Refactor CPUID to make it thread safe

Needed for #1819 and unfortunately Windows does not allow thread local
data to be stored as a member of a DLL exported class. So hide it
behind an accessor function instead.

This slows down CPUID test somewhat and I would like to address that
but it seems hard without breaking the CPUID API, which is for better
or worse public.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/tests/test_utils.cpp b/src/tests/test_utils.cpp
index de9db6683..52d10058b 100644
--- a/src/tests/test_utils.cpp
+++ b/src/tests/test_utils.cpp
@@ -976,6 +976,12 @@ class CPUID_Tests final : public Test
             result.test_eq("If endian is big, it is not also little endian", Botan::CPUID::is_little_endian(), false);
             }
 
+         const size_t cache_line_size = Botan::CPUID::cache_line_size();
+
+         result.test_gte("Cache line size is >= 16", cache_line_size, 16);
+         result.test_lte("Cache line size is <= 256", cache_line_size, 256);
+         result.confirm("Cache line size is a power of 2", Botan::is_power_of_2(cache_line_size));
+
          const std::string cpuid_string = Botan::CPUID::to_string();
          result.test_success("CPUID::to_string doesn't crash");