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Don't bitshift by negative amounts.

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Don't bitshift by negative amounts when encoding/decoding run sizes in
chunk header maps.  This affected systems with page sizes greater than 8
KiB.

Reported by Ingvar Hagelund <ingvar@redpill-linpro.com>.
This commit is contained in:
Jason Evans 2015-08-19 14:12:05 -07:00
parent 6e98caf8f0
commit 5ef33a9f2b
4 changed files with 50 additions and 13 deletions
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6
ChangeLog
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@ -4,6 +4,12 @@ brevity. Much more detail can be found in the git revision history:
https://github.com/jemalloc/jemalloc
* 4.x.x (XXX)
Bug fixes:
- Don't bitshift by negative amounts when encoding/decoding run sizes in chunk
header maps. This affected systems with page sizes greater than 8 KiB.
* 4.0.0 (August 17, 2015)
This version contains many speed and space optimizations, both minor and

48
include/jemalloc/internal/arena.h
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@ -519,6 +519,7 @@ arena_chunk_map_misc_t *arena_run_to_miscelm(arena_run_t *run);
size_t *arena_mapbitsp_get(arena_chunk_t *chunk, size_t pageind);
size_t arena_mapbitsp_read(size_t *mapbitsp);
size_t arena_mapbits_get(arena_chunk_t *chunk, size_t pageind);
size_t arena_mapbits_size_decode(size_t mapbits);
size_t arena_mapbits_unallocated_size_get(arena_chunk_t *chunk,
size_t pageind);
size_t arena_mapbits_large_size_get(arena_chunk_t *chunk, size_t pageind);
@ -530,6 +531,7 @@ size_t arena_mapbits_decommitted_get(arena_chunk_t *chunk, size_t pageind);
size_t arena_mapbits_large_get(arena_chunk_t *chunk, size_t pageind);
size_t arena_mapbits_allocated_get(arena_chunk_t *chunk, size_t pageind);
void arena_mapbitsp_write(size_t *mapbitsp, size_t mapbits);
size_t arena_mapbits_size_encode(size_t size);
void arena_mapbits_unallocated_set(arena_chunk_t *chunk, size_t pageind,
size_t size, size_t flags);
void arena_mapbits_unallocated_size_set(arena_chunk_t *chunk, size_t pageind,
@ -652,6 +654,21 @@ arena_mapbits_get(arena_chunk_t *chunk, size_t pageind)
return (arena_mapbitsp_read(arena_mapbitsp_get(chunk, pageind)));
}
JEMALLOC_ALWAYS_INLINE size_t
arena_mapbits_size_decode(size_t mapbits)
{
size_t size;
if (CHUNK_MAP_SIZE_SHIFT > 0)
size = (mapbits & CHUNK_MAP_SIZE_MASK) >> CHUNK_MAP_SIZE_SHIFT;
else if (CHUNK_MAP_SIZE_SHIFT == 0)
size = mapbits & CHUNK_MAP_SIZE_MASK;
else
size = (mapbits & CHUNK_MAP_SIZE_MASK) << -CHUNK_MAP_SIZE_SHIFT;
return (size);
}
JEMALLOC_ALWAYS_INLINE size_t
arena_mapbits_unallocated_size_get(arena_chunk_t *chunk, size_t pageind)
{
@ -659,7 +676,7 @@ arena_mapbits_unallocated_size_get(arena_chunk_t *chunk, size_t pageind)
mapbits = arena_mapbits_get(chunk, pageind);
assert((mapbits & (CHUNK_MAP_LARGE|CHUNK_MAP_ALLOCATED)) == 0);
return ((mapbits & CHUNK_MAP_SIZE_MASK) >> CHUNK_MAP_SIZE_SHIFT);
return (arena_mapbits_size_decode(mapbits));
}
JEMALLOC_ALWAYS_INLINE size_t
@ -670,7 +687,7 @@ arena_mapbits_large_size_get(arena_chunk_t *chunk, size_t pageind)
mapbits = arena_mapbits_get(chunk, pageind);
assert((mapbits & (CHUNK_MAP_LARGE|CHUNK_MAP_ALLOCATED)) ==
(CHUNK_MAP_LARGE|CHUNK_MAP_ALLOCATED));
return ((mapbits & CHUNK_MAP_SIZE_MASK) >> CHUNK_MAP_SIZE_SHIFT);
return (arena_mapbits_size_decode(mapbits));
}
JEMALLOC_ALWAYS_INLINE size_t
@ -754,6 +771,22 @@ arena_mapbitsp_write(size_t *mapbitsp, size_t mapbits)
*mapbitsp = mapbits;
}
JEMALLOC_ALWAYS_INLINE size_t
arena_mapbits_size_encode(size_t size)
{
size_t mapbits;
if (CHUNK_MAP_SIZE_SHIFT > 0)
mapbits = size << CHUNK_MAP_SIZE_SHIFT;
else if (CHUNK_MAP_SIZE_SHIFT == 0)
mapbits = size;
else
mapbits = size >> -CHUNK_MAP_SIZE_SHIFT;
assert((mapbits & ~CHUNK_MAP_SIZE_MASK) == 0);
return (mapbits);
}
JEMALLOC_ALWAYS_INLINE void
arena_mapbits_unallocated_set(arena_chunk_t *chunk, size_t pageind, size_t size,
size_t flags)
@ -761,11 +794,10 @@ arena_mapbits_unallocated_set(arena_chunk_t *chunk, size_t pageind, size_t size,
size_t *mapbitsp = arena_mapbitsp_get(chunk, pageind);
assert((size & PAGE_MASK) == 0);
assert(((size << CHUNK_MAP_SIZE_SHIFT) & ~CHUNK_MAP_SIZE_MASK) == 0);
assert((flags & CHUNK_MAP_FLAGS_MASK) == flags);
assert((flags & CHUNK_MAP_DECOMMITTED) == 0 || (flags &
(CHUNK_MAP_DIRTY|CHUNK_MAP_UNZEROED)) == 0);
arena_mapbitsp_write(mapbitsp, (size << CHUNK_MAP_SIZE_SHIFT) |
arena_mapbitsp_write(mapbitsp, arena_mapbits_size_encode(size) |
CHUNK_MAP_BININD_INVALID | flags);
}
@ -777,10 +809,9 @@ arena_mapbits_unallocated_size_set(arena_chunk_t *chunk, size_t pageind,
size_t mapbits = arena_mapbitsp_read(mapbitsp);
assert((size & PAGE_MASK) == 0);
assert(((size << CHUNK_MAP_SIZE_SHIFT) & ~CHUNK_MAP_SIZE_MASK) == 0);
assert((mapbits & (CHUNK_MAP_LARGE|CHUNK_MAP_ALLOCATED)) == 0);
arena_mapbitsp_write(mapbitsp, (size << CHUNK_MAP_SIZE_SHIFT) | (mapbits
& ~CHUNK_MAP_SIZE_MASK));
arena_mapbitsp_write(mapbitsp, arena_mapbits_size_encode(size) |
(mapbits & ~CHUNK_MAP_SIZE_MASK));
}
JEMALLOC_ALWAYS_INLINE void
@ -799,11 +830,10 @@ arena_mapbits_large_set(arena_chunk_t *chunk, size_t pageind, size_t size,
size_t *mapbitsp = arena_mapbitsp_get(chunk, pageind);
assert((size & PAGE_MASK) == 0);
assert(((size << CHUNK_MAP_SIZE_SHIFT) & ~CHUNK_MAP_SIZE_MASK) == 0);
assert((flags & CHUNK_MAP_FLAGS_MASK) == flags);
assert((flags & CHUNK_MAP_DECOMMITTED) == 0 || (flags &
(CHUNK_MAP_DIRTY|CHUNK_MAP_UNZEROED)) == 0);
arena_mapbitsp_write(mapbitsp, (size << CHUNK_MAP_SIZE_SHIFT) |
arena_mapbitsp_write(mapbitsp, arena_mapbits_size_encode(size) |
CHUNK_MAP_BININD_INVALID | flags | CHUNK_MAP_LARGE |
CHUNK_MAP_ALLOCATED);
}

