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PowerPC: Influence cpu/arch hwcap features via GLIBC_TUNABLES

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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 hwcap tunables only used in the IFUNC selection.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Mahesh Bodapati 2023-08-01 07:41:17 -05:00 committed by Rajalakshmi Srinivasaraghavan
parent 5c37d20652
commit 21841f0d56
13 changed files with 414 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
manual/tunables.texi
View File

@ -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

32
sysdeps/powerpc/cpu-features.c
View File

@ -1,32 +0,0 @@
/* Initialize cpu feature data. PowerPC version.
Copyright (C) 2017-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdint.h>
#include <cpu-features.h>
#include <elf/dl-tunables.h>
static inline void
init_cpu_features (struct cpu_features *cpu_features)
{
/* 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);
}

28
sysdeps/powerpc/cpu-features.h
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@ -1,28 +0,0 @@
/* Initialize cpu feature data. PowerPC version.
Copyright (C) 2017-2023 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef __CPU_FEATURES_POWERPC_H
# define __CPU_FEATURES_POWERPC_H
#include <stdbool.h>
struct cpu_features
{
bool use_cached_memopt;
};
#endif /* __CPU_FEATURES_H */

3
sysdeps/powerpc/dl-tunables.list
View File

@ -24,5 +24,8 @@ glibc {
maxval: 1
default: 0
}
hwcaps {
type: STRING
}
}
}

4
sysdeps/powerpc/hwcapinfo.c
View File

@ -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);

4
sysdeps/powerpc/powerpc32/power4/multiarch/ifunc-impl-list.c
View File

@ -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)

10
sysdeps/powerpc/powerpc32/power4/multiarch/init-arch.h
View File

@ -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) \

2
sysdeps/powerpc/powerpc64/dl-machine.h
View File

@ -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

7
sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
View File

@ -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

11
sysdeps/unix/sysv/linux/powerpc/Makefile
View File

@ -23,9 +23,14 @@ ifeq ($(subdir),misc)
sysdep_headers += bits/ppc.h
sysdep_routines += get_timebase_freq
tests-static += test-gettimebasefreq-static
tests += $(tests-static)
tests += test-gettimebasefreq
tests += test-powerpc-linux-sysconf
tests += \
$(tests-static) \
test-gettimebasefreq \
test-powerpc-linux-sysconf \
tst-hwcap-tunables \
# tests
tst-hwcap-tunables-ARGS = -- $(host-test-program-cmd)
endif
ifeq ($(subdir),csu)

124
sysdeps/unix/sysv/linux/powerpc/cpu-features.c Normal file
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@ -0,0 +1,124 @@
/* Initialize cpu feature data. PowerPC version.
Copyright (C) 2017-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <array_length.h>
#include <stdint.h>
#include <cpu-features.h>
#include <elf/dl-tunables.h>
#include <unistd.h>
#include <string.h>
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, offset = 0;
/* 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 < array_length (hwcap_tunables); ++i)
{
const char *hwcap_name = hwcap_names + offset;
size_t hwcap_name_len = strlen (hwcap_name);
/* Check the tunable name on the supported list. */
if (hwcap_name_len == feature_len
&& memcmp (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 check 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 += hwcap_name_len + 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, 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));
}

130
sysdeps/unix/sysv/linux/powerpc/cpu-features.h Normal file
View File

@ -0,0 +1,130 @@
/* Initialize cpu feature data. PowerPC version.
Copyright (C) 2017-2023 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef __CPU_FEATURES_POWERPC_H
# 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 */

128
sysdeps/unix/sysv/linux/powerpc/tst-hwcap-tunables.c Normal file
View File

@ -0,0 +1,128 @@
/* Tests for powerpc GLIBC_TUNABLES=glibc.cpu.hwcaps filter.
Copyright (C) 2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <array_length.h>
#include <getopt.h>
#include <ifunc-impl-list.h>
#include <spawn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/support.h>
#include <support/xunistd.h>
#include <sys/auxv.h>
#include <sys/wait.h>
/* Nonzero if the program gets called via `exec'. */
#define CMDLINE_OPTIONS \
{ "restart", no_argument, &restart, 1 },
static int restart;
/* Hold the four initial argument used to respawn the process, plus the extra
'--direct', '--restart', and the function to check */
static char *spargs[8];
static int fc;
/* Called on process re-execution. */
_Noreturn static void
handle_restart (int argc, char *argv[])
{
TEST_VERIFY_EXIT (argc == 1);
const char *funcname = argv[0];
struct libc_ifunc_impl impls[32];
int cnt = __libc_ifunc_impl_list ("memcpy", impls, array_length (impls));
if (cnt == 0)
_exit (EXIT_SUCCESS);
TEST_VERIFY_EXIT (cnt >= 1);
for (int i = 0; i < cnt; i++) {
if (strcmp (impls[i].name, funcname) == 0)
{
TEST_COMPARE (impls[i].usable, false);
break;
}
}
_exit (EXIT_SUCCESS);
}
static void
run_test (const char *filter, const char *funcname)
{
printf ("info: checking filter %s (expect %s ifunc selection to be removed)\n",
filter, funcname);
char *tunable = xasprintf ("GLIBC_TUNABLES=glibc.cpu.hwcaps=%s", filter);
char *const newenvs[] = { (char*) tunable, NULL };
spargs[fc] = (char *) funcname;
pid_t pid;
TEST_COMPARE (posix_spawn (&pid, spargs[0], NULL, NULL, spargs, newenvs), 0);
int status;
TEST_COMPARE (xwaitpid (pid, &status, 0), pid);
TEST_VERIFY (WIFEXITED (status));
TEST_VERIFY (!WIFSIGNALED (status));
TEST_COMPARE (WEXITSTATUS (status), 0);
free (tunable);
}
static int
do_test (int argc, char *argv[])
{
if (restart)
handle_restart (argc - 1, &argv[1]);
TEST_VERIFY_EXIT (argc == 2 || argc == 5);
int i;
for (i = 0; i < argc - 1; i++)
spargs[i] = argv[i + 1];
spargs[i++] = (char *) "--direct";
spargs[i++] = (char *) "--restart";
fc = i++;
spargs[i] = NULL;
unsigned long int hwcap = getauxval (AT_HWCAP);
unsigned long int hwcap2 = getauxval (AT_HWCAP2);
if (__WORDSIZE == 64)
{
if (hwcap2 & PPC_FEATURE2_ARCH_3_1)
run_test ("-arch_3_1", "__memcpy_power10");
if (hwcap2 & PPC_FEATURE2_ARCH_2_07)
run_test ("-arch_2_07", "__memcpy_power8_cached");
if (hwcap & PPC_FEATURE_ARCH_2_06)
run_test ("-arch_2_06", "__memcpy_power7");
if (hwcap & PPC_FEATURE_ARCH_2_05)
run_test ("-arch_2_06,-arch_2_05","__memcpy_power6");
run_test ("-arch_2_06,-arch_2_05,-power5+,-power5,-power4", "__memcpy_power4");
}
else
{
if (hwcap & PPC_FEATURE_HAS_VSX)
run_test ("-vsx", "__memcpy_power7");
if (hwcap & PPC_FEATURE_ARCH_2_06)
run_test ("-arch_2_06", "__memcpy_a2");
if (hwcap & PPC_FEATURE_ARCH_2_05)
run_test ("-arch_2_05", "__memcpy_power6");
}
return 0;
}
#define TEST_FUNCTION_ARGV do_test
#include <support/test-driver.c>