commit 1d401d1fccb85046402089268b94d86d822070e6 Author: Aurelien Jarno Date: Mon Jan 17 19:41:40 2022 +0100 x86: use default cache size if it cannot be determined [BZ #28784] In some cases (e.g QEMU, non-Intel/AMD CPU) the cache information can not be retrieved and the corresponding values are set to 0. Commit 2d651eb9265d ("x86: Move x86 processor cache info to cpu_features") changed the behaviour in such case by defining the __x86_shared_cache_size and __x86_data_cache_size variables to 0 instead of using the default values. This cause an issue with the i686 SSE2 optimized bzero/routine which assumes that the cache size is at least 128 bytes, and otherwise tries to zero/set the whole address space minus 128 bytes. Fix that by restoring the original code to only update __x86_shared_cache_size and __x86_data_cache_size variables if the corresponding cache sizes are not zero. Fixes bug 28784 Fixes commit 2d651eb9265d Reviewed-by: H.J. Lu (cherry picked from commit c242fcce06e3102ca663b2f992611d0bda4f2668) diff --git a/sysdeps/x86/cacheinfo.h b/sysdeps/x86/cacheinfo.h index 41d2c81369840ada..63f36877e3f35d99 100644 --- a/sysdeps/x86/cacheinfo.h +++ b/sysdeps/x86/cacheinfo.h @@ -61,14 +61,20 @@ init_cacheinfo (void) long int data = cpu_features->data_cache_size; /* Round data cache size to multiple of 256 bytes. */ data = data & ~255L; - __x86_data_cache_size_half = data / 2; - __x86_data_cache_size = data; + if (data > 0) + { + __x86_data_cache_size_half = data / 2; + __x86_data_cache_size = data; + } long int shared = cpu_features->shared_cache_size; /* Round shared cache size to multiple of 256 bytes. */ shared = shared & ~255L; - __x86_shared_cache_size_half = shared / 2; - __x86_shared_cache_size = shared; + if (shared > 0) + { + __x86_shared_cache_size_half = shared / 2; + __x86_shared_cache_size = shared; + } __x86_shared_non_temporal_threshold = cpu_features->non_temporal_threshold;