diff options
Diffstat (limited to 'x86-use-default-cache-size-if-it-cannot-be-determine.patch')
| -rw-r--r-- | x86-use-default-cache-size-if-it-cannot-be-determine.patch | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/x86-use-default-cache-size-if-it-cannot-be-determine.patch b/x86-use-default-cache-size-if-it-cannot-be-determine.patch new file mode 100644 index 0000000..7eeae68 --- /dev/null +++ b/x86-use-default-cache-size-if-it-cannot-be-determine.patch @@ -0,0 +1,61 @@ +From c242fcce06e3102ca663b2f992611d0bda4f2668 Mon Sep 17 00:00:00 2001 +From: Aurelien Jarno <aurelien@aurel32.net> +Date: Mon, 17 Jan 2022 19:41:40 +0100 +Subject: [PATCH] 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 <hjl.tools@gmail.com> +--- + sysdeps/x86/cacheinfo.h | 14 ++++++++++---- + 1 file changed, 10 insertions(+), 4 deletions(-) + +diff --git a/sysdeps/x86/cacheinfo.h b/sysdeps/x86/cacheinfo.h +index 4f91a1e98d..65132a9d19 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; +-- +2.27.0 + |