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 | |
| 20 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 21 | |
| 22 | #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ |
| 23 | #define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */ |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 24 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 25 | #define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */ |
| 26 | #define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */ |
| 27 | #define INSN_NOP 0x00000000 /* nop */ |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 28 | #define INSN_JAL(addr) \ |
| 29 | ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK))) |
| 30 | |
| 31 | static unsigned int insn_jal_ftrace_caller __read_mostly; |
| 32 | static unsigned int insn_lui_v1_hi16_mcount __read_mostly; |
| 33 | static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly; |
| 34 | |
| 35 | static inline void ftrace_dyn_arch_init_insns(void) |
| 36 | { |
| 37 | u32 *buf; |
| 38 | unsigned int v1; |
| 39 | |
| 40 | /* lui v1, hi16_mcount */ |
| 41 | v1 = 3; |
| 42 | buf = (u32 *)&insn_lui_v1_hi16_mcount; |
| 43 | UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR); |
| 44 | |
| 45 | /* jal (ftrace_caller + 8), jump over the first two instruction */ |
| 46 | buf = (u32 *)&insn_jal_ftrace_caller; |
| 47 | uasm_i_jal(&buf, (FTRACE_ADDR + 8)); |
| 48 | |
| 49 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 50 | /* j ftrace_graph_caller */ |
| 51 | buf = (u32 *)&insn_j_ftrace_graph_caller; |
| 52 | uasm_i_j(&buf, (unsigned long)ftrace_graph_caller); |
| 53 | #endif |
| 54 | } |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 55 | |
| 56 | static int ftrace_modify_code(unsigned long ip, unsigned int new_code) |
| 57 | { |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 58 | int faulted; |
| 59 | |
| 60 | /* *(unsigned int *)ip = new_code; */ |
| 61 | safe_store_code(new_code, ip, faulted); |
| 62 | |
| 63 | if (unlikely(faulted)) |
| 64 | return -EFAULT; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 65 | |
| 66 | flush_icache_range(ip, ip + 8); |
| 67 | |
| 68 | return 0; |
| 69 | } |
| 70 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 71 | int ftrace_make_nop(struct module *mod, |
| 72 | struct dyn_ftrace *rec, unsigned long addr) |
| 73 | { |
| 74 | unsigned int new; |
| 75 | unsigned long ip = rec->ip; |
| 76 | |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 77 | /* |
| 78 | * We have compiled module with -mlong-calls, but compiled the kernel |
| 79 | * without it, we need to cope with them respectively. |
| 80 | */ |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 81 | if (ip & 0x40000000) { |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 82 | #if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT) |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 83 | /* |
| 84 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005) |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 85 | * addiu v1, v1, low_16bit_of_mcount |
| 86 | * move at, ra |
| 87 | * move $12, ra_address |
| 88 | * jalr v1 |
| 89 | * sub sp, sp, 8 |
| 90 | * 1: offset = 5 instructions |
| 91 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 92 | new = INSN_B_1F_5; |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 93 | #else |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 94 | /* |
| 95 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004) |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 96 | * addiu v1, v1, low_16bit_of_mcount |
| 97 | * move at, ra |
| 98 | * jalr v1 |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 99 | * nop | move $12, ra_address | sub sp, sp, 8 |
| 100 | * 1: offset = 4 instructions |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 101 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 102 | new = INSN_B_1F_4; |
Wu Zhangjin | 3a2af2d | 2010-05-14 19:08:30 +0800 | [diff] [blame] | 103 | #endif |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 104 | } else { |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 105 | /* |
| 106 | * move at, ra |
| 107 | * jal _mcount --> nop |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 108 | */ |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 109 | new = INSN_NOP; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 110 | } |
| 111 | return ftrace_modify_code(ip, new); |
| 112 | } |
| 113 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 114 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 115 | { |
| 116 | unsigned int new; |
| 117 | unsigned long ip = rec->ip; |
| 118 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 119 | /* ip, module: 0xc0000000, kernel: 0x80000000 */ |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 120 | new = (ip & 0x40000000) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 121 | |
| 122 | return ftrace_modify_code(ip, new); |
| 123 | } |
| 124 | |
| 125 | #define FTRACE_CALL_IP ((unsigned long)(&ftrace_call)) |
| 126 | |
| 127 | int ftrace_update_ftrace_func(ftrace_func_t func) |
| 128 | { |
| 129 | unsigned int new; |
| 130 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 131 | new = INSN_JAL((unsigned long)func); |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 132 | |
| 133 | return ftrace_modify_code(FTRACE_CALL_IP, new); |
| 134 | } |
| 135 | |
| 136 | int __init ftrace_dyn_arch_init(void *data) |
| 137 | { |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 138 | /* Encode the instructions when booting */ |
| 139 | ftrace_dyn_arch_init_insns(); |
| 140 | |
| 141 | /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */ |
| 142 | ftrace_modify_code(MCOUNT_ADDR, INSN_NOP); |
| 143 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 144 | /* The return code is retured via data */ |
| 145 | *(unsigned long *)data = 0; |
| 146 | |
| 147 | return 0; |
| 148 | } |
| 149 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 150 | |
| 151 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 152 | |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 153 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 154 | |
| 155 | extern void ftrace_graph_call(void); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 156 | #define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call)) |
