[Commits] r20479 - in /fsf/trunk/libc: ChangeLog NEWS sysdeps/x86_64/dl-machine.h

[eglibc@xxxxxxxxxx]

Author: eglibc
Date: Mon Sep  3 00:01:44 2012
New Revision: 20479

Log:
Import glibc-mainline for 2012-09-03

Modified:
    fsf/trunk/libc/ChangeLog
    fsf/trunk/libc/NEWS
    fsf/trunk/libc/sysdeps/x86_64/dl-machine.h

Modified: fsf/trunk/libc/ChangeLog
==============================================================================
--- fsf/trunk/libc/ChangeLog (original)
+++ fsf/trunk/libc/ChangeLog Mon Sep  3 00:01:44 2012
@@ -1,8 +1,16 @@
+2012-09-02  H.J. Lu  <hongjiu.lu@xxxxxxxxx>
+
+	[BZ #14538]
+	* sysdeps/x86_64/dl-machine.h (elf_machine_dynamic): Use the
+	first element of the GOT.
+	(elf_machine_load_address): Return the difference between
+	the runtime address of _DYNAMIC and elf_machine_dynamic ().
+
 2012-09-01  Allan McRae  <allan@xxxxxxxxxxxxx>
 
-        [BZ #13412]
-        * configure.in (AWK): Require gawk version 3.0 or later.
-        * configure: Regenerated.
+	[BZ #13412]
+	* configure.in (AWK): Require gawk version 3.0 or later.
+	* configure: Regenerated.
 
 2012-09-01  Joseph Myers  <joseph@xxxxxxxxxxxxxxxx>
 

Modified: fsf/trunk/libc/NEWS
==============================================================================
--- fsf/trunk/libc/NEWS (original)
+++ fsf/trunk/libc/NEWS Mon Sep  3 00:01:44 2012
@@ -12,7 +12,7 @@
   3479, 5400, 6778, 6808, 9685, 11607, 13412, 13717, 13696, 13939, 14042,
   14090, 14166, 14150, 14151, 14154, 14157, 14166, 14173, 14195, 14252,
   14283, 14298, 14303, 14307, 14328, 14331, 14336, 14337, 14347, 14349,
-  14459, 14476, 14505, 14516, 14519, 14532
+  14459, 14476, 14505, 14516, 14519, 14532, 14538
 
 * Support for STT_GNU_IFUNC symbols added for s390 and s390x.
   Optimized versions of memcpy, memset, and memcmp added for System z10 and

Modified: fsf/trunk/libc/sysdeps/x86_64/dl-machine.h
==============================================================================
--- fsf/trunk/libc/sysdeps/x86_64/dl-machine.h (original)
+++ fsf/trunk/libc/sysdeps/x86_64/dl-machine.h Mon Sep  3 00:01:44 2012
@@ -41,13 +41,9 @@
 static inline ElfW(Addr) __attribute__ ((unused))
 elf_machine_dynamic (void)
 {
-  ElfW(Addr) addr;
-
-  /* This works because we have our GOT address available in the small PIC
-     model.  */
-  addr = (ElfW(Addr)) &_DYNAMIC;
-
-  return addr;
+  /* This produces an IP-relative reloc which is resolved at link time. */
+  extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
+  return _GLOBAL_OFFSET_TABLE_[0];
 }
 
 
@@ -55,31 +51,11 @@
 static inline ElfW(Addr) __attribute__ ((unused))
 elf_machine_load_address (void)
 {
-  ElfW(Addr) addr;
-
-  /* The easy way is just the same as on x86:
-       leaq _dl_start, %0
-       leaq _dl_start(%%rip), %1
-       subq %0, %1
-     but this does not work with binutils since we then have
-     a R_X86_64_32S relocation in a shared lib.
-
-     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.  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 ("lea _dl_start(%%rip), %0\n\t"
-       "sub 1f(%%rip), %0\n\t"
-       ".section\t.data.rel.ro\n"
-       "1:\t" ASM_ADDR " _dl_start\n\t"
-       ".previous\n\t"
-       : "=r" (addr) : : "cc");
-
-  return addr;
+  /* Compute the difference between the runtime address of _DYNAMIC as seen
+     by an IP-relative reference, and the link-time address found in the
+     special unrelocated first GOT entry.  */
+  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
+  return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic ();
 }
 
 /* Set up the loaded object described by L so its unrelocated PLT

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