From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: bmahi496@linux.ibm.com, libc-alpha@sourceware.org
Cc: rajis@linux.ibm.com, bergner@linux.ibm.com,
Mahesh Bodapati <mahesh.bodapati@ibm.com>
Subject: Re: [PATCH v5] PowerPC: Influence cpu/arch hwcap features via GLIBC_TUNABLES.
Date: Tue, 11 Jul 2023 10:45:39 -0300 [thread overview]
Message-ID: <2b71d409-0649-f47c-0626-f4726456256d@linaro.org> (raw)
In-Reply-To: <20230710182150.2376678-1-bmahi496@linux.ibm.com>
On 10/07/23 15:21, bmahi496@linux.ibm.com wrote:
> From: Mahesh Bodapati <mahesh.bodapati@ibm.com>
>
> This patch enables the option to influence hwcaps used by PowerPC.
> The environment variable, GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,-zzz....,
> can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature xxx
> and zzz, where the feature name is case-sensitive and has to match the ones
> mentioned in the file{sysdeps/powerpc/dl-procinfo.c}.
>
> Note that the tunable only handles the features which are really used
> in the IFUNC selection. All others are ignored as the values are only
> used inside glibc.
It is still missing a regression test to check if tunable work as intended.
> ---
> manual/tunables.texi | 5 +-
> sysdeps/powerpc/cpu-features.c | 97 ++++++++++++++++-
> sysdeps/powerpc/cpu-features.h | 102 ++++++++++++++++++
> sysdeps/powerpc/dl-tunables.list | 3 +
> sysdeps/powerpc/hwcapinfo.c | 4 +
> .../power4/multiarch/ifunc-impl-list.c | 4 +-
> .../powerpc32/power4/multiarch/init-arch.h | 10 +-
> sysdeps/powerpc/powerpc64/dl-machine.h | 2 -
> .../powerpc64/multiarch/ifunc-impl-list.c | 7 +-
> 9 files changed, 222 insertions(+), 12 deletions(-)
>
> diff --git a/manual/tunables.texi b/manual/tunables.texi
> index 4ca0e42a11..776fd93fd9 100644
> --- a/manual/tunables.texi
> +++ b/manual/tunables.texi
> @@ -513,7 +513,10 @@ On s390x, the supported HWCAP and STFLE features can be found in
> @code{sysdeps/s390/cpu-features.c}. In addition the user can also set
> a CPU arch-level like @code{z13} instead of single HWCAP and STFLE features.
>
> -This tunable is specific to i386, x86-64 and s390x.
> +On powerpc, the supported HWCAP and HWCAP2 features can be found in
> +@code{sysdeps/powerpc/dl-procinfo.c}.
> +
> +This tunable is specific to i386, x86-64, s390x and powerpc.
> @end deftp
>
> @deftp Tunable glibc.cpu.cached_memopt
> diff --git a/sysdeps/powerpc/cpu-features.c b/sysdeps/powerpc/cpu-features.c
> index 0ef3cf89d2..bf1c5353da 100644
> --- a/sysdeps/powerpc/cpu-features.c
> +++ b/sysdeps/powerpc/cpu-features.c
> @@ -19,14 +19,109 @@
> #include <stdint.h>
> #include <cpu-features.h>
> #include <elf/dl-tunables.h>
> +#include <unistd.h>
> +#include <string.h>
> +#define MEMCMP_DEFAULT memcmp
> +#define STRLEN_DEFAULT strlen
> +
> +static void
> +TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
> +{
> + /* The current IFUNC selection is always using the most recent
> + features which are available via AT_HWCAP or AT_HWCAP2. But in
> + some scenarios it is useful to adjust this selection.
> +
> + The environment variable:
> +
> + GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,....
