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-rw-r--r--linuxthreads/sysdeps/i386/tls.h28
1 files changed, 25 insertions, 3 deletions
diff --git a/linuxthreads/sysdeps/i386/tls.h b/linuxthreads/sysdeps/i386/tls.h
index 7715303d95..8bbe5f28e6 100644
--- a/linuxthreads/sysdeps/i386/tls.h
+++ b/linuxthreads/sysdeps/i386/tls.h
@@ -43,8 +43,17 @@ typedef struct
#endif
-/* We can support TLS only if the floating-stack support is available. */
-#if defined FLOATING_STACKS && defined HAVE_TLS_SUPPORT
+/* We can support TLS only if the floating-stack support is available.
+ However, we want to compile in the support and test at runtime whether
+ the running kernel can support it or not. To avoid bothering with the
+ TLS support code at all, use configure --without-tls.
+
+ We need USE_TLS to be consistently defined, for ldsodefs.h conditionals.
+ But some of the code below can cause problems in building libpthread
+ (e.g. useldt.h will defined FLOATING_STACKS when it shouldn't). */
+
+#if defined HAVE_TLS_SUPPORT \
+ && (defined FLOATING_STACKS || !defined IS_IN_libpthread)
/* Signal that TLS support is available. */
# define USE_TLS 1
@@ -96,8 +105,21 @@ typedef struct
# define TLS_LOAD_EBX
# endif
+# if __ASSUME_LDT_WORKS > 0
+# define TLS_DO_MODIFY_LDT_KERNEL_CHECK /* Nothing to do. */
+# else
+# include "useldt.h" /* For the structure. */
+# define TLS_DO_MODIFY_LDT_KERNEL_CHECK \
+ if (__builtin_expect (GL(dl_osversion) < 131939, 0)) \
+ _dl_fatal_printf ("kernel %u.%u.%u cannot support thread-local storage\n",\
+ (GL(dl_osversion) >> 16) & 0xff, \
+ (GL(dl_osversion) >> 8) & 0xff, \
+ (GL(dl_osversion) >> 0) & 0xff);
+# endif
+
# define TLS_DO_MODIFY_LDT(descr, nr) \
({ \
+ TLS_DO_MODIFY_LDT_KERNEL_CHECK \
struct modify_ldt_ldt_s ldt_entry = \
{ nr, (unsigned long int) (descr), 0xfffff /* 4GB in pages */, \
1, 0, 0, 1, 0, 1, 0 }; \
@@ -177,7 +199,7 @@ typedef struct
({ struct _pthread_descr_struct *__descr; \
THREAD_GETMEM (__descr, p_header.data.dtvp); })
-# endif /* FLOATING_STACKS && HAVE_TLS_SUPPORT */
+# endif /* HAVE_TLS_SUPPORT && (FLOATING_STACKS || !IS_IN_libpthread) */
#endif /* __ASSEMBLER__ */
#endif /* tls.h */