2 * SPDX-License-Identifier: LGPL-2.1-or-later
4 * Copyright (C) 2009 Pierre-Marc Fournier
5 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 * Do _not_ define _LGPL_SOURCE because we don't want to create a
10 * circular dependency loop between this malloc wrapper, liburcu and
13 #include <ust-dlfcn.h>
14 #include <sys/types.h>
17 #include <urcu/system.h>
18 #include <urcu/uatomic.h>
19 #include <urcu/compiler.h>
20 #include <urcu/tls-compat.h>
21 #include <urcu/arch.h>
22 #include <ust-helper.h>
23 #include "ust-compat.h"
25 #define TRACEPOINT_DEFINE
26 #define TRACEPOINT_CREATE_PROBES
27 #define TP_IP_PARAM ip
30 #define STATIC_CALLOC_LEN 4096
31 static char static_calloc_buf
[STATIC_CALLOC_LEN
];
32 static unsigned long static_calloc_buf_offset
;
34 struct alloc_functions
{
35 void *(*calloc
)(size_t nmemb
, size_t size
);
36 void *(*malloc
)(size_t size
);
37 void (*free
)(void *ptr
);
38 void *(*realloc
)(void *ptr
, size_t size
);
39 void *(*memalign
)(size_t alignment
, size_t size
);
40 int (*posix_memalign
)(void **memptr
, size_t alignment
, size_t size
);
44 struct alloc_functions cur_alloc
;
47 * Make sure our own use of the LTS compat layer will not cause infinite
48 * recursion by calling calloc.
52 void *static_calloc(size_t nmemb
, size_t size
);
55 * pthread mutex replacement for URCU tls compat layer.
57 static int ust_malloc_lock
;
60 void ust_malloc_spin_lock(pthread_mutex_t
*lock
)
61 __attribute__((unused
));
63 void ust_malloc_spin_lock(pthread_mutex_t
*lock
)
66 * The memory barrier within cmpxchg takes care of ordering
67 * memory accesses with respect to the start of the critical
70 while (uatomic_cmpxchg(&ust_malloc_lock
, 0, 1) != 0)
75 void ust_malloc_spin_unlock(pthread_mutex_t
*lock
)
76 __attribute__((unused
));
78 void ust_malloc_spin_unlock(pthread_mutex_t
*lock
)
81 * Ensure memory accesses within the critical section do not
85 uatomic_set(&ust_malloc_lock
, 0);
88 #define calloc static_calloc
89 #define pthread_mutex_lock ust_malloc_spin_lock
90 #define pthread_mutex_unlock ust_malloc_spin_unlock
91 static DEFINE_URCU_TLS(int, malloc_nesting
);
92 #undef pthread_mutex_unlock
93 #undef pthread_mutex_lock
97 * Static allocator to use when initially executing dlsym(). It keeps a
98 * size_t value of each object size prior to the object.
101 void *static_calloc_aligned(size_t nmemb
, size_t size
, size_t alignment
)
103 size_t prev_offset
, new_offset
, res_offset
, aligned_offset
;
105 if (nmemb
* size
== 0) {
110 * Protect static_calloc_buf_offset from concurrent updates
111 * using a cmpxchg loop rather than a mutex to remove a
112 * dependency on pthread. This will minimize the risk of bad
113 * interaction between mutex and malloc instrumentation.
