[1/3] Replace BZERO_P/PIC with USE_AS_BZERO/SHARED
Commit Message
Replace BZERO_P with USE_AS_BZERO in i586/i686 memset.S to support i386
multi-arch memset. Also we should check SHARED not PIC for libc.so
since libc.a may be compiled with PIC.
OK for master?
H.J.
---
* sysdeps/i386/i586/bzero.S (USE_AS_BZERO): New.
* sysdeps/i386/i686/bzero.S (USE_AS_BZERO): Likewise.
* sysdeps/i386/i586/memset.S (BZERO_P): Removed.
Check USE_AS_BZERO/SHARED instead of BZERO_P/PIC.
(__memset_zero_constant_len_parameter): New.
* sysdeps/i386/i686/memset.S (BZERO_P): Removed.
Check USE_AS_BZERO/SHARED instead of BZERO_P/PIC.
(__memset_zero_constant_len_parameter): Don't define if
__memset_chk or USE_AS_BZERO are defined.
---
sysdeps/i386/i586/bzero.S | 1 +
sysdeps/i386/i586/memset.S | 22 +++++++++++-----------
sysdeps/i386/i686/bzero.S | 1 +
sysdeps/i386/i686/memset.S | 20 +++++++-------------
4 files changed, 20 insertions(+), 24 deletions(-)
Comments
On Wed, Aug 26, 2015 at 06:43:31AM -0700, H.J. Lu wrote:
> Replace BZERO_P with USE_AS_BZERO in i586/i686 memset.S to support i386
> multi-arch memset. Also we should check SHARED not PIC for libc.so
> since libc.a may be compiled with PIC.
>
> OK for master?
>
This is ok as patch.
However as I noted in x64 memset this is ineffective as it doubles code
size for mostly identical code. So as followup one needs to create bzero
stub that jumps into memset. Should I do it?
On Wed, Aug 26, 2015 at 6:59 AM, Ondřej Bílka <neleai@seznam.cz> wrote:
> On Wed, Aug 26, 2015 at 06:43:31AM -0700, H.J. Lu wrote:
>> Replace BZERO_P with USE_AS_BZERO in i586/i686 memset.S to support i386
>> multi-arch memset. Also we should check SHARED not PIC for libc.so
>> since libc.a may be compiled with PIC.
>>
>> OK for master?
>>
> This is ok as patch.
>
> However as I noted in x64 memset this is ineffective as it doubles code
> size for mostly identical code. So as followup one needs to create bzero
> stub that jumps into memset. Should I do it?
IA32 doesn't pass argument in registers. Can we have a second
entry point in memset for bzero?
On Wed, Aug 26, 2015 at 07:38:53AM -0700, H.J. Lu wrote:
> On Wed, Aug 26, 2015 at 6:59 AM, Ondřej Bílka <neleai@seznam.cz> wrote:
> > On Wed, Aug 26, 2015 at 06:43:31AM -0700, H.J. Lu wrote:
> >> Replace BZERO_P with USE_AS_BZERO in i586/i686 memset.S to support i386
> >> multi-arch memset. Also we should check SHARED not PIC for libc.so
> >> since libc.a may be compiled with PIC.
> >>
> >> OK for master?
> >>
> > This is ok as patch.
> >
> > However as I noted in x64 memset this is ineffective as it doubles code
> > size for mostly identical code. So as followup one needs to create bzero
> > stub that jumps into memset. Should I do it?
>
> IA32 doesn't pass argument in registers. Can we have a second
> entry point in memset for bzero?
>
Yes, that is what I wanted.
