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Re: [PATCH 1/4] powerpc: Fix static-linked version of __ppc_get_timebase_freq [BZ #24640]
On 13/06/2019 12:11, Raoni Fassina Firmino wrote:
> From: Stan Shebs <stanshebs@google.com>
>
> __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.
>
> ChangeLog:
>
> 2019-06-13 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.
Please include the testcase [1] on this patch. LGTM with this change.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
[1] https://sourceware.org/ml/libc-alpha/2019-06/msg00285.html
> ---
> sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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
>