path: root/src/ldso/x32
diff options
authorRich Felker <>2015-04-13 02:56:26 -0400
committerRich Felker <>2015-04-13 03:04:42 -0400
commitf3ddd173806fd5c60b3f034528ca24542aecc5b9 (patch)
tree63cc7432a3c40f011c4818de32ef6257acbf0e73 /src/ldso/x32
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 'src/ldso/x32')
1 files changed, 0 insertions, 24 deletions
diff --git a/src/ldso/x32/start.s b/src/ldso/x32/start.s
deleted file mode 100644
index 3c3800aa..00000000
--- a/src/ldso/x32/start.s
+++ /dev/null
@@ -1,24 +0,0 @@
-.text _dlstart
- mov (%rsp),%rdi /* move argc into 1st argument slot */
- lea 4(%rsp),%rsi /* move argv into 2nd argument slot */
- call __dynlink
- /* in case the dynlinker was called directly, it sets the "consumed"
- argv values to -1. so we must loop over the array as long as -1
- is in the top argv slot, decrement argc, and then set the stackpointer
- to the new argc as well as argc's new value.
- as the x32 abi has longs in the argv array, we cannot use push/pop.*/
- movl (%rsp),%edi /* copy argc into edi */
- xor %rdx,%rdx /* we use rdx as an offset to the current argv member */
-1: dec %edi
- addl $4, %edx
- movl (%rsp, %rdx), %esi
- cmp $-1,%esi
- jz 1b
- inc %edi
- subl $4, %edx
- lea (%rsp, %rdx), %rsp /* set rsp to new argv[-1] */
- movl %edi, (%rsp) /* write new argc there */
- xor %edx,%edx
- jmp *%rax