2
include/jemalloc/internal/private_symbols.txt
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@ -50,6 +50,8 @@ arena_mapbits_large_size_get
arena_mapbitsp_get
arena_mapbitsp_read
arena_mapbitsp_write
arena_mapbits_size_decode
arena_mapbits_size_encode
arena_mapbits_small_runind_get
arena_mapbits_small_set
arena_mapbits_unallocated_set

7
src/arena.c
View File

@ -39,7 +39,7 @@ JEMALLOC_INLINE_C arena_chunk_map_misc_t *
arena_miscelm_key_create(size_t size)
{
return ((arena_chunk_map_misc_t *)((size << CHUNK_MAP_SIZE_SHIFT) |
return ((arena_chunk_map_misc_t *)(arena_mapbits_size_encode(size) |
CHUNK_MAP_KEY));
}
@ -58,8 +58,7 @@ arena_miscelm_key_size_get(const arena_chunk_map_misc_t *miscelm)
assert(arena_miscelm_is_key(miscelm));
return (((uintptr_t)miscelm & CHUNK_MAP_SIZE_MASK) >>
CHUNK_MAP_SIZE_SHIFT);
return (arena_mapbits_size_decode((uintptr_t)miscelm));
}
JEMALLOC_INLINE_C size_t
@ -73,7 +72,7 @@ arena_miscelm_size_get(arena_chunk_map_misc_t *miscelm)
chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(miscelm);
pageind = arena_miscelm_to_pageind(miscelm);
mapbits = arena_mapbits_get(chunk, pageind);
return ((mapbits & CHUNK_MAP_SIZE_MASK) >> CHUNK_MAP_SIZE_SHIFT);
return (arena_mapbits_size_decode(mapbits));
}
JEMALLOC_INLINE_C int