Read MIDR_EL1 system register on aarch64

MIDR_EL1 system register exposes microarchitecture information so that
people can make micro-arch related optimization such as exposing as
much instruction level parallelism as possible.

MIDR_EL1 register can be read only if HWCAP_CPUID feature is supported.

Change-Id: Iabb8a36c5d31b184dba6399f378598058d394d4e

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/11744)

3 files changed, 62 insertions, 0 deletions

diff --git a/crypto/arm64cpuid.pl b/crypto/arm64cpuid.pl
index 0eadcc43f2..ac76dd449f 100755
--- a/crypto/arm64cpuid.pl
+++ b/crypto/arm64cpuid.pl
@@ -81,6 +81,13 @@ _armv8_sha512_probe:
 	ret
 .size	_armv8_sha512_probe,.-_armv8_sha512_probe
 
+.globl	_armv8_cpuid_probe
+.type	_armv8_cpuid_probe,%function
+_armv8_cpuid_probe:
+	mrs	x0, midr_el1
+	ret
+.size	_armv8_cpuid_probe,.-_armv8_cpuid_probe
+
 .globl	OPENSSL_cleanse
 .type	OPENSSL_cleanse,%function
 .align	5
diff --git a/crypto/arm_arch.h b/crypto/arm_arch.h
index 2d279d6459..d98154bddb 100644
--- a/crypto/arm_arch.h
+++ b/crypto/arm_arch.h
@@ -71,6 +71,7 @@
 
 # ifndef __ASSEMBLER__
 extern unsigned int OPENSSL_armcap_P;
+extern unsigned int OPENSSL_arm_midr;
 # endif
 
 # define ARMV7_NEON      (1<<0)
@@ -80,5 +81,48 @@ extern unsigned int OPENSSL_armcap_P;
 # define ARMV8_SHA256    (1<<4)
 # define ARMV8_PMULL     (1<<5)
 # define ARMV8_SHA512    (1<<6)
+# define ARMV8_CPUID     (1<<7)
 
+/*
+ * MIDR_EL1 system register
+ *
+ * 63___ _ ___32_31___ _ ___24_23_____20_19_____16_15__ _ __4_3_______0
+ * |            |             |         |         |          |        |
+ * |RES0        | Implementer | Variant | Arch    | PartNum  |Revision|
+ * |____ _ _____|_____ _ _____|_________|_______ _|____ _ ___|________|
+ *
+ */
+
+# define ARM_CPU_IMP_ARM           0x41
+
+# define ARM_CPU_PART_CORTEX_A72   0xD08
+# define ARM_CPU_PART_N1           0xD0C
+
+# define MIDR_PARTNUM_SHIFT       4
+# define MIDR_PARTNUM_MASK        (0xfff << MIDR_PARTNUM_SHIFT)
+# define MIDR_PARTNUM(midr)       \
+           (((midr) & MIDR_PARTNUM_MASK) >> MIDR_PARTNUM_SHIFT)
+
+# define MIDR_IMPLEMENTER_SHIFT   24
+# define MIDR_IMPLEMENTER_MASK    (0xff << MIDR_IMPLEMENTER_SHIFT)
+# define MIDR_IMPLEMENTER(midr)   \
+           (((midr) & MIDR_IMPLEMENTER_MASK) >> MIDR_IMPLEMENTER_SHIFT)
+
+# define MIDR_ARCHITECTURE_SHIFT  16
+# define MIDR_ARCHITECTURE_MASK   (0xf << MIDR_ARCHITECTURE_SHIFT)
+# define MIDR_ARCHITECTURE(midr)  \
+           (((midr) & MIDR_ARCHITECTURE_MASK) >> MIDR_ARCHITECTURE_SHIFT)
+
+# define MIDR_CPU_MODEL_MASK \
+           (MIDR_IMPLEMENTER_MASK | \
+            MIDR_PARTNUM_MASK     | \
+            MIDR_ARCHITECTURE_MASK)
+
+# define MIDR_CPU_MODEL(imp, partnum) \
+           (((imp)     << MIDR_IMPLEMENTER_SHIFT)  | \
+            (0xf       << MIDR_ARCHITECTURE_SHIFT) | \
+            ((partnum) << MIDR_PARTNUM_SHIFT))
+
+# define MIDR_IS_CPU_MODEL(midr, imp, partnum) \
+           (((midr) & MIDR_CPU_MODEL_MASK) == MIDR_CPU_MODEL(imp, partnum))
 #endif
diff --git a/crypto/armcap.c b/crypto/armcap.c
index 70d2719ba7..7bd82f8ebc 100644
--- a/crypto/armcap.c
+++ b/crypto/armcap.c
@@ -18,6 +18,7 @@
 #include "arm_arch.h"
 
 unsigned int OPENSSL_armcap_P = 0;
+unsigned int OPENSSL_arm_midr = 0;
 
 #if __ARM_MAX_ARCH__<7
 void OPENSSL_cpuid_setup(void)
@@ -48,6 +49,7 @@ void _armv8_sha256_probe(void);
 void _armv8_pmull_probe(void);
 # ifdef __aarch64__
 void _armv8_sha512_probe(void);
+unsigned int _armv8_cpuid_probe(void);
 # endif
 uint32_t _armv7_tick(void);
 
@@ -95,6 +97,7 @@ void OPENSSL_cpuid_setup(void) __attribute__ ((constructor));
 #  define HWCAP_CE_PMULL         (1 << 4)
 #  define HWCAP_CE_SHA1          (1 << 5)
 #  define HWCAP_CE_SHA256        (1 << 6)
+#  define HWCAP_CPUID            (1 << 11)
 #  define HWCAP_CE_SHA512        (1 << 21)
 # endif
 
@@ -155,6 +158,9 @@ void OPENSSL_cpuid_setup(void)
 #  ifdef __aarch64__
         if (hwcap & HWCAP_CE_SHA512)
             OPENSSL_armcap_P |= ARMV8_SHA512;
+
+        if (hwcap & HWCAP_CPUID)
+            OPENSSL_armcap_P |= ARMV8_CPUID;
 #  endif
     }
 # endif
@@ -210,5 +216,10 @@ void OPENSSL_cpuid_setup(void)
 
     sigaction(SIGILL, &ill_oact, NULL);
     sigprocmask(SIG_SETMASK, &oset, NULL);
+
+# ifdef __aarch64__
+    if (OPENSSL_armcap_P & ARMV8_CPUID)
+        OPENSSL_arm_midr = _armv8_cpuid_probe();
+# endif
 }
 #endif