| 156 | |
| 157 | /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */ |
| 158 | ftrace_modify_code(MCOUNT_ADDR, INSN_NOP); |
| 159 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 160 | /* The return code is retured via data */ |
| 161 | *(unsigned long *)data = 0; |
| 162 | |
| 163 | return 0; |
| 164 | } |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 165 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 166 | |
| 167 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 168 | |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 169 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 170 | |
| 171 | extern void ftrace_graph_call(void); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 172 | #define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call)) |
| 173 | |
| 174 | int ftrace_enable_ftrace_graph_caller(void) |
| 175 | { |
| 176 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 177 | insn_j_ftrace_graph_caller); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 178 | } |
| 179 | |
| 180 | int ftrace_disable_ftrace_graph_caller(void) |
| 181 | { |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 182 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 183 | } |
| 184 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 185 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 186 | |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 187 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 188 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 189 | #define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */ |
| 190 | #define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */ |
| 191 | #define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */ |
| 192 | |
| 193 | unsigned long ftrace_get_parent_addr(unsigned long self_addr, |
| 194 | unsigned long parent, |
| 195 | unsigned long parent_addr, |
| 196 | unsigned long fp) |
| 197 | { |
| 198 | unsigned long sp, ip, ra; |
| 199 | unsigned int code; |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 200 | int faulted; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 201 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 202 | /* |
| 203 | * For module, move the ip from calling site of mcount to the |
| 204 | * instruction "lui v1, hi_16bit_of_mcount"(offset is 20), but for |
| 205 | * kernel, move to the instruction "move ra, at"(offset is 12) |
| 206 | */ |
Wu Zhangjin | c9f8487 | 2010-05-14 19:08:34 +0800 | [diff] [blame] | 207 | ip = self_addr - (in_module(self_addr) ? 20 : 12); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 208 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 209 | /* |
| 210 | * search the text until finding the non-store instruction or "s{d,w} |
| 211 | * ra, offset(sp)" instruction |
| 212 | */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 213 | do { |
| 214 | ip -= 4; |
| 215 | |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 216 | /* get the code at "ip": code = *(unsigned int *)ip; */ |
| 217 | safe_load_code(code, ip, faulted); |
| 218 | |
| 219 | if (unlikely(faulted)) |
| 220 | return 0; |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 221 | /* |
| 222 | * If we hit the non-store instruction before finding where the |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 223 | * ra is stored, then this is a leaf function and it does not |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 224 | * store the ra on the stack |
| 225 | */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 226 | if ((code & S_R_SP) != S_R_SP) |
| 227 | return parent_addr; |
| 228 | |
| 229 | } while (((code & S_RA_SP) != S_RA_SP)); |
| 230 | |
| 231 | sp = fp + (code & OFFSET_MASK); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 232 | |
| 233 | /* ra = *(unsigned long *)sp; */ |
| 234 | safe_load_stack(ra, sp, faulted); |
| 235 | if (unlikely(faulted)) |
| 236 | return 0; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 237 | |
| 238 | if (ra == parent) |
| 239 | return sp; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 240 | return 0; |
| 241 | } |
| 242 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 243 | #endif /* !KBUILD_MCOUNT_RA_ADDRESS */ |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 244 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 245 | /* |
| 246 | * Hook the return address and push it in the stack of return addrs |
| 247 | * in current thread info. |
| 248 | */ |
| 249 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, |
| 250 | unsigned long fp) |
| 251 | { |
| 252 | unsigned long old; |
| 253 | struct ftrace_graph_ent trace; |
| 254 | unsigned long return_hooker = (unsigned long) |
| 255 | &return_to_handler; |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 256 | int faulted; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 257 | |
| 258 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
| 259 | return; |
| 260 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 261 | /* |
| 262 | * "parent" is the stack address saved the return address of the caller |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 263 | * of _mcount. |
| 264 | * |
| 265 | * if the gcc < 4.5, a leaf function does not save the return address |
| 266 | * in the stack address, so, we "emulate" one in _mcount's stack space, |
| 267 | * and hijack it directly, but for a non-leaf function, it save the |
| 268 | * return address to the its own stack space, we can not hijack it |
| 269 | * directly, but need to find the real stack address, |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 270 | * ftrace_get_parent_addr() does it! |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 271 | * |
| 272 | * if gcc>= 4.5, with the new -mmcount-ra-address option, for a |
| 273 | * non-leaf function, the location of the return address will be saved |
| 274 | * to $12 for us, and for a leaf function, only put a zero into $12. we |
| 275 | * do it in ftrace_graph_caller of mcount.S. |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 276 | */ |
| 277 | |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 278 | /* old = *parent; */ |
| 279 | safe_load_stack(old, parent, faulted); |
| 280 | if (unlikely(faulted)) |
| 281 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 282 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 283 | parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old, |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 284 | (unsigned long)parent, fp); |
| 285 | /* |
| 286 | * If fails when getting the stack address of the non-leaf function's |
| 287 | * ra, stop function graph tracer and return |
| 288 | */ |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 289 | if (parent == 0) |
| 290 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 291 | #endif |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 292 | /* *parent = return_hooker; */ |
| 293 | safe_store_stack(return_hooker, parent, faulted); |
| 294 | if (unlikely(faulted)) |
| 295 | goto out; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 296 | |
| 297 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) == |
| 298 | -EBUSY) { |
| 299 | *parent = old; |
| 300 | return; |
| 301 | } |
| 302 | |
| 303 | trace.func = self_addr; |
| 304 | |
| 305 | /* Only trace if the calling function expects to */ |
| 306 | if (!ftrace_graph_entry(&trace)) { |
| 307 | current->curr_ret_stack--; |
| 308 | *parent = old; |
| 309 | } |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 310 | return; |
| 311 | out: |
| 312 | ftrace_graph_stop(); |
| 313 | WARN_ON(1); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 314 | } |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 315 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |