diff options
Diffstat (limited to 'linker')
| -rw-r--r-- | linker/README.TXT | 43 | ||||
| -rw-r--r-- | linker/linker.c | 6 |
2 files changed, 3 insertions, 46 deletions
diff --git a/linker/README.TXT b/linker/README.TXT index 0be9be4..4fff14e 100644 --- a/linker/README.TXT +++ b/linker/README.TXT @@ -112,46 +112,3 @@ On x86, the lists of constructors and destructors are placed in special sections named ".ctors" and ".dtors", and the DT_INIT / DT_FINI functions are in charge of calling them explicitely. - -C Library Usage Restrictions: ------------------------------ - -The dynamic linker executable (/system/bin/linker) is built using the -static version of the C library (libc.a), in order to use various functions -and system calls provided by it. - -However, it will normally, at runtime, map the shared library version -of the C library (/system/lib/libc.so) as well in the process' address -space. This means that: - -- any global variable defined by the C library will appear twice in - the process address space, at different addresses. - -- some functions will be duplicated too, though those that refer to - global variables will refer to distinct addresses. - -This can lead to subtle conflicts, typically for process-specific data that -is managed through the kernel. A good example is the handling of the -end of the data segment, which is normally done through the 'sbrk' or -'brk' system call by the malloc implementation. - -If two similar, but distinct, malloc implementations run at the same time, -and if each one thinks it exclusively manages some process settings, hideous -corruption or crashes may occur. - -For this very reason, THE DYNAMIC LINKER CANNOT USE malloc()/free() ! -That's why it is linked to a special version of the C library that will -abort when any of these functions (or calloc()/realloc()) is called. - -Moreover, it cannot use any C library feature that could use these -indirectly. Experience as shown that this meant: - -- avoiding any FILE* - related stdio function (fopen, fread, fprintf, etc...) -- avoiding snprintf() with any floating-point formatter ("%f", "%g") - -There are probably other cases that haven't been discovered yet, so the -code needs to be very frugal in its use of the C library. - -This also explains why the linker's tracing macros are all disabled by -default. Enabling them sometimes creates problems, depending on the process -being loaded, so they should be considered an experimental feature for now. diff --git a/linker/linker.c b/linker/linker.c index e7d5ab4..e398f82 100644 --- a/linker/linker.c +++ b/linker/linker.c @@ -44,7 +44,7 @@ #include <sys/atomics.h> /* special private C library header - see Android.mk */ -#include <bionic_preinit.h> +#include <bionic_tls.h> #include "linker.h" #include "linker_debug.h" @@ -1691,7 +1691,6 @@ int main(int argc, char **argv) #define ANDROID_TLS_SLOTS BIONIC_TLS_SLOTS static void * __tls_area[ANDROID_TLS_SLOTS]; -static pthread_internal_t __main_thread; unsigned __linker_init(unsigned **elfdata) { @@ -1710,7 +1709,8 @@ unsigned __linker_init(unsigned **elfdata) gettimeofday(&t0, 0); #endif - __libc_preinit(&__main_thread, __tls_area); + __set_tls(__tls_area); + ((unsigned *)__get_tls())[TLS_SLOT_THREAD_ID] = gettid(); debugger_init(); |