From: Borislav Petkov <bp@alien8•de>
To: "Kirill A. Shutemov" <kirill.shutemov@linux•intel.com>
Cc: linux-mips@linux-mips•org, linux-sh@vger•kernel.org,
linux-mm@kvack•org, Jan Beulich <JBeulich@suse•com>,
"H. Peter Anvin" <hpa@zytor•com>,
sparclinux@vger•kernel.org,
Andrea Arcangeli <aarcange@redhat•com>,
Andi Kleen <ak@linux•intel.com>,
Robert Richter <robert.richter@amd•com>,
x86@kernel•org, Hugh Dickins <hughd@google•com>,
Ingo Molnar <mingo@redhat•com>, Mel Gorman <mgorman@suse•de>,
Alex Shi <alex.shu@intel•com>,
Thomas Gleixner <tglx@linutronix•de>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp•fujitsu.com>,
Tim Chen <tim.c.chen@linux•intel.com>,
linux-kernel@vger•kernel.org,
Andy Lutomirski <luto@amacapital•net>,
Johannes Weiner <hannes@cmpxchg•org>,
Andrew Morton <akpm@linux-foundation•org>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH v2 4/6] x86: Add clear_page_nocache
Date: Mon, 13 Aug 2012 19:04:02 +0200 [thread overview]
Message-ID: <20120813170402.GB15530@x1.osrc.amd.com> (raw)
In-Reply-To: <20120813114334.GA21855@otc-wbsnb-06>
On Mon, Aug 13, 2012 at 02:43:34PM +0300, Kirill A. Shutemov wrote:
> $ cat test.c
> #include <stdio.h>
> #include <sys/mman.h>
>
> #define SIZE 1024*1024*1024
>
> void clear_page_nocache_sse2(void *page) __attribute__((regparm(1)));
>
> int main(int argc, char** argv)
> {
> char *p;
> unsigned long i, j;
>
> p = mmap(NULL, SIZE, PROT_WRITE|PROT_READ,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE, -1, 0);
> for(j = 0; j < 100; j++) {
> for(i = 0; i < SIZE; i += 4096) {
> clear_page_nocache_sse2(p + i);
> }
> }
>
> return 0;
> }
> $ cat clear_page_nocache_unroll32.S
> .globl clear_page_nocache_sse2
> .align 4,0x90
> clear_page_nocache_sse2:
> .cfi_startproc
> mov %eax,%edx
> xorl %eax,%eax
> movl $4096/32,%ecx
> .p2align 4
> .Lloop_sse2:
> decl %ecx
> #define PUT(x) movnti %eax,x*4(%edx)
> PUT(0)
> PUT(1)
> PUT(2)
> PUT(3)
> PUT(4)
> PUT(5)
> PUT(6)
> PUT(7)
> #undef PUT
> lea 32(%edx),%edx
> jnz .Lloop_sse2
> nop
> ret
> .cfi_endproc
> .type clear_page_nocache_sse2, @function
> .size clear_page_nocache_sse2, .-clear_page_nocache_sse2
> $ cat clear_page_nocache_unroll64.S
> .globl clear_page_nocache_sse2
> .align 4,0x90
> clear_page_nocache_sse2:
> .cfi_startproc
> mov %eax,%edx
This must still be the 32-bit version becaue it segfaults here. Here's
why:
mmap above gives a ptr which, on 64-bit, is larger than 32-bit, i.e. it
looks like 0x7fffxxxxx000, i.e. starting from top of userspace.
Now, the mov above truncates that ptr and the thing segfaults.
Doing s/edx/rdx/g fixes it though.
Thanks.
--
Regards/Gruss,
Boris.
next prev parent reply other threads:[~2012-08-13 17:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-09 15:02 [PATCH v2 0/6] Avoid cache trashing on clearing huge/gigantic page Kirill A. Shutemov
2012-08-09 15:02 ` [PATCH v2 1/6] THP: Use real address for NUMA policy Kirill A. Shutemov
2012-08-09 15:02 ` [PATCH v2 2/6] mm: make clear_huge_page tolerate non aligned address Kirill A. Shutemov
2012-08-09 15:03 ` [PATCH v2 3/6] THP: Pass real, not rounded, address to clear_huge_page Kirill A. Shutemov
2012-08-09 15:03 ` [PATCH v2 4/6] x86: Add clear_page_nocache Kirill A. Shutemov
2012-08-09 15:22 ` Jan Beulich
2012-08-13 11:43 ` Kirill A. Shutemov
2012-08-13 12:02 ` Jan Beulich
2012-08-13 16:27 ` Andi Kleen
2012-08-13 17:04 ` Borislav Petkov [this message]
2012-08-13 19:07 ` Kirill A. Shutemov
2012-08-09 15:23 ` H. Peter Anvin
2012-08-09 15:03 ` [PATCH v2 5/6] mm: make clear_huge_page cache clear only around the fault address Kirill A. Shutemov
2012-08-09 15:03 ` [PATCH v2 6/6] x86: switch the 64bit uncached page clear to SSE/AVX v2 Kirill A. Shutemov
2012-08-09 15:28 ` Jan Beulich
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