selftests/arm64: Implement cmpbr_sigill() to hwcap test

Yifan Wu · ctmarinas · commit 74cd4e0e5399 · 2026-03-14T16:58:16.000Z
The function executes a CBEQ instruction which is valid if the CPU
supports the CMPBR extension. The CBEQ branches to skip the following
UDF instruction, and no SIGILL is generated. Otherwise, it will
generate a SIGILL.

Signed-off-by: Yifan Wu &lt;wuyifan50@huawei.com&gt;
Reviewed-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
diff --git a/tools/testing/selftests/arm64/abi/hwcap.c b/tools/testing/selftests/arm64/abi/hwcap.c
@@ -56,7 +56,8 @@ static void atomics_sigill(void)
 
 static void cmpbr_sigill(void)
 {
-	/* Not implemented, too complicated and unreliable anyway */
+	asm volatile(".inst 0x74C00040\n" /* CBEQ w0, w0, +8 */
+		     "udf #0" : : : "cc"); /* UDF #0 */
 }
 
 static void crc32_sigill(void)

Original file line number	Diff line number	Diff line change
`@@ -56,7 +56,8 @@ static void atomics_sigill(void)`
`56`	`56`
`57`	`57`	`static void cmpbr_sigill(void)`
`58`	`58`	`{`
`59`		`- /* Not implemented, too complicated and unreliable anyway */`
	`59`	`+ asm volatile(".inst 0x74C00040\n" /* CBEQ w0, w0, +8 */`
	`60`	`+ "udf #0" : : : "cc"); /* UDF #0 */`
`60`	`61`	`}`
`61`	`62`
`62`	`63`	`static void crc32_sigill(void)`