Commit | Line | Data |
---|---|---|
4e491d14 SR |
1 | /* |
2 | * Code for replacing ftrace calls with jumps. | |
3 | * | |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | |
5 | * | |
6 | * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. | |
7 | * | |
8 | */ | |
9 | ||
10 | #include <linux/spinlock.h> | |
11 | #include <linux/hardirq.h> | |
e4486fe3 | 12 | #include <linux/uaccess.h> |
f48cb8b4 | 13 | #include <linux/module.h> |
4e491d14 SR |
14 | #include <linux/ftrace.h> |
15 | #include <linux/percpu.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/list.h> | |
18 | ||
19 | #include <asm/cacheflush.h> | |
f48cb8b4 | 20 | #include <asm/code-patching.h> |
395a59d0 | 21 | #include <asm/ftrace.h> |
4e491d14 | 22 | |
f48cb8b4 SR |
23 | #if 0 |
24 | #define DEBUGP printk | |
25 | #else | |
26 | #define DEBUGP(fmt , ...) do { } while (0) | |
27 | #endif | |
4e491d14 | 28 | |
f48cb8b4 | 29 | static unsigned int ftrace_nop = PPC_NOP_INSTR; |
4e491d14 SR |
30 | |
31 | #ifdef CONFIG_PPC32 | |
32 | # define GET_ADDR(addr) addr | |
33 | #else | |
34 | /* PowerPC64's functions are data that points to the functions */ | |
f48cb8b4 | 35 | # define GET_ADDR(addr) (*(unsigned long *)addr) |
4e491d14 SR |
36 | #endif |
37 | ||
395a59d0 | 38 | |
15adc048 | 39 | static unsigned int ftrace_calc_offset(long ip, long addr) |
4e491d14 | 40 | { |
395a59d0 | 41 | return (int)(addr - ip); |
4e491d14 SR |
42 | } |
43 | ||
8fd6e5a8 | 44 | static unsigned char *ftrace_nop_replace(void) |
4e491d14 SR |
45 | { |
46 | return (char *)&ftrace_nop; | |
47 | } | |
48 | ||
8fd6e5a8 | 49 | static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) |
4e491d14 SR |
50 | { |
51 | static unsigned int op; | |
52 | ||
ccbfac29 SR |
53 | /* |
54 | * It would be nice to just use create_function_call, but that will | |
55 | * update the code itself. Here we need to just return the | |
56 | * instruction that is going to be modified, without modifying the | |
57 | * code. | |
58 | */ | |
4e491d14 SR |
59 | addr = GET_ADDR(addr); |
60 | ||
61 | /* Set to "bl addr" */ | |
ccbfac29 | 62 | op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc); |
4e491d14 SR |
63 | |
64 | /* | |
65 | * No locking needed, this must be called via kstop_machine | |
66 | * which in essence is like running on a uniprocessor machine. | |
67 | */ | |
68 | return (unsigned char *)&op; | |
69 | } | |
70 | ||
71 | #ifdef CONFIG_PPC64 | |
72 | # define _ASM_ALIGN " .align 3 " | |
73 | # define _ASM_PTR " .llong " | |
74 | #else | |
75 | # define _ASM_ALIGN " .align 2 " | |
76 | # define _ASM_PTR " .long " | |
77 | #endif | |
78 | ||
8fd6e5a8 | 79 | static int |
4e491d14 SR |
80 | ftrace_modify_code(unsigned long ip, unsigned char *old_code, |
81 | unsigned char *new_code) | |
82 | { | |
e4486fe3 | 83 | unsigned char replaced[MCOUNT_INSN_SIZE]; |
4e491d14 | 84 | |
4e491d14 SR |
85 | /* |
86 | * Note: Due to modules and __init, code can | |
87 | * disappear and change, we need to protect against faulting | |
e4486fe3 SR |
88 | * as well as code changing. We do this by using the |
89 | * probe_kernel_* functions. | |
4e491d14 SR |
90 | * |
91 | * No real locking needed, this code is run through | |
e4486fe3 | 92 | * kstop_machine, or before SMP starts. |
4e491d14 | 93 | */ |
e4486fe3 SR |
94 | |
95 | /* read the text we want to modify */ | |
96 | if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) | |
97 | return -EFAULT; | |
98 | ||
99 | /* Make sure it is what we expect it to be */ | |
100 | if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) | |
101 | return -EINVAL; | |
102 | ||
103 | /* replace the text with the new text */ | |
