mirror of
https://sourceware.org/git/glibc.git
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f4c142bb9f
Instead of __dl_iterate_phdr. On ARM dlfo_eh_frame/dlfo_eh_count
maps to PT_ARM_EXIDX vaddr start / length.
On a Neoverse N1 machine with 160 cores, the following program:
$ cat test.c
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>
enum {
niter = 1024,
ntimes = 128,
};
static void *
tf (void *arg)
{
int a = (int) arg;
for (int i = 0; i < niter; i++)
{
void *p[ntimes];
for (int j = 0; j < ntimes; j++)
p[j] = malloc (a * 128);
for (int j = 0; j < ntimes; j++)
free (p[j]);
}
return NULL;
}
int main (int argc, char *argv[])
{
enum { nthreads = 16 };
pthread_t t[nthreads];
for (int i = 0; i < nthreads; i ++)
assert (pthread_create (&t[i], NULL, tf, (void *) i) == 0);
for (int i = 0; i < nthreads; i++)
{
void *r;
assert (pthread_join (t[i], &r) == 0);
assert (r == NULL);
}
return 0;
}
$ arm-linux-gnueabihf-gcc -fsanitize=address test.c -o test
Improves from ~15s to 0.5s.
Checked on arm-linux-gnueabihf.
146 lines
6.0 KiB
C
146 lines
6.0 KiB
C
#ifndef _DLFCN_H
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#include <dlfcn/dlfcn.h>
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#ifndef _ISOMAC
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#include <link.h> /* For ElfW. */
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#include <stdbool.h>
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extern __typeof (_dl_find_object) __dl_find_object;
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hidden_proto (__dl_find_object)
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/* Internally used flag. */
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#define __RTLD_DLOPEN 0x80000000
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#define __RTLD_SPROF 0x40000000
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#define __RTLD_OPENEXEC 0x20000000
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#define __RTLD_CALLMAP 0x10000000
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#define __RTLD_AUDIT 0x08000000
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#define __RTLD_SECURE 0x04000000 /* Apply additional security checks. */
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#define __RTLD_NOIFUNC 0x02000000 /* Suppress calling ifunc functions. */
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#define __RTLD_VDSO 0x01000000 /* Tell _dl_new_object the object is
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system-loaded. */
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#define __LM_ID_CALLER -2
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/* These variables are defined and initialized in the startup code. */
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extern int __libc_argc attribute_hidden;
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extern char **__libc_argv attribute_hidden;
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/* Now define the internal interfaces. */
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/* Use RTLD_NOW here because:
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1. In pthread_cancel_init we want to use RTLD_NOW to reduce the stack usage
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of future cancellation operations, particularly when the target thread
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is running with a small stack. Likewise for consistency we do the same
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thing in __libgcc_s_init. RTLD_NOW will rarely make a difference for
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__libgcc_s_init because unwinding is already in progress, so libgcc_s.so
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has already been loaded if its unwinder is used (Bug 22636).
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2. It allows us to provide robust fallback code at dlopen time for
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incorrectly configured systems that mix old libnss_* modules
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with newly installed libraries e.g. old libnss_dns.so.2 with new
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libresolv.so.2. Using RTLD_LAZY here causes a failure at the
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time the symbol is called and at that point it is much harder to
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safely return an error (Bug 22766).
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The use of RTLD_NOW also impacts gconv module loading, backtracing
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(where the unwinder form libgcc_s.so is used), and IDNA functions
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(which load libidn2), all of which load their respective DSOs on
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demand, and so should not impact program startup. That is to say
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that the DSOs are loaded as part of an API call and therefore we
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will be calling that family of API functions shortly so RTLD_NOW or
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RTLD_LAZY is not a big difference in performance, but RTLD_NOW has
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better error handling semantics for the library. */
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#define __libc_dlopen(name) \
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__libc_dlopen_mode (name, RTLD_NOW | __RTLD_DLOPEN)
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extern void *__libc_dlopen_mode (const char *__name, int __mode)
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attribute_hidden;
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extern void *__libc_dlsym (void *__map, const char *__name)
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attribute_hidden;
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extern void *__libc_dlvsym (void *map, const char *name, const char *version)
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attribute_hidden;
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extern int __libc_dlclose (void *__map)
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attribute_hidden;
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/* Locate shared object containing the given address. */
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#ifdef ElfW
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extern int _dl_addr (const void *address, Dl_info *info,
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struct link_map **mapp, const ElfW(Sym) **symbolp)
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attribute_hidden;
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#endif
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struct link_map;
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/* Close an object previously opened by _dl_open. */
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extern void _dl_close (void *map) attribute_hidden;
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/* Same as above, but without locking and safety checks for user
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provided map arguments. */
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extern void _dl_close_worker (struct link_map *map, bool force)
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attribute_hidden;
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/* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
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RTLD_NEXT). WHO is the calling function, for RTLD_NEXT. Returns
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the symbol value, which may be NULL. */
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extern void *_dl_sym (void *handle, const char *name, void *who)
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attribute_hidden;
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/* Look up version VERSION of symbol NAME in shared object HANDLE
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(which may be RTLD_DEFAULT or RTLD_NEXT). WHO is the calling
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function, for RTLD_NEXT. Returns the symbol value, which may be
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NULL. */
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extern void *_dl_vsym (void *handle, const char *name, const char *version,
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void *who) attribute_hidden;
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/* Helper function for <dlfcn.h> functions. Runs the OPERATE function via
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_dl_catch_error. Returns zero for success, nonzero for failure; and
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arranges for `dlerror' to return the error details.
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ARGS is passed as argument to OPERATE. */
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extern int _dlerror_run (void (*operate) (void *), void *args) attribute_hidden;
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/* This structure is used to make the outer (statically linked)
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implementation of dlopen and related functions to the inner libc
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after static dlopen, via the GLRO (dl_dlfcn_hook) pointer. */
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struct dlfcn_hook
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{
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/* Public interfaces. */
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void *(*dlopen) (const char *file, int mode, void *dl_caller);
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int (*dlclose) (void *handle);
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void *(*dlsym) (void *handle, const char *name, void *dl_caller);
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void *(*dlvsym) (void *handle, const char *name, const char *version,
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void *dl_caller);
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char *(*dlerror) (void);
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int (*dladdr) (const void *address, Dl_info *info);
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int (*dladdr1) (const void *address, Dl_info *info,
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void **extra_info, int flags);
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int (*dlinfo) (void *handle, int request, void *arg);
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void *(*dlmopen) (Lmid_t nsid, const char *file, int mode, void *dl_caller);
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/* Internal interfaces. */
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void* (*libc_dlopen_mode) (const char *__name, int __mode);
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void* (*libc_dlsym) (void *map, const char *name);
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void* (*libc_dlvsym) (void *map, const char *name, const char *version);
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int (*libc_dlclose) (void *map);
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};
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/* Note: These prototypes are for initializing _dlfcn_hook in static
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builds; see __rtld_static_init. Internal calls in glibc should use
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the __libc_dl* functions defined in elf/dl-libc.c instead. */
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extern void *__dlopen (const char *file, int mode, void *caller);
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extern void *__dlmopen (Lmid_t nsid, const char *file, int mode,
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void *dl_caller);
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extern int __dlclose (void *handle);
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extern void *__dlsym (void *handle, const char *name, void *dl_caller);
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extern void *__dlvsym (void *handle, const char *name, const char *version,
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void *dl_caller);
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extern int __dladdr (const void *address, Dl_info *info);
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extern int __dladdr1 (const void *address, Dl_info *info,
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void **extra_info, int flags);
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extern int __dlinfo (void *handle, int request, void *arg);
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extern char *__dlerror (void);
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#ifndef SHARED
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# undef DL_CALL_FCT
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# define DL_CALL_FCT(fctp, args) ((fctp) args)
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#endif
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#endif
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#endif
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