Messages in this thread Patch in this message | | | From | Ross Zwisler <> | Subject | [PATCH] x86: improve algorithm in clflush_cache_range | Date | Tue, 28 Apr 2015 16:13:12 -0600 |
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The current algorithm used in clflush_cache_range() can cause the last cache line of the buffer to be flushed twice. Fix that algorithm so that each cache line will only be flushed once.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reported-by: H. Peter Anvin <hpa@zytor.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: x86@kernel.org Cc: Borislav Petkov <bp@suse.de> --- arch/x86/mm/pageattr.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 89af288ec674..338e507f95b8 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -129,16 +129,15 @@ within(unsigned long addr, unsigned long start, unsigned long end) */ void clflush_cache_range(void *vaddr, unsigned int size) { - void *vend = vaddr + size - 1; + unsigned long clflush_mask = boot_cpu_data.x86_clflush_size - 1; + char *vend = (char *)vaddr + size; + char *p; mb(); - for (; vaddr < vend; vaddr += boot_cpu_data.x86_clflush_size) - clflushopt(vaddr); - /* - * Flush any possible final partial cacheline: - */ - clflushopt(vend); + for (p = (char *)((unsigned long)vaddr & ~clflush_mask); + p < vend; p += boot_cpu_data.x86_clflush_size) + clflushopt(p); mb(); } -- 1.9.3
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