104 | if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE)) | |
105 | return -EPERM; | |
106 | ||
107 | flush_icache_range(ip, ip + 8); | |
108 | ||
109 | return 0; | |
4e491d14 SR |
110 | } |
111 | ||
f48cb8b4 SR |
112 | /* |
113 | * Helper functions that are the same for both PPC64 and PPC32. | |
114 | */ | |
8fd6e5a8 SR |
115 | static int test_24bit_addr(unsigned long ip, unsigned long addr) |
116 | { | |
8fd6e5a8 | 117 | |
0029ff87 SR |
118 | /* use the create_branch to verify that this offset can be branched */ |
119 | return create_branch((unsigned int *)ip, addr, 0); | |
8fd6e5a8 SR |
120 | } |
121 | ||
f48cb8b4 SR |
122 | static int is_bl_op(unsigned int op) |
123 | { | |
124 | return (op & 0xfc000003) == 0x48000001; | |
125 | } | |
126 | ||
f48cb8b4 SR |
127 | static unsigned long find_bl_target(unsigned long ip, unsigned int op) |
128 | { | |
129 | static int offset; | |
130 | ||
131 | offset = (op & 0x03fffffc); | |
132 | /* make it signed */ | |
133 | if (offset & 0x02000000) | |
134 | offset |= 0xfe000000; | |
135 | ||
136 | return ip + (long)offset; | |
137 | } | |
138 | ||
f48cb8b4 SR |
139 | #ifdef CONFIG_PPC64 |
140 | static int | |
141 | __ftrace_make_nop(struct module *mod, | |
142 | struct dyn_ftrace *rec, unsigned long addr) | |
143 | { | |
d9af12b7 SR |
144 | unsigned int op; |
145 | unsigned int jmp[5]; | |
146 | unsigned long ptr; | |
f48cb8b4 SR |
147 | unsigned long ip = rec->ip; |
148 | unsigned long tramp; | |
149 | int offset; | |
150 | ||
151 | /* read where this goes */ | |
d9af12b7 | 152 | if (probe_kernel_read(&op, (void *)ip, sizeof(int))) |
f48cb8b4 SR |
153 | return -EFAULT; |
154 | ||
155 | /* Make sure that that this is still a 24bit jump */ | |
d9af12b7 SR |
156 | if (!is_bl_op(op)) { |
157 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); | |
f48cb8b4 SR |
158 | return -EINVAL; |
159 | } | |
160 | ||
161 | /* lets find where the pointer goes */ | |
d9af12b7 | 162 | tramp = find_bl_target(ip, op); |
f48cb8b4 SR |
163 | |
164 | /* | |
165 | * On PPC64 the trampoline looks like: | |
166 | * 0x3d, 0x82, 0x00, 0x00, addis r12,r2, <high> | |
167 | * 0x39, 0x8c, 0x00, 0x00, addi r12,r12, <low> | |
168 | * Where the bytes 2,3,6 and 7 make up the 32bit offset | |
169 | * to the TOC that holds the pointer. | |
170 | * to jump to. | |
171 | * 0xf8, 0x41, 0x00, 0x28, std r2,40(r1) | |
172 | * 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12) | |
173 | * The actually address is 32 bytes from the offset | |
174 | * into the TOC. | |
175 | * 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12) | |
176 | */ | |
177 | ||
178 | DEBUGP("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc); | |
179 | ||
180 | /* Find where the trampoline jumps to */ | |
d9af12b7 | 181 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
f48cb8b4 SR |
182 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
183 | return -EFAULT; | |
184 | } | |
185 | ||
d9af12b7 SR |
186 | DEBUGP(" %08x %08x", jmp[0], jmp[1]); |
187 | ||
188 | /* verify that this is what we expect it to be */ | |
189 | if (((jmp[0] & 0xffff0000) != 0x3d820000) || | |
190 | ((jmp[1] & 0xffff0000) != 0x398c0000) || | |
191 | (jmp[2] != 0xf8410028) || | |
192 | (jmp[3] != 0xe96c0020) || | |
193 | (jmp[4] != 0xe84c0028)) { | |
194 | printk(KERN_ERR "Not a trampoline\n"); | |
195 | return -EINVAL; | |
196 | } | |
f48cb8b4 | 197 | |
f25f9074 SR |
198 | /* The bottom half is signed extended */ |
199 | offset = ((unsigned)((unsigned short)jmp[0]) << 16) + | |
200 | (int)((short)jmp[1]); | |
f48cb8b4 SR |
201 | |
202 | DEBUGP(" %x ", offset); | |
203 | ||