> +
> + Can be used to enable HWCAP/HWCAP2 feature yyy, disable HWCAP/HWCAP2
> + feature xxx, where the feature name is case-sensitive and has to match
> + the ones mentioned in the file{sysdeps/powerpc/dl-procinfo.c}. */
> +
> + /* Copy the features from dl_powerpc_cpu_features, which contains the
> + features provided by AT_HWCAP and AT_HWCAP2. */
> + struct cpu_features *cpu_features = &GLRO(dl_powerpc_cpu_features);
> + unsigned long int tcbv_hwcap = cpu_features->hwcap;
> + unsigned long int tcbv_hwcap2 = cpu_features->hwcap2;
> + unsigned int tun_count;
> + const char *token = valp->strval;
> + tun_count = sizeof(hwcap_tunables)/sizeof(hwcap_tunables[0]);
> + do
> + {
> + const char *token_end, *feature;
> + bool disable;
> + unsigned short offset=0;
> + size_t token_len, i, feature_len;
> + /* Find token separator or end of string. */
> + for (token_end = token; *token_end != ','; token_end++)
> + if (*token_end == '\0')
> + break;
> +
> + /* Determine feature. */
> + token_len = token_end - token;
> + if (*token == '-')
> + {
> + disable = true;
> + feature = token + 1;
> + feature_len = token_len - 1;
> + }
> + else
> + {
> + disable = false;
> + feature = token;
> + feature_len = token_len;
> + }
> + for (i = 0; i < tun_count; ++i)
> + {
> + const char *hwcap_name = hwcap_names + offset;
> + /* Check the tunable name on the supported list. */
> + if (STRLEN_DEFAULT (hwcap_name) == feature_len
> + && MEMCMP_DEFAULT (feature, hwcap_name, feature_len)
> + == 0)
> + {
> + /* Update the hwcap and hwcap2 bits. */
> + if (disable)
> + {
> + /* Id is 1 for hwcap2 tunable. */
> + if (hwcap_tunables[i].id)
> + cpu_features->hwcap2 &= ~(hwcap_tunables[i].mask);
> + else
> + cpu_features->hwcap &= ~(hwcap_tunables[i].mask);
> + }
> + else
> + {
> + /* Enable the features and also checking that no unsupported
> + features were enabled by user. */
> + if (hwcap_tunables[i].id)
> + cpu_features->hwcap2 |= (tcbv_hwcap2 & hwcap_tunables[i].mask);
> + else
> + cpu_features->hwcap |= (tcbv_hwcap & hwcap_tunables[i].mask);
> + }
> + break;
> + }
> + offset = offset + STRLEN_DEFAULT (hwcap_name) + 1;
> + }
> + token += token_len;
> + /* ... and skip token separator for next round. */
> + if (*token == ',') token++;
> + }
> + while (*token != '\0');
> +}
>
> static inline void
> -init_cpu_features (struct cpu_features *cpu_features)
> +init_cpu_features (struct cpu_features *cpu_features, uint64_t hwcaps[])
> {
> + /* Fill the cpu_features with the supported hwcaps
> + which are set by __tcb_parse_hwcap_and_convert_at_platform. */
> + cpu_features->hwcap = hwcaps[0];
> + cpu_features->hwcap2 = hwcaps[1];
> /* Default is to use aligned memory access on optimized function unless
> tunables is enable, since for this case user can explicit disable
> unaligned optimizations. */
> int32_t cached_memfunc = TUNABLE_GET (glibc, cpu, cached_memopt, int32_t,
> NULL);
> cpu_features->use_cached_memopt = (cached_memfunc > 0);
> + TUNABLE_GET (glibc, cpu, hwcaps, tunable_val_t *,
> + TUNABLE_CALLBACK (set_hwcaps));
> }
> diff --git a/sysdeps/powerpc/cpu-features.h b/sysdeps/powerpc/cpu-features.h
> index d316dc3d64..e5fce88e5e 100644
> --- a/sysdeps/powerpc/cpu-features.h
> +++ b/sysdeps/powerpc/cpu-features.h
> @@ -19,10 +19,112 @@
> # define __CPU_FEATURES_POWERPC_H
>
> #include <stdbool.h>
> +#include <sys/auxv.h>
>
> struct cpu_features
> {
> bool use_cached_memopt;
> + unsigned long int hwcap;
> + unsigned long int hwcap2;
> +};
> +
> +static const char hwcap_names[] = {
> + "4xxmac\0"
> + "altivec\0"
> + "arch_2_05\0"
> + "arch_2_06\0"
> + "archpmu\0"
> + "booke\0"
> + "cellbe\0"
> + "dfp\0"
> + "efpdouble\0"
