[kvm-unit-tests PATCH 2/2] powerpc: restore TOC pointer

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As the TOC pointer can be corrupted by the main program,
we must restore it in the exception handler.

As we know where we are loaded, we can now compute it easily.

To compute it only in the common part of the exception handler
(call_handler), store the address of call_handler at an absolute
address in memory to be able to call the handler from the exception
table (as SLOF does).

Reported-by: Thomas Huth <thuth@xxxxxxxxxx>
Signed-off-by: Laurent Vivier <lvivier@xxxxxxxxxx>
---
 powerpc/cstart64.S | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
index c47b67d..1ddfa13 100644
--- a/powerpc/cstart64.S
+++ b/powerpc/cstart64.S
@@ -13,6 +13,8 @@
 
 #include "spapr.h"
 
+#define P_HANDLER	0x2ff8
+
 .section .init
 
 /*
@@ -46,6 +48,11 @@ start:
 	add	r4, r4, r31
 	bl	relocate
 
+	/* compute address of call_handler */
+
+	LOAD_REG_ADDR(r4, call_handler)
+	std	r4, P_HANDLER(0)
+
 	/* relocate vector table to base address 0x0 (MSR_IP = 0) */
 
 	/* source: r4, dest end: r5, destination: r6 */
@@ -166,6 +173,12 @@ call_handler:
 	mfsrr1	r0
 	std	r0, _MSR(r1)
 
+	/* restore TOC pointer */
+
+	LOAD_REG_IMMEDIATE(r31, SPAPR_KERNEL_LOAD_ADDR)
+	ld	r2, (p_toc - start)(r31)
+	add	r2, r2, r31
+
 	/* FIXME: build stack frame */
 
 	/* call generic handler */
@@ -221,7 +234,7 @@ call_handler:
 	mfctr	r0
 	std	r0,_CTR(r1)
 
-	LOAD_REG_ADDR(r0, call_handler)
+	ld	r0, P_HANDLER(0)
 	mtctr	r0
 
 	li	r0,\vec
@@ -245,3 +258,5 @@ VECTOR(0x900)
 	.align 7
 	.globl __end_interrupts
 __end_interrupts:
+	.org	P_HANDLER
+	.llong	0
-- 
2.5.5

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