From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Kosina <jkosina@suse.cz>, Andi Kleen <andi@firstfloor.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Andi Kleen <ak@linux.intel.com>, Ingo Molnar <mingo@kernel.org>,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH?] uprobes: change uprobe_write_opcode() to modify the page directly
Date: Tue, 03 Dec 2013 15:47:47 -0800 [thread overview]
Message-ID: <529E6DA3.5060705@zytor.com> (raw)
In-Reply-To: <CA+55aFxKk+O4e51sq6iqunVWAwKfNAnZ-3=aZT-VuRpDAZUnzQ@mail.gmail.com>
On 12/03/2013 02:01 PM, Linus Torvalds wrote:
> On Tue, Dec 3, 2013 at 12:54 PM, Oleg Nesterov <oleg@redhat.com> wrote:
>>
>> So do you think the patch I sent is wrong? Why?
>
> I think the TLB shootdown should guarantee that it's ok on other
> CPU's, since that's basically what we do on mmap.
>
I think that is true for other CPUs; however, there are definitely CPUs
out there (which Linux supports) for which you have to synchronize the I
and D sides "manually" after writing code through memory, at least
through the CPU. That is at least one reason why MIPS has a
cacheflush() system call, for example.
> But looking closer at this, I think I see why the old code did what it
> did. I think it's breaking shared mmap pages on purpose rather than
> dirtying them. Which is probably the right thing to do.
>
In other words, treating them as MAP_PRIVATE? Wouldn't it be better to
throw an error if we can't honor the semantics of the mapping that we
are using?
-hpa
next prev parent reply other threads:[~2013-12-03 23:49 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 0:37 [PATCH] Add a text_poke syscall v2 Andi Kleen
2013-11-26 19:05 ` Andy Lutomirski
2013-11-26 19:11 ` Andi Kleen
2013-11-26 20:03 ` Linus Torvalds
2013-11-27 19:57 ` H. Peter Anvin
2013-11-27 22:02 ` H. Peter Anvin
2013-11-27 22:21 ` Andy Lutomirski
2013-11-27 22:21 ` Borislav Petkov
2013-11-27 22:24 ` H. Peter Anvin
2013-11-27 22:25 ` H. Peter Anvin
2013-11-27 22:29 ` Borislav Petkov
2013-11-27 22:31 ` H. Peter Anvin
2013-11-27 23:04 ` Linus Torvalds
2013-11-27 23:13 ` Borislav Petkov
2013-11-27 22:40 ` H. Peter Anvin
2013-11-27 23:10 ` Borislav Petkov
2013-11-27 23:20 ` H. Peter Anvin
2013-11-27 23:40 ` Borislav Petkov
2013-11-27 23:47 ` H. Peter Anvin
2013-11-27 22:41 ` Linus Torvalds
2013-11-27 22:53 ` H. Peter Anvin
2013-11-27 23:15 ` Linus Torvalds
2013-11-27 23:28 ` H. Peter Anvin
2013-11-28 2:01 ` Linus Torvalds
2013-11-28 2:10 ` H. Peter Anvin
2013-11-28 9:12 ` Jiri Kosina
2013-11-27 23:44 ` Andi Kleen
2013-11-29 18:35 ` Oleg Nesterov
2013-11-29 19:54 ` Andi Kleen
2013-11-29 20:05 ` Oleg Nesterov
2013-11-29 20:17 ` H. Peter Anvin
2013-11-29 20:35 ` Oleg Nesterov
2013-11-29 21:24 ` H. Peter Anvin
2013-11-30 14:56 ` Oleg Nesterov
2013-11-29 23:24 ` Jiri Kosina
2013-11-30 0:22 ` Linus Torvalds
2013-12-03 18:49 ` [PATCH?] uprobes: change uprobe_write_opcode() to modify the page directly Oleg Nesterov
2013-12-03 19:00 ` Linus Torvalds
2013-12-03 19:20 ` H. Peter Anvin
2013-12-03 20:01 ` Oleg Nesterov
2013-12-03 20:21 ` H. Peter Anvin
2013-12-03 20:38 ` Oleg Nesterov
2013-12-03 20:43 ` H. Peter Anvin
2013-12-03 20:54 ` Oleg Nesterov
2013-12-03 22:01 ` Linus Torvalds
2013-12-03 23:47 ` H. Peter Anvin [this message]
2013-12-04 11:30 ` Oleg Nesterov
2013-12-04 11:11 ` Oleg Nesterov
2013-12-04 16:01 ` H. Peter Anvin
2013-12-04 16:48 ` Oleg Nesterov
2013-12-04 16:54 ` H. Peter Anvin
2013-12-04 17:15 ` Linus Torvalds
2013-12-04 17:43 ` Oleg Nesterov
2013-12-05 17:23 ` Oleg Nesterov
2013-12-05 17:49 ` Borislav Petkov
2013-12-05 18:45 ` Oleg Nesterov
2013-12-04 18:32 ` H. Peter Anvin
2013-12-05 8:28 ` Jon Medhurst (Tixy)
2013-12-03 22:42 ` H. Peter Anvin
2013-12-03 19:53 ` Oleg Nesterov
2013-11-30 15:20 ` [PATCH] Add a text_poke syscall v2 Oleg Nesterov
2013-11-30 16:51 ` Oleg Nesterov
2013-11-30 17:31 ` Oleg Nesterov
2013-11-30 5:16 ` H. Peter Anvin
2013-11-30 14:52 ` Oleg Nesterov
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