204 | /* get the address this jumps too */ | |
205 | tramp = mod->arch.toc + offset + 32; | |
206 | DEBUGP("toc: %lx", tramp); | |
207 | ||
208 | if (probe_kernel_read(jmp, (void *)tramp, 8)) { | |
209 | printk(KERN_ERR "Failed to read %lx\n", tramp); | |
210 | return -EFAULT; | |
211 | } | |
212 | ||
d9af12b7 SR |
213 | DEBUGP(" %08x %08x\n", jmp[0], jmp[1]); |
214 | ||
215 | ptr = ((unsigned long)jmp[0] << 32) + jmp[1]; | |
f48cb8b4 SR |
216 | |
217 | /* This should match what was called */ | |
d9af12b7 SR |
218 | if (ptr != GET_ADDR(addr)) { |
219 | printk(KERN_ERR "addr does not match %lx\n", ptr); | |
f48cb8b4 SR |
220 | return -EINVAL; |
221 | } | |
222 | ||
223 | /* | |
224 | * We want to nop the line, but the next line is | |
225 | * 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1) | |
226 | * This needs to be turned to a nop too. | |
227 | */ | |
d9af12b7 | 228 | if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) |
f48cb8b4 SR |
229 | return -EFAULT; |
230 | ||
d9af12b7 SR |
231 | if (op != 0xe8410028) { |
232 | printk(KERN_ERR "Next line is not ld! (%08x)\n", op); | |
f48cb8b4 SR |
233 | return -EINVAL; |
234 | } | |
235 | ||
236 | /* | |
237 | * Milton Miller pointed out that we can not blindly do nops. | |
238 | * If a task was preempted when calling a trace function, | |
239 | * the nops will remove the way to restore the TOC in r2 | |
240 | * and the r2 TOC will get corrupted. | |
241 | */ | |
242 | ||
243 | /* | |
244 | * Replace: | |
245 | * bl <tramp> <==== will be replaced with "b 1f" | |
246 | * ld r2,40(r1) | |
247 | * 1: | |
248 | */ | |
d9af12b7 | 249 | op = 0x48000008; /* b +8 */ |
f48cb8b4 | 250 | |
d9af12b7 | 251 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
f48cb8b4 SR |
252 | return -EPERM; |
253 | ||
ec682cef SR |
254 | |
255 | flush_icache_range(ip, ip + 8); | |
256 | ||
f48cb8b4 SR |
257 | return 0; |
258 | } | |
259 | ||
260 | #else /* !PPC64 */ | |
261 | static int | |
262 | __ftrace_make_nop(struct module *mod, | |
263 | struct dyn_ftrace *rec, unsigned long addr) | |
264 | { | |
d9af12b7 SR |
265 | unsigned int op; |
266 | unsigned int jmp[4]; | |
7cc45e64 SR |
267 | unsigned long ip = rec->ip; |
268 | unsigned long tramp; | |
7cc45e64 | 269 | |
d9af12b7 | 270 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
271 | return -EFAULT; |
272 | ||
273 | /* Make sure that that this is still a 24bit jump */ | |
d9af12b7 SR |
274 | if (!is_bl_op(op)) { |
275 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); | |
7cc45e64 SR |
276 | return -EINVAL; |
277 | } | |
278 | ||
279 | /* lets find where the pointer goes */ | |
d9af12b7 | 280 | tramp = find_bl_target(ip, op); |
7cc45e64 SR |
281 | |
282 | /* | |
283 | * On PPC32 the trampoline looks like: | |
d9af12b7 SR |
284 | * 0x3d, 0x60, 0x00, 0x00 lis r11,sym@ha |
285 | * 0x39, 0x6b, 0x00, 0x00 addi r11,r11,sym@l | |
286 | * 0x7d, 0x69, 0x03, 0xa6 mtctr r11 | |
287 | * 0x4e, 0x80, 0x04, 0x20 bctr | |
7cc45e64 SR |
288 | */ |
289 | ||
290 | DEBUGP("ip:%lx jumps to %lx", ip, tramp); | |
291 | ||
292 | /* Find where the trampoline jumps to */ | |
d9af12b7 | 293 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
7cc45e64 SR |
294 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
295 | return -EFAULT; | |
296 | } | |
297 | ||
d9af12b7 SR |
298 | DEBUGP(" %08x %08x ", jmp[0], jmp[1]); |
299 | ||
300 | /* verify that this is what we expect it to be */ | |
301 | if (((jmp[0] & 0xffff0000) != 0x3d600000) || | |
302 | ((jmp[1] & 0xffff0000) != 0x396b0000) || | |
303 | (jmp[2] != 0x7d6903a6) || | |
304 | (jmp[3] != 0x4e800420)) { | |
305 | printk(KERN_ERR "Not a trampoline\n"); | |
