diff options
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | include/dlfcn.h | 23 | ||||
| -rw-r--r-- | sysdeps/gnu/unwind-resume.c | 7 | ||||
| -rw-r--r-- | sysdeps/nptl/unwind-forcedunwind.c | 3 |
4 files changed, 34 insertions, 7 deletions
@@ -1,3 +1,11 @@ +2018-04-26 Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com> + + [BZ #22766] + * include/dlfcn.h [__libc_dl_open]: Replace RTLD_LAZY with RTLD_NOW. + * sysdeps/gnu/unwind-resume.c (__lib_gcc_s_init): Replace + __libc_dlopen_mode() using RTLD_NOW with __libc_dlopen. + * sysdeps/nptl/unwind-forcedunwind.c: Likewise. + 2018-04-25 Adhemerval Zanella <adhemerval.zanella@linaro.org> * sysdeps/unix/sysv/linux/getdirentries.c (getdirentries): Build iff diff --git a/include/dlfcn.h b/include/dlfcn.h index 12ef913..694e71c 100644 --- a/include/dlfcn.h +++ b/include/dlfcn.h @@ -31,8 +31,29 @@ extern char **__libc_argv attribute_hidden; /* Now define the internal interfaces. */ +/* Use RTLD_NOW here because: + 1. In pthread_cancel_init we want to use RTLD_NOW to reduce the stack usage + of future cancellation operations, particularly when the target thread + is running with a small stack. Likewise for consistency we do the same + thing in __libgcc_s_init. RTLD_NOW will rarely make a difference for + __libgcc_s_init because unwinding is already in progress, so libgcc_s.so + has already been loaded if its unwinder is used (Bug 22636). + 2. It allows us to provide robust fallback code at dlopen time for + incorrectly configured systems that mix old libnss_* modules with newly + installed libraries e.g. old libnss_nis.so.2 with new libnsl.so.1. Using + RTLD_LAZY here causes a failure at the time the symbol is called and at + that point it is much harder to safely return an error (Bug 22766). + + The use of RTLD_NOW also impacts gconv module loading, backtracing + (where the unwinder form libgcc_s.so is used), and IDNA functions + (which load libidn), all of which load their respective DSOs on + demand, and so should not impact program startup. That is to say + that the DSOs are loaded as part of an API call and therefore we + will be calling that family of API functions shortly so RTLD_NOW or + RTLD_LAZY is not a big difference in performance, but RTLD_NOW has + better error handling semantics for the library. */ #define __libc_dlopen(name) \ - __libc_dlopen_mode (name, RTLD_LAZY | __RTLD_DLOPEN) + __libc_dlopen_mode (name, RTLD_NOW | __RTLD_DLOPEN) extern void *__libc_dlopen_mode (const char *__name, int __mode); extern void *__libc_dlsym (void *__map, const char *__name); extern void *__libc_dlvsym (void *map, const char *name, const char *version); diff --git a/sysdeps/gnu/unwind-resume.c b/sysdeps/gnu/unwind-resume.c index 7f9a1bf..9283d92 100644 --- a/sysdeps/gnu/unwind-resume.c +++ b/sysdeps/gnu/unwind-resume.c @@ -35,11 +35,8 @@ __libgcc_s_init (void) void *resume, *personality; void *handle; - /* Use RTLD_NOW here for consistency with pthread_cancel_init. - RTLD_NOW will rarely make a difference here because unwinding is - already in progress, so libgcc_s.so has already been loaded if - its unwinder is used. */ - handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN); + /* See include/dlfcn.h. Use of __libc_dlopen requires RTLD_NOW. */ + handle = __libc_dlopen (LIBGCC_S_SO); if (handle == NULL || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL diff --git a/sysdeps/nptl/unwind-forcedunwind.c b/sysdeps/nptl/unwind-forcedunwind.c index 67b8e74..0621c80 100644 --- a/sysdeps/nptl/unwind-forcedunwind.c +++ b/sysdeps/nptl/unwind-forcedunwind.c @@ -49,7 +49,8 @@ pthread_cancel_init (void) return; } - handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN); + /* See include/dlfcn.h. Use of __libc_dlopen requires RTLD_NOW. */ + handle = __libc_dlopen (LIBGCC_S_SO); if (handle == NULL || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL |