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malloc: Refactor TAG_ macros to avoid indirection

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This does not change behaviour, just removes one layer of indirection
in the internal memory tagging logic.

Use tag_ and mtag_ prefixes instead of __tag_ and __mtag_ since these
are all symbols with internal linkage, private to malloc.c, so there
is no user namespace pollution issue.

Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Szabolcs Nagy
2021-02-16 14:12:25 +00:00
parent e865dcbb7b
commit 0c719cf42c
3 changed files with 51 additions and 56 deletions
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81
malloc/malloc.c
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@@ -413,26 +413,26 @@ void *(*__morecore)(ptrdiff_t) = __default_morecore;
operations can continue to be used. Support macros are used to do
this:
void *TAG_NEW_MEMSET (void *ptr, int, val, size_t size)
void *tag_new_memset (void *ptr, int, val, size_t size)
Has the same interface as memset(), but additionally allocates a
new tag, colors the memory with that tag and returns a pointer that
is correctly colored for that location. The non-tagging version
will simply call memset.
void *TAG_REGION (void *ptr, size_t size)
void *tag_region (void *ptr, size_t size)
Color the region of memory pointed to by PTR and size SIZE with
the color of PTR. Returns the original pointer.
void *TAG_NEW_USABLE (void *ptr)
void *tag_new_usable (void *ptr)
Allocate a new random color and use it to color the user region of
a chunk; this may include data from the subsequent chunk's header
if tagging is sufficiently fine grained. Returns PTR suitably
recolored for accessing the memory there.
void *TAG_AT (void *ptr)
void *tag_at (void *ptr)
Read the current color of the memory at the address pointed to by
PTR (ignoring it's current color) and return PTR recolored to that
@@ -455,25 +455,20 @@ __default_tag_nop (void *ptr)
return ptr;
}
static int __mtag_mmap_flags = 0;
static size_t __mtag_granule_mask = ~(size_t)0;
static int mtag_mmap_flags = 0;
static size_t mtag_granule_mask = ~(size_t)0;
static void *(*__tag_new_memset)(void *, int, size_t) = memset;
static void *(*__tag_region)(void *, size_t) = __default_tag_region;
static void *(*__tag_new_usable)(void *) = __default_tag_nop;
static void *(*__tag_at)(void *) = __default_tag_nop;
static void *(*tag_new_memset)(void *, int, size_t) = memset;
static void *(*tag_region)(void *, size_t) = __default_tag_region;
static void *(*tag_new_usable)(void *) = __default_tag_nop;
static void *(*tag_at)(void *) = __default_tag_nop;
# define MTAG_MMAP_FLAGS __mtag_mmap_flags
# define TAG_NEW_MEMSET(ptr, val, size) __tag_new_memset (ptr, val, size)
# define TAG_REGION(ptr, size) __tag_region (ptr, size)
# define TAG_NEW_USABLE(ptr) __tag_new_usable (ptr)
# define TAG_AT(ptr) __tag_at (ptr)
#else
# define MTAG_MMAP_FLAGS 0
# define TAG_NEW_MEMSET(ptr, val, size) memset (ptr, val, size)
# define TAG_REGION(ptr, size) (ptr)
# define TAG_NEW_USABLE(ptr) (ptr)
# define TAG_AT(ptr) (ptr)
# define mtag_mmap_flags 0
# define tag_new_memset(ptr, val, size) memset (ptr, val, size)
# define tag_region(ptr, size) (ptr)
# define tag_new_usable(ptr) (ptr)
# define tag_at(ptr) (ptr)
#endif
#include <string.h>
@@ -1305,8 +1300,8 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/* Convert between user mem pointers and chunk pointers, updating any
memory tags on the pointer to respect the tag value at that
location. */
#define chunk2mem(p) ((void*)TAG_AT (((char*)(p) + CHUNK_HDR_SZ)))
#define mem2chunk(mem) ((mchunkptr)TAG_AT (((char*)(mem) - CHUNK_HDR_SZ)))
#define chunk2mem(p) ((void *)tag_at (((char*)(p) + CHUNK_HDR_SZ)))
#define mem2chunk(mem) ((mchunkptr)tag_at (((char*)(mem) - CHUNK_HDR_SZ)))
/* The smallest possible chunk */
#define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
@@ -1337,7 +1332,7 @@ nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
#ifdef USE_MTAG
#define CHUNK_AVAILABLE_SIZE(p) \
((chunksize (p) + (chunk_is_mmapped (p) ? 0 : SIZE_SZ)) \
& __mtag_granule_mask)
& mtag_granule_mask)
#else
#define CHUNK_AVAILABLE_SIZE(p) \
(chunksize (p) + (chunk_is_mmapped (p) ? 0 : SIZE_SZ))
@@ -1361,7 +1356,7 @@ checked_request2size (size_t req, size_t *sz) __nonnull (1)
number. Ideally, this would be part of request2size(), but that
must be a macro that produces a compile time constant if passed
a constant literal. */
req = (req + ~__mtag_granule_mask) & __mtag_granule_mask;
req = (req + ~mtag_granule_mask) & mtag_granule_mask;
#endif
*sz = request2size (req);
@@ -2467,7 +2462,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
if ((unsigned long) (size) > (unsigned long) (nb))
{
mm = (char *) (MMAP (0, size,
MTAG_MMAP_FLAGS | PROT_READ | PROT_WRITE, 0));
mtag_mmap_flags | PROT_READ | PROT_WRITE, 0));
if (mm != MAP_FAILED)
{
@@ -2665,7 +2660,7 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
if ((unsigned long) (size) > (unsigned long) (nb))
{
char *mbrk = (char *) (MMAP (0, size,
MTAG_MMAP_FLAGS | PROT_READ | PROT_WRITE,
mtag_mmap_flags | PROT_READ | PROT_WRITE,
0));
if (mbrk != MAP_FAILED)
@@ -3221,14 +3216,14 @@ __libc_malloc (size_t bytes)
&& tcache->counts[tc_idx] > 0)
{
victim = tcache_get (tc_idx);
return TAG_NEW_USABLE (victim);
return tag_new_usable (victim);
}
DIAG_POP_NEEDS_COMMENT;
#endif
if (SINGLE_THREAD_P)
{
victim = TAG_NEW_USABLE (_int_malloc (&main_arena, bytes));
victim = tag_new_usable (_int_malloc (&main_arena, bytes));
assert (!victim || chunk_is_mmapped (mem2chunk (victim)) ||
&main_arena == arena_for_chunk (mem2chunk (victim)));
return victim;
@@ -3249,7 +3244,7 @@ __libc_malloc (size_t bytes)
if (ar_ptr != NULL)
__libc_lock_unlock (ar_ptr->mutex);
victim = TAG_NEW_USABLE (victim);
victim = tag_new_usable (victim);
assert (!victim || chunk_is_mmapped (mem2chunk (victim)) ||
ar_ptr == arena_for_chunk (mem2chunk (victim)));
@@ -3305,7 +3300,7 @@ __libc_free (void *mem)
MAYBE_INIT_TCACHE ();
/* Mark the chunk as belonging to the library again. */
(void)TAG_REGION (chunk2rawmem (p),
(void)tag_region (chunk2rawmem (p),
CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ);
ar_ptr = arena_for_chunk (p);
@@ -3408,7 +3403,7 @@ __libc_realloc (void *oldmem, size_t bytes)
reused. There's a performance hit for both us and the
caller for doing this, so we might want to
reconsider. */
return TAG_NEW_USABLE (newmem);
return tag_new_usable (newmem);
}
#endif
/* Note the extra SIZE_SZ overhead. */
@@ -3451,7 +3446,7 @@ __libc_realloc (void *oldmem, size_t bytes)
{
size_t sz = CHUNK_AVAILABLE_SIZE (oldp) - CHUNK_HDR_SZ;
