This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH v2] powerpc: Fix static-linked version of __ppc_get_timebase_freq [BZ #24640]
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Wed, 19 Jun 2019 16:10:17 -0300
- Subject: Re: [PATCH v2] powerpc: Fix static-linked version of __ppc_get_timebase_freq [BZ #24640]
- References: <20190619180901.16240-1-raoni@linux.ibm.com>
On 19/06/2019 15:09, Raoni Fassina Firmino wrote:
> From: Stan Shebs <stanshebs@google.com>
>
> Originally part of a larger pathset[1].
>
> Changes since v1:
>
> - Merged fix & testcase in one patch.
> Originally patches #1 and #2[2,3].
>
> [1] https://www.sourceware.org/ml/libc-alpha/2019-06/msg00283.html
> [2] https://www.sourceware.org/ml/libc-alpha/2019-06/msg00284.html
> [3] https://www.sourceware.org/ml/libc-alpha/2019-06/msg00285.html
>
> ---- 8< ----
>
> __ppc_get_timebase_freq() always return 0 when using static linked
> glibc.
>
> This is a minimal example.c to reproduce:
>
> /******************************/
> #include <inttypes.h>
> #include <stdint.h>
> #include <stdio.h>
> #include <sys/platform/ppc.h>
>
> int main() {
> uint64_t freq = __ppc_get_timebase_freq();
> printf("Time Base frequency = %"PRIu64" Hz\n", freq);
> if (freq == 0)
> return -1;
> return 0;
> }
> /******************************/
>
> Compile command: gcc -static example.c
>
> This bug has been reproduced, fixed and tested on all powerpc platforms
> (ppc32, ppc64 and ppc64le).
>
> The underlying code of __ppc_get_timebase_freq uses __get_timebase_freq
> that has a different implementation for shared and static version of
> glibc. In the static version, there is an incorrect sense in the if
> check for the fd returned when opening /proc/cpuinfo.
>
> This solution is mostly a cherry-pick from:
>
> commit 4791e4f773d060c1a37b27aac5b03cdfa9327afc
> Author: Stan Shebs <stanshebs@google.com>
> Date: Fri May 17 12:25:19 2019 -0700
> Subject: Fix sense of a test in the static-linking version of ppc get_clockfreq
>
> That is in branch glibc/google/grte/v5-2.27/master and was mentioned for
> inclusion on master here:
>
> https://www.sourceware.org/ml/libc-alpha/2019-05/msg00409.html
>
> Adapted from original fix for get_clockfreq. That code was moved to
> get_timebase_freq.
>
> Also added a static-build testcase for __ppc_get_timebase_freq since the
> underlying function has different implementations for shared and static
> build.
>
> ChangeLog:
>
> 2019-06-19 Stan Shebs <stanshebs@google.com>
> Raoni Fassina Firmino <raoni@linux.ibm.com>
>
> [BZ #24640]
> * sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> [!SHARED] (__get_timebase_freq): Fix sense of a test in the
> static-linking version.
>
> * sysdeps/unix/sysv/linux/powerpc/Makefile
> (tests-static): Add test-gettimebasefreq-static.
> (tests): Likewise.
> * sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq-static.c:
> New file.
LGTM with the following change.
> ---
> sysdeps/unix/sysv/linux/powerpc/Makefile | 2 ++
> .../sysv/linux/powerpc/get_timebase_freq.c | 2 +-
> .../powerpc/test-gettimebasefreq-static.c | 19 +++++++++++++++++++
> 3 files changed, 22 insertions(+), 1 deletion(-)
> create mode 100644 sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq-static.c
>
> diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile
> index 19ac59d862..4b7198dcec 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/Makefile
> +++ b/sysdeps/unix/sysv/linux/powerpc/Makefile
> @@ -25,6 +25,8 @@ endif
> ifeq ($(subdir),misc)
> sysdep_headers += bits/ppc.h
> sysdep_routines += get_timebase_freq
> +tests-static += test-gettimebasefreq-static
> +tests += test-gettimebasefreq-static
Use $(tests-static) instead.
> tests += test-gettimebasefreq
> tests += test-powerpc-linux-sysconf
> endif
> diff --git a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> index 23e7694d87..c245e97526 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> @@ -39,7 +39,7 @@ __get_timebase_freq (void)
> timebase : 33333333
> We search for this line and convert the number into an integer. */
> int fd = __open_nocancel ("/proc/cpuinfo", O_RDONLY);
> - if (__glibc_likely (fd != -1))
> + if (__glibc_unlikely (fd == -1))
> return result;
>
> /* The timebase will be in the 1st 1024 bytes for systems with up
> diff --git a/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq-static.c b/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq-static.c
> new file mode 100644
> index 0000000000..58b4eee98d
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/powerpc/test-gettimebasefreq-static.c
> @@ -0,0 +1,19 @@
> +/* Check __ppc_get_timebase_freq() for architecture changes
> + Copyright (C) 2019 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#include "test-gettimebasefreq.c"
>