commit c50842df47970eab459f13490c152aac85fc02f2
author Chris Zankel <chris@zankel.net> Sat Feb 23 19:35:57 2013 -0800
committer Chris Zankel <chris@zankel.net> Sat Feb 23 19:35:57 2013 -0800
tree d2933b4d9641067002ba6d662b0abf6ee3011375
parent b0c438e642699f8c47b84de957f30cf586cdbebd

xtensa: add support for TLS

The Xtensa architecture provides a global register called THREADPTR
for the purpose of Thread Local Storage (TLS) support. This allows us
to use a fairly simple implementation, keeping the thread pointer in
the regset and simply saving and restoring it upon entering/exiting
the from user space.

Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/kernel/process.c

diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 0dd5784..5cd82e9 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -259,9 +259,10 @@
 			memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
 			       &regs->areg[XCHAL_NUM_AREGS - len/4], len);
 		}
-// FIXME: we need to set THREADPTR in thread_info...
+
+		/* The thread pointer is passed in the '4th argument' (= a5) */
 		if (clone_flags & CLONE_SETTLS)
-			childregs->areg[2] = childregs->areg[6];
+			childregs->threadptr = childregs->areg[5];
 	} else {
 		p->thread.ra = MAKE_RA_FOR_CALL(
 				(unsigned long)ret_from_kernel_thread, 1);