[kvm-unit-tests v4 02/12] powerpc: Add some checking to exception handler install

[Nicholas Piggin]

Check to ensure exception handlers are not being overwritten or
invalid exception numbers are used.

Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
Since v3:
- Simplified code as suggested by Thomas.

 lib/powerpc/processor.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c
index 05b4b04f..0550e4fc 100644
--- a/lib/powerpc/processor.c
+++ b/lib/powerpc/processor.c
@@ -19,12 +19,16 @@ static struct {
 void handle_exception(int trap, void (*func)(struct pt_regs *, void *),
                      void * data)
 {
+       assert(!(trap & ~0xf00));
+
        trap >>= 8;
 
-       if (trap < 16) {
-               handlers[trap].func = func;
-               handlers[trap].data = data;
+       if (func && handlers[trap].func) {
+               printf("exception handler installed twice %#x\n", trap);
+               abort();
        }
+       handlers[trap].func = func;
+       handlers[trap].data = data;
 }
 
 void do_handle_exception(struct pt_regs *regs)
-- 
2.40.1