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* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-12 17:18 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-12 17:18 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=27498bbc768372541e4379794656ac2778d33035

commit 27498bbc768372541e4379794656ac2778d33035
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden matters with static PIE: extern symbol access in position
    independent code usually involves GOT indirections which needs
    RELATIVE relocs in a static linked PIE. Using So hidden avoids
    indirections and RELATIVE relocs on targets that can access symbols
    pc-relative.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    static libraries can use hidden visibility to avoid indirections,
    however the test system links objects from libcrypt.a into dynamic
    linked test binaries so hidden does not work there.  I think mixing
    static and shared libc components in the same binary should not be
    supported usage, but to be safe only use hidden in libc.a.
    
    From -static-pie linked 'int main(){}' this shaves off 73 relative
    relocs on aarch64 and reduces code size too.

Diff:
---
 include/libc-symbols.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..93e63ee889 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,17 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-20 15:23 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-20 15:23 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d7eb5cfd6953e9689c0306d808e234bd00741e6e

commit d7eb5cfd6953e9689c0306d808e234bd00741e6e
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden visibility can avoid indirections and RELATIVE relocs in
    static PIE libc.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    symbols are defined locally in static PIE and the optimization is
    useful in all libraries not just libc. However the test system
    links objects from libcrypt.a into dynamic linked test binaries
    where hidden visibility does not work.  I think mixing static and
    shared libc components in the same binary should not be supported
    usage, but to be safe only use hidden in libc.a.
    
    On some targets (i386) this optimization cannot be applied because
    hidden visibility PIE ifunc functions don't work, so it is gated by
    NO_HIDDEN_EXTERN_FUNC_IN_PIE.
    
    From -static-pie linked 'int main(){}' this shaves off 71 relative
    relocs on aarch64 and reduces code size by about 2k.

Diff:
---
 include/libc-symbols.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..f4dd735555 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,18 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE \
+    && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-19 15:59 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-19 15:59 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=84877b5e3f3f9fae476ead79e2676865018db0e3

commit 84877b5e3f3f9fae476ead79e2676865018db0e3
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden matters with static PIE: extern symbol access in position
    independent code usually involves GOT indirections which needs
    RELATIVE relocs in a static linked PIE. Hidden visibility avoids
    indirections and RELATIVE relocs on targets that can access symbols
    pc-relative.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    static libraries can use hidden visibility to avoid indirections,
    however the test system links objects from libcrypt.a into dynamic
    linked test binaries so hidden does not work there.  I think mixing
    static and shared libc components in the same binary should not be
    supported usage, but to be safe only use hidden in libc.a.
    
    This is an optimization. But on some targets (i386) it cannot be
    applied because hidden visibility PIE ifunc functions don't work,
    so it is gated by NO_HIDDEN_EXTERN_FUNC_IN_PIE.
    
    From -static-pie linked 'int main(){}' this shaves off 71 relative
    relocs on aarch64 and reduces code size by about 2k.

Diff:
---
 include/libc-symbols.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..f4dd735555 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,18 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE \
+    && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-18 16:16 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-18 16:16 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4b939181155fc70ccb708530c1244eb0c2fafbef

commit 4b939181155fc70ccb708530c1244eb0c2fafbef
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden matters with static PIE: extern symbol access in position
    independent code usually involves GOT indirections which needs
    RELATIVE relocs in a static linked PIE. Hidden visibility avoids
    indirections and RELATIVE relocs on targets that can access symbols
    pc-relative.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    static libraries can use hidden visibility to avoid indirections,
    however the test system links objects from libcrypt.a into dynamic
    linked test binaries so hidden does not work there.  I think mixing
    static and shared libc components in the same binary should not be
    supported usage, but to be safe only use hidden in libc.a.
    
    This is an optimization. But on some targets (i386) it cannot be
    applied because hidden visibility PIE ifunc functions don't work,
    so it is gated by NO_HIDDEN_EXTERN_FUNC_IN_PIE.
    
    From -static-pie linked 'int main(){}' this shaves off 71 relative
    relocs on aarch64 and reduces code size by about 2k.

Diff:
---
 include/libc-symbols.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..f4dd735555 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,18 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE \
+    && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-14 11:12 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-14 11:12 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=dfffe46e62b310e9cadd86e99d85121951e8f881

commit dfffe46e62b310e9cadd86e99d85121951e8f881
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden matters with static PIE: extern symbol access in position
    independent code usually involves GOT indirections which needs
    RELATIVE relocs in a static linked PIE. Hidden visibility avoids
    indirections and RELATIVE relocs on targets that can access symbols
    pc-relative.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    static libraries can use hidden visibility to avoid indirections,
    however the test system links objects from libcrypt.a into dynamic
    linked test binaries so hidden does not work there.  I think mixing
    static and shared libc components in the same binary should not be
    supported usage, but to be safe only use hidden in libc.a.
    
    There are targets (i686) where hidden visibility functions are
    problematic in PIE code so hidden cannot be applied to all symbols.
    Then static PIE requires extern object access without relocations
    (e.g. by relying on copy relocations in shared libraries instead of
    GOT access in PIE code). See bug 14961.
    
    From -static-pie linked 'int main(){}' this shaves off 73 relative
    relocs on aarch64 and reduces code size too.

Diff:
---
 include/libc-symbols.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..f4dd735555 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,18 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE \
+    && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/nsz/bug27072] Make libc symbols hidden in static PIE
@ 2021-01-11 10:48 Szabolcs Nagy
  0 siblings, 0 replies; 6+ messages in thread
From: Szabolcs Nagy @ 2021-01-11 10:48 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=45aaf8c6154298d3e00e8f6e1eb0558875a84121

commit 45aaf8c6154298d3e00e8f6e1eb0558875a84121
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Jan 6 11:31:04 2021 +0000

    Make libc symbols hidden in static PIE
    
    Hidden matters with static PIE: extern symbol access in position
    independent code usually involves GOT indirections which needs
    RELATIVE relocs in a static linked PIE. Using So hidden avoids
    indirections and RELATIVE relocs on targets that can access symbols
    pc-relative.
    
    The check should use IS_IN_LIB instead of IS_IN(libc) since all
    static libraries can use hidden visibility to avoid indirections,
    however the test system links objects from libcrypt.a into dynamic
    linked test binaries so hidden does not work there.  I think mixing
    static and shared libc components in the same binary should not be
    supported usage, but to be safe only use hidden in libc.a.
    
    From -static-pie linked 'int main(){}' this shaves off 73 relative
    relocs on aarch64 and reduces code size too.

Diff:
---
 include/libc-symbols.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index ea126ae70c..93e63ee889 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -434,13 +434,17 @@ for linking")
   strong_alias(real, name)
 #endif
 
-#if defined SHARED || defined LIBC_NONSHARED \
-  || (BUILD_PIE_DEFAULT && IS_IN (libc))
+#if defined SHARED || defined LIBC_NONSHARED
 # define attribute_hidden __attribute__ ((visibility ("hidden")))
 #else
 # define attribute_hidden
 #endif
 
+/* Mark all symbols hidden in static PIE libc to avoid GOT indirections.  */
+#if BUILD_PIE_DEFAULT && IS_IN (libc) && !defined LIBC_NONSHARED
+# pragma GCC visibility push(hidden)
+#endif
+
 #define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
 
 #define attribute_relro __attribute__ ((section (".data.rel.ro")))


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-01-20 15:23 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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