@@ -1,3 +1,4 @@
+#define USE_AS_BZERO
#define memset __bzero
#include <sysdeps/i386/i586/memset.S>
weak_alias (__bzero, bzero)
@@ -21,13 +21,10 @@
#include <sysdep.h>
#include "asm-syntax.h"
-/* BEWARE: `#ifdef memset' means that memset is redefined as `bzero' */
-#define BZERO_P (defined memset)
-
#define PARMS 4+4 /* space for 1 saved reg */
#define RTN PARMS
#define DEST RTN
-#if BZERO_P
+#ifdef USE_AS_BZERO
# define LEN DEST+4
#else
# define CHR DEST+4
@@ -35,7 +32,7 @@
#endif
.text
-#if defined PIC && IS_IN (libc) && !BZERO_P
+#if defined SHARED && IS_IN (libc) && !defined USE_AS_BZERO
ENTRY (__memset_chk)
movl 12(%esp), %eax
cmpl %eax, 16(%esp)
@@ -50,7 +47,7 @@ ENTRY (memset)
movl DEST(%esp), %edi
cfi_rel_offset (edi, 0)
movl LEN(%esp), %edx
-#if BZERO_P
+#ifdef USE_AS_BZERO
xorl %eax, %eax /* we fill with 0 */
#else
movb CHR(%esp), %al
@@ -104,7 +101,7 @@ L(2): shrl $2, %ecx /* convert byte count to longword count */
rep
stosb
-#if !BZERO_P
+#ifndef USE_AS_BZERO
/* Load result (only if used as memset). */
movl DEST(%esp), %eax /* start address of destination is result */
#endif
@@ -112,10 +109,13 @@ L(2): shrl $2, %ecx /* convert byte count to longword count */
cfi_adjust_cfa_offset (-4)
cfi_restore (edi)
-#if BZERO_P
- ret
-#else
ret
-#endif
END (memset)
libc_hidden_builtin_def (memset)
+
+#if defined SHARED && IS_IN (libc) && !defined __memset_chk \
+ && !defined USE_AS_BZERO
+strong_alias (__memset_chk, __memset_zero_constant_len_parameter)
+ .section .gnu.warning.__memset_zero_constant_len_parameter
+ .string "memset used with constant zero length parameter; this could be due to transposed parameters"
+#endif
@@ -1,3 +1,4 @@
+#define USE_AS_BZERO
#define memset __bzero
#include <sysdeps/i386/i686/memset.S>
weak_alias (__bzero, bzero)
@@ -21,11 +21,8 @@
#include <sysdep.h>
#include "asm-syntax.h"
-/* BEWARE: `#ifdef memset' means that memset is redefined as `bzero' */
-#define BZERO_P (defined memset)
-
#define PARMS 4+4 /* space for 1 saved reg */
-#if BZERO_P
+#ifdef USE_AS_BZERO
# define DEST PARMS
# define LEN DEST+4
#else
@@ -36,7 +33,7 @@
#endif
.text
-#if defined PIC && IS_IN (libc) && !BZERO_P
+#if defined SHARED && IS_IN (libc) && !defined USE_AS_BZERO
ENTRY_CHK (__memset_chk)
movl 12(%esp), %eax
cmpl %eax, 16(%esp)
@@ -50,7 +47,7 @@ ENTRY (memset)
cfi_adjust_cfa_offset (4)
movl DEST(%esp), %edx
movl LEN(%esp), %ecx
-#if BZERO_P
+#ifdef USE_AS_BZERO
xorl %eax, %eax /* fill with 0 */
#else
movzbl CHR(%esp), %eax
@@ -74,7 +71,7 @@ ENTRY (memset)
2: movl %ecx, %edx
shrl $2, %ecx
andl $3, %edx
-#if !BZERO_P
+#ifndef USE_AS_BZERO
imul $0x01010101, %eax
#endif
rep
@@ -84,22 +81,19 @@ ENTRY (memset)
stosb
1:
-#if !BZERO_P
+#ifndef USE_AS_BZERO
movl DEST(%esp), %eax /* start address of destination is result */
#endif
popl %edi
cfi_adjust_cfa_offset (-4)
cfi_restore (edi)
-#if BZERO_P
- ret
-#else
ret
-#endif
END (memset)
libc_hidden_builtin_def (memset)
-#if defined PIC && IS_IN (libc) && !BZERO_P
+#if defined SHARED && IS_IN (libc) && !defined __memset_chk \
+ && !defined USE_AS_BZERO
strong_alias (__memset_chk, __memset_zero_constant_len_parameter)
.section .gnu.warning.__memset_zero_constant_len_parameter
.string "memset used with constant zero length parameter; this could be due to transposed parameters"