306 | return -EINVAL; | |
307 | } | |
7cc45e64 | 308 | |
d9af12b7 SR |
309 | tramp = (jmp[1] & 0xffff) | |
310 | ((jmp[0] & 0xffff) << 16); | |
7cc45e64 SR |
311 | if (tramp & 0x8000) |
312 | tramp -= 0x10000; | |
313 | ||
314 | DEBUGP(" %x ", tramp); | |
315 | ||
316 | if (tramp != addr) { | |
317 | printk(KERN_ERR | |
318 | "Trampoline location %08lx does not match addr\n", | |
319 | tramp); | |
320 | return -EINVAL; | |
321 | } | |
322 | ||
d9af12b7 | 323 | op = PPC_NOP_INSTR; |
7cc45e64 | 324 | |
d9af12b7 | 325 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
326 | return -EPERM; |
327 | ||
ec682cef SR |
328 | flush_icache_range(ip, ip + 8); |
329 | ||
f48cb8b4 SR |
330 | return 0; |
331 | } | |
332 | #endif /* PPC64 */ | |
333 | ||
8fd6e5a8 SR |
334 | int ftrace_make_nop(struct module *mod, |
335 | struct dyn_ftrace *rec, unsigned long addr) | |
336 | { | |
337 | unsigned char *old, *new; | |
f48cb8b4 | 338 | unsigned long ip = rec->ip; |
8fd6e5a8 SR |
339 | |
340 | /* | |
341 | * If the calling address is more that 24 bits away, | |
342 | * then we had to use a trampoline to make the call. | |
343 | * Otherwise just update the call site. | |
344 | */ | |
f48cb8b4 | 345 | if (test_24bit_addr(ip, addr)) { |
8fd6e5a8 | 346 | /* within range */ |
f48cb8b4 | 347 | old = ftrace_call_replace(ip, addr); |
8fd6e5a8 | 348 | new = ftrace_nop_replace(); |
f48cb8b4 SR |
349 | return ftrace_modify_code(ip, old, new); |
350 | } | |
351 | ||
f48cb8b4 SR |
352 | /* |
353 | * Out of range jumps are called from modules. | |
354 | * We should either already have a pointer to the module | |
355 | * or it has been passed in. | |
356 | */ | |
357 | if (!rec->arch.mod) { | |
358 | if (!mod) { | |
359 | printk(KERN_ERR "No module loaded addr=%lx\n", | |
360 | addr); | |
361 | return -EFAULT; | |
362 | } | |
363 | rec->arch.mod = mod; | |
364 | } else if (mod) { | |
365 | if (mod != rec->arch.mod) { | |
366 | printk(KERN_ERR | |
367 | "Record mod %p not equal to passed in mod %p\n", | |
368 | rec->arch.mod, mod); | |
369 | return -EINVAL; | |
370 | } | |
371 | /* nothing to do if mod == rec->arch.mod */ | |
372 | } else | |
373 | mod = rec->arch.mod; | |
f48cb8b4 SR |
374 | |
375 | return __ftrace_make_nop(mod, rec, addr); | |
376 | ||
377 | } | |
378 | ||
379 | #ifdef CONFIG_PPC64 | |
380 | static int | |
381 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
382 | { | |
d9af12b7 | 383 | unsigned int op[2]; |
f48cb8b4 | 384 | unsigned long ip = rec->ip; |
f48cb8b4 SR |
385 | |
386 | /* read where this goes */ | |
d9af12b7 | 387 | if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2)) |
f48cb8b4 SR |
388 | return -EFAULT; |
389 | ||
390 | /* | |
391 | * It should be pointing to two nops or | |
392 | * b +8; ld r2,40(r1) | |
393 | */ | |
394 | if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) && | |
395 | ((op[0] != PPC_NOP_INSTR) || (op[1] != PPC_NOP_INSTR))) { | |
396 | printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]); | |
397 | return -EINVAL; | |
398 | } | |
399 | ||
400 | /* If we never set up a trampoline to ftrace_caller, then bail */ | |
401 | if (!rec->arch.mod->arch.tramp) { | |
402 | printk(KERN_ERR "No ftrace trampoline\n"); | |
403 | return -EINVAL; | |
404 | } | |
405 | ||
0029ff87 SR |
406 | /* create the branch to the trampoline */ |
407 | op[0] = create_branch((unsigned int *)ip, | |
408 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); | |
409 | if (!op[0]) { | |
410 | printk(KERN_ERR "REL24 out of range!\n"); | |
f48cb8b4 | 411 | return -EINVAL; |
8fd6e5a8 SR |
412 | } |
413 | ||
f48cb8b4 SR |
414 | /* ld r2,40(r1) */ |
415 | op[1] = 0xe8410028; | |
416 | ||
417 | DEBUGP("write to %lx\n", rec->ip); | |
418 | ||
d9af12b7 | 419 | if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2)) |
f48cb8b4 SR |
420 | return -EPERM; |
421 | ||
ec682cef SR |
422 | flush_icache_range(ip, ip + 8); |
423 | ||
8fd6e5a8 SR |
424 | return 0; |
425 | } | |
f48cb8b4 SR |
426 | #else |
427 | static int | |
428 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
429 | { | |
d9af12b7 | 430 | unsigned int op; |
7cc45e64 | 431 | unsigned long ip = rec->ip; |
7cc45e64 SR |
432 | |
433 | /* read where this goes */ | |
d9af12b7 | 434 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
435 | return -EFAULT; |
436 | ||
437 | /* It should be pointing to a nop */ | |
d9af12b7 SR |
438 | if (op != PPC_NOP_INSTR) { |
439 | printk(KERN_ERR "Expected NOP but have %x\n", op); | |
7cc45e64 SR |
440 | return -EINVAL; |
441 | } | |
442 | ||
443 | /* If we never set up a trampoline to ftrace_caller, then bail */ | |
444 | if (!rec->arch.mod->arch.tramp) { | |
445 | printk(KERN_ERR "No ftrace trampoline\n"); | |
446 | return -EINVAL; | |
447 | } | |
448 | ||
0029ff87 SR |
449 | /* create the branch to the trampoline */ |
450 | op = create_branch((unsigned int *)ip, | |
451 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); | |
452 | if (!op) { | |
453 | printk(KERN_ERR "REL24 out of range!\n"); | |
7cc45e64 SR |
454 | return -EINVAL; |
455 | } | |
456 | ||
7cc45e64 SR |
457 | DEBUGP("write to %lx\n", rec->ip); |
458 | ||
d9af12b7 | 459 | if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) |
7cc45e64 SR |
460 | return -EPERM; |
461 | ||
ec682cef SR |
462 | flush_icache_range(ip, ip + 8); |
463 | ||
f48cb8b4 SR |
464 | return 0; |
465 | } | |
466 | #endif /* CONFIG_PPC64 */ | |
8fd6e5a8 SR |
467 | |
468 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) | |
469 | { | |
470 | unsigned char *old, *new; | |
f48cb8b4 | 471 | unsigned long ip = rec->ip; |
8fd6e5a8 SR |
472 | |
473 | /* | |
474 | * If the calling address is more that 24 bits away, | |
475 | * then we had to use a trampoline to make the call. | |
476 | * Otherwise just update the call site. | |
477 | */ | |
f48cb8b4 | 478 | if (test_24bit_addr(ip, addr)) { |
8fd6e5a8 SR |
479 | /* within range */ |
480 | old = ftrace_nop_replace(); | |
f48cb8b4 SR |
481 | new = ftrace_call_replace(ip, addr); |
482 | return ftrace_modify_code(ip, old, new); | |
8fd6e5a8 SR |
483 | } |
484 | ||
f48cb8b4 SR |
485 | /* |
486 | * Out of range jumps are called from modules. | |
487 | * Being that we are converting from nop, it had better | |
488 | * already have a module defined. | |
489 | */ | |
490 | if (!rec->arch.mod) { | |
491 | printk(KERN_ERR "No module loaded\n"); | |
492 | return -EINVAL; | |
493 | } | |
f48cb8b4 SR |
494 | |
495 | return __ftrace_make_call(rec, addr); | |
8fd6e5a8 SR |
496 | } |
497 | ||
15adc048 | 498 | int ftrace_update_ftrace_func(ftrace_func_t func) |
4e491d14 SR |
499 | { |
500 | unsigned long ip = (unsigned long)(&ftrace_call); | |
395a59d0 | 501 | unsigned char old[MCOUNT_INSN_SIZE], *new; |
4e491d14 SR |
502 | int ret; |
503 | ||
395a59d0 | 504 | memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE); |
4e491d14 SR |
505 | new = ftrace_call_replace(ip, (unsigned long)func); |
506 | ret = ftrace_modify_code(ip, old, new); | |
507 | ||
508 | return ret; | |
509 | } | |
510 | ||
4e491d14 SR |
511 | int __init ftrace_dyn_arch_init(void *data) |
512 | { | |
8fd6e5a8 SR |
513 | /* caller expects data to be zero */ |
514 | unsigned long *p = data; | |
4e491d14 | 515 | |
8fd6e5a8 | 516 | *p = 0; |
4e491d14 SR |
517 | |
518 | return 0; | |
519 | } |