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authorUlrich Drepper <drepper@redhat.com>2005-07-31 17:50:49 +0000
committerUlrich Drepper <drepper@redhat.com>2005-07-31 17:50:49 +0000
commit943525d000abb3ddcbffe52923f653913073298e (patch)
treeae891bb69e88c5042a0cbe08961b52fda174947e
parent960095134b82c023a53f082d80f8811172108af2 (diff)
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helper variable into .data.rel.ro. Simplify the code. Extend
comment to explain prelinking.
-rw-r--r--ChangeLog3
-rw-r--r--sysdeps/x86_64/dl-machine.h17
2 files changed, 12 insertions, 8 deletions
diff --git a/ChangeLog b/ChangeLog
index a734d1f88a..fa42d54e48 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,8 @@
2005-07-31 Ulrich Drepper <drepper@redhat.com>
* sysdeps/x86_64/dl-machine.h (elf_machine_load_address): Move
- helper variable into .data.rel.ro. Remove unnecessary label.
+ helper variable into .data.rel.ro. Simplify the code. Extend
+ comment to explain prelinking.
2005-07-31 Andreas Jaeger <aj@suse.de>
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index 40291be08c..73e271775a 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -55,7 +55,7 @@ elf_machine_dynamic (void)
static inline Elf64_Addr __attribute__ ((unused))
elf_machine_load_address (void)
{
- register Elf64_Addr addr, tmp;
+ Elf64_Addr addr;
/* The easy way is just the same as on x86:
leaq _dl_start, %0
@@ -66,15 +66,18 @@ elf_machine_load_address (void)
Instead we store the address of _dl_start in the data section
and compare it with the current value that we can get via
- an RIP relative addressing mode. */
-
- asm ("movq 1f(%%rip), %1\n"
- "leaq _dl_start(%%rip), %0\n\t"
- "subq %1, %0\n\t"
+ an RIP relative addressing mode. Note that this is the address
+ of _dl_start before any relocation performed at runtime. In case
+ the binary is prelinked the resulting "address" is actually a
+ load offset which is zero if the binary was loaded at the address
+ it is prelinked for. */
+
+ asm ("leaq _dl_start(%%rip), %0\n\t"
+ "subq 1f(%%rip), %0\n\t"
".section\t.data.rel.ro\n"
"1:\t.quad _dl_start\n\t"
".previous\n\t"
- : "=r" (addr), "=r" (tmp) : : "cc");
+ : "=r" (addr) : : "cc");
return addr;
}