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28cfa3a48e
Add a new tunable (glibc.tune.cpu) to override CPU identification on aarch64. This is useful in two cases: one where it is desirable to pretend to be another CPU for purposes of testing or because routines written for that CPU are beneficial for specific workloads and second where the underlying kernel does not support emulation of MRS to get the MIDR of the CPU. * elf/dl-tunables.h (tunable_is_name): Move from... * elf/dl-tunables.c (is_name): ... here. (parse_tunables, __tunables_init): Adjust. * manual/tunables.texi: Document glibc.tune.cpu. * sysdeps/aarch64/dl-tunables.list: New file. * sysdeps/unix/sysv/linux/aarch64/cpu-features.c (struct cpu_list): New type. (cpu_list): New list of CPU names and their MIDR. (get_midr_from_mcpu): New function. (init_cpu_features): Override MIDR if necessary.
133 lines
4.5 KiB
C++
133 lines
4.5 KiB
C++
/* The tunable framework. See the README to know how to use the tunable in
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a glibc module.
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _TUNABLES_H_
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#define _TUNABLES_H_
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#if !HAVE_TUNABLES
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static inline void
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__always_inline
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__tunables_init (char **unused __attribute__ ((unused)))
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{
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/* This is optimized out if tunables are not enabled. */
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}
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#else
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# include <stddef.h>
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# include "dl-tunable-types.h"
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/* A tunable. */
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struct _tunable
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{
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const char *name; /* Internal name of the tunable. */
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tunable_type_t type; /* Data type of the tunable. */
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tunable_val_t val; /* The value. */
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bool initialized; /* Flag to indicate that the tunable is
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initialized. */
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tunable_seclevel_t security_level; /* Specify the security level for the
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tunable with respect to AT_SECURE
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programs. See description of
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tunable_seclevel_t to see a
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description of the values.
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Note that even if the tunable is
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read, it may not get used by the
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target module if the value is
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considered unsafe. */
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/* Compatibility elements. */
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const char *env_alias; /* The compatibility environment
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variable name. */
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};
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typedef struct _tunable tunable_t;
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/* Full name for a tunable is top_ns.tunable_ns.id. */
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# define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
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# define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)
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# define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id
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# include "dl-tunable-list.h"
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extern void __tunables_init (char **);
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extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
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extern void __tunable_set_val (tunable_id_t, void *);
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rtld_hidden_proto (__tunables_init)
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rtld_hidden_proto (__tunable_get_val)
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/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
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TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
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tunables within a module. */
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#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
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# define TUNABLE_GET(__id, __type, __cb) \
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TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
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# define TUNABLE_SET(__id, __type, __val) \
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TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)
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#else
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# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
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TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
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# define TUNABLE_SET(__top, __ns, __id, __type, __val) \
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TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)
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#endif
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/* Get and return a tunable value. If the tunable was set externally and __CB
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is defined then call __CB before returning the value. */
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# define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
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({ \
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tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
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__type ret; \
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__tunable_get_val (id, &ret, __cb); \
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ret; \
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})
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/* Set a tunable value. */
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# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
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({ \
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__tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
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& (__type) {__val}); \
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})
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/* Namespace sanity for callback functions. Use this macro to keep the
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namespace of the modules clean. */
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# define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
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# define TUNABLES_FRONTEND_valstring 1
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/* The default value for TUNABLES_FRONTEND. */
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# define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring
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/* Compare two name strings, bounded by the name hardcoded in glibc. */
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static inline bool
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__always_inline
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tunable_is_name (const char *orig, const char *envname)
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{
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for (;*orig != '\0' && *envname != '\0'; envname++, orig++)
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if (*orig != *envname)
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break;
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/* The ENVNAME is immediately followed by a value. */
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if (*orig == '\0' && *envname == '=')
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return true;
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else
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return false;
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}
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#endif
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#endif
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