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Fix the C library runtime initialization order.

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This allows libc.so to run the C runtime initializer as soon as the
dynamic linker loads the shared library, i.e. before any other initializers
(e.g. static C++ constructors in other shared libraries the executable depends
on).

This also removes the bug where the initializers from the executable itself
were run twice: once by the dynamic linker, and another time by __libc_init
as defined by libc_init_dynamic.c
This commit is contained in:
David 'Digit' Turner 2009-07-18 01:11:10 +02:00
parent ef0bd18570
commit b56b5659b3
4 changed files with 117 additions and 102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
libc/bionic/libc_init_common.c
View File

@ -39,23 +39,6 @@
#include <bionic_tls.h>
#include <errno.h>
extern void _init(void);
extern void _fini(void);
static void call_array(void(**list)())
{
// First element is -1, list is null-terminated
while (*++list) {
(*list)();
}
}
static void __bionic_do_global_dtors(structors_array_t const * const p)
{
call_array(p->fini_array);
//_fini();
}
extern unsigned __get_sp(void);
extern pid_t gettid(void);
@ -69,23 +52,23 @@ unsigned int __page_shift = PAGE_SHIFT;
int __system_properties_init(void);
void __libc_init_common(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors,
void (*pre_ctor_hook)())
{
pthread_internal_t thread;
pthread_attr_t thread_attr;
void *tls_area[BIONIC_TLS_SLOTS];
int argc;
char **argv, **envp, **envend;
struct auxentry *auxentry;
unsigned int page_size = 0, page_shift = 0;
#ifdef MALLOCK_LEAK_CHECK
void malloc_debug_init(void);
#endif
/* The main thread's stack has empirically shown to be 84k */
void __libc_init_common(uintptr_t *elfdata)
{
int argc = *elfdata;
char** argv = (char**)(elfdata + 1);
char** envp = argv + argc + 1;
pthread_attr_t thread_attr;
static pthread_internal_t thread;
static void* tls_area[BIONIC_TLS_SLOTS];
/* setup pthread runtime and maint thread descriptor */
unsigned stacktop = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
unsigned stacksize = 128 * 1024; //84 * 1024;
unsigned stacksize = 128 * 1024;
unsigned stackbottom = stacktop - stacksize;
pthread_attr_init(&thread_attr);
@ -93,30 +76,20 @@ void __libc_init_common(uintptr_t *elfdata,
_init_thread(&thread, gettid(), &thread_attr, (void*)stackbottom);
__init_tls(tls_area, &thread);
argc = (int) *elfdata++;
argv = (char**) elfdata;
envp = argv+(argc+1);
environ = envp;
__progname = argv[0] ? argv[0] : "<unknown>";
/* clear errno - requires TLS area */
errno = 0;
/* set program name */
__progname = argv[0] ? argv[0] : "<unknown>";
/* setup environment pointer */
environ = envp;
/* setup system properties - requires environment */
__system_properties_init();
if (pre_ctor_hook) pre_ctor_hook();
// XXX: we should execute the .fini_array upon exit
// pre-init array.
// XXX: I'm not sure what's the different with the init array.
call_array(structors->preinit_array);
// for compatibility with non-eabi binary, call the .ctors section
call_array(structors->ctors_array);
// call static constructors
call_array(structors->init_array);
exit(slingshot(argc, argv, envp));
/* setup malloc leak checker, requires system properties */
#if MALLOC_LEAK_CHECK
malloc_debug_init();
#endif
}

6
libc/bionic/libc_init_common.h
View File

@ -38,10 +38,6 @@ typedef struct
void (**ctors_array)(void);
} structors_array_t;
extern __noreturn void __libc_init_common(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors,
void (*pre_ctor_hook)());
extern void __libc_init_common(uintptr_t *elfdata);
#endif

