Ian Lance Taylor <i...@google.com> writes:
> Ian Lance Taylor <i...@google.com> writes:
>
>> Right now it looks like there is a bug, or at least an incompatibility,
>> in the 64-bit versions of getcontext and setcontext. It looks like
>> calling setcontext on the 32-bit version does not change the value of
>> TLS variables, which is also the case on GNU/Linux. In the 64-bit
>> version, calling setcontext does change the value of TLS variables.
>> That is, on the 64-bit version, getcontext preserves the value of TLS
>> variables and setcontext restores the old value. (Of course it's really
>> the pointer, not the TLS variables themselves). This incompatibility
>> has to be a bug, and of course I would prefer that the incompatibility
>> be resolved in favor of the implementation used on GNU/Linux.
>
> Well, I thought I could fix this in a sensible way, but I really
> couldn't. It's a fairly serious bug. Calling setcontext in thread T2
> when getcontext was called in thread T1 causes T2 to start using T1's
> TLS variables, T1's pthread_getspecific values, and even T1's
> pthread_self. I couldn't figure out any way that T2 could do any thread
> specific.
>
> So I cheated and wrote a system-specific hack. With this patch applied,
> I see only 4 failures running the testsuite on x86/x86_64 Solaris.
> Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu, where the
> code is not used. Committed to mainline.
Excellent, works like a charm, thanks. The patches for Solaris 10 and
11 are expected within the next month or two. I only noticed two
problems:
* On Solaris 8/x86 with native TLS, SETCONTEXT_CLOBBERS_TLS was
incorrectly defined, causing a proc.c compilation failure:
/vol/gcc/src/hg/trunk/local/libgo/runtime/proc.c:105:4: error: #error unknown
case for SETCONTEXT_CLOBBERS_TLS
/vol/gcc/src/hg/trunk/local/libgo/runtime/proc.c: In function 'runtime_gogo':
/vol/gcc/src/hg/trunk/local/libgo/runtime/proc.c:299:2: error: implicit
declaration of function 'fixcontext' [-Werror=implicit-function-declaration]
/vol/gcc/src/hg/trunk/local/libgo/runtime/proc.c: In function
'runtime_schedinit':
/vol/gcc/src/hg/trunk/local/libgo/runtime/proc.c:366:2: error: implicit
declaration of function 'initcontext' [-Werror=implicit-function-declaration]
cc1: all warnings being treated as errors
make[4]: *** [proc.lo] Error 1
The configure test failed like this:
configure:14894: ./conftest
ld.so.1: conftest: fatal: conftest: object requires TLS, but TLS failed to initi
alize
/vol/gcc/src/hg/trunk/local/libgo/configure[20]: 28491 Killed
The problem is that on Solaris 8 one needs to link with -pthread which
takes care of finding the correct libthread.so. The following patch
takes care of that and gives decent testsuite results.
* In the cross-compilation case, one needs to test both the
i?86-*-solaris2.1[01] and x86_64-*-solaris2.1[10] target triplets, but
only for 64-bit. The first is the default, while one can configure
for the second if need be. The patch contains the necessary change,
adapted from libgcc/configure.ac's type size detection. Besides, the
bug affects both Solaris 10 and 11, so the workaround should trigger
on either, too.
Rainer
diff --git a/libgo/configure.ac b/libgo/configure.ac
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -584,8 +584,12 @@ fi
dnl See whether setcontext changes the value of TLS variables.
AC_CACHE_CHECK([whether setcontext clobbers TLS variables],
[libgo_cv_lib_setcontext_clobbers_tls],
-[LIBS_hold="$LIBS"
+[CFLAGS_hold="$CFLAGS"
+CFLAGS="$PTHREAD_CFLAGS"
+LIBS_hold="$LIBS"
LIBS="$LIBS $PTHREAD_LIBS"
+AC_CHECK_SIZEOF([void *])
+AS_VAR_ARITH([ptr_type_size], [$ac_cv_sizeof_void_p \* 8])
AC_RUN_IFELSE(
[AC_LANG_SOURCE([
#include <pthread.h>
@@ -650,11 +654,14 @@ main ()
])],
[libgo_cv_lib_setcontext_clobbers_tls=no],
[libgo_cv_lib_setcontext_clobbers_tls=yes],
-[case "$target" in
- x86_64*-*-solaris2.10) libgo_cv_lib_setcontext_clobbers_tls=yes ;;
- *) libgo_cv_lib_setcontext_clobbers_tls=no ;;
+[case "$target:$ptr_type_size" in
+ i?86-*-solaris2.1[[01]]:64 | x86_64*-*-solaris2.1[[01]]:64)
+ libgo_cv_lib_setcontext_clobbers_tls=yes ;;
+ *)
+ libgo_cv_lib_setcontext_clobbers_tls=no ;;
esac
])
+CFLAGS="$CFLAGS_hold"
LIBS="$LIBS_hold"
])
if test "$libgo_cv_lib_setcontext_clobbers_tls" = "yes"; then
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University
