arm64: elf: use cpuid_feature_extract_field for hwcap detection

cpuid_feature_extract_field takes care of the fiddly ID register
field sign-extension, so use that instead of rolling our own version.

Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/setup.c

@@ -223,7 +223,8 @@ void __init up_late_init(void)
 
 static void __init setup_processor(void)
 {
-	u64 features, block;
+	u64 features;
+	s64 block;
 	u32 cwg;
 	int cls;
 
@@ -253,8 +254,8 @@ static void __init setup_processor(void)
 	 * for non-negative values. Negative values are reserved.
 	 */
 	features = read_cpuid(ID_AA64ISAR0_EL1);
-	block = (features >> 4) & 0xf;
-	if (!(block & 0x8)) {
+	block = cpuid_feature_extract_field(features, 4);
+	if (block > 0) {
 		switch (block) {
 		default:
 		case 2:
@@ -266,20 +267,17 @@ static void __init setup_processor(void)
 		}
 	}
 
-	block = (features >> 8) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 8) > 0)
 		elf_hwcap |= HWCAP_SHA1;
 
-	block = (features >> 12) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 12) > 0)
 		elf_hwcap |= HWCAP_SHA2;
 
-	block = (features >> 16) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 16) > 0)
 		elf_hwcap |= HWCAP_CRC32;
 
-	block = (features >> 20) & 0xf;
-	if (!(block & 0x8)) {
+	block = cpuid_feature_extract_field(features, 20);
+	if (block > 0) {
 		switch (block) {
 		default:
 		case 2:
@@ -294,11 +292,11 @@ static void __init setup_processor(void)
 #ifdef CONFIG_COMPAT
 	/*
 	 * ID_ISAR5_EL1 carries similar information as above, but pertaining to
-	 * the Aarch32 32-bit execution state.
+	 * the AArch32 32-bit execution state.
 	 */
 	features = read_cpuid(ID_ISAR5_EL1);
-	block = (features >> 4) & 0xf;
-	if (!(block & 0x8)) {
+	block = cpuid_feature_extract_field(features, 4);
+	if (block > 0) {
 		switch (block) {
 		default:
 		case 2:
@@ -310,16 +308,13 @@ static void __init setup_processor(void)
 		}
 	}
 
-	block = (features >> 8) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 8) > 0)
 		compat_elf_hwcap2 |= COMPAT_HWCAP2_SHA1;
 
-	block = (features >> 12) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 12) > 0)
 		compat_elf_hwcap2 |= COMPAT_HWCAP2_SHA2;
 
-	block = (features >> 16) & 0xf;
-	if (block && !(block & 0x8))
+	if (cpuid_feature_extract_field(features, 16) > 0)
 		compat_elf_hwcap2 |= COMPAT_HWCAP2_CRC32;
 #endif
 }