If libopen64rt_shared.a can be used for executable except for shared
library, I'll support the checkin. Not perfect, but it can work for the
current trunk. Otherwise we must notice the PIE issue.
I just explain the PIE linking. I don't konw the function of libopen64rt.a
and libopen64rt.a. Why does open64 need them? Why memset.o and cacheinfo.o
are removed from libopen64rt_shared.a?
All objects participating in -pie link must be compiled with -fPIE. PIE is
not PIC. PIE is for executable (-pie link) and PIC is for shared library
(-shared link). So we cannot replace PIE objects with PIC objects.
It is a mere coincidence that there is no linker error with
libopen64rt_shared.a at -fPIE. Only cacheinfo.o has dynamic relocation info
(GOT/PLT) at PIE/PIC, but it is removed from libopen64rt_shared.a (see
below).
The generation of the two libraries:
ar cru libopen64rt.a fastcopy_gh.o malloc_opt.o memset.o cacheinfo.o
ar cru libopen64rt_shared.a fastcopy_gh.o malloc_opt.o memset.o cacheinfo.o
ar dv libopen64rt_shared.a memset.o cacheinfo.o
The two libraries use the same objects. Note objects in libopen64rt_shared.a
are NOT compiled with -fPIC.
Why "non -fPIC" libopen64rt_shared.a also works for -shared?
Just a mere coincidence... I look through malloc_opt.c and fastcopy_gh.s
which constitute libopen64rt_shared.a. The codes are simple and have no
global symbols, so they don't need GOT/PLT and there is no difference
between -fPIC and "non -fPIC". Note if we add new functions to the library,
we must pay attention to this issue!
On Wed, Aug 4, 2010 at 6:48 AM, Steve Ellcey <s...@cup.hp.com> wrote:
> This patch is my proposed fix for bug 577, The problem is that when
> linking a program using the -pie (-fPIE, -fpie) option to create a
> position independent executable we link in libopen64rt.a which contains
> non-PIC code and this causes us to get a link-time error.
>
> My fix is to link in libopen64rt_shared.a instead of libopen64rt.a when
> linking PIE code since the code in libopen64rt_shared.a is built with
> the -fPIC option. We already link in libopen64rt_shared.a instead of
> libopen64rt.a when building shared libraries.
>
> I tested the patch on a small test case that calls bzero (one of the
> functions defined in libopen64rt) and verified that it fixes the bug on
> x86 and since the libopen64rt libraries are only used for x86 targets
> this won't affect any other targets.
>
> Can a gatekeeper approve this patch?
>
> Steve Ellcey
> s...@cup.hp.com
>
>
> Defect report:
>
> http://bugs.open64.net/show_bug.cgi?id=577
>
>
> Patch:
>
> Index: osprey/driver/phases.c
> ===================================================================
> --- osprey/driver/phases.c (revision 3298)
> +++ osprey/driver/phases.c (working copy)
> @@ -2124,7 +2124,8 @@ add_final_ld_args (string_list_t *args,
> // Bug 3995.
> if (!option_was_seen(O_fno_fast_stdlib) &&
> !option_was_seen(O_nolibopen64rt)) { // bug 9611
> - if (option_was_seen(O_shared)) {
> + if (option_was_seen(O_shared) || option_was_seen(O_pie) ||
> + option_was_seen(O_fpie) || option_was_seen(O_fPIE)) {
> add_library(args, "open64rt_shared");
> } else {
> add_library(args, "open64rt");
>
>
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--
Regards,
Peng Yuan (袁鹏)
Performance that will make your eyes water!
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