revert switch to elf_aux_info(); it breaks the install media

1 files changed, 63 insertions, 19 deletions

diff --git a/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c b/src/lib/libcrypto/arch/aarch64/crypto_cpu_caps.c
index 4b0074df51..7927fd247c 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 1.3 2026/08/04 21:21:26 naddy Exp $ */
+/* $OpenBSD: crypto_cpu_caps.c,v 1.4 2026/08/07 12:17:33 naddy Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -15,7 +15,10 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <sys/auxv.h>
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
+#include <machine/cpu.h>
 
 #include <stddef.h>
 #include <stdio.h>
@@ -25,29 +28,70 @@
 /* Machine dependent CPU capabilities. */
 uint64_t crypto_cpu_caps_aarch64;
 
-void
-crypto_cpu_caps_init(void)
+static inline uint64_t
+extract_bits(uint64_t val, int start, int end)
 {
-        unsigned long hwcap;
+        return (val >> end) & (1ULL << (1 + start - end)) - 1;
+}
 
-        if (elf_aux_info(AT_HWCAP, &hwcap, sizeof(hwcap)) != 0)
-                return;
+static uint64_t
+parse_isar0(uint64_t isar0)
+{
+        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;
 
-        if (hwcap & HWCAP_AES)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_AES;
+        /* SHA1 - bits [11:8] */
+        feature = extract_bits(isar0, 11, 8);
+        if (feature >= 1)
+                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA1;
 
-        if (hwcap & HWCAP_PMULL)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_PMULL;
+        /* 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;
 
-        if (hwcap & HWCAP_SHA1)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA1;
+        /* SHA3 - bits [35:32] */
+        feature = extract_bits(isar0, 35, 32);
+        if (feature >= 1)
+                caps |= CRYPTO_CPU_CAPS_AARCH64_SHA3;
 
-        if (hwcap & HWCAP_SHA2)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA2;
+        return caps;
+}
+
+static int
+read_isar0(uint64_t *isar0)
+{
+        uint64_t isar;
+        int mib[2];
+        size_t len;
 
-        if (hwcap & HWCAP_SHA512)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA512;
+        mib[0] = CTL_MACHDEP;
+        mib[1] = CPU_ID_AA64ISAR0;
+        len = sizeof(isar);
+        if (sysctl(mib, 2, &isar, &len, NULL, 0) == -1)
+                return 0;
+
+        *isar0 = isar;
+
+        return 1;
+}
+
+void
+crypto_cpu_caps_init(void)
+{
+        uint64_t isar = 0;
+
+        if (!read_isar0(&isar))
+                return;
 
-        if (hwcap & HWCAP_SHA3)
-                crypto_cpu_caps_aarch64 |= CRYPTO_CPU_CAPS_AARCH64_SHA3;
+        crypto_cpu_caps_aarch64 = parse_isar0(isar);
 }