[RFC 8/9] elf: Remove LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Tue Jun 11 20:04:00 GMT 2024
On 07/06/24 08:42, Stefan Liebler wrote:
> Remove the environment variable LD_HWCAP_MASK and the tunable
> glibc.cpu.hwcap_mask as those are not used anymore in common-code
> after removal in elf/dl-cache.c:search_cache().
>
> The only remaining user is sparc32 where it is used in
> elf_machine_matches_host(). If sparc32 does not need it anymore,
> we can get rid of it at all. Otherwise we could also move
> LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask to be sparc32 specific.
I don't think sparc32 would miss this.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> elf/dl-tunables.list | 7 -------
> elf/tst-env-setuid.c | 1 -
> manual/README.tunables | 12 ++++++------
> manual/tunables.texi | 11 -----------
> sysdeps/generic/unsecvars.h | 1 -
> sysdeps/sparc/sparc32/dl-machine.h | 6 ------
> 6 files changed, 6 insertions(+), 32 deletions(-)
>
> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
> index 1186272c81..40ac5b3776 100644
> --- a/elf/dl-tunables.list
> +++ b/elf/dl-tunables.list
> @@ -83,13 +83,6 @@ glibc {
> minval: 0
> }
> }
> - cpu {
> - hwcap_mask {
> - type: UINT_64
> - env_alias: LD_HWCAP_MASK
> - default: HWCAP_IMPORTANT
> - }
> - }
>
> elision {
> enable {
> diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c
> index 43047c48f3..59f2ffeb88 100644
> --- a/elf/tst-env-setuid.c
> +++ b/elf/tst-env-setuid.c
> @@ -52,7 +52,6 @@ static const struct envvar_t filtered_envvars[] =
> {
> { "GLIBC_TUNABLES", FILTERED_VALUE },
> { "LD_AUDIT", FILTERED_VALUE },
> - { "LD_HWCAP_MASK", FILTERED_VALUE },
> { "LD_LIBRARY_PATH", FILTERED_VALUE },
> { "LD_PRELOAD", FILTERED_VALUE },
> { "LD_PROFILE", PROFILE_LIB },
> diff --git a/manual/README.tunables b/manual/README.tunables
> index 72ae00dc02..594879397b 100644
> --- a/manual/README.tunables
> +++ b/manual/README.tunables
> @@ -96,11 +96,11 @@ where 'check' is the tunable name and 'val' is a value of same type.
> To get and set tunables in a different namespace from that module, use the full
> form of the macros as follows:
>
> - val = TUNABLE_GET_FULL (glibc, cpu, hwcap_mask, uint64_t, NULL)
> + val = TUNABLE_GET_FULL (glibc, malloc, mmap_max, int32_t, NULL)
>
> - TUNABLE_SET_FULL (glibc, cpu, hwcap_mask, val)
> + TUNABLE_SET_FULL (glibc, malloc, mmap_max, val)
>
> -where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
> +where 'glibc' is the top namespace, 'malloc' is the tunable namespace and the
> remaining arguments are the same as the short form macros.
>
> The minimum and maximum values can updated together with the tunable value
> @@ -114,11 +114,11 @@ where 'check' is the tunable name, 'val' is a value of same type, 'min' and
> To set the minimum and maximum values of tunables in a different namespace
> from that module, use the full form of the macros as follows:
>
> - val = TUNABLE_GET_FULL (glibc, cpu, hwcap_mask, uint64_t, NULL)
> + val = TUNABLE_GET_FULL (glibc, malloc, mmap_max, int32_t, NULL)
>
> - TUNABLE_SET_WITH_BOUNDS_FULL (glibc, cpu, hwcap_mask, val, min, max)
> + TUNABLE_SET_WITH_BOUNDS_FULL (glibc, malloc, mmap_max, val, min, max)
>
> -where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
> +where 'glibc' is the top namespace, 'malloc' is the tunable namespace and the
> remaining arguments are the same as the short form macros.
>
> When TUNABLE_NAMESPACE is not defined in a module, TUNABLE_GET is equivalent to
> diff --git a/manual/tunables.texi b/manual/tunables.texi
> index 8dd02d8149..0b1b2898c0 100644
> --- a/manual/tunables.texi
> +++ b/manual/tunables.texi
> @@ -55,7 +55,6 @@ glibc.cpu.x86_non_temporal_threshold: 0xc0000 (min: 0x4040, max: 0xfffffffffffff
> glibc.cpu.x86_memset_non_temporal_threshold: 0xc0000 (min: 0x4040, max: 0xfffffffffffffff)
> glibc.cpu.x86_shstk:
> glibc.pthread.stack_cache_size: 0x2800000 (min: 0x0, max: 0xffffffffffffffff)
> -glibc.cpu.hwcap_mask: 0x6 (min: 0x0, max: 0xffffffffffffffff)
> glibc.malloc.mmap_max: 0 (min: 0, max: 2147483647)
> glibc.elision.skip_trylock_internal_abort: 3 (min: 0, max: 2147483647)
> glibc.cpu.plt_rewrite: 0 (min: 0, max: 2)
> @@ -504,16 +503,6 @@ Behavior of @theglibc{} can be tuned to assume specific hardware capabilities
> by setting the following tunables in the @code{cpu} namespace:
> @end deftp
>
> -@deftp Tunable glibc.cpu.hwcap_mask
> -This tunable supersedes the @env{LD_HWCAP_MASK} environment variable and is
> -identical in features.
> -
> -The @code{AT_HWCAP} key in the Auxiliary Vector specifies instruction set
> -extensions available in the processor at runtime for some architectures. The
> -@code{glibc.cpu.hwcap_mask} tunable allows the user to mask out those
> -capabilities at runtime, thus disabling use of those extensions.
> -@end deftp
> -
> @deftp Tunable glibc.cpu.hwcaps
> The @code{glibc.cpu.hwcaps=-xxx,yyy,-zzz...} tunable allows the user to
> enable CPU/ARCH feature @code{yyy}, disable CPU/ARCH feature @code{xxx}
> diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
> index f1724efe0f..97857a11aa 100644
> --- a/sysdeps/generic/unsecvars.h
> +++ b/sysdeps/generic/unsecvars.h
> @@ -12,7 +12,6 @@
> "LD_DEBUG\0" \
> "LD_DEBUG_OUTPUT\0" \
> "LD_DYNAMIC_WEAK\0" \
> - "LD_HWCAP_MASK\0" \
> "LD_LIBRARY_PATH\0" \
> "LD_ORIGIN_PATH\0" \
> "LD_PRELOAD\0" \
> diff --git a/sysdeps/sparc/sparc32/dl-machine.h b/sysdeps/sparc/sparc32/dl-machine.h
> index d855c66fe3..2c56d8a80e 100644
> --- a/sysdeps/sparc/sparc32/dl-machine.h
> +++ b/sysdeps/sparc/sparc32/dl-machine.h
> @@ -39,13 +39,7 @@ elf_machine_matches_host (const Elf32_Ehdr *ehdr)
> return 1;
> else if (ehdr->e_machine == EM_SPARC32PLUS)
> {
> -#if defined SHARED
> - uint64_t hwcap_mask = TUNABLE_GET (glibc, cpu, hwcap_mask, uint64_t,
> - NULL);
> - return GLRO(dl_hwcap) & hwcap_mask & HWCAP_SPARC_V9;
> -#else
> return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
> -#endif
> }
> else
> return 0;
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