[PATCH v1] x86: Fix `#define STRCPY` guard in strcpy-sse2.S

[PATCH v1] x86: Fix `#define STRCPY` guard in strcpy-sse2.S

[Noah Goldstein]

`#ifndef STPCPY` is incorrect for checking if `STRCPY` is already
defined.  It doesn't end up mattering as the whole check is
guarded by `#if IS_IN (libc)` but is incorrect none the less.
---
 sysdeps/x86_64/multiarch/strcpy-sse2.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2.S b/sysdeps/x86_64/multiarch/strcpy-sse2.S
index e29b411314..d6b9bae5f8 100644
--- a/sysdeps/x86_64/multiarch/strcpy-sse2.S
+++ b/sysdeps/x86_64/multiarch/strcpy-sse2.S
@@ -22,7 +22,7 @@
 
 # include <sysdep.h>
 
-# ifndef STPCPY
+# ifndef STRCPY
 #  define STRCPY __strcpy_sse2
 # endif
 
-- 
2.34.1

[PATCH v1] elf: Replace `strcpy` call with `memcpy` [BZ #29454]

[Noah Goldstein]

GCC normally does this optimization for us in
strlen_pass::handle_builtin_strcpy but only for optimized
build. To avoid needing to include strcpy.S in the rtld build to
support the debug build, just do the optimization by hand.
---
 elf/dl-cache.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/elf/dl-cache.c b/elf/dl-cache.c
index 8bbf110d02..b97c17b3a9 100644
--- a/elf/dl-cache.c
+++ b/elf/dl-cache.c
@@ -509,8 +509,9 @@ _dl_load_cache_lookup (const char *name)
      we are accessing. Therefore we must make the copy of the
      mapping data without using malloc.  */
   char *temp;
-  temp = alloca (strlen (best) + 1);
-  strcpy (temp, best);
+  size_t best_len = strlen (best) + 1;
+  temp = alloca (best_len);
+  memcpy (temp, best, best_len);
   return __strdup (temp);
 }
 
-- 
2.34.1

Re: [PATCH v1] elf: Replace `strcpy` call with `memcpy` [BZ #29454]

[Yann Droneaud]

Hi,


Le 08/08/2022 à 05:26, Noah Goldstein via Libc-alpha a écrit :
> GCC normally does this optimization for us in
> strlen_pass::handle_builtin_strcpy but only for optimized
> build. To avoid needing to include strcpy.S in the rtld build to
> support the debug build, just do the optimization by hand.

It does fixes this build issue I had when using -Og (using gcc 11.2, on amd64):

     gcc   -nostdlib -nostartfiles -shared -o .../build/elf/ld.so.new        \
           -Wl,-z,relro -Wl,-z,defs     \
           -Wl,-z,pack-relative-relocs \
           .../build/elf/librtld.os -Wl,--version-script=.../build/ld.map        \
           -Wl,-soname=ld-linux-x86-64.so.2
     /usr/bin/ld: .../build/elf/librtld.os: in function `_dl_load_cache_lookup':
     .../elf/dl-cache.c:513: undefined reference to `strcpy'
     collect2: error: ld returned 1 exit status
     make[2]: *** [Makefile:1347: .../build/elf/ld.so] Error 1
     make[2]: Leaving directory '.../elf'
     make[1]: *** [Makefile:484: elf/subdir_lib] Error 2
     make[1]: Leaving directory '...'
     make: *** [Makefile:9: all] Error 2

Thanks.

> ---
>   elf/dl-cache.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/elf/dl-cache.c b/elf/dl-cache.c
> index 8bbf110d02..b97c17b3a9 100644
> --- a/elf/dl-cache.c
> +++ b/elf/dl-cache.c
> @@ -509,8 +509,9 @@ _dl_load_cache_lookup (const char *name)
>        we are accessing. Therefore we must make the copy of the
>        mapping data without using malloc.  */
>     char *temp;
> -  temp = alloca (strlen (best) + 1);
> -  strcpy (temp, best);
> +  size_t best_len = strlen (best) + 1;
> +  temp = alloca (best_len);
> +  memcpy (temp, best, best_len);
>     return __strdup (temp);
>   }
>   


Regards.

