1 /* Initialize cpu feature data. PowerPC version.
2 Copyright (C) 2017-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
19 #include <array_length.h>
21 #include <cpu-features.h>
22 #include <elf/dl-tunables.h>
23 #include <dl-tunables-parse.h>
28 TUNABLE_CALLBACK (set_hwcaps
) (tunable_val_t
*valp
)
30 /* The current IFUNC selection is always using the most recent
31 features which are available via AT_HWCAP or AT_HWCAP2. But in
32 some scenarios it is useful to adjust this selection.
34 The environment variable:
36 GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,....
38 Can be used to enable HWCAP/HWCAP2 feature yyy, disable HWCAP/HWCAP2
39 feature xxx, where the feature name is case-sensitive and has to match
40 the ones mentioned in the file{sysdeps/powerpc/dl-procinfo.c}. */
42 /* Copy the features from dl_powerpc_cpu_features, which contains the
43 features provided by AT_HWCAP and AT_HWCAP2. */
44 struct cpu_features
*cpu_features
= &GLRO(dl_powerpc_cpu_features
);
45 unsigned long int tcbv_hwcap
= cpu_features
->hwcap
;
46 unsigned long int tcbv_hwcap2
= cpu_features
->hwcap2
;
48 struct tunable_str_comma_state_t ts
;
49 tunable_str_comma_init (&ts
, valp
);
51 struct tunable_str_comma_t t
;
52 while (tunable_str_comma_next (&ts
, &t
))
58 for (int i
= 0; i
< array_length (hwcap_tunables
); ++i
)
60 const char *hwcap_name
= hwcap_names
+ offset
;
61 size_t hwcap_name_len
= strlen (hwcap_name
);
62 /* Check the tunable name on the supported list. */
63 if (tunable_str_comma_strcmp (&t
, hwcap_name
, hwcap_name_len
))
65 /* Update the hwcap and hwcap2 bits. */
68 /* Id is 1 for hwcap2 tunable. */
69 if (hwcap_tunables
[i
].id
)
70 cpu_features
->hwcap2
&= ~(hwcap_tunables
[i
].mask
);
72 cpu_features
->hwcap
&= ~(hwcap_tunables
[i
].mask
);
76 /* Enable the features and also check that no unsupported
77 features were enabled by user. */
78 if (hwcap_tunables
[i
].id
)
79 cpu_features
->hwcap2
|= (tcbv_hwcap2
& hwcap_tunables
[i
].mask
);
81 cpu_features
->hwcap
|= (tcbv_hwcap
& hwcap_tunables
[i
].mask
);
85 offset
+= hwcap_name_len
+ 1;
91 init_cpu_features (struct cpu_features
*cpu_features
, uint64_t hwcaps
[])
93 /* Fill the cpu_features with the supported hwcaps
94 which are set by __tcb_parse_hwcap_and_convert_at_platform. */
95 cpu_features
->hwcap
= hwcaps
[0];
96 cpu_features
->hwcap2
= hwcaps
[1];
97 cpu_features
->hwcap3
= hwcaps
[2];
98 cpu_features
->hwcap4
= hwcaps
[3];
99 /* Default is to use aligned memory access on optimized function unless
100 tunables is enable, since for this case user can explicit disable
101 unaligned optimizations. */
102 int32_t cached_memfunc
= TUNABLE_GET (glibc
, cpu
, cached_memopt
, int32_t,
104 cpu_features
->use_cached_memopt
= (cached_memfunc
> 0);
105 TUNABLE_GET (glibc
, cpu
, hwcaps
, tunable_val_t
*,
106 TUNABLE_CALLBACK (set_hwcaps
));