path: root/arch/mips/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/mips/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/mips/crt_arch.h')
1 files changed, 28 insertions, 21 deletions
diff --git a/arch/mips/crt_arch.h b/arch/mips/crt_arch.h
index d4ae52d1..33bde4e6 100644
--- a/arch/mips/crt_arch.h
+++ b/arch/mips/crt_arch.h
@@ -1,21 +1,28 @@
-.set push\n\
-.set noreorder\n\ __start\n\ _start\n\
-.type __start, @function\n\
-.type _start, @function\n\
- bal 1f \n\
- move $fp, $0 \n\
-2: .gpword 2b \n\
-1: lw $gp, 0($ra) \n\
- subu $gp, $ra, $gp \n\
- move $4, $sp \n\
- subu $sp, $sp, 16 \n\
- and $sp, $sp, -8 \n\
- lw $25, %call16(__cstart)($gp) \n\
- jalr $25 \n\
- nop \n\
-.set pop");
+".set push\n"
+".set noreorder\n"
+".global _" START "\n"
+".global " START "\n"
+".type _" START ", @function\n"
+".type " START ", @function\n"
+"_" START ":\n"
+"" START ":\n"
+" bal 1f \n"
+" move $fp, $0 \n"
+"2: .gpword 2b \n"
+ .gpword " START "_c \n"
+".weak _DYNAMIC \n"
+".hidden _DYNAMIC \n"
+" .gpword _DYNAMIC \n"
+"1: lw $gp, 0($ra) \n"
+" subu $gp, $ra, $gp \n"
+" move $4, $sp \n"
+" lw $5, 8($ra) \n"
+" addu $5, $5, $gp \n"
+" lw $25, 4($ra) \n"
+" addu $25, $25, $gp \n"
+" subu $sp, $sp, 16 \n"
+" jalr $25 \n"
+" and $sp, $sp, -8 \n"
+".set pop \n"