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authorBorislav Petkov <borislav.petkov@amd.com>2011-08-05 15:15:08 +0200
committerH. Peter Anvin <hpa@linux.intel.com>2011-08-05 12:26:44 -0700
commitdfb09f9b7ab03fd367740e541a5caf830ed56726 (patch)
tree8bd8fdbbf3fb67f7d0aed73a1e8e1c7034ed2d54 /arch/x86/vdso
parent13f9a3737c903ace57d8aaebe81a3bbaeb0aa0a2 (diff)
x86, amd: Avoid cache aliasing penalties on AMD family 15h
This patch provides performance tuning for the "Bulldozer" CPU. With its shared instruction cache there is a chance of generating an excessive number of cache cross-invalidates when running specific workloads on the cores of a compute module. This excessive amount of cross-invalidations can be observed if cache lines backed by shared physical memory alias in bits [14:12] of their virtual addresses, as those bits are used for the index generation. This patch addresses the issue by clearing all the bits in the [14:12] slice of the file mapping's virtual address at generation time, thus forcing those bits the same for all mappings of a single shared library across processes and, in doing so, avoids instruction cache aliases. It also adds the command line option "align_va_addr=(32|64|on|off)" with which virtual address alignment can be enabled for 32-bit or 64-bit x86 individually, or both, or be completely disabled. This change leaves virtual region address allocation on other families and/or vendors unaffected. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Link: http://lkml.kernel.org/r/1312550110-24160-2-git-send-email-bp@amd64.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/vdso')
-rw-r--r--arch/x86/vdso/vma.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 7abd2be0f9b9..caa42ce17577 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -69,6 +69,15 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
addr = start + (offset << PAGE_SHIFT);
if (addr >= end)
addr = end;
+
+ /*
+ * page-align it here so that get_unmapped_area doesn't
+ * align it wrongfully again to the next page. addr can come in 4K
+ * unaligned here as a result of stack start randomization.
+ */
+ addr = PAGE_ALIGN(addr);
+ addr = align_addr(addr, NULL, ALIGN_VDSO);
+
return addr;
}