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[3/4] powerpc: Refactor of _get_timebase_freq

Message ID 20190613151145.22243-4-raoni@linux.ibm.com
State Dropped
Headers show

Commit Message

Raoni Fassina Firmino June 13, 2019, 3:11 p.m. UTC
Since BZ#19767 is at least fixed for powerpc, we can now use the same
code in an agnostic way for static and shared linkage. Also because all
vDSO symbol do no fail we can simplify the vDSO calling without most of
the wrapper macros.

We keep the /proc/cpuinfo parsing as fallback if a kernel is built
without vDSO support

This implements the solution drafted by Adhemerval Zanella
<adhemerval.zanella@linaro.org> on the mailing list:

  https://www.sourceware.org/ml/libc-alpha/2019-05/msg00658.html

ChangeLog:

2019-06-13  Raoni Fassina Firmino  <raoni@linux.ibm.com>

	* sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
	(__get_timebase_freq): Refactoring.
---
 sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

Comments

Adhemerval Zanella Netto June 14, 2019, 3:24 p.m. UTC | #1
On 13/06/2019 12:11, Raoni Fassina Firmino wrote:
> Since BZ#19767 is at least fixed for powerpc, we can now use the same
> code in an agnostic way for static and shared linkage. Also because all
> vDSO symbol do no fail we can simplify the vDSO calling without most of
> the wrapper macros.
> 
> We keep the /proc/cpuinfo parsing as fallback if a kernel is built
> without vDSO support
> 
> This implements the solution drafted by Adhemerval Zanella
> <adhemerval.zanella@linaro.org> on the mailing list:
> 
>   https://www.sourceware.org/ml/libc-alpha/2019-05/msg00658.html
> 
> ChangeLog:
> 
> 2019-06-13  Raoni Fassina Firmino  <raoni@linux.ibm.com>
> 
> 	* sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> 	(__get_timebase_freq): Refactoring.
> ---
>  sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> index c245e97526..959c311acb 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
> @@ -28,12 +28,12 @@ __get_timebase_freq (void)
>  {
>    hp_timing_t result = 0L;
>  
> -#ifdef SHARED
> -  /* The vDSO does not return an error (it clear cr0.so on returning).  */
> -  INTERNAL_SYSCALL_DECL (err);
> -  result =
> -    INTERNAL_VSYSCALL_NO_SYSCALL_FALLBACK (get_tbfreq, err, uint64_t, 0);
> -#else
> +  /* The vDSO does not fail (it clears cr0.so on returning).  */
> +  __typeof (VDSO_SYMBOL(get_tbfreq)) vdsop = VDSO_SYMBOL(get_tbfreq);
> +  PTR_DEMANGLE (vdsop);
> +  if (vdsop != NULL)
> +    return vdsop ();
> +

This will fail on powerpc64 elfv1 because kernel vDSO does not provide ODP
entries (check sysdeps/unix/sysv/linux/powerpc/libc-vdso.h comment about it).
You will need to use VDSO_IFUNC_RET macros, as for gettimeofday and time
powerpc implementation.

As a side note, I will send it shortly a vDSO refactor that would make
use of internal vDSO symbol more simple on powerpc.

>    /* We read the information from the /proc filesystem.  /proc/cpuinfo
>       contains at least one line like:
>       timebase        : 33333333
> @@ -99,7 +99,6 @@ __get_timebase_freq (void)
>  	    }
>  	}
>      }
> -#endif
>  
>    return result;
>  }
>
diff mbox

Patch

diff --git a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
index c245e97526..959c311acb 100644
--- a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
+++ b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
@@ -28,12 +28,12 @@  __get_timebase_freq (void)
 {
   hp_timing_t result = 0L;
 
-#ifdef SHARED
-  /* The vDSO does not return an error (it clear cr0.so on returning).  */
-  INTERNAL_SYSCALL_DECL (err);
-  result =
-    INTERNAL_VSYSCALL_NO_SYSCALL_FALLBACK (get_tbfreq, err, uint64_t, 0);
-#else
+  /* The vDSO does not fail (it clears cr0.so on returning).  */
+  __typeof (VDSO_SYMBOL(get_tbfreq)) vdsop = VDSO_SYMBOL(get_tbfreq);
+  PTR_DEMANGLE (vdsop);
+  if (vdsop != NULL)
+    return vdsop ();
+
   /* We read the information from the /proc filesystem.  /proc/cpuinfo
      contains at least one line like:
      timebase        : 33333333
@@ -99,7 +99,6 @@  __get_timebase_freq (void)
 	    }
 	}
     }
-#endif
 
   return result;
 }