From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH 5/7] tunables: Use glibc.tune.hwcap_mask tunable instead of _dl_hwcap_mask
Date: Wed, 17 May 2017 15:29:00 -0000 [thread overview]
Message-ID: <6b4bb6a1-6220-22b7-8235-5b11c31e8ffc@linaro.org> (raw)
In-Reply-To: <1494514306-4167-6-git-send-email-siddhesh@sourceware.org>
On 11/05/2017 11:51, Siddhesh Poyarekar wrote:
> Drop _dl_hwcap_mask when building with tunables. This completes the
> transition of hwcap_mask reading from _dl_hwcap_mask to tunables.
>
> * elf/dl-cache.c: Include dl-tunables.h.
> (_dl_load_cache_lookup)[HAVE_TUNABLES]: Read
> glibc.tune.hwcap_mask.
> * elf/dl-hwcaps.c: Include dl-tunables.h.
> (_dl_important_hwcaps)[HAVE_TUNABLES]: Read and update
> glibc.tune.hwcap_mask.
> * sysdeps/sparc/sparc32/dl-machine.h: Likewise.
> * elf/dl-support.c (_dl_hwcap2)[HAVE_TUNABLES]: Drop
> _dl_hwcap_mask.
> * elf/dl-tunables.c (__tunable_set_val): Make a hidden alias.
> * elf/dl-tunables.h (__tunable_set_val): Likewise.
> * elf/rtld.c (rtld_global_ro)[HAVE_TUNABLES]: Drop
> _dl_hwcap_mask.
> (process_envvars)[HAVE_TUNABLES]: Likewise.
> * sysdeps/generic/ldsodefs.h (rtld_global_ro)[HAVE_TUNABLES]:
> Likewise.
> * sysdeps/x86/cpu-features.c (init_cpu_features): Don't
> initialize dl_hwcap_mask when tunables are enabled.
I would recommend to incorporate the fix for LD_HWCAP_MASK on tst-end-setuid
you sent before [1] to avoid this fail on some configuration (mine for
instance). Also I think we should open a bugzilla to iron out the
elf/dl-hwcaps.c allocation scheme which is triggering this issue.
[1] https://sourceware.org/ml/libc-alpha/2017-05/msg00340.html
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index f26a8b2..695ac24 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -515,8 +515,10 @@ struct rtld_global_ro
> /* Mask for hardware capabilities that are available. */
> EXTERN uint64_t _dl_hwcap;
>
> +#if !HAVE_TUNABLES
> /* Mask for important hardware capabilities we honour. */
> EXTERN uint64_t _dl_hwcap_mask;
> +#endif
>
> #ifdef HAVE_AUX_VECTOR
> /* Pointer to the auxv list supplied to the program at startup. */
> diff --git a/sysdeps/sparc/sparc32/dl-machine.h b/sysdeps/sparc/sparc32/dl-machine.h
> index cf7272f..6923e47 100644
> --- a/sysdeps/sparc/sparc32/dl-machine.h
> +++ b/sysdeps/sparc/sparc32/dl-machine.h
> @@ -39,7 +39,12 @@ elf_machine_matches_host (const Elf32_Ehdr *ehdr)
> /* XXX The following is wrong! Dave Miller rejected to implement it
> correctly. If this causes problems shoot *him*! */
> #ifdef SHARED
> - return GLRO(dl_hwcap) & GLRO(dl_hwcap_mask) & HWCAP_SPARC_V9;
> +# if HAVE_TUNABLES
> + uint64_t hwcap_mask = TUNABLE_GET (glibc, tune, hwcap_mask);
You are missing '#include <elf/dl-tunables.h>' and the final type argument for
TUNABLE_GET (it fails to build for sparcv9 with tunable enabled).
> +# else
> + uint64_t hwcap_mask = GLRO(dl_hwcap_mask);
> +# endif
> + return GLRO(dl_hwcap) & hwcap_mask & HWCAP_SPARC_V9;
> #else
> return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
> #endif
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index b481f50..4fe58bf 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -316,7 +316,11 @@ no_cpuid:
> /* Reuse dl_platform, dl_hwcap and dl_hwcap_mask for x86. */
> GLRO(dl_platform) = NULL;
> GLRO(dl_hwcap) = 0;
> +#if !HAVE_TUNABLES
> + /* The glibc.tune.hwcap_mask tunable is initialized already, so no need to do
> + this. */
> GLRO(dl_hwcap_mask) = HWCAP_IMPORTANT;
> +#endif
>
> # ifdef __x86_64__
> if (cpu_features->kind == arch_kind_intel)
>
next prev parent reply other threads:[~2017-05-17 15:29 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-11 14:51 [PATCH v1.1 0/7] aarch64: Allow overriding HWCAP_CPUID feature check Siddhesh Poyarekar
2017-05-11 14:52 ` [PATCH 1/7] tunables: Specify a default value for tunables Siddhesh Poyarekar
2017-05-15 21:13 ` Adhemerval Zanella
2017-05-15 21:55 ` Adhemerval Zanella
2017-05-11 14:52 ` [PATCH 3/7] tunables: Add hooks to get and update tunables Siddhesh Poyarekar
2017-05-16 20:30 ` Adhemerval Zanella
2017-05-17 7:17 ` Siddhesh Poyarekar
2017-05-17 13:53 ` Adhemerval Zanella
2017-05-11 14:52 ` [PATCH 5/7] tunables: Use glibc.tune.hwcap_mask tunable instead of _dl_hwcap_mask Siddhesh Poyarekar
2017-05-17 15:29 ` Adhemerval Zanella
2017-05-17 15:29 ` Adhemerval Zanella [this message]
2017-05-18 20:20 ` Siddhesh Poyarekar
2017-05-11 14:52 ` [PATCH 2/7] tunables: Add support for tunables of uint64_t type Siddhesh Poyarekar
2017-05-15 22:09 ` Adhemerval Zanella
2017-05-17 7:07 ` Siddhesh Poyarekar
2017-05-17 13:49 ` Adhemerval Zanella
2017-05-11 14:52 ` [PATCH 6/7] Delay initialization of CPU features struct in static binaries Siddhesh Poyarekar
2017-05-17 19:20 ` Adhemerval Zanella
2017-05-11 14:52 ` [PATCH 7/7] aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK Siddhesh Poyarekar
2017-05-17 19:22 ` Adhemerval Zanella
2017-05-18 20:44 ` Siddhesh Poyarekar
2017-05-11 14:52 ` [PATCH 4/7] tunables: Add LD_HWCAP_MASK to tunables Siddhesh Poyarekar
2017-05-16 20:35 ` Adhemerval Zanella
2017-05-17 7:18 ` Siddhesh Poyarekar
2017-05-17 9:44 ` Siddhesh Poyarekar
2017-05-17 13:53 ` Adhemerval Zanella
2017-05-11 15:38 ` [PATCH v1.1 0/7] aarch64: Allow overriding HWCAP_CPUID feature check Adhemerval Zanella
2017-05-11 16:49 ` Siddhesh Poyarekar
2017-05-12 12:10 ` Szabolcs Nagy
2017-05-12 13:44 ` Siddhesh Poyarekar
2017-05-12 13:55 ` Adhemerval Zanella
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