memcpy (newp, oldmem, sz);
(void) TAG_REGION (chunk2rawmem (oldp), sz);
(void) tag_region (chunk2rawmem (oldp), sz);
_int_free (ar_ptr, oldp, 0);
}
}
@@ -3509,7 +3504,7 @@ _mid_memalign (size_t alignment, size_t bytes, void *address)
p = _int_memalign (&main_arena, alignment, bytes);
assert (!p || chunk_is_mmapped (mem2chunk (p)) ||
&main_arena == arena_for_chunk (mem2chunk (p)));
return TAG_NEW_USABLE (p);
return tag_new_usable (p);
}
arena_get (ar_ptr, bytes + alignment + MINSIZE);
@@ -3527,7 +3522,7 @@ _mid_memalign (size_t alignment, size_t bytes, void *address)
assert (!p || chunk_is_mmapped (mem2chunk (p)) ||
ar_ptr == arena_for_chunk (mem2chunk (p)));
return TAG_NEW_USABLE (p);
return tag_new_usable (p);
}
/* For ISO C11. */
weak_alias (__libc_memalign, aligned_alloc)
@@ -3544,7 +3539,7 @@ __libc_valloc (size_t bytes)
void *address = RETURN_ADDRESS (0);
size_t pagesize = GLRO (dl_pagesize);
p = _mid_memalign (pagesize, bytes, address);
return TAG_NEW_USABLE (p);
return tag_new_usable (p);
}
void *
@@ -3569,7 +3564,7 @@ __libc_pvalloc (size_t bytes)
rounded_bytes = rounded_bytes & -(pagesize - 1);
p = _mid_memalign (pagesize, rounded_bytes, address);
return TAG_NEW_USABLE (p);
return tag_new_usable (p);
}
void *
@@ -3666,7 +3661,7 @@ __libc_calloc (size_t n, size_t elem_size)
regardless of MORECORE_CLEARS, so we zero the whole block while
doing so. */
#ifdef USE_MTAG
return TAG_NEW_MEMSET (mem, 0, CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ);
return tag_new_memset (mem, 0, CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ);
#else
INTERNAL_SIZE_T csz = chunksize (p);
@@ -4821,7 +4816,7 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
av->top = chunk_at_offset (oldp, nb);
set_head (av->top, (newsize - nb) | PREV_INUSE);
check_inuse_chunk (av, oldp);
return TAG_NEW_USABLE (chunk2rawmem (oldp));
return tag_new_usable (chunk2rawmem (oldp));
}
/* Try to expand forward into next chunk; split off remainder below */
@@ -4856,8 +4851,8 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
{
void *oldmem = chunk2rawmem (oldp);
size_t sz = CHUNK_AVAILABLE_SIZE (oldp) - CHUNK_HDR_SZ;
(void) TAG_REGION (oldmem, sz);
newmem = TAG_NEW_USABLE (newmem);
(void) tag_region (oldmem, sz);
newmem = tag_new_usable (newmem);
memcpy (newmem, oldmem, sz);
_int_free (av, oldp, 1);
check_inuse_chunk (av, newp);
@@ -4881,7 +4876,7 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
{
remainder = chunk_at_offset (newp, nb);
/* Clear any user-space tags before writing the header. */
remainder = TAG_REGION (remainder, remainder_size);
remainder = tag_region (remainder, remainder_size);
set_head_size (newp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
set_head (remainder, remainder_size | PREV_INUSE |
(av != &main_arena ? NON_MAIN_ARENA : 0));
@@ -4891,7 +4886,7 @@ _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
}
check_inuse_chunk (av, newp);
return TAG_NEW_USABLE (chunk2rawmem (newp));
return tag_new_usable (chunk2rawmem (newp));
}
/*
@@ -5108,7 +5103,7 @@ musable (void *mem)
/* The usable space may be reduced if memory tagging is needed,
since we cannot share the user-space data with malloc's internal
data structure. */
result &= __mtag_granule_mask;
result &= mtag_granule_mask;
#endif
return result;
}