From: bmahi496@linux.ibm.com
To: libc-alpha@sourceware.org
Cc: rajis@linux.ibm.com, bergner@linux.ibm.com,
Mahesh Bodapati <mahesh.bodapati@ibm.com>
Subject: [PATCH v3] PowerPC: Influence cpu/arch hwcap features via GLIBC_TUNABLES.
Date: Thu, 6 Jul 2023 07:25:44 -0500 [thread overview]
Message-ID: <20230706122544.175643-1-bmahi496@linux.ibm.com> (raw)
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.
---
manual/tunables.texi | 5 +-
sysdeps/powerpc/cpu-features.c | 91 ++++++++++++++++++-
sysdeps/powerpc/cpu-features.h | 57 ++++++++++++
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, 171 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..40d945ba03 100644
--- a/sysdeps/powerpc/cpu-features.c
+++ b/sysdeps/powerpc/cpu-features.c
@@ -19,14 +19,103 @@
#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;
+ const char *token = valp->strval;
+ do
+ {
+ const char *token_end, *feature;
+ bool disable;
+ 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; hwcap_tunables[i].name != NULL; ++i)
+ {
+ /* Check the tunable name on the supported list. */
+ if (STRLEN_DEFAULT (hwcap_tunables[i].name) == feature_len
+ && MEMCMP_DEFAULT (feature, hwcap_tunables[i].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);
+ }
+ }
+ }
+ 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..6839c3085b 100644
--- a/sysdeps/powerpc/cpu-features.h
+++ b/sysdeps/powerpc/cpu-features.h
@@ -19,10 +19,67 @@
# 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 struct
+{
+ const char *name;
+ int mask;
+ bool id;
+} hwcap_tunables[] = {
+ /* AT_HWCAP tunable masks. */
+ { "4xxmac", PPC_FEATURE_HAS_4xxMAC, 0 },
+ { "altivec", PPC_FEATURE_HAS_ALTIVEC, 0 },
+ { "arch_2_05", PPC_FEATURE_ARCH_2_05, 0 },
+ { "arch_2_06", PPC_FEATURE_ARCH_2_06, 0 },
+ { "archpmu", PPC_FEATURE_PSERIES_PERFMON_COMPAT, 0 },
+ { "booke", PPC_FEATURE_BOOKE, 0 },
+ { "cellbe", PPC_FEATURE_CELL_BE, 0 },
+ { "dfp", PPC_FEATURE_HAS_DFP, 0 },
+ { "efpdouble", PPC_FEATURE_HAS_EFP_DOUBLE, 0 },
+ { "efpsingle", PPC_FEATURE_HAS_EFP_SINGLE, 0 },
+ { "fpu", PPC_FEATURE_HAS_FPU, 0 },
+ { "ic_snoop", PPC_FEATURE_ICACHE_SNOOP, 0 },
+ { "mmu", PPC_FEATURE_HAS_MMU, 0 },
+ { "notb", PPC_FEATURE_NO_TB, 0 },
+ { "pa6t", PPC_FEATURE_PA6T, 0 },
+ { "power4", PPC_FEATURE_POWER4, 0 },
+ { "power5", PPC_FEATURE_POWER5, 0 },
+ { "power5+", PPC_FEATURE_POWER5_PLUS, 0 },
+ { "power6x", PPC_FEATURE_POWER6_EXT, 0 },
+ { "ppc32", PPC_FEATURE_32, 0 },
+ { "ppc601", PPC_FEATURE_601_INSTR, 0 },
+ { "ppc64", PPC_FEATURE_64, 0 },
+ { "ppcle", PPC_FEATURE_PPC_LE, 0 },
+ { "smt", PPC_FEATURE_SMT, 0 },
+ { "spe", PPC_FEATURE_HAS_SPE, 0 },
+ { "true_le", PPC_FEATURE_TRUE_LE, 0 },
+ { "ucache", PPC_FEATURE_UNIFIED_CACHE, 0 },
+ { "vsx", PPC_FEATURE_HAS_VSX, 0 },
+
+ /* AT_HWCAP2 tunable masks. */
+ { "arch_2_07", PPC_FEATURE2_ARCH_2_07, 1 },
+ { "dscr", PPC_FEATURE2_HAS_DSCR, 1 },
+ { "ebb", PPC_FEATURE2_HAS_EBB, 1 },
+ { "htm", PPC_FEATURE2_HAS_HTM, 1 },
+ { "htm-nosc", PPC_FEATURE2_HTM_NOSC, 1 },
+ { "htm-no-suspend", PPC_FEATURE2_HTM_NO_SUSPEND, 1 },
+ { "isel", PPC_FEATURE2_HAS_ISEL, 1 },
+ { "tar", PPC_FEATURE2_HAS_TAR, 1 },
+ { "vcrypto", PPC_FEATURE2_HAS_VEC_CRYPTO, 1 },
+ { "arch_3_00", PPC_FEATURE2_ARCH_3_00, 1 },
+ { "ieee128", PPC_FEATURE2_HAS_IEEE128, 1 },
+ { "darn", PPC_FEATURE2_DARN, 1 },
+ { "scv", PPC_FEATURE2_SCV, 1 },
+ { "arch_3_1", PPC_FEATURE2_ARCH_3_1, 1 },
+ { "mma", 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
--
2.39.3
next reply other threads:[~2023-07-06 12:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-06 12:25 bmahi496 [this message]
2023-07-06 13:16 ` Adhemerval Zanella Netto
2023-07-06 20:38 ` Peter Bergner
2023-07-07 10:44 ` MAHESH BODAPATI
2023-07-06 21:05 ` Peter Bergner
2023-07-07 10:52 ` MAHESH BODAPATI
2023-07-07 16:40 ` Peter Bergner
2023-07-07 14:25 ` Adhemerval Zanella Netto
2023-07-07 16:07 ` Peter Bergner
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