Implement _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]

This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly.  This removes a writable function pointer from the
rtld_global variable.

For use during initial relocation, minimal implementations of these
functions are provided in ld.so.  These are eventually interposed
by the libc.so implementations.  This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.

As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.

1 files changed, 3 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/alpha/localplt.data b/sysdeps/unix/sysv/linux/alpha/localplt.data
index 351596cf57..298439365f 100644
--- a/sysdeps/unix/sysv/linux/alpha/localplt.data
+++ b/sysdeps/unix/sysv/linux/alpha/localplt.data
@@ -33,3 +33,6 @@ ld.so: malloc + RELA R_ALPHA_GLOB_DAT
 ld.so: calloc + RELA R_ALPHA_GLOB_DAT
 ld.so: realloc + RELA R_ALPHA_GLOB_DAT
 ld.so: free + RELA R_ALPHA_GLOB_DAT
+# The TLS-enabled version of these functions is interposed from libc.so.
+ld.so: _dl_signal_error + RELA R_ALPHA_GLOB_DAT
+ld.so: _dl_catch_error + RELA R_ALPHA_GLOB_DAT