Commit a4d44266 authored Feb 05, 2017 by Stafford Horne

openrisc: head: Init r0 to 0 on start



Originally openrisc spec 0 specified that r0 would be wired to ground.
This is no longer the case.  r0 is not guaranteed to be 0 at init, so we
need to initialize it to 0 before using it.

Also, if we are clearing r0 we cant use r0 to clear itself. Change the
the CLEAR_GPR macro to use movhi for clearing.

Reported-by: Jakob Viketoft <jakob.viketoft@aacmicrotec.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

parent a0eba4f7

arch/openrisc/kernel/head.S

+4 −1

Original line number	Diff line number	Diff line
		@@ -35,7 +35,7 @@
		l.add rd,rd,rs

		#define CLEAR_GPR(gpr) \
		l.or gpr,r0,r0
		l.movhi gpr,0x0

		#define LOAD_SYMBOL_2_GPR(gpr,symbol) \
		l.movhi gpr,hi(symbol) ;\
		@@ -443,6 +443,9 @@ _dispatch_do_ipage_fault:
		__HEAD
		.global _start
		_start:
		/* Init r0 to zero as per spec */
		CLEAR_GPR(r0)

		/* save kernel parameters */
		l.or r25,r0,r3 /* pointer to fdt */