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musl/arch/arm/crt_arch.h

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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.
2015-04-13 06:56:26 +00:00
__asm__(
".global " START " \n"
".type " START ",%function \n"
START ": \n"
" mov fp, #0 \n"
" mov lr, #0 \n"
" mov a1, sp \n"
" ldr a2, 1f \n"
"2: add a2, pc, a2 \n"
" and sp, sp, #-16 \n"
" bl " START "_c \n"
".weak _DYNAMIC \n"
".hidden _DYNAMIC \n"
"1: .word _DYNAMIC-2b-8 \n"
);