From 3721c7fe276dbbc93e584359f87913e58f96626e Mon Sep 17 00:00:00 2001
From: Sitsofe Wheeler <sitsofe@yahoo.com>
Date: Mon, 6 Dec 2021 20:02:53 +0000
Subject: [PATCH] os: detect PMULL support before enabling accelerated crc32c
 on ARM

Issue #1239 shows a crash on a FUJITSU/A64FX ARM platform at the
following line:

crc/crc32c-arm64.c:
 64                 t1 = (uint64_t)vmull_p64(crc1, k2);

On armv8 PMULL crypto instructions like vmull_p64 are defined as
optional (see
https://github.com/google/crc32c/pull/6#issuecomment-328713398 and
https://github.com/dotnet/runtime/issues/35143#issuecomment-617263508 ).

Avoid the crash by gating use of the hardware accelerated ARM crc32c
path behind runtime detection of PMULL.

Fixes: https://github.com/axboe/fio/issues/1239

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Pavel Reichl <preichl@redhat.com>
---
 os/os-linux.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/os/os-linux.h b/os/os-linux.h
index 808f1d02..3001140c 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -20,6 +20,9 @@
 
 #ifdef ARCH_HAVE_CRC_CRYPTO
 #include <sys/auxv.h>
+#ifndef HWCAP_PMULL
+#define HWCAP_PMULL             (1 << 4)
+#endif /* HWCAP_PMULL */
 #ifndef HWCAP_CRC32
 #define HWCAP_CRC32             (1 << 7)
 #endif /* HWCAP_CRC32 */
@@ -405,7 +408,8 @@ static inline bool os_cpu_has(cpu_features feature)
 #ifdef ARCH_HAVE_CRC_CRYPTO
 	case CPU_ARM64_CRC32C:
 		hwcap = getauxval(AT_HWCAP);
-		have_feature = (hwcap & HWCAP_CRC32) != 0;
+		have_feature = (hwcap & (HWCAP_PMULL | HWCAP_CRC32)) ==
+			       (HWCAP_PMULL | HWCAP_CRC32);
 		break;
 #endif
 	default:
-- 
2.38.1