> + "efpsingle\0"
> + "fpu\0"
> + "ic_snoop\0"
> + "mmu\0"
> + "notb\0"
> + "pa6t\0"
> + "power4\0"
> + "power5\0"
> + "power5+\0"
> + "power6x\0"
> + "ppc32\0"
> + "ppc601\0"
> + "ppc64\0"
> + "ppcle\0"
> + "smt\0"
> + "spe\0"
> + "true_le\0"
> + "ucache\0"
> + "vsx\0"
> + "arch_2_07\0"
> + "dscr\0"
> + "ebb\0"
> + "htm\0"
> + "htm-nosc\0"
> + "htm-no-suspend\0"
> + "isel\0"
> + "tar\0"
> + "vcrypto\0"
> + "arch_3_00\0"
> + "ieee128\0"
> + "darn\0"
> + "scv\0"
> + "arch_3_1\0"
> + "mma\0"
> +};
> +
> +static const struct
> +{
> + unsigned int mask;
> + bool id;
> +} hwcap_tunables[] = {
> + /* AT_HWCAP tunable masks. */
> + { PPC_FEATURE_HAS_4xxMAC, 0 },
> + { PPC_FEATURE_HAS_ALTIVEC, 0 },
> + { PPC_FEATURE_ARCH_2_05, 0 },
> + { PPC_FEATURE_ARCH_2_06, 0 },
> + { PPC_FEATURE_PSERIES_PERFMON_COMPAT, 0 },
> + { PPC_FEATURE_BOOKE, 0 },
> + { PPC_FEATURE_CELL_BE, 0 },
> + { PPC_FEATURE_HAS_DFP, 0 },
> + { PPC_FEATURE_HAS_EFP_DOUBLE, 0 },
> + { PPC_FEATURE_HAS_EFP_SINGLE, 0 },
> + { PPC_FEATURE_HAS_FPU, 0 },
> + { PPC_FEATURE_ICACHE_SNOOP, 0 },
> + { PPC_FEATURE_HAS_MMU, 0 },
> + { PPC_FEATURE_NO_TB, 0 },
> + { PPC_FEATURE_PA6T, 0 },
> + { PPC_FEATURE_POWER4, 0 },
> + { PPC_FEATURE_POWER5, 0 },
> + { PPC_FEATURE_POWER5_PLUS, 0 },
> + { PPC_FEATURE_POWER6_EXT, 0 },
> + { PPC_FEATURE_32, 0 },
> + { PPC_FEATURE_601_INSTR, 0 },
> + { PPC_FEATURE_64, 0 },
> + { PPC_FEATURE_PPC_LE, 0 },
> + { PPC_FEATURE_SMT, 0 },
> + { PPC_FEATURE_HAS_SPE, 0 },
> + { PPC_FEATURE_TRUE_LE, 0 },
> + { PPC_FEATURE_UNIFIED_CACHE, 0 },
> + { PPC_FEATURE_HAS_VSX, 0 },
> +
> + /* AT_HWCAP2 tunable masks. */
> + { PPC_FEATURE2_ARCH_2_07, 1 },
> + { PPC_FEATURE2_HAS_DSCR, 1 },
> + { PPC_FEATURE2_HAS_EBB, 1 },
> + { PPC_FEATURE2_HAS_HTM, 1 },
> + { PPC_FEATURE2_HTM_NOSC, 1 },
> + { PPC_FEATURE2_HTM_NO_SUSPEND, 1 },
> + { PPC_FEATURE2_HAS_ISEL, 1 },
> + { PPC_FEATURE2_HAS_TAR, 1 },
> + { PPC_FEATURE2_HAS_VEC_CRYPTO, 1 },
> + { PPC_FEATURE2_ARCH_3_00, 1 },
> + { PPC_FEATURE2_HAS_IEEE128, 1 },
> + { PPC_FEATURE2_DARN, 1 },
> + { PPC_FEATURE2_SCV, 1 },
> + { PPC_FEATURE2_ARCH_3_1, 1 },
> + { PPC_FEATURE2_MMA, 1 },
> };
>
> #endif /* __CPU_FEATURES_H */
> diff --git a/sysdeps/powerpc/dl-tunables.list b/sysdeps/powerpc/dl-tunables.list
> index 87d6235c75..807b7f8013 100644
> --- a/sysdeps/powerpc/dl-tunables.list
> +++ b/sysdeps/powerpc/dl-tunables.list
> @@ -24,5 +24,8 @@ glibc {
> maxval: 1
> default: 0
> }
> + hwcaps {
> + type: STRING
> + }
> }
> }
> diff --git a/sysdeps/powerpc/hwcapinfo.c b/sysdeps/powerpc/hwcapinfo.c
> index e26e64d99e..f2c473c556 100644
> --- a/sysdeps/powerpc/hwcapinfo.c
> +++ b/sysdeps/powerpc/hwcapinfo.c
> @@ -19,6 +19,7 @@
> #include <unistd.h>
> #include <shlib-compat.h>
> #include <dl-procinfo.h>
> +#include <cpu-features.c>
>
> tcbhead_t __tcb __attribute__ ((visibility ("hidden")));
>
> @@ -63,6 +64,9 @@ __tcb_parse_hwcap_and_convert_at_platform (void)
> else if (h1 & PPC_FEATURE_POWER5)
> h1 |= PPC_FEATURE_POWER4;
>
> + uint64_t array_hwcaps[] = { h1, h2 };
> + init_cpu_features (&GLRO(dl_powerpc_cpu_features), array_hwcaps);
> +
> /* Consolidate both HWCAP and HWCAP2 into a single doubleword so that
> we can read both in a single load later. */
> __tcb.hwcap = (h1 << 32) | (h2 & 0xffffffff);
> diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
> index b4f80539e7..986c37d71e 100644
> --- a/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
> @@ -21,6 +21,7 @@
> #include <wchar.h>
> #include <ldsodefs.h>
> #include <ifunc-impl-list.h>
> +#include <cpu-features.h>
>
> size_t
> __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> @@ -28,7 +29,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> {
