From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Denys Vlasenko <dvlasenk@redhat.com>,
Brian Gerst <brgerst@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH 0/7] x86/entry: Create a home for the x86 entry code in arch/x86/entry/
Date: Wed, 03 Jun 2015 11:18:54 -0700 [thread overview]
Message-ID: <556F450E.1020902@zytor.com> (raw)
In-Reply-To: <556F41A2.7000207@zytor.com>
On 06/03/2015 11:04 AM, H. Peter Anvin wrote:
> On 06/03/2015 10:22 AM, Andy Lutomirski wrote:
>>
>> I'm convinced. If "entry" means entry into code provided by the
>> kernel as opposed to entry via hardware-provided entry mechanism, then
>> the vdso is indeed a pile of entries into the kernel.
>>
>
> No, it isn't. It is user space code provided by the kernel. It is a
> very different beast, and this is highly and unnecessarily confusing. I
> am thrilled we finally have managed to get the vdso code separated out,
> this just muddles the situation.
>
So let me clarify this: vdso code is really a kind of system calls, that
just happen to be executed in user space, thus *bypassing* kernel entry.
We don't want to put all the system call code (or even the x86-specific
ones) in entry/ as that would completely eliminate the point and we have
once again re-invented the kernel/ catch-all.
-hpa
next prev parent reply other threads:[~2015-06-03 18:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-03 16:59 [RFC PATCH 0/7] x86/entry: Create a home for the x86 entry code in arch/x86/entry/ Ingo Molnar
2015-06-03 16:59 ` [PATCH 1/7] x86/asm/entry: Move entry_64.S and entry_32.S to arch/x86/entry/ Ingo Molnar
2015-06-03 16:59 ` [PATCH 2/7] x