| Message ID | e1aafaed-c810-eac2-35f0-8489b4c24d05@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On 06/08/2017 02:02 PM, Stefan Liebler wrote: > Question about glibc configure flag --disable-hidden-plt: > Is this option supported or is it used by somebody? > It defines NO_HIDDEN which influences the definition of HIDDEN_JUMPTARGET. > I've tried to build glibc with this configure flag on s390, but it fails > due to several reasons. I think we can remove --disable-hidden-plt. It is broken on x86-64 as well, and I think the whole thing stopped working with PLT avoidance for hidden symbols in binutils and switching to namespace-clean names (which are generally hidden). Thanks, Florian
On Fri, 9 Jun 2017, Florian Weimer wrote: > On 06/08/2017 02:02 PM, Stefan Liebler wrote: > > Question about glibc configure flag --disable-hidden-plt: > > Is this option supported or is it used by somebody? > > It defines NO_HIDDEN which influences the definition of HIDDEN_JUMPTARGET. > > I've tried to build glibc with this configure flag on s390, but it fails > > due to several reasons. > > I think we can remove --disable-hidden-plt. It is broken on x86-64 as > well, and I think the whole thing stopped working with PLT avoidance for > hidden symbols in binutils and switching to namespace-clean names (which > are generally hidden). Do note however the unconditional definition of NO_HIDDEN in sysdeps/mach/hurd/configure.ac (and the corresponding comment pointing to a discussion of that). We really need Hurd people to get current glibc working on Hurd without external patches and contribute build-many-glibcs.py support for it so it's possible to make sure changes don't break Hurd.
On Jun 08 2017, Stefan Liebler <stli@linux.vnet.ibm.com> wrote: > [BZ #21537] > * sysdeps/s390/s390-32/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): > Check SHARED instead of PIC. > (SYSCALL_PIC_SETUP): Add missing semicolons. > * sysdeps/s390/s390-64/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): > Check SHARED instead of PIC. > * sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S > (__makecontext_ret): Adjust code to jump to exit. Ok. Andreas.
On 06/12/2017 02:05 PM, Andreas Schwab wrote: > On Jun 08 2017, Stefan Liebler <stli@linux.vnet.ibm.com> wrote: > >> [BZ #21537] >> * sysdeps/s390/s390-32/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): >> Check SHARED instead of PIC. >> (SYSCALL_PIC_SETUP): Add missing semicolons. >> * sysdeps/s390/s390-64/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): >> Check SHARED instead of PIC. >> * sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S >> (__makecontext_ret): Adjust code to jump to exit. > > Ok. > > Andreas. > Committed. Thanks. Stefan
commit a1d6669382f30e16edf787adfa87b6f77a309357
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date: Thu Jun 8 13:13:27 2017 +0200
S390: Fix build with gcc configured with --enable-default-pie. [BZ #21537]
Building glibc with gcc configured with --enable-default-pie failed on s390
due to assembler messages:
../sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S:44:
Error: junk at end of line, first unrecognized character is `@'
HIDDEN_JUMPTARGET was expanded to exit@PLT@GOTOFF.
If SHARED is not defined, HIDDEN_JUMPTARGET is defined to JUMPTARGET
in sysdeps/s390/s390-32/sysdep.h. There it expanded to exit@PLT
in non SHARED case as PIC is defined if gcc is configured with
--enable-default-pie. Thus I've changed the "ifdef PIC" to "ifdef SHARED"
as we do not want PLTs in the static obj files. I've also changed this
in sysdeps/s390/s390-64/sysdep.h.
I've also adjusted sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S.
If glibc is configured with --disable-hidden-plt, then NO_HIDDEN is defined.
In SHARED case HIDDEN_JUMPTARGET would be expanded to exit@PLT@GOTOFF
instead of __GI_exit@GOTOFF.
Now we jump to:
- __GI_exit if SHARED is defined
- exit@PLT if SHARED and NO_HIDDEN is defined
- exit if both are not defined.
On s390 31bit we have to setup GOT pointer in r12 if we use a PLT stub.
Therefore I use SYSCALL_PIC_SETUP from sysdep.h and added the missing semicolons.
ChangeLog:
[BZ #21537]
* sysdeps/s390/s390-32/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP):
Check SHARED instead of PIC.
(SYSCALL_PIC_SETUP): Add missing semicolons.
* sysdeps/s390/s390-64/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP):
Check SHARED instead of PIC.
* sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
(__makecontext_ret): Adjust code to jump to exit.
diff --git a/sysdeps/s390/s390-32/sysdep.h b/sysdeps/s390/s390-32/sysdep.h
index 15a4e3e..60cf1e7 100644
--- a/sysdeps/s390/s390-32/sysdep.h
+++ b/sysdeps/s390/s390-32/sysdep.h
@@ -82,14 +82,14 @@ lose: SYSCALL_PIC_SETUP \
END (name)
#undef JUMPTARGET
-#ifdef PIC
+#ifdef SHARED
#define JUMPTARGET(name) name##@PLT
#define SYSCALL_PIC_SETUP \
- bras %r12,1f \
-0: .long _GLOBAL_OFFSET_TABLE_-0b \
+ bras %r12,1f; \
+0: .long _GLOBAL_OFFSET_TABLE_-0b; \
1: al %r12,0(%r12)
#else
-#define JUMPTARGET(name) name
+#define JUMPTARGET(name) name
#define SYSCALL_PIC_SETUP /* Nothing. */
#endif
diff --git a/sysdeps/s390/s390-64/sysdep.h b/sysdeps/s390/s390-64/sysdep.h
index a4dfc67..419cd01 100644
--- a/sysdeps/s390/s390-64/sysdep.h
+++ b/sysdeps/s390/s390-64/sysdep.h
@@ -77,7 +77,7 @@ lose: SYSCALL_PIC_SETUP \
END (name)
#undef JUMPTARGET
-#ifdef PIC
+#ifdef SHARED
#define JUMPTARGET(name) name##@PLT
#define SYSCALL_PIC_SETUP \
larl %r12,_GLOBAL_OFFSET_TABLE_
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
index f32cd3c..887d841 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S
@@ -32,25 +32,18 @@ ENTRY(__makecontext_ret)
lr %r2,%r8
br %r9
1: lhi %r2,0 /* EXIT return value. */
- basr %r13,0
-2:
-#ifdef PIC
- l %r12,4f-2b(%r13)
- la %r12,0(%r12,%r13) /* GOT pointer in r12 after this. */
- l %r1,3f-2b(%r13)
- bas %r14,0(%r1,%r12)
- .align 4
-3:
- .long HIDDEN_JUMPTARGET (exit)@GOTOFF
-4:
- .long _GLOBAL_OFFSET_TABLE_-2b
-#else
- l %r1,3f-2b(%r13)
- basr %r14,%r1
- .align 4
-3:
- .long HIDDEN_JUMPTARGET (exit)
+#ifdef NO_HIDDEN
+ /* If SHARED and NO_HIDDEN is defined, we need to setup got pointer
+ as HIDDEN_JUMPTARGET expands to JUMPTARGET which expands to
+ exit@PLT. Otherwise HIDDEN_JUMPTARGET expands to __GI_exit if
+ SHARED is defined and to exit if SHARED is not defined. */
+ SYSCALL_PIC_SETUP
#endif
- .align 2
+ basr %r1,0
+2:
+ al %r1,3f-2b(%r1)
+ basr %r14,%r1 /* Call exit. */
j .+2 /* Trap if exit returns for some reason. */
+3:
+ .long HIDDEN_JUMPTARGET (exit) - 2b
END(__makecontext_ret)
Hi, Building glibc with gcc configured with --enable-default-pie failed on s390 due to assembler messages: ../sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S:44: Error: junk at end of line, first unrecognized character is `@' HIDDEN_JUMPTARGET was expanded to exit@PLT@GOTOFF. If SHARED is not defined, HIDDEN_JUMPTARGET is defined to JUMPTARGET in sysdeps/s390/s390-32/sysdep.h. There it expanded to exit@PLT in non SHARED case as PIC is defined if gcc is configured with --enable-default-pie. Thus I've changed the "ifdef PIC" to "ifdef SHARED" as we do not want PLTs in the static obj files. I've also changed this in sysdeps/s390/s390-64/sysdep.h. I've also adjusted sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S. If glibc is configured with --disable-hidden-plt, then NO_HIDDEN is defined. In SHARED case HIDDEN_JUMPTARGET would be expanded to exit@PLT@GOTOFF instead of __GI_exit@GOTOFF. Now we jump to: - __GI_exit if SHARED is defined - exit@PLT if SHARED and NO_HIDDEN is defined - exit if both are not defined. On s390 31bit we have to setup GOT pointer in r12 if we use a PLT stub. Therefore I use SYSCALL_PIC_SETUP from sysdep.h and added the missing semicolons. Question about glibc configure flag --disable-hidden-plt: Is this option supported or is it used by somebody? It defines NO_HIDDEN which influences the definition of HIDDEN_JUMPTARGET. I've tried to build glibc with this configure flag on s390, but it fails due to several reasons. The glibc internal symbols of the ifunc'ed symbols are generated by using __hidden_ver1 which does not exist if NO_HIDDEN is defined. Thus for further testing I've used --disable-multi-arch to avoid the ifuncs. Furthermore I get undefined references to __GI_memset/cpy/move due to asm ("memxyz = __GI_memxyz"); in sysdeps/generic/symbol-hacks.h. There are also undefined references to __nss_next2 and __inet6_scopeid_pton while linking nscd/nscd. Usually libc.so contains those symbols: xyz@@GLIBC_PRIVATE. But with --disable-hidden-plt those symbols are only local. For testing I've removed attribute_hidden at those prototypes. Then glibc builds and the testsuite runs without fails except elf/check-localplt which detects the PLTs due to --disable-hidden-plt. ChangeLog: [BZ #21537] * sysdeps/s390/s390-32/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): Check SHARED instead of PIC. (SYSCALL_PIC_SETUP): Add missing semicolons. * sysdeps/s390/s390-64/sysdep.h (JUMPTARGET, SYSCALL_PIC_SETUP): Check SHARED instead of PIC. * sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S (__makecontext_ret): Adjust code to jump to exit.