From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Dan Williams <dan.j.williams@intel.com>,
Borislav Petkov <bp@suse.de>
Subject: [PATCH] x86: improve algorithm in clflush_cache_range
Date: Wed, 11 Mar 2015 15:04:59 -0600 [thread overview]
Message-ID: <1426107899-27933-1-git-send-email-ross.zwisler@linux.intel.com> (raw)
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,
and remove arithmetic on void pointers. Void pointer arithmetic is
allowed by GCC extensions, but isn't part of the base C standards.
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: Dan Williams <dan.j.williams@intel.com>
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 ae242a7c11c7..b75ecac859f2 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -131,16 +131,15 @@ 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
next reply other threads:[~2015-03-11 21:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-11 21:04 Ross Zwisler [this message]
2015-03-12 11:09 ` [PATCH] x86: improve algorithm in clflush_cache_range Ingo Molnar
2015-03-13 2:00 ` Ross Zwisler
2015-04-28 22:13 Ross Zwisler
2015-04-29 10:28 ` Borislav Petkov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1426107899-27933-1-git-send-email-ross.zwisler@linux.intel.com \
--to=ross.zwisler@linux.intel.com \
--cc=bp@suse.de \
--cc=dan.j.williams@intel.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.