ANDROID: arm64: simd: omit capability check in may_use_simd()

may_use_simd() should only be called by code that may use FP/SIMD when
it is available, and so checking whether the system supports FP/SIMD in
the first place should be redundant - the caller in question (e.g., a
SIMD crypto algorithm) should never be initialized in the first place.

Checking the system capability involves jump labels and therefore code
patching, which interferes with our ability to perform an integrity
check on some of the crypto code. So let's get rid of the capability
check altogether.

Bug: 153614920
Bug: 188620248
Change-Id: Ia8df624f4648cc980a12a44eeb82e8f186d5f961
Signed-off-by: Ard Biesheuvel <ardb@google.com>

arch/arm64/include/asm/simd.h

@@ -35,9 +35,7 @@ static __must_check inline bool may_use_simd(void)
 	 * migrated, and if it's clear we cannot be migrated to a CPU
 	 * where it is set.
 	 */
-	return !WARN_ON(!system_capabilities_finalized()) &&
-	       system_supports_fpsimd() &&
-	       !in_irq() && !irqs_disabled() && !in_nmi() &&
+	return !in_irq() && !irqs_disabled() && !in_nmi() &&
 	       !this_cpu_read(fpsimd_context_busy);
 }