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More stack alignment fixes. Arrange so we call _rtld() in ld-elf.so.1

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with the correct alignment.  This is important because this calls to
library static constructors are made from here.  The bug in the old crt*.s
files hid this because in this case, two wrongs do indeed make a right.
Also, call _rtld_bind() with the correct alignment, because it calls back
into the pthread library locking functions.  If things happen just
the wrong way, we get a SIG10 due to the broken stack alignment.
This commit is contained in:
peter 2004-03-21 01:43:39 +00:00
parent 51e2585455
commit 88a11443a2
1 changed files with 9 additions and 8 deletions
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17
libexec/rtld-elf/amd64/rtld_start.S
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@ -31,14 +31,13 @@
.type .rtld_start,@function
.rtld_start:
xorq %rbp,%rbp # Clear frame pointer for good form
subq $16,%rsp # A place to store exit procedure addr
subq $24,%rsp # A place to store exit procedure addr
movq %rdi,%r12
movq %rsp,%rsi # save address of exit proc
movq %rsp,%rdx # construct address of obj_main
addq $8,%rdx
call _rtld@PLT # Call rtld(sp); returns entry point
popq %rsi # Get exit procedure address
addq $8,%rsp # Ignore obj_main
movq %r12,%rdi # *ap
/*
* At this point, %rax contains the entry point of the main program, and
@ -62,8 +61,9 @@
* assembly-language code that is not ABI-compliant.
*
* Stack map:
* reloff 0x58
* obj 0x50
* reloff 0x60
* obj 0x58
* spare 0x50
* rflags 0x48
* rax 0x40
* rdx 0x38
@ -79,6 +79,7 @@
.globl _rtld_bind_start
.type _rtld_bind_start,@function
_rtld_bind_start:
subq $8,%rsp
pushfq # Save rflags
pushq %rax # Save %rax
pushq %rdx # Save %rdx
@ -90,15 +91,15 @@ _rtld_bind_start:
pushq %r10 # Save %r10
pushq %r11 # Save %r11
movq 0x50(%rsp),%rdi # Fetch obj argument
movq 0x58(%rsp),%rsi # Fetch reloff argument
movq 0x58(%rsp),%rdi # Fetch obj argument
movq 0x60(%rsp),%rsi # Fetch reloff argument
leaq (%rsi,%rsi,2),%rsi # multiply by 3
leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela)
call _rtld_bind@PLT # Transfer control to the binder
/* Now %rax contains the entry point of the function being called. */
movq %rax,0x58(%rsp) # Store target over reloff argument
movq %rax,0x60(%rsp) # Store target over reloff argument
popq %r11 # Restore %r11
popq %r10 # Restore %r10
popq %r9 # Restore %r9
@ -109,5 +110,5 @@ _rtld_bind_start:
popq %rdx # Restore %rdx
popq %rax # Restore %rax
popfq # Restore rflags
leaq 8(%rsp),%rsp # Discard obj, do not change rflags
leaq 16(%rsp),%rsp # Discard spare, obj, do not change rflags
ret # "Return" to target address