-- 

Yann Droneaud

OPTEYA

Re: [PATCH v1] elf: Replace `strcpy` call with `memcpy` [BZ #29454]

[H.J. Lu]

On Sun, Aug 7, 2022 at 8:26 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> GCC normally does this optimization for us in
> strlen_pass::handle_builtin_strcpy but only for optimized
> build. To avoid needing to include strcpy.S in the rtld build to
> support the debug build, just do the optimization by hand.
> ---
>  elf/dl-cache.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/elf/dl-cache.c b/elf/dl-cache.c
> index 8bbf110d02..b97c17b3a9 100644
> --- a/elf/dl-cache.c
> +++ b/elf/dl-cache.c
> @@ -509,8 +509,9 @@ _dl_load_cache_lookup (const char *name)
>       we are accessing. Therefore we must make the copy of the
>       mapping data without using malloc.  */
>    char *temp;
> -  temp = alloca (strlen (best) + 1);
> -  strcpy (temp, best);
> +  size_t best_len = strlen (best) + 1;
> +  temp = alloca (best_len);
> +  memcpy (temp, best, best_len);
>    return __strdup (temp);
>  }
>
> --
> 2.34.1
>

LGTM.

Thanks.

-- 
H.J.

Re: [PATCH v1] elf: Replace `strcpy` call with `memcpy` [BZ #29454]

[Noah Goldstein]

On Mon, Aug 8, 2022 at 10:24 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sun, Aug 7, 2022 at 8:26 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > GCC normally does this optimization for us in
> > strlen_pass::handle_builtin_strcpy but only for optimized
> > build. To avoid needing to include strcpy.S in the rtld build to
> > support the debug build, just do the optimization by hand.
> > ---
> >  elf/dl-cache.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/elf/dl-cache.c b/elf/dl-cache.c
> > index 8bbf110d02..b97c17b3a9 100644
> > --- a/elf/dl-cache.c
> > +++ b/elf/dl-cache.c
> > @@ -509,8 +509,9 @@ _dl_load_cache_lookup (const char *name)
> >       we are accessing. Therefore we must make the copy of the
> >       mapping data without using malloc.  */
> >    char *temp;
> > -  temp = alloca (strlen (best) + 1);
> > -  strcpy (temp, best);
> > +  size_t best_len = strlen (best) + 1;
> > +  temp = alloca (best_len);
> > +  memcpy (temp, best, best_len);
> >    return __strdup (temp);
> >  }
> >
> > --
> > 2.34.1
> >
>
> LGTM.
>
> Thanks.
>
> --
> H.J.

Any objections to backporting this to 2.36?

Re: [PATCH v1] x86: Fix `#define STRCPY` guard in strcpy-sse2.S

[H.J. Lu]

On Sun, Aug 7, 2022 at 8:26 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> `#ifndef STPCPY` is incorrect for checking if `STRCPY` is already
> defined.  It doesn't end up mattering as the whole check is
> guarded by `#if IS_IN (libc)` but is incorrect none the less.
> ---
>  sysdeps/x86_64/multiarch/strcpy-sse2.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2.S b/sysdeps/x86_64/multiarch/strcpy-sse2.S
> index e29b411314..d6b9bae5f8 100644
> --- a/sysdeps/x86_64/multiarch/strcpy-sse2.S
> +++ b/sysdeps/x86_64/multiarch/strcpy-sse2.S
> @@ -22,7 +22,7 @@
>
>  # include <sysdep.h>
>
> -# ifndef STPCPY
> +# ifndef STRCPY
>  #  define STRCPY __strcpy_sse2
>  # endif
>
> --
> 2.34.1
>

LGTM.

Thanks.

-- 
H.J.