69
libc/bionic/libc_init_dynamic.c
View File

@ -26,41 +26,74 @@
* SUCH DAMAGE.
*/
/*
* libc_init_static.c
* libc_init_dynamic.c
*
* This function takes the raw data block set up by the ELF loader
* in the kernel and parses it. It is invoked by crt0.S which makes
* any necessary adjustments and passes calls this function using
* the standard C calling convention.
* This source files provides two important functions for dynamic
* executables:
*
* The arguments are:
* uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
* Basically a pointer to argc.
* void (*onexit)(void) -- Function to install into onexit
* - a C runtime initializer (__libc_preinit), which is called by
* the dynamic linker when libc.so is loaded. This happens before
* any other initializer (e.g. static C++ constructors in other
* shared libraries the program depends on).
*
* - a program launch function (__libc_init), which is called after
* all dynamic linking has been performed. Technically, it is called
* from arch-$ARCH/bionic/crtbegin_dynamic.S which is itself called
* by the dynamic linker after all libraries have been loaded and
* initialized.
*/
/*
* Several Linux ABIs don't pass the onexit pointer, and the ones that
* do never use it. Therefore, unless USE_ONEXIT is defined, we just
* ignore the onexit pointer.
*/
/* #define USE_ONEXIT */
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <elf.h>
#include "pthread_internal.h"
#include "atexit.h"
#include "libc_init_common.h"
#include <bionic_tls.h>
extern void malloc_debug_init();
/* We flag the __libc_preinit function as a constructor to ensure
* that its address is listed in libc.so's .init_array section.
* This ensures that the function is called by the dynamic linker
* as soon as the shared library is loaded.
*/
void __attribute__((constructor)) __libc_prenit(void);
void __libc_prenit(void)
{
/* Read the ELF data pointer form a special slot of the
* TLS area, then call __libc_init_common with it.
*
* Note that:
* - we clear the slot so no other initializer sees its value.
* - __libc_init_common() will change the TLS area so the old one
* won't be accessible anyway.
*/
void** tls_area = (void**)__get_tls();
unsigned* elfdata = tls_area[TLS_SLOT_BIONIC_PREINIT];
tls_area[TLS_SLOT_BIONIC_PREINIT] = NULL;
__libc_init_common(elfdata);
}
__noreturn void __libc_init(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors)
{
__libc_init_common(elfdata, onexit, slingshot, structors, malloc_debug_init);
/* When we reach this point, all initializers have been already
* run by the dynamic linker, so ignore 'structors'.
*/
int argc = (int)*elfdata;
char** argv = (char**)(elfdata + 1);
char** envp = argv + argc + 1;
/* Several Linux ABIs don't pass the onexit pointer, and the ones that
* do never use it. Therefore, we ignore it.
*/
exit(slingshot(argc, argv, envp));
}

61
libc/bionic/libc_init_static.c
View File

@ -28,24 +28,15 @@
/*
* libc_init_static.c
*
* This function takes the raw data block set up by the ELF loader
* in the kernel and parses it. It is invoked by crt0.S which makes
* any necessary adjustments and passes calls this function using
* the standard C calling convention.
* The program startup function __libc_init() defined here is
* used for static executables only (i.e. those that don't depend
* on shared libraries). It is called from arch-$ARCH/bionic/crtbegin_static.S
* which is directly invoked by the kernel when the program is launched.
*
* The arguments are:
* uintptr_t *elfdata -- The ELF loader data block; usually from the stack.
* Basically a pointer to argc.
* void (*onexit)(void) -- Function to install into onexit
* The 'structors' parameter contains pointers to various initializer
* arrays that must be run before the program's 'main' routine is launched.
*/
/*
* Several Linux ABIs don't pass the onexit pointer, and the ones that
* do never use it. Therefore, unless USE_ONEXIT is defined, we just
* ignore the onexit pointer.
*/
/* #define USE_ONEXIT */
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
@ -58,19 +49,41 @@
#include <bionic_tls.h>
#include <errno.h>
static void call_array(void(**list)())
{
// First element is -1, list is null-terminated
while (*++list) {
(*list)();
}
}
__noreturn void __libc_init(uintptr_t *elfdata,
void (*onexit)(void),
int (*slingshot)(int, char**, char**),
structors_array_t const * const structors)
{
/*
* To enable malloc checks for statically linked programs, add
* "WITH_MALLOC_CHECK_LIBC_A := true" in device/buildspec.mk
int argc;
char **argv, **envp;
/* Initialize the C runtime environment */
__libc_init_common(elfdata);
/* Several Linux ABIs don't pass the onexit pointer, and the ones that
* do never use it. Therefore, we ignore it.
*/
#ifdef MALLOC_LEAK_CHECK
extern void malloc_debug_init();
__libc_init_common(elfdata, onexit, slingshot, structors, malloc_debug_init);
#else
__libc_init_common(elfdata, onexit, slingshot, structors, NULL);
#endif
/* pre-init array. */
call_array(structors->preinit_array);
/* .ctors section initializers, for non-arm-eabi ABIs */
call_array(structors->ctors_array);
// call static constructors
call_array(structors->init_array);
argc = (int) *elfdata;
argv = (char**)(elfdata + 1);
envp = argv + argc + 1;
exit(slingshot(argc, argv, envp));
}