115 res_offset
= CMM_LOAD_SHARED(static_calloc_buf_offset
);
117 prev_offset
= res_offset
;
118 aligned_offset
= LTTNG_UST_ALIGN(prev_offset
+ sizeof(size_t), alignment
);
119 new_offset
= aligned_offset
+ nmemb
* size
;
120 if (new_offset
> sizeof(static_calloc_buf
)) {
123 } while ((res_offset
= uatomic_cmpxchg(&static_calloc_buf_offset
,
124 prev_offset
, new_offset
)) != prev_offset
);
125 *(size_t *) &static_calloc_buf
[aligned_offset
- sizeof(size_t)] = size
;
126 return &static_calloc_buf
[aligned_offset
];
130 void *static_calloc(size_t nmemb
, size_t size
)
134 retval
= static_calloc_aligned(nmemb
, size
, 1);
139 void *static_malloc(size_t size
)
143 retval
= static_calloc_aligned(1, size
, 1);
148 void static_free(void *ptr
)
154 void *static_realloc(void *ptr
, size_t size
)
156 size_t *old_size
= NULL
;
165 old_size
= (size_t *) ptr
- 1;
166 if (size
<= *old_size
) {
167 /* We can re-use the old entry. */
173 /* We need to expand. Don't free previous memory location. */
174 retval
= static_calloc_aligned(1, size
, 1);
177 memcpy(retval
, ptr
, *old_size
);
183 void *static_memalign(size_t alignment
, size_t size
)
187 retval
= static_calloc_aligned(1, size
, alignment
);
192 int static_posix_memalign(void **memptr
, size_t alignment
, size_t size
)
196 /* Check for power of 2, larger than void *. */
197 if (alignment
& (alignment
- 1)
198 || alignment
< sizeof(void *)
202 ptr
= static_calloc_aligned(1, size
, alignment
);
209 void setup_static_allocator(void)
211 assert(cur_alloc
.calloc
== NULL
);
212 cur_alloc
.calloc
= static_calloc
;
213 assert(cur_alloc
.malloc
== NULL
);
214 cur_alloc
.malloc
= static_malloc
;
215 assert(cur_alloc
.free
== NULL
);
216 cur_alloc
.free
= static_free
;
217 assert(cur_alloc
.realloc
== NULL
);
218 cur_alloc
.realloc
= static_realloc
;
219 assert(cur_alloc
.memalign
== NULL
);
220 cur_alloc
.memalign
= static_memalign
;
221 assert(cur_alloc
.posix_memalign
== NULL
);
222 cur_alloc
.posix_memalign
= static_posix_memalign
;
226 void lookup_all_symbols(void)
228 struct alloc_functions af
;
231 * Temporarily redirect allocation functions to
232 * static_calloc_aligned, and free function to static_free
233 * (no-op), until the dlsym lookup has completed.
235 setup_static_allocator();
237 /* Perform the actual lookups */
238 af
.calloc
= dlsym(RTLD_NEXT
, "calloc");
239 af
.malloc
= dlsym(RTLD_NEXT
, "malloc");
240 af
.free
= dlsym(RTLD_NEXT
, "free");
241 af
.realloc
= dlsym(RTLD_NEXT
, "realloc");
242 af
.memalign
= dlsym(RTLD_NEXT
, "memalign");
243 af
.posix_memalign
= dlsym(RTLD_NEXT
, "posix_memalign");
245 /* Populate the new allocator functions */
246 memcpy(&cur_alloc
, &af
, sizeof(cur_alloc
));
249 void *malloc(size_t size
)
253 URCU_TLS(malloc_nesting
)++;
254 if (cur_alloc
.malloc
== NULL
) {
255 lookup_all_symbols();
256 if (cur_alloc
.malloc
== NULL
) {
257 fprintf(stderr
, "mallocwrap: unable to find malloc\n");
261 retval
= cur_alloc
.malloc(size
);
262 if (URCU_TLS(malloc_nesting
) == 1) {
263 tracepoint(lttng_ust_libc
, malloc
,
264 size
, retval
, LTTNG_UST_CALLER_IP());
266 URCU_TLS(malloc_nesting
)--;
272 URCU_TLS(malloc_nesting
)++;
274 * Check whether the memory was allocated with
275 * static_calloc_align, in which case there is nothing to free.
277 if (caa_unlikely((char *)ptr
>= static_calloc_buf
&&
278 (char *)ptr
< static_calloc_buf
+ STATIC_CALLOC_LEN
)) {
282 if (URCU_TLS(malloc_nesting
) == 1) {
283 tracepoint(lttng_ust_libc
, free
,
284 ptr
, LTTNG_UST_CALLER_IP());
287 if (cur_alloc
.free
== NULL
) {
288 lookup_all_symbols();
289 if (cur_alloc
.free
== NULL
) {
290 fprintf(stderr
, "mallocwrap: unable to find free\n");
296 URCU_TLS(malloc_nesting
)--;
299 void *calloc(size_t nmemb
, size_t size
)
303 URCU_TLS(malloc_nesting
)++;
304 if (cur_alloc
.calloc
== NULL
) {
305 lookup_all_symbols();
306 if (cur_alloc
.calloc
== NULL
) {
307 fprintf(stderr
, "callocwrap: unable to find calloc\n");
311 retval
= cur_alloc
.calloc(nmemb
, size
);
312 if (URCU_TLS(malloc_nesting
) == 1) {
313 tracepoint(lttng_ust_libc
, calloc
,
314 nmemb
, size
, retval
, LTTNG_UST_CALLER_IP());
316 URCU_TLS(malloc_nesting
)--;
320 void *realloc(void *ptr
, size_t size
)
324 URCU_TLS(malloc_nesting
)++;
326 * Check whether the memory was allocated with
327 * static_calloc_align, in which case there is nothing
328 * to free, and we need to copy the old data.
330 if (caa_unlikely((char *)ptr
>= static_calloc_buf
&&
331 (char *)ptr
< static_calloc_buf
+ STATIC_CALLOC_LEN
)) {
334 old_size
= (size_t *) ptr
- 1;
335 if (cur_alloc
.calloc
== NULL
) {
336 lookup_all_symbols();
337 if (cur_alloc
.calloc
== NULL
) {
338 fprintf(stderr
, "reallocwrap: unable to find calloc\n");
342 retval
= cur_alloc
.calloc(1, size
);
344 memcpy(retval
, ptr
, *old_size
);
347 * Mimick that a NULL pointer has been received, so
348 * memory allocation analysis based on the trace don't
349 * get confused by the address from the static
356 if (cur_alloc
.realloc
== NULL
) {
357 lookup_all_symbols();
358 if (cur_alloc
.realloc
== NULL
) {
359 fprintf(stderr
, "reallocwrap: unable to find realloc\n");
363 retval
= cur_alloc
.realloc(ptr
, size
);
365 if (URCU_TLS(malloc_nesting
) == 1) {
366 tracepoint(lttng_ust_libc
, realloc
,
367 ptr
, size
, retval
, LTTNG_UST_CALLER_IP());
369 URCU_TLS(malloc_nesting
)--;
373 void *memalign(size_t alignment
, size_t size
)
377 URCU_TLS(malloc_nesting
)++;
378 if (cur_alloc
.memalign
== NULL
) {
379 lookup_all_symbols();
380 if (cur_alloc
.memalign
== NULL
) {
381 fprintf(stderr
, "memalignwrap: unable to find memalign\n");
385 retval
= cur_alloc
.memalign(alignment
, size
);
386 if (URCU_TLS(malloc_nesting
) == 1) {
387 tracepoint(lttng_ust_libc
, memalign
,
388 alignment
, size
, retval
,
389 LTTNG_UST_CALLER_IP());
391 URCU_TLS(malloc_nesting
)--;
395 int posix_memalign(void **memptr
, size_t alignment
, size_t size
)
399 URCU_TLS(malloc_nesting
)++;
400 if (cur_alloc
.posix_memalign
== NULL
) {
401 lookup_all_symbols();
402 if (cur_alloc
.posix_memalign
== NULL
) {
403 fprintf(stderr
, "posix_memalignwrap: unable to find posix_memalign\n");
407 retval
= cur_alloc
.posix_memalign(memptr
, alignment
, size
);
408 if (URCU_TLS(malloc_nesting
) == 1) {
409 tracepoint(lttng_ust_libc
, posix_memalign
,
410 *memptr
, alignment
, size
,
411 retval
, LTTNG_UST_CALLER_IP());
413 URCU_TLS(malloc_nesting
)--;
418 void lttng_ust_fixup_malloc_nesting_tls(void)
420 asm volatile ("" : : "m" (URCU_TLS(malloc_nesting
)));
423 void lttng_ust_libc_wrapper_malloc_init(void)
425 /* Initialization already done */
426 if (cur_alloc
.calloc
) {
429 lttng_ust_fixup_malloc_nesting_tls();
431 * Ensure the allocator is in place before the process becomes
434 lookup_all_symbols();