musl/crt/rcrt1.c

#define SHARED
#define START "_start"
#define _dlstart_c _start_c
#include "../ldso/dlstart.c"

int main();
void _init() __attribute__((weak));
void _fini() __attribute__((weak));
_Noreturn int __libc_start_main(int (*)(), int, char **,
	void (*)(), void(*)(), void(*)());

__attribute__((__visibility__("hidden")))
_Noreturn void __dls2(unsigned char *base, size_t *sp)
{
	__libc_start_main(main, *sp, (void *)(sp+1), _init, _fini, 0);
}
add rcrt1 start file for fully static-linked PIE static-linked PIE files need startup code to relocate themselves, much like the dynamic linker does. rcrt1.c reuses the code in dlstart.c, stage 1 of the dynamic linker, which in turn reuses crt_arch.h, to achieve static PIE with no new code. only relative relocations are supported. existing toolchains that don't yet support static PIE directly can be repurposed by passing "-shared -Wl,-Bstatic -Wl,-Bsymbolic" instead of "-static -pie" and substituting rcrt1.o in place of crt1.o. all libraries being linked must be built as PIC/PIE; TEXTRELs are not supported at this time. 2015-05-26 03:37:41 -04:00			`#define SHARED`
			`#define START "_start"`
			`#define _dlstart_c _start_c`
move dynamic linker to its own top-level directory, ldso this eliminates the last need for the SHARED macro to control how files in the src tree are compiled. the same code is used for both libc.a and libc.so, with additional code for the dynamic linker (from the new ldso tree) being added to libc.so but not libc.a. separate .o and .lo object files still exist for the src tree, but the only difference is that the .lo files are built as PIC. in the future, if/when we add dlopen support for static-linked programs, much of the code in dynlink.c may be moved back into the src tree, but properly factored into separate source files. in that case, the code in the ldso tree will be reduced to just the dynamic linker entry point, self-relocation, and loading of libraries needed by the main application. 2016-01-25 19:29:55 -05:00			`#include "../ldso/dlstart.c"`
add rcrt1 start file for fully static-linked PIE static-linked PIE files need startup code to relocate themselves, much like the dynamic linker does. rcrt1.c reuses the code in dlstart.c, stage 1 of the dynamic linker, which in turn reuses crt_arch.h, to achieve static PIE with no new code. only relative relocations are supported. existing toolchains that don't yet support static PIE directly can be repurposed by passing "-shared -Wl,-Bstatic -Wl,-Bsymbolic" instead of "-static -pie" and substituting rcrt1.o in place of crt1.o. all libraries being linked must be built as PIC/PIE; TEXTRELs are not supported at this time. 2015-05-26 03:37:41 -04:00
			`int main();`
			`void _init() __attribute__((weak));`
			`void _fini() __attribute__((weak));`
			`_Noreturn int __libc_start_main(int ()(), int, char *,`
			`void ()(), void()(), void(*)());`

fix visibility mismatch in dynamic linker stage 2 function definition since commits 2907afb8dbd4c1d34825c3c9bd2b41564baca210 and 6fc30c2493fcfedec89e45088bea87766a1e3286, __dls2 is no longer called via symbol lookup, but instead uses relative addressing that needs to be resolved at link time. on some linker versions, and/or if -Bsymbolic-functions is not used, the linker may leave behind a dynamic relocation, which is not suitable for bootstrapping the dynamic linker, if the reference to __dls2 is marked hidden but the definition is not actually hidden. correcting the definition to use hidden visibility fixes the problem. the static-PIE entry point rcrt1 was likewise affected and is also fixed by this patch. 2015-10-15 17:38:54 -04:00			`__attribute__((__visibility__("hidden")))`
add rcrt1 start file for fully static-linked PIE static-linked PIE files need startup code to relocate themselves, much like the dynamic linker does. rcrt1.c reuses the code in dlstart.c, stage 1 of the dynamic linker, which in turn reuses crt_arch.h, to achieve static PIE with no new code. only relative relocations are supported. existing toolchains that don't yet support static PIE directly can be repurposed by passing "-shared -Wl,-Bstatic -Wl,-Bsymbolic" instead of "-static -pie" and substituting rcrt1.o in place of crt1.o. all libraries being linked must be built as PIC/PIE; TEXTRELs are not supported at this time. 2015-05-26 03:37:41 -04:00			`_Noreturn void __dls2(unsigned char base, size_t sp)`
			`{`
			`__libc_start_main(main, sp, (void )(sp+1), _init, _fini, 0);`
			`}`