/* mmap.c -- Memory allocation with mmap.
- Copyright (C) 2012-2013 Free Software Foundation, Inc.
+ Copyright (C) 2012-2020 Free Software Foundation, Inc.
Written by Ian Lance Taylor, Google.
Redistribution and use in source and binary forms, with or without
met:
(1) Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
+ 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.
-
+ 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.
#include "backtrace.h"
#include "internal.h"
+#ifndef HAVE_DECL_GETPAGESIZE
+extern int getpagesize (void);
+#endif
+
/* 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. */
#define MAP_ANONYMOUS MAP_ANON
#endif
+#ifndef MAP_FAILED
+#define MAP_FAILED ((void *)-1)
+#endif
+
/* A list of free memory blocks. */
struct backtrace_freelist_struct
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. */
+ /* Just leak small blocks. We don't have to be perfect. Don't put
+ more than 16 entries on the free list, to avoid wasting time
+ searching when allocating a block. If we have more than 16
+ entries, leak the smallest entry. */
+
if (size >= sizeof (struct backtrace_freelist_struct))
{
+ size_t c;
+ struct backtrace_freelist_struct **ppsmall;
+ struct backtrace_freelist_struct **pp;
struct backtrace_freelist_struct *p;
+ c = 0;
+ ppsmall = NULL;
+ for (pp = &state->freelist; *pp != NULL; pp = &(*pp)->next)
+ {
+ if (ppsmall == NULL || (*pp)->size < (*ppsmall)->size)
+ ppsmall = pp;
+ ++c;
+ }
+ if (c >= 16)
+ {
+ if (size <= (*ppsmall)->size)
+ return;
+ *ppsmall = (*ppsmall)->next;
+ }
+
p = (struct backtrace_freelist_struct *) addr;
p->next = state->freelist;
p->size = size;
}
}
-/* Allocate memory like malloc. */
+/* Allocate memory like malloc. If ERROR_CALLBACK is NULL, don't
+ report an error. */
void *
backtrace_alloc (struct backtrace_state *state,
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);
+ if (page == MAP_FAILED)
+ {
+ if (error_callback)
+ error_callback (data, "mmap", errno);
+ }
else
{
size = (size + 7) & ~ (size_t) 7;
{
int locked;
+ /* If we are freeing a large aligned block, just release it back to
+ the system. This case arises when growing a vector for a large
+ binary with lots of debug info. Calling munmap here may cause us
+ to call mmap again if there is also a large shared library; we
+ just live with that. */
+ if (size >= 16 * 4096)
+ {
+ size_t pagesize;
+
+ pagesize = getpagesize ();
+ if (((uintptr_t) addr & (pagesize - 1)) == 0
+ && (size & (pagesize - 1)) == 0)
+ {
+ /* If munmap fails for some reason, just add the block to
+ the freelist. */
+ if (munmap (addr, size) == 0)
+ return;
+ }
+ }
+
/* 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
alc = pagesize;
}
else
- alc = (alc + pagesize - 1) & ~ (pagesize - 1);
+ {
+ alc *= 2;
+ 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);
+ backtrace_free (state, vec->base, vec->size + vec->alc,
+ error_callback, data);
}
vec->base = base;
vec->alc = alc - vec->size;
/* Finish the current allocation on VEC. */
-void
-backtrace_vector_finish (struct backtrace_state *state ATTRIBUTE_UNUSED,
- struct backtrace_vector *vec)
+void *
+backtrace_vector_finish (
+ struct backtrace_state *state ATTRIBUTE_UNUSED,
+ struct backtrace_vector *vec,
+ backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
+ void *data ATTRIBUTE_UNUSED)
{
+ void *ret;
+
+ ret = vec->base;
vec->base = (char *) vec->base + vec->size;
vec->size = 0;
+ return ret;
}
/* Release any extra space allocated for VEC. */
backtrace_free (state, (char *) vec->base + aligned, alc,
error_callback, data);
vec->alc = 0;
+ if (vec->size == 0)
+ vec->base = NULL;
return 1;
}
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