switch aarch64 CPU feature detection to elf_aux_info()

ok kettenis@ tb@

1 files changed, 19 insertions, 63 deletions

diff --git a/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c b/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c
index b31a50ef75..4b0074df51 100644
--- a/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c
+++ b/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: crypto_cpu_caps.c,v 1.2 2024/11/12 13:52:31 jsing Exp $ */
+/* $OpenBSD: crypto_cpu_caps.c,v 1.3 2026/08/04 21:21:26 naddy Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -15,10 +15,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <sys/types.h>
-#include <sys/sysctl.h>
-
-#include <machine/cpu.h>
+#include <sys/auxv.h>
 
 #include <stddef.h>
 #include <stdio.h>
@@ -28,70 +25,29 @@
 /* Machine dependent CPU capabilities. */
 uint64_t crypto_cpu_caps_aarch64;
 
-static inline uint64_t
-extract_bits(uint64_t val, int start, int end)
-{
-        return (val >> end) & (1ULL << (1 + start - end)) - 1;
-}
-
-static uint64_t
-parse_isar0(uint64_t isar0)
+void
+crypto_cpu_caps_init(void)
 {
-        uint64_t caps = 0;
-        uint64_t feature;
-
-        /* AES - bits [7:4] */
-        feature = extract_bits(isar0, 7, 4);
-        if (feature >= 1)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_AES;
-        if (feature >= 2)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_PMULL;
-
-        /* SHA1 - bits [11:8] */
-        feature = extract_bits(isar0, 11, 8);
-        if (feature >= 1)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA1;
-
-        /* SHA2 - bits [15:12] */
-        feature = extract_bits(isar0, 15, 12);
-        if (feature >= 1)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA2;
-        if (feature >= 2)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA512;
-
-        /* SHA3 - bits [35:32] */
-        feature = extract_bits(isar0, 35, 32);
-        if (feature >= 1)
-                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA3;
+        unsigned long hwcap;
 
-        return caps;
-}
+        if (elf_aux_info(AT_HWCAP, &hwcap, sizeof(hwcap)) != 0)
+                return;
 
-static int
-read_isar0(uint64_t *isar0)
-{
-        uint64_t isar;
-        int mib[2];
-        size_t len;
+        if (hwcap & HWCAP_AES)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_AES;
 
-        mib[0] = CTL_MACHDEP;
-        mib[1] = CPU_ID_AA64ISAR0;
-        len = sizeof(isar);
-        if (sysctl(mib, 2, &isar, &len, NULL, 0) == -1)
-                return 0;
+        if (hwcap & HWCAP_PMULL)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_PMULL;
 
-        *isar0 = isar;
+        if (hwcap & HWCAP_SHA1)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA1;
 
-        return 1;
-}
+        if (hwcap & HWCAP_SHA2)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA2;
 
-void
-crypto_cpu_caps_init(void)
-{
-        uint64_t isar = 0;
-
-        if (!read_isar0(&isar))
-                return;
+        if (hwcap & HWCAP_SHA512)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA512;
 
-        crypto_cpu_caps_aarch64 = parse_isar0(isar);
+        if (hwcap & HWCAP_SHA3)
+                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA3;
 }