From f3ddd173806fd5c60b3f034528ca24542aecc5b9 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Mon, 13 Apr 2015 02:56:26 -0400 Subject: dynamic linker bootstrap overhaul this overhaul further reduces the amount of arch-specific code needed by the dynamic linker and removes a number of assumptions, including: - that symbolic function references inside libc are bound at link time via the linker option -Bsymbolic-functions. - that libc functions used by the dynamic linker do not require access to data symbols. - that static/internal function calls and data accesses can be made without performing any relocations, or that arch-specific startup code handled any such relocations needed. removing these assumptions paves the way for allowing libc.so itself to be built with stack protector (among other things), and is achieved by a three-stage bootstrap process: 1. relative relocations are processed with a flat function. 2. symbolic relocations are processed with no external calls/data. 3. main program and dependency libs are processed with a fully-functional libc/ldso. reduction in arch-specific code is achived through the following: - crt_arch.h, used for generating crt1.o, now provides the entry point for the dynamic linker too. - asm is no longer responsible for skipping the beginning of argv[] when ldso is invoked as a command. - the functionality previously provided by __reloc_self for heavily GOT-dependent RISC archs is now the arch-agnostic stage-1. - arch-specific relocation type codes are mapped directly as macros rather than via an inline translation function/switch statement. --- crt/crt1.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'crt') diff --git a/crt/crt1.c b/crt/crt1.c index 14c4a52..af02af9 100644 --- a/crt/crt1.c +++ b/crt/crt1.c @@ -1,5 +1,7 @@ #include +#define START "_start" + #include "crt_arch.h" int main(); @@ -8,7 +10,7 @@ void _fini() __attribute__((weak)); _Noreturn int __libc_start_main(int (*)(), int, char **, void (*)(), void(*)(), void(*)()); -void __cstart(long *p) +void _start_c(long *p) { int argc = p[0]; char **argv = (void *)(p+1); -- cgit v1.1