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authorH.J. Lu <hjl.tools@gmail.com>2015-05-28 05:06:27 -0700
committerH.J. Lu <hjl.tools@gmail.com>2015-05-28 05:06:53 -0700
commit58007e9e68913290b1f4f73afc1055f779a8ed5d (patch)
tree6a76be39e885bdcd159ba571f25b9eea83f709c0 /elf
parentbe2e25bbd78f9fdf27bed254d02915d019c5b363 (diff)
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Make sure that calloc is called at least once
PLT relocations aren't required when -z now used. Linker on master with: commit 25070364b0ce33eed46aa5d78ebebbec6accec7e Author: H.J. Lu <hjl.tools@gmail.com> Date: Sat May 16 07:00:21 2015 -0700 Don't generate PLT relocations for now binding There is no need for PLT relocations with -z now. We can use GOT relocations, which take less space, instead and replace 16-byte .plt entres with 8-byte .plt.got entries. bfd/ * elf32-i386.c (elf_i386_check_relocs): Create .plt.got section for now binding. (elf_i386_allocate_dynrelocs): Use .plt.got section for now binding. * elf64-x86-64.c (elf_x86_64_check_relocs): Create .plt.got section for now binding. (elf_x86_64_allocate_dynrelocs): Use .plt.got section for now binding. won't generate PLT relocations with -z now. elf/tst-audit2.c expect certain order of execution in ld.so.  With PLT relocations, the GOTPLT entry of calloc is update to calloc defined in tst-audit2: (gdb) bt     skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,     version=<optimized out>, sym=<optimized out>, map=<optimized out>)     at ../sysdeps/i386/dl-machine.h:329 out>,     nrelative=<optimized out>, relsize=<optimized out>,     reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137 reloc_mode=reloc_mode@entry=0,     consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258     user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133     start_argptr=start_argptr@entry=0xffffcfb0,     dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at ../elf/dl-sysdep.c:249    from /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so (gdb) and then calloc is called: (gdb) c Continuing. Breakpoint 4, calloc (n=n@entry=20, m=4) at tst-audit2.c:18 18 { (gdb) bt     reloc_mode=reloc_mode@entry=0, consider_profiling=1,     consider_profiling@entry=0) at dl-reloc.c:272     user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133     start_argptr=start_argptr@entry=0xffffcfb0,     dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at ../elf/dl-sysdep.c:249    from /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so (gdb) With GOT relocation, calloc in ld.so is called first: (gdb) bt     consider_profiling=1) at dl-reloc.c:272     user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2074     start_argptr=start_argptr@entry=0xffffcfa0,     dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at ../elf/dl-sysdep.c:249    from /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so (gdb) and then the GOT entry of calloc is updated: (gdb) bt     skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,     version=<optimized out>, sym=<optimized out>, map=<optimized out>)     at ../sysdeps/i386/dl-machine.h:329 out>,     nrelative=<optimized out>, relsize=<optimized out>,     reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137 reloc_mode=reloc_mode@entry=0,     consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258     user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2133     start_argptr=start_argptr@entry=0xffffcfa0,     dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at ../elf/dl-sysdep.c:249    from /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so (gdb) After that, since calloc isn't called from ld.so nor any other modules, magic in tst-audit2 isn't updated.  Both orders are correct. This patch makes sure that calloc in tst-audit2.c is called at least once from ld.so. [BZ #18422] * Makefile ($(objpfx)tst-audit2): Depend on $(libdl). ($(objpfx)tst-audit2.out): Also depend on $(objpfx)tst-auditmod9b.so. * elf/tst-audit2.c: Include <dlfcn.h>. (calloc_called): New. (calloc): Allow to be called more than once. (do_test): dllopen/dlclose $ORIGIN/tst-auditmod9b.so.
Diffstat (limited to 'elf')
-rw-r--r--elf/Makefile3
-rw-r--r--elf/tst-audit2.c26
2 files changed, 22 insertions, 7 deletions
diff --git a/elf/Makefile b/elf/Makefile
index b06e0a7..dedf3c7 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -1034,7 +1034,8 @@ $(objpfx)tst-dlmopen3.out: $(objpfx)tst-dlmopen1mod.so
$(objpfx)tst-audit1.out: $(objpfx)tst-auditmod1.so
tst-audit1-ENV = LD_AUDIT=$(objpfx)tst-auditmod1.so
-$(objpfx)tst-audit2.out: $(objpfx)tst-auditmod1.so
+$(objpfx)tst-audit2: $(libdl)
+$(objpfx)tst-audit2.out: $(objpfx)tst-auditmod1.so $(objpfx)tst-auditmod9b.so
# Prevent GCC-5 from translating a malloc/memset pair into calloc
CFLAGS-tst-audit2.c += -fno-builtin
tst-audit2-ENV = LD_AUDIT=$(objpfx)tst-auditmod1.so
diff --git a/elf/tst-audit2.c b/elf/tst-audit2.c
index acad1b0..1d69cd6 100644
--- a/elf/tst-audit2.c
+++ b/elf/tst-audit2.c
@@ -3,26 +3,35 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <dlfcn.h>
#define MAGIC1 0xabcdef72
#define MAGIC2 0xd8675309
static __thread unsigned int magic[] = { MAGIC1, MAGIC2 };
+static __thread int calloc_called;
#undef calloc
/* This calloc definition will be called by the dynamic linker itself.
- We test that it has initialized our TLS block by the time it does so. */
+ We test that interposed calloc is called by the dynamic loader, and
+ that TLS is fully initialized by then. */
void *
calloc (size_t n, size_t m)
{
- if (magic[0] != MAGIC1 || magic[1] != MAGIC2)
+ if (!calloc_called)
{
- printf ("{%x, %x} != {%x, %x}\n", magic[0], magic[1], MAGIC1, MAGIC2);
- abort ();
+ /* Allow our calloc to be called more than once. */
+ calloc_called = 1;
+ if (magic[0] != MAGIC1 || magic[1] != MAGIC2)
+ {
+ printf ("{%x, %x} != {%x, %x}\n",
+ magic[0], magic[1], MAGIC1, MAGIC2);
+ abort ();
+ }
+ magic[0] = MAGIC2;
+ magic[1] = MAGIC1;
}
- magic[0] = MAGIC2;
- magic[1] = MAGIC1;
n *= m;
void *ptr = malloc (n);
@@ -34,6 +43,11 @@ calloc (size_t n, size_t m)
static int
do_test (void)
{
+ /* Make sure that our calloc is called from the dynamic linker at least
+ once. */
+ void *h = dlopen("$ORIGIN/tst-auditmod9b.so", RTLD_LAZY);
+ if (h != NULL)
+ dlclose (h);
if (magic[1] != MAGIC1 || magic[0] != MAGIC2)
{
printf ("{%x, %x} != {%x, %x}\n", magic[0], magic[1], MAGIC2, MAGIC1);