| 157 | |
| 158 | int ftrace_enable_ftrace_graph_caller(void) |
| 159 | { |
| 160 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame^] | 161 | insn_j_ftrace_graph_caller); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 162 | } |
| 163 | |
| 164 | int ftrace_disable_ftrace_graph_caller(void) |
| 165 | { |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 166 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 167 | } |
| 168 | |
| 169 | #endif /* !CONFIG_DYNAMIC_FTRACE */ |
| 170 | |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 171 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 172 | #define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */ |
| 173 | #define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */ |
| 174 | #define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */ |
| 175 | |
| 176 | unsigned long ftrace_get_parent_addr(unsigned long self_addr, |
| 177 | unsigned long parent, |
| 178 | unsigned long parent_addr, |
| 179 | unsigned long fp) |
| 180 | { |
| 181 | unsigned long sp, ip, ra; |
| 182 | unsigned int code; |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 183 | int faulted; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 184 | |
| 185 | /* in module or kernel? */ |
| 186 | if (self_addr & 0x40000000) { |
| 187 | /* module: move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */ |
| 188 | ip = self_addr - 20; |
| 189 | } else { |
| 190 | /* kernel: move to the instruction "move ra, at" */ |
| 191 | ip = self_addr - 12; |
| 192 | } |
| 193 | |
| 194 | /* search the text until finding the non-store instruction or "s{d,w} |
| 195 | * ra, offset(sp)" instruction */ |
| 196 | do { |
| 197 | ip -= 4; |
| 198 | |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 199 | /* get the code at "ip": code = *(unsigned int *)ip; */ |
| 200 | safe_load_code(code, ip, faulted); |
| 201 | |
| 202 | if (unlikely(faulted)) |
| 203 | return 0; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 204 | |
| 205 | /* If we hit the non-store instruction before finding where the |
| 206 | * ra is stored, then this is a leaf function and it does not |
| 207 | * store the ra on the stack. */ |
| 208 | if ((code & S_R_SP) != S_R_SP) |
| 209 | return parent_addr; |
| 210 | |
| 211 | } while (((code & S_RA_SP) != S_RA_SP)); |
| 212 | |
| 213 | sp = fp + (code & OFFSET_MASK); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 214 | |
| 215 | /* ra = *(unsigned long *)sp; */ |
| 216 | safe_load_stack(ra, sp, faulted); |
| 217 | if (unlikely(faulted)) |
| 218 | return 0; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 219 | |
| 220 | if (ra == parent) |
| 221 | return sp; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 222 | return 0; |
| 223 | } |
| 224 | |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 225 | #endif |
| 226 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 227 | /* |
| 228 | * Hook the return address and push it in the stack of return addrs |
| 229 | * in current thread info. |
| 230 | */ |
| 231 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, |
| 232 | unsigned long fp) |
| 233 | { |
| 234 | unsigned long old; |
| 235 | struct ftrace_graph_ent trace; |
| 236 | unsigned long return_hooker = (unsigned long) |
| 237 | &return_to_handler; |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 238 | int faulted; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 239 | |
| 240 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
| 241 | return; |
| 242 | |
| 243 | /* "parent" is the stack address saved the return address of the caller |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 244 | * of _mcount. |
| 245 | * |
| 246 | * if the gcc < 4.5, a leaf function does not save the return address |
| 247 | * in the stack address, so, we "emulate" one in _mcount's stack space, |
| 248 | * and hijack it directly, but for a non-leaf function, it save the |
| 249 | * return address to the its own stack space, we can not hijack it |
| 250 | * directly, but need to find the real stack address, |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 251 | * ftrace_get_parent_addr() does it! |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 252 | * |
| 253 | * if gcc>= 4.5, with the new -mmcount-ra-address option, for a |
| 254 | * non-leaf function, the location of the return address will be saved |
| 255 | * to $12 for us, and for a leaf function, only put a zero into $12. we |
| 256 | * do it in ftrace_graph_caller of mcount.S. |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 257 | */ |
| 258 | |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 259 | /* old = *parent; */ |
| 260 | safe_load_stack(old, parent, faulted); |
| 261 | if (unlikely(faulted)) |
| 262 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 263 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 264 | parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old, |
| 265 | (unsigned long)parent, |
| 266 | fp); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 267 | /* If fails when getting the stack address of the non-leaf function's |
| 268 | * ra, stop function graph tracer and return */ |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 269 | if (parent == 0) |
| 270 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 271 | #endif |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 272 | /* *parent = return_hooker; */ |
| 273 | safe_store_stack(return_hooker, parent, faulted); |
| 274 | if (unlikely(faulted)) |
| 275 | goto out; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 276 | |
| 277 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) == |
| 278 | -EBUSY) { |
| 279 | *parent = old; |
| 280 | return; |
| 281 | } |
| 282 | |
| 283 | trace.func = self_addr; |
| 284 | |
| 285 | /* Only trace if the calling function expects to */ |
| 286 | if (!ftrace_graph_entry(&trace)) { |
| 287 | current->curr_ret_stack--; |
| 288 | *parent = old; |
| 289 | } |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 290 | return; |
| 291 | out: |
| 292 | ftrace_graph_stop(); |
| 293 | WARN_ON(1); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 294 | } |
| 295 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |