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 | d9cdb2f | 2011-01-20 03:28:29 +0800 | [diff] [blame] | 20 | #include <asm-generic/sections.h> |
Wu Zhangjin | c9f8487 | 2010-05-14 19:08:34 +0800 | [diff] [blame] | 21 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 22 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 23 | |
| 24 | #define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ |
| 25 | #define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */ |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 26 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 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 | |
Wu Zhangjin | d9cdb2f | 2011-01-20 03:28:29 +0800 | [diff] [blame] | 56 | /* |
| 57 | * Check if the address is in kernel space |
| 58 | * |
| 59 | * Clone core_kernel_text() from kernel/extable.c, but doesn't call |
| 60 | * init_kernel_text() for Ftrace doesn't trace functions in init sections. |
| 61 | */ |
| 62 | static inline int in_kernel_space(unsigned long ip) |
| 63 | { |
| 64 | if (ip >= (unsigned long)_stext && |
| 65 | ip <= (unsigned long)_etext) |
| 66 | return 1; |
| 67 | return 0; |
| 68 | } |
| 69 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 70 | static int ftrace_modify_code(unsigned long ip, unsigned int new_code) |
| 71 | { |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 72 | int faulted; |
| 73 | |
| 74 | /* *(unsigned int *)ip = new_code; */ |
| 75 | safe_store_code(new_code, ip, faulted); |
| 76 | |
| 77 | if (unlikely(faulted)) |
| 78 | return -EFAULT; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 79 | |
| 80 | flush_icache_range(ip, ip + 8); |
| 81 | |
| 82 | return 0; |
| 83 | } |
| 84 | |
Wu Zhangjin | 7f21a60 | 2011-01-20 03:28:31 +0800 | [diff] [blame] | 85 | /* |
| 86 | * The details about the calling site of mcount on MIPS |
| 87 | * |
| 88 | * 1. For kernel: |
| 89 | * |
| 90 | * move at, ra |
| 91 | * jal _mcount --> nop |
| 92 | * |
| 93 | * 2. For modules: |
| 94 | * |
| 95 | * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT |
| 96 | * |
| 97 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005) |
| 98 | * addiu v1, v1, low_16bit_of_mcount |
| 99 | * move at, ra |
| 100 | * move $12, ra_address |
| 101 | * jalr v1 |
| 102 | * sub sp, sp, 8 |
| 103 | * 1: offset = 5 instructions |
| 104 | * 2.2 For the Other situations |
| 105 | * |
| 106 | * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004) |
| 107 | * addiu v1, v1, low_16bit_of_mcount |
| 108 | * move at, ra |
| 109 | * jalr v1 |
| 110 | * nop | move $12, ra_address | sub sp, sp, 8 |
| 111 | * 1: offset = 4 instructions |
| 112 | */ |
| 113 | |
| 114 | #if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT) |
| 115 | #define MCOUNT_OFFSET_INSNS 5 |
| 116 | #else |
| 117 | #define MCOUNT_OFFSET_INSNS 4 |
| 118 | #endif |
| 119 | #define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS) |
| 120 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 121 | int ftrace_make_nop(struct module *mod, |
| 122 | struct dyn_ftrace *rec, unsigned long addr) |
| 123 | { |
| 124 | unsigned int new; |
| 125 | unsigned long ip = rec->ip; |
| 126 | |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 127 | /* |
Wu Zhangjin | d9cdb2f | 2011-01-20 03:28:29 +0800 | [diff] [blame] | 128 | * If ip is in kernel space, no long call, otherwise, long call is |
| 129 | * needed. |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 130 | */ |
Wu Zhangjin | 7f21a60 | 2011-01-20 03:28:31 +0800 | [diff] [blame] | 131 | new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F; |
| 132 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 133 | return ftrace_modify_code(ip, new); |
| 134 | } |
| 135 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 136 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 137 | { |
| 138 | unsigned int new; |
| 139 | unsigned long ip = rec->ip; |
| 140 | |
Wu Zhangjin | d9cdb2f | 2011-01-20 03:28:29 +0800 | [diff] [blame] | 141 | new = in_kernel_space(ip) ? insn_jal_ftrace_caller : |
| 142 | insn_lui_v1_hi16_mcount; |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 143 | |
| 144 | return ftrace_modify_code(ip, new); |
| 145 | } |
| 146 | |
| 147 | #define FTRACE_CALL_IP ((unsigned long)(&ftrace_call)) |
| 148 | |
| 149 | int ftrace_update_ftrace_func(ftrace_func_t func) |
| 150 | { |
| 151 | unsigned int new; |
| 152 | |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 153 | new = INSN_JAL((unsigned long)func); |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 154 | |
| 155 | return ftrace_modify_code(FTRACE_CALL_IP, new); |
| 156 | } |
| 157 | |
| 158 | int __init ftrace_dyn_arch_init(void *data) |
| 159 | { |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 160 | /* Encode the instructions when booting */ |
| 161 | ftrace_dyn_arch_init_insns(); |
| 162 | |
| 163 | /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */ |
| 164 | ftrace_modify_code(MCOUNT_ADDR, INSN_NOP); |
| 165 | |
Wu Zhangjin | 538f195 | 2009-11-20 20:34:32 +0800 | [diff] [blame] | 166 | /* The return code is retured via data */ |
| 167 | *(unsigned long *)data = 0; |
| 168 | |
| 169 | return 0; |
| 170 | } |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 171 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 172 | |
| 173 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 174 | |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 175 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 176 | |
| 177 | extern void ftrace_graph_call(void); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 178 | #define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call)) |
| 179 | |
| 180 | int ftrace_enable_ftrace_graph_caller(void) |
| 181 | { |
| 182 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, |
Wu Zhangjin | e424054 | 2010-05-14 19:08:32 +0800 | [diff] [blame] | 183 | insn_j_ftrace_graph_caller); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 184 | } |
| 185 | |
| 186 | int ftrace_disable_ftrace_graph_caller(void) |
| 187 | { |
Wu Zhangjin | 4d6829f | 2010-05-14 19:08:31 +0800 | [diff] [blame] | 188 | return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP); |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 189 | } |
| 190 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 191 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
Wu Zhangjin | e17ff5f | 2009-11-20 20:34:35 +0800 | [diff] [blame] | 192 | |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 193 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 194 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 195 | #define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */ |
| 196 | #define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */ |
| 197 | #define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */ |
| 198 | |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 199 | unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long |
| 200 | old_parent_ra, unsigned long parent_ra_addr, unsigned long fp) |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 201 | { |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 202 | unsigned long sp, ip, tmp; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 203 | unsigned int code; |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 204 | int faulted; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 205 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 206 | /* |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 207 | * For module, move the ip from the return address after the |
Wu Zhangjin | 9a620a5 | 2011-01-20 03:28:27 +0800 | [diff] [blame] | 208 | * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for |
| 209 | * kernel, move after the instruction "move ra, at"(offset is 16) |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 210 | */ |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 211 | ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 212 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 213 | /* |
| 214 | * search the text until finding the non-store instruction or "s{d,w} |
| 215 | * ra, offset(sp)" instruction |
| 216 | */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 217 | do { |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 218 | /* get the code at "ip": code = *(unsigned int *)ip; */ |
| 219 | safe_load_code(code, ip, faulted); |
| 220 | |
| 221 | if (unlikely(faulted)) |
| 222 | return 0; |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 223 | /* |
| 224 | * If we hit the non-store instruction before finding where the |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 225 | * 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] | 226 | * store the ra on the stack |
| 227 | */ |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 228 | if ((code & S_R_SP) != S_R_SP) |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 229 | return parent_ra_addr; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 230 | |
Wu Zhangjin | 9a620a5 | 2011-01-20 03:28:27 +0800 | [diff] [blame] | 231 | /* Move to the next instruction */ |
| 232 | ip -= 4; |
| 233 | } while ((code & S_RA_SP) != S_RA_SP); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 234 | |
| 235 | sp = fp + (code & OFFSET_MASK); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 236 | |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 237 | /* tmp = *(unsigned long *)sp; */ |
| 238 | safe_load_stack(tmp, sp, faulted); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 239 | if (unlikely(faulted)) |
| 240 | return 0; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 241 | |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 242 | if (tmp == old_parent_ra) |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 243 | return sp; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 244 | return 0; |
| 245 | } |
| 246 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 247 | #endif /* !KBUILD_MCOUNT_RA_ADDRESS */ |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 248 | |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 249 | /* |
| 250 | * Hook the return address and push it in the stack of return addrs |
| 251 | * in current thread info. |
| 252 | */ |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 253 | void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 254 | unsigned long fp) |
| 255 | { |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 256 | unsigned long old_parent_ra; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 257 | struct ftrace_graph_ent trace; |
| 258 | unsigned long return_hooker = (unsigned long) |
| 259 | &return_to_handler; |
Wu Zhangjin | b9f07eb | 2011-01-22 02:01:53 +0800 | [diff] [blame^] | 260 | int faulted, insns; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 261 | |
| 262 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
| 263 | return; |
| 264 | |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 265 | /* |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 266 | * "parent_ra_addr" is the stack address saved the return address of |
| 267 | * the caller of _mcount. |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 268 | * |
| 269 | * if the gcc < 4.5, a leaf function does not save the return address |
| 270 | * in the stack address, so, we "emulate" one in _mcount's stack space, |
| 271 | * and hijack it directly, but for a non-leaf function, it save the |
| 272 | * return address to the its own stack space, we can not hijack it |
| 273 | * directly, but need to find the real stack address, |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 274 | * ftrace_get_parent_addr() does it! |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 275 | * |
| 276 | * if gcc>= 4.5, with the new -mmcount-ra-address option, for a |
| 277 | * non-leaf function, the location of the return address will be saved |
| 278 | * to $12 for us, and for a leaf function, only put a zero into $12. we |
| 279 | * do it in ftrace_graph_caller of mcount.S. |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 280 | */ |
| 281 | |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 282 | /* old_parent_ra = *parent_ra_addr; */ |
| 283 | safe_load_stack(old_parent_ra, parent_ra_addr, faulted); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 284 | if (unlikely(faulted)) |
| 285 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 286 | #ifndef KBUILD_MCOUNT_RA_ADDRESS |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 287 | parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra, |
| 288 | old_parent_ra, (unsigned long)parent_ra_addr, fp); |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 289 | /* |
| 290 | * If fails when getting the stack address of the non-leaf function's |
| 291 | * ra, stop function graph tracer and return |
| 292 | */ |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 293 | if (parent_ra_addr == 0) |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 294 | goto out; |
Wu Zhangjin | 7326c4e | 2009-11-20 20:34:38 +0800 | [diff] [blame] | 295 | #endif |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 296 | /* *parent_ra_addr = return_hooker; */ |
| 297 | safe_store_stack(return_hooker, parent_ra_addr, faulted); |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 298 | if (unlikely(faulted)) |
| 299 | goto out; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 300 | |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 301 | if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp) |
| 302 | == -EBUSY) { |
| 303 | *parent_ra_addr = old_parent_ra; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 304 | return; |
| 305 | } |
| 306 | |
Wu Zhangjin | b9f07eb | 2011-01-22 02:01:53 +0800 | [diff] [blame^] | 307 | /* |
| 308 | * Get the recorded ip of the current mcount calling site in the |
| 309 | * __mcount_loc section, which will be used to filter the function |
| 310 | * entries configured through the tracing/set_graph_function interface. |
| 311 | */ |
| 312 | |
| 313 | insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1; |
| 314 | trace.func = self_ra - (MCOUNT_INSN_SIZE * insns); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 315 | |
| 316 | /* Only trace if the calling function expects to */ |
| 317 | if (!ftrace_graph_entry(&trace)) { |
| 318 | current->curr_ret_stack--; |
Wu Zhangjin | 2816e32 | 2011-01-20 03:28:30 +0800 | [diff] [blame] | 319 | *parent_ra_addr = old_parent_ra; |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 320 | } |
Wu Zhangjin | 046199c | 2009-11-20 20:34:36 +0800 | [diff] [blame] | 321 | return; |
| 322 | out: |
| 323 | ftrace_graph_stop(); |
| 324 | WARN_ON(1); |
Wu Zhangjin | 29c5d34 | 2009-11-20 20:34:34 +0800 | [diff] [blame] | 325 | } |
Wu Zhangjin | 68ccf75 | 2010-05-14 19:08:33 +0800 | [diff] [blame] | 326 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |