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author | Ian Lance Taylor <iant@google.com> | 2012-09-17 16:38:38 +0000 |
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committer | Ian Lance Taylor <ian@gcc.gnu.org> | 2012-09-17 16:38:38 +0000 |
commit | eff02e4f8421170b613b80e266b5b1893c588ea6 (patch) | |
tree | faa7758f2b343cc2da8066591b1f81f7833aca15 /libbacktrace/mmap.c | |
parent | 142c8954fd43340a3207f26b260f793685d9b3cd (diff) | |
download | gcc-eff02e4f8421170b613b80e266b5b1893c588ea6.zip gcc-eff02e4f8421170b613b80e266b5b1893c588ea6.tar.gz gcc-eff02e4f8421170b613b80e266b5b1893c588ea6.tar.bz2 |
libbacktrace/:
* Initial implementation.
./:
* MAINTAINERS (Various Maintainers): Add libbacktrace.
* configure.ac (host_libs): Add libbacktrace.
(target_libraries): Add libbacktrace.
* Makefile.def (host_modules): Add libbacktrace.
(target_modules): Likewise.
* configure, Makefile.in: Rebuild.
gcc/go:
* config-lang.in (target_libs): Add target-libbacktrace.
From-SVN: r191397
Diffstat (limited to 'libbacktrace/mmap.c')
-rw-r--r-- | libbacktrace/mmap.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/libbacktrace/mmap.c b/libbacktrace/mmap.c new file mode 100644 index 0000000..e8e9861 --- /dev/null +++ b/libbacktrace/mmap.c @@ -0,0 +1,235 @@ +/* mmap.c -- Memory allocation with mmap. + Copyright (C) 2012 Free Software Foundation, Inc. + Written by Ian Lance Taylor, Google. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + + (1) Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + (2) Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in + the documentation and/or other materials provided with the + distribution. + + (3) The name of the author may not be used to + endorse or promote products derived from this software without + specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, +INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING +IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +POSSIBILITY OF SUCH DAMAGE. */ + +#include "config.h" + +#include <errno.h> +#include <string.h> +#include <unistd.h> +#include <sys/mman.h> + +#include "backtrace.h" +#include "internal.h" + +/* Memory allocation on systems that provide anonymous mmap. This + permits the backtrace functions to be invoked from a signal + handler, assuming that mmap is async-signal safe. */ + +#ifndef MAP_ANONYMOUS +#define MAP_ANONYMOUS MAP_ANON +#endif + +/* A list of free memory blocks. */ + +struct backtrace_freelist_struct +{ + /* Next on list. */ + struct backtrace_freelist_struct *next; + /* Size of this block, including this structure. */ + size_t size; +}; + +/* Free memory allocated by backtrace_alloc. */ + +static void +backtrace_free_locked (struct backtrace_state *state, void *addr, size_t size) +{ + /* Just leak small blocks. We don't have to be perfect. */ + if (size >= sizeof (struct backtrace_freelist_struct)) + { + struct backtrace_freelist_struct *p; + + p = (struct backtrace_freelist_struct *) addr; + p->next = state->freelist; + p->size = size; + state->freelist = p; + } +} + +/* Allocate memory like malloc. */ + +void * +backtrace_alloc (struct backtrace_state *state, + size_t size, backtrace_error_callback error_callback, + void *data) +{ + void *ret; + struct backtrace_freelist_struct **pp; + size_t pagesize; + size_t asksize; + void *page; + + ret = NULL; + + /* If we can acquire the lock, then see if there is space on the + free list. If we can't acquire the lock, drop straight into + using mmap. __sync_lock_test_and_set returns the old state of + the lock, so we have acquired it if it returns 0. */ + + if (!__sync_lock_test_and_set (&state->lock_alloc, 1)) + { + for (pp = &state->freelist; *pp != NULL; pp = &(*pp)->next) + { + if ((*pp)->size >= size) + { + struct backtrace_freelist_struct *p; + + p = *pp; + *pp = p->next; + + /* Round for alignment; we assume that no type we care about + is more than 8 bytes. */ + size = (size + 7) & ~ (size_t) 7; + if (size < p->size) + backtrace_free_locked (state, (char *) p + size, + p->size - size); + + ret = (void *) p; + + break; + } + } + + __sync_lock_release (&state->lock_alloc); + } + + if (ret == NULL) + { + /* Allocate a new page. */ + + pagesize = getpagesize (); + asksize = (size + pagesize - 1) & ~ (pagesize - 1); + page = mmap (NULL, asksize, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (page == NULL) + error_callback (data, "mmap", errno); + else + { + size = (size + 7) & ~ (size_t) 7; + if (size < asksize) + backtrace_free (state, (char *) page + size, asksize - size, + error_callback, data); + + ret = page; + } + } + + return ret; +} + +/* Free memory allocated by backtrace_alloc. */ + +void +backtrace_free (struct backtrace_state *state, void *addr, size_t size, + backtrace_error_callback error_callback ATTRIBUTE_UNUSED, + void *data ATTRIBUTE_UNUSED) +{ + /* If we can acquire the lock, add the new space to the free list. + If we can't acquire the lock, just leak the memory. + __sync_lock_test_and_set returns the old state of the lock, so we + have acquired it if it returns 0. */ + if (!__sync_lock_test_and_set (&state->lock_alloc, 1)) + { + backtrace_free_locked (state, addr, size); + + __sync_lock_release (&state->lock_alloc); + } +} + +/* Grow VEC by SIZE bytes. */ + +void * +backtrace_vector_grow (struct backtrace_state *state,size_t size, + backtrace_error_callback error_callback, + void *data, struct backtrace_vector *vec) +{ + void *ret; + + if (size > vec->alc) + { + size_t pagesize; + size_t alc; + void *base; + + pagesize = getpagesize (); + alc = vec->size + size; + if (vec->size == 0) + alc = 16 * size; + else if (alc < pagesize) + { + alc *= 2; + if (alc > pagesize) + alc = pagesize; + } + else + alc = (alc + pagesize - 1) & ~ (pagesize - 1); + base = backtrace_alloc (state, alc, error_callback, data); + if (base == NULL) + return NULL; + if (vec->base != NULL) + { + memcpy (base, vec->base, vec->size); + backtrace_free (state, vec->base, vec->alc, error_callback, data); + } + vec->base = base; + vec->alc = alc - vec->size; + } + + ret = (char *) vec->base + vec->size; + vec->size += size; + vec->alc -= size; + return ret; +} + +/* Finish the current allocation on VEC. */ + +void +backtrace_vector_finish (struct backtrace_state *state ATTRIBUTE_UNUSED, + struct backtrace_vector *vec) +{ + vec->base = (char *) vec->base + vec->size; + vec->size = 0; +} + +/* Release any extra space allocated for VEC. */ + +int +backtrace_vector_release (struct backtrace_state *state, + struct backtrace_vector *vec, + backtrace_error_callback error_callback, + void *data) +{ + backtrace_free (state, (char *) vec->base + vec->size, vec->alc, + error_callback, data); + vec->alc = 0; + return 1; +} |