path: root/arch/arm/crt_arch.h
diff options
authorRich Felker <>2015-04-13 02:56:26 -0400
committerRich Felker <>2015-04-13 03:04:42 -0400
commitf3ddd173806fd5c60b3f034528ca24542aecc5b9 (patch)
tree63cc7432a3c40f011c4818de32ef6257acbf0e73 /arch/arm/crt_arch.h
parent385c01112c083eb383d972da45836d497cc0556d (diff)
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 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.
Diffstat (limited to 'arch/arm/crt_arch.h')
1 files changed, 15 insertions, 10 deletions
diff --git a/arch/arm/crt_arch.h b/arch/arm/crt_arch.h
index bed99c27..d1f9a662 100644
--- a/arch/arm/crt_arch.h
+++ b/arch/arm/crt_arch.h
@@ -1,10 +1,15 @@
-__asm__("\ _start \n\
-.type _start,%function \n\
-_start: \n\
- mov fp, #0 \n\
- mov lr, #0 \n\
- mov a1, sp \n\
- and sp, sp, #-16 \n\
- bl __cstart \n\
+".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"