> size_t i = max;
>
> - unsigned long int hwcap = GLRO(dl_hwcap);
> + const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features);
> + unsigned long int hwcap = features->hwcap;
> /* hwcap contains only the latest supported ISA, the code checks which is
> and fills the previous supported ones. */
> if (hwcap & PPC_FEATURE_ARCH_2_06)
> diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h b/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
> index 3dd00e02ee..a0bbd12012 100644
> --- a/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
> +++ b/sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
> @@ -16,6 +16,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <ldsodefs.h>
> +#include <cpu-features.h>
>
> /* The code checks if _rtld_global_ro was realocated before trying to access
> the dl_hwcap field. The assembly is to make the compiler not optimize the
> @@ -32,11 +33,12 @@
> # define __GLRO(value) GLRO(value)
> #endif
>
> -/* dl_hwcap contains only the latest supported ISA, the macro checks which is
> - and fills the previous ones. */
> +/* Get the hardware information post the tunables set , the macro checks
> + it and fills the previous ones. */
> #define INIT_ARCH() \
> - unsigned long int hwcap = __GLRO(dl_hwcap); \
> - unsigned long int __attribute__((unused)) hwcap2 = __GLRO(dl_hwcap2); \
> + const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features); \
> + unsigned long int hwcap = features->hwcap; \
> + unsigned long int __attribute__((unused)) hwcap2 = features->hwcap2; \
> bool __attribute__((unused)) use_cached_memopt = \
> __GLRO(dl_powerpc_cpu_features.use_cached_memopt); \
> if (hwcap & PPC_FEATURE_ARCH_2_06) \
> diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
> index 9b8943bc91..449208e86f 100644
> --- a/sysdeps/powerpc/powerpc64/dl-machine.h
> +++ b/sysdeps/powerpc/powerpc64/dl-machine.h
> @@ -27,7 +27,6 @@
> #include <dl-tls.h>
> #include <sysdep.h>
> #include <hwcapinfo.h>
> -#include <cpu-features.c>
> #include <dl-static-tls.h>
> #include <dl-funcdesc.h>
> #include <dl-machine-rel.h>
> @@ -297,7 +296,6 @@ static inline void __attribute__ ((unused))
> dl_platform_init (void)
> {
> __tcb_parse_hwcap_and_convert_at_platform ();
> - init_cpu_features (&GLRO(dl_powerpc_cpu_features));
> }
> #endif
>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> index ebe9434052..fc26dd0e17 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> @@ -17,6 +17,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <assert.h>
> +#include <cpu-features.h>
> #include <string.h>
> #include <wchar.h>
> #include <ldsodefs.h>
> @@ -27,9 +28,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> size_t max)
> {
> size_t i = max;
> -
> - unsigned long int hwcap = GLRO(dl_hwcap);
> - unsigned long int hwcap2 = GLRO(dl_hwcap2);
> + const struct cpu_features *features = &GLRO(dl_powerpc_cpu_features);
> + unsigned long int hwcap = features->hwcap;
> + unsigned long int hwcap2 = features->hwcap2;
> #ifdef SHARED
> int cacheline_size = GLRO(dl_cache_line_size);
> #endif
next prev parent reply other threads:[~2023-07-11 13:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 18:21 bmahi496
2023-07-10 21:28 ` Peter Bergner
2023-07-11 12:24 ` Adhemerval Zanella Netto
2023-07-11 16:05 ` MAHESH BODAPATI
2023-07-11 13:45 ` Adhemerval Zanella Netto [this message]
2023-07-11 16:03 ` MAHESH BODAPATI
2023-07-11 16:23 ` Adhemerval Zanella Netto
2023-07-11 16:23 ` Adhemerval Zanella Netto
2023-07-12 11:04 ` MAHESH BODAPATI
2023-07-12 14:07 ` Adhemerval Zanella Netto
2023-07-13 13:17 ` MAHESH BODAPATI
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