From 4ce3cb5cddda7b4ee9643e1f75ee5b8f1f191906 Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Mon, 6 Feb 2012 14:39:09 -0500
Subject: add support for init/finit (constructors and destructors)

this is mainly in hopes of supporting c++ (not yet possible for other
reasons) but will also help applications/libraries which use (and more
often, abuse) the gcc __attribute__((__constructor__)) feature in "C"
code.

x86_64 and arm versions of the new startup asm are untested and may
have minor problems.
---
 crt/x86_64/crt1.s | 8 +++++---
 crt/x86_64/crti.s | 7 +++++++
 crt/x86_64/crtn.s | 5 +++++
 3 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 crt/x86_64/crti.s
 create mode 100644 crt/x86_64/crtn.s

(limited to 'crt/x86_64')

diff --git a/crt/x86_64/crt1.s b/crt/x86_64/crt1.s
index 45cbb9db..50222f1c 100644
--- a/crt/x86_64/crt1.s
+++ b/crt/x86_64/crt1.s
@@ -1,4 +1,6 @@
 /* Written 2011 Nicholas J. Kain, released as Public Domain */
+.weak _init
+.weak _fini
 .text
 .global _start
 _start:
@@ -9,8 +11,8 @@ _start:
 	andq $-16,%rsp  /* align stack pointer */
 	push %rax       /* 8th arg: glibc ABI compatible */
 	push %rsp       /* 7th arg: glibc ABI compatible */
-	xor %r8,%r8     /* 5th arg: always 0 */
-	xor %rcx,%rcx   /* 4th arg: always 0 */
+	mov $_fini,%r8  /* 5th arg: fini/dtors function */
+	mov $_init,%rcx /* 4th arg: init/ctors function */
 	mov $main,%rdi  /* 1st arg: application entry ip */
 	call __libc_start_main /* musl init will run the program */
-.L0:	jmp .L0
+1:	jmp 1b
diff --git a/crt/x86_64/crti.s b/crt/x86_64/crti.s
new file mode 100644
index 00000000..2eb23ed5
--- /dev/null
+++ b/crt/x86_64/crti.s
@@ -0,0 +1,7 @@
+.section .init
+.global _init
+_init:
+
+.section .fini
+.global _fini
+_fini:
diff --git a/crt/x86_64/crtn.s b/crt/x86_64/crtn.s
new file mode 100644
index 00000000..055451ed
--- /dev/null
+++ b/crt/x86_64/crtn.s
@@ -0,0 +1,5 @@
+.section .init
+	ret
+
+.section .fini
+	ret
-- 
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