openrisc: Add thread-local storage (TLS) support
Historically OpenRISC GCC has reserved r10 which we now use to hold
the thread pointer for thread-local storage (TLS).
Signed-off-by: Christian Svensson <blue@cmd.nu>
Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Stafford Horne <shorne@gmail.com>
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 7095dfe..277123b 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -173,6 +173,19 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
if (usp)
userregs->sp = usp;
+
+ /*
+ * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
+ *
+ * The kernel entry is:
+ * int clone (long flags, void *child_stack, int *parent_tid,
+ * int *child_tid, struct void *tls)
+ *
+ * This makes the source r7 in the kernel registers.
+ */
+ if (clone_flags & CLONE_SETTLS)
+ userregs->gpr[10] = userregs->gpr[7];
+
userregs->gpr[11] = 0; /* Result from fork() */
kregs->gpr[20] = 0; /* Userspace thread */