arm64/cache: Fix cache_type_cwg() for register generation

Ard noticed that since we converted CTR_EL0 to automatic generation we have
been seeing errors on some systems handling the value of cache_type_cwg()
such as

   CPU features: No Cache Writeback Granule information, assuming 128

This is because the manual definition of CTR_EL0_CWG_MASK was done without
a shift while our convention is to define the mask after shifting. This
means that the user in cache_type_cwg() was broken as it was written for
the manually written shift then mask. Fix this by converting to use
SYS_FIELD_GET().

The only other field where the _MASK for this register is used is IminLine
which is at offset 0 so unaffected.

Fixes: 9a3634d ("arm64/sysreg: Convert CTR_EL0 to automatic generation")
Reported-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: broonie

arch/arm64/include/asm/cache.h

@@ -71,7 +71,7 @@ static __always_inline int icache_is_vpipt(void)
 
 static inline u32 cache_type_cwg(void)
 {
-	return (read_cpuid_cachetype() >> CTR_EL0_CWG_SHIFT) & CTR_EL0_CWG_MASK;
+	return SYS_FIELD_GET(CTR_EL0, CWG, read_cpuid_cachetype());
 }
 
 #define __read_mostly __section(".data..read_mostly")