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Re: [PATCH] Simplify perturb_byte logic.
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Paul Eggert <eggert at cs dot ucla dot edu>
- Cc: libc-alpha at sourceware dot org
- Date: Mon, 9 Dec 2013 17:27:24 +0100
- Subject: Re: [PATCH] Simplify perturb_byte logic.
- Authentication-results: sourceware.org; auth=none
- References: <20131209141613 dot GA15247 at domone dot podge> <52A5E9E3 dot 4020505 at cs dot ucla dot edu>
On Mon, Dec 09, 2013 at 08:03:47AM -0800, Paul Eggert wrote:
> OndÅej BÃlka wrote:
> > + memset (p, perturb_byte & 0xff, n);
>
> While you're simplifying, you can safely omit that '& 0xff'.
> Similarly for alloc_perturb.
Ok, I commited this with these changes.
diff --git a/ChangeLog b/ChangeLog
index e04ee34..bbd241c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2013-12-09 OndÅej BÃlka <neleai@seznam.cz>
+ * malloc/malloc.c (alloc_perturb, free_perturb): Convert from
+ macro to a function. Check for zero perturb_byte.
+ (_int_malloc, _int_free): Remove zero perturb_byte checks.
+
+2013-12-09 OndÅej BÃlka <neleai@seznam.cz>
+
* malloc/malloc.c: (force_reg): Remove.
(__malloc_assert, __libc_malloc, __libc_free, __libc_realloc,
_mid_memalign, __libc_calloc, sysmalloc, systrim): Replace
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 4821deb..ac8c3f6 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1870,8 +1870,20 @@ static int check_action = DEFAULT_CHECK_ACTION;
static int perturb_byte;
-#define alloc_perturb(p, n) memset (p, (perturb_byte ^ 0xff) & 0xff, n)
-#define free_perturb(p, n) memset (p, perturb_byte & 0xff, n)
+static inline void
+alloc_perturb (char *p, size_t n)
+{
+ if (__glibc_unlikely (perturb_byte))
+ memset (p, perturb_byte ^ 0xff, n);
+}
+
+static inline void
+free_perturb (char *p, size_t n)
+{
+ if (__glibc_unlikely (perturb_byte))
+ memset (p, perturb_byte, n);
+}
+
#include <stap-probe.h>
@@ -3287,8 +3299,7 @@ _int_malloc(mstate av, size_t bytes)
}
check_remalloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
}
@@ -3323,8 +3334,7 @@ _int_malloc(mstate av, size_t bytes)
victim->size |= NON_MAIN_ARENA;
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
}
@@ -3403,8 +3413,7 @@ _int_malloc(mstate av, size_t bytes)
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
@@ -3420,8 +3429,7 @@ _int_malloc(mstate av, size_t bytes)
victim->size |= NON_MAIN_ARENA;
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
@@ -3545,8 +3553,7 @@ _int_malloc(mstate av, size_t bytes)
}
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
}
@@ -3649,8 +3656,7 @@ _int_malloc(mstate av, size_t bytes)
}
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
}
@@ -3684,8 +3690,7 @@ _int_malloc(mstate av, size_t bytes)
check_malloced_chunk(av, victim, nb);
void *p = chunk2mem(victim);
- if (__builtin_expect (perturb_byte, 0))
- alloc_perturb (p, bytes);
+ alloc_perturb (p, bytes);
return p;
}
@@ -3705,7 +3710,7 @@ _int_malloc(mstate av, size_t bytes)
*/
else {
void *p = sysmalloc(nb, av);
- if (p != NULL && __builtin_expect (perturb_byte, 0))
+ if (p != NULL)
alloc_perturb (p, bytes);
return p;
}
@@ -3798,8 +3803,7 @@ _int_free(mstate av, mchunkptr p, int have_lock)
}
}
- if (__builtin_expect (perturb_byte, 0))
- free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
+ free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
set_fastchunks(av);
unsigned int idx = fastbin_index(size);
@@ -3881,8 +3885,7 @@ _int_free(mstate av, mchunkptr p, int have_lock)
goto errout;
}
- if (__builtin_expect (perturb_byte, 0))
- free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
+ free_perturb (chunk2mem(p), size - 2 * SIZE_SZ);
/* consolidate backward */
if (!prev_inuse(p)) {