From 664cd341921007cea52c8891f27ce35927dca378 Mon Sep 17 00:00:00 2001
From: rofl0r <retnyg@gmx.net>
Date: Tue, 7 Jan 2014 22:53:38 +0100
Subject: x32 port (diff against vanilla x86_64)

---
 src/ldso/x32/start.s | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

(limited to 'src/ldso/x32')

diff --git a/src/ldso/x32/start.s b/src/ldso/x32/start.s
index 80c1d08d..0fcf46dc 100644
--- a/src/ldso/x32/start.s
+++ b/src/ldso/x32/start.s
@@ -1,16 +1,24 @@
 .text
 .global _start
 _start:
-	mov (%rsp),%rdi
-	lea 8(%rsp),%rsi
+	mov (%rsp),%rdi  /* move argc into 1st argument slot */
+	lea 4(%rsp),%rsi /* move argv into 2nd argument slot */
 	call __dynlink
-	pop %rdi
+	/* 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
-	pop %rsi
-	cmp $-1,%rsi
+	addl $4, %edx
+	movl (%rsp, %rdx), %esi
+	cmp $-1,%esi
 	jz 1b
 	inc %edi
-	push %rsi
-	push %rdi
+	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
-- 
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