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

From: Nicholas Piggin <[email-masked]>
Date: Thu, 8 Jun 2023 17:58:16 +1000

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

Signed-off-by: Nicholas Piggin <[email-masked]>
---
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