kselftest/arm64: add jscvt feature to hwcap test

Add the jscvt feature check in the set of hwcap tests.

Due to the requirement of jscvt feature, a compiler configuration
of v8.3 or above is needed to support assembly. Therefore, hand
encode is used here instead.
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230815040915.3966955-5-zengheng4@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

tools/testing/selftests/arm64/abi/hwcap.c

@@ -68,6 +68,12 @@ static void ilrcpc_sigill(void)
 	asm volatile(".inst 0x994083e0" : : : );
 }
 
+static void jscvt_sigill(void)
+{
+	/* FJCVTZS W0, D0 */
+	asm volatile(".inst 0x1e7e0000" : : : );
+}
+
 static void lrcpc_sigill(void)
 {
 	/* LDAPR W0, [SP, #0] */
@@ -313,6 +319,13 @@ static const struct hwcap_data {
 		.cpuinfo = "fp",
 		.sigill_fn = fp_sigill,
 	},
+	{
+		.name = "JSCVT",
+		.at_hwcap = AT_HWCAP,
+		.hwcap_bit = HWCAP_JSCVT,
+		.cpuinfo = "jscvt",
+		.sigill_fn = jscvt_sigill,
+	},
 	{
 		.name = "LRCPC",
 		.at_hwcap = AT_HWCAP,