[git commit] NPTL/arc: notify kernel of the TP value

Bernhard Reutner-Fischer rep.dot.nop at gmail.com
Sun Jul 5 20:09:46 UTC 2015

commit: http://git.uclibc.org/uClibc/commit/?id=ca1c74d67dd115d059a875150e10b8560a9c35a8
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/master

Native gdb makes a ptrace (GET_THREAD_AREA) which needs to return the
TP. however when libc sets up TP reg (for main thread), it doesn't call
arc_settls syscall so kernel doesn't know of TP register details
(moreso because clone doesnt have SETTLS flag)

Note that kernel doesn't know about r25 being TP etc.

This commit got lost in merge of NPTL tools into arc-mainline-dev and
showed up again as STAR 9000919529 (native gdb can't debug threaded

	[ARCLinux]# gdb ./pth
	Reading symbols from ./pth...(no debugging symbols found)...done.
	(gdb) b main
	Breakpoint 1 at 0x106f2
	(gdb) r
	Starting program: /pth
	[Thread debugging using libthread_db enabled]
	Using host libthread_db library "/lib/libthread_db.so.1".
	thread_get_info_callback: cannot get thread info: generic error
	(gdb) q
Debugged-by: Anton Kolesov <akolesov at synopsys.com>
Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop at gmail.com>
 libpthread/nptl/sysdeps/arc/tls.h |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/libpthread/nptl/sysdeps/arc/tls.h b/libpthread/nptl/sysdeps/arc/tls.h
index 63dd113..4af415a 100644
--- a/libpthread/nptl/sysdeps/arc/tls.h
+++ b/libpthread/nptl/sysdeps/arc/tls.h
@@ -104,8 +104,11 @@ typedef struct
    operation can cause a failure 'errno' must not be touched.  */
 # define TLS_INIT_TP(tcbp, secondcall)          \
   ({                                            \
-        __builtin_set_thread_pointer(tcbp);     \
-        NULL;                                   \
+	long result_var;			\
+	__builtin_set_thread_pointer(tcbp);     \
+	result_var = INTERNAL_SYSCALL (arc_settls, err, 1, (tcbp));	\
+	INTERNAL_SYSCALL_ERROR_P (result_var, err)			\
+	? "unknown error" : NULL;		\
 /* Return the address of the dtv for the current thread.

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