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eb0e8fa0b1960cff4bd65ebefc798f70273b0bc9
musl/src/internal/libc.h

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initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
#ifndef LIBC_H
#define LIBC_H
#include <stdlib.h>
#include <stdio.h>
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
struct __libc {
reorganize the __libc structure for threaded performance issues we want to keep atomically updated fields (locks and thread count) and really anything writable far away from frequently-needed function pointers. stuff some rarely-needed function pointers in between to pad, hopefully up to a cache line boundary.
2011-04-01 22:35:20 -04:00
int *(*errno_location)(void);
overhaul pthread cancellation this patch improves the correctness, simplicity, and size of cancellation-related code. modulo any small errors, it should now be completely conformant, safe, and resource-leak free. the notion of entering and exiting cancellation-point context has been completely eliminated and replaced with alternative syscall assembly code for cancellable syscalls. the assembly is responsible for setting up execution context information (stack pointer and address of the syscall instruction) which the cancellation signal handler can use to determine whether the interrupted code was in a cancellable state. these changes eliminate race conditions in the previous generation of cancellation handling code (whereby a cancellation request received just prior to the syscall would not be processed, leaving the syscall to block, potentially indefinitely), and remedy an issue where non-cancellable syscalls made from signal handlers became cancellable if the signal handler interrupted a cancellation point. x86_64 asm is untested and may need a second try to get it right.
2011-04-17 11:43:03 -04:00
void (*testcancel)(void);
reorganize the __libc structure for threaded performance issues we want to keep atomically updated fields (locks and thread count) and really anything writable far away from frequently-needed function pointers. stuff some rarely-needed function pointers in between to pad, hopefully up to a cache line boundary.
2011-04-01 22:35:20 -04:00
void (*lock)(volatile int *);
void (*lockfile)(FILE *);
simplify pthread tsd key handling
2011-04-03 02:40:18 -04:00
void (*fork_handler)(int);
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
int (*atexit)(void (*)(void));
void (*fini)(void);
void (*ldso_fini)(void);
volatile int threads_minus_1;
reorganize the __libc structure for threaded performance issues we want to keep atomically updated fields (locks and thread count) and really anything writable far away from frequently-needed function pointers. stuff some rarely-needed function pointers in between to pad, hopefully up to a cache line boundary.
2011-04-01 22:35:20 -04:00
int ofl_lock;
implement flockfile api, rework stdio locking
2011-03-12 21:55:45 -05:00
FILE *ofl_head;
optimize cancellation enable/disable code the goal is to be able to use pthread_setcancelstate internally in the implementation, whenever a function might want to use functions which are cancellation points but avoid becoming a cancellation point itself. i could have just used a separate internal function for temporarily inhibiting cancellation, but the solution in this commit is better because (1) it's one less implementation-specific detail in functions that need to use it, and (2) application code can also get the same benefit. previously, pthread_setcancelstate dependend on pthread_self, which would pull in unwanted thread setup overhead for non-threaded programs. now, it temporarily stores the state in the global libc struct if threads have not been initialized, and later moves it if needed. this way we can instead use __pthread_self, which has no dependencies and assumes that the thread register is already valid.
2011-04-17 13:21:13 -04:00
int canceldisable;
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
};
various changes in preparation for dynamic linking support prefer using visibility=hidden for __libc internal data, rather than an accessor function, if the compiler has visibility. optimize with -O3 for PIC targets (shared library). without heavy inlining, reloading the GOT register in small functions kills performance. 20-30% size increase for a single libc.so is not a big deal, compared to comparaible size increase in every static binaries. use -Bsymbolic-functions, not -Bsymbolic. global variables are subject to COPY relocations, and thus binding their addresses in the library at link time will cause library functions to read the wrong (original) copies instead of the copies made in the main program's bss section. add entry point, _start, for dynamic linker.
2011-02-24 16:37:21 -05:00
#if 100*__GNUC__+__GNUC_MINOR__ >= 303 || defined(__PCC__) || defined(__TINYC__)
extern struct __libc __libc __attribute__((visibility("hidden")));
#define libc __libc
#elif !defined(__PIC__)
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
extern struct __libc __libc;
#define libc __libc
various changes in preparation for dynamic linking support prefer using visibility=hidden for __libc internal data, rather than an accessor function, if the compiler has visibility. optimize with -O3 for PIC targets (shared library). without heavy inlining, reloading the GOT register in small functions kills performance. 20-30% size increase for a single libc.so is not a big deal, compared to comparaible size increase in every static binaries. use -Bsymbolic-functions, not -Bsymbolic. global variables are subject to COPY relocations, and thus binding their addresses in the library at link time will cause library functions to read the wrong (original) copies instead of the copies made in the main program's bss section. add entry point, _start, for dynamic linker.
2011-02-24 16:37:21 -05:00
#else
#define USE_LIBC_ACCESSOR
extern struct __libc *__libc_loc(void) __attribute__((const));
#define libc (*__libc_loc())
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
#endif
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
/* Designed to avoid any overhead in non-threaded processes */
void __lock(volatile int *);
implement flockfile api, rework stdio locking
2011-03-12 21:55:45 -05:00
void __lockfile(FILE *);
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
#define LOCK(x) (libc.threads_minus_1 ? (__lock(x),1) : ((void)(x),1))
#define UNLOCK(x) (*(x)=0)
move rsyscall out of pthread_create module this is something of a tradeoff, as now set*id() functions, rather than pthread_create, are what pull in the code overhead for dealing with linux's refusal to implement proper POSIX thread-vs-process semantics. my motivations are: 1. it's cleaner this way, especially cleaner to optimize out the rsyscall locking overhead from pthread_create when it's not needed. 2. it's expected that only a tiny number of core system programs will ever use set*id() functions, whereas many programs may want to use threads, and making thread overhead tiny is an incentive for "light" programs to try threads.
2011-04-06 20:27:07 -04:00
int __rsyscall(int, long, long, long, long, long, long);
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
extern char **__environ;
#define environ __environ
#undef weak_alias
#define weak_alias(old, new) \
extern __typeof(old) new __attribute__((weak, alias(#old)))
#undef LFS64_2
//#define LFS64_2(x, y) weak_alias(x, y)
#define LFS64_2(x, y) extern __typeof(x) y
#undef LFS64
#define LFS64(x) LFS64_2(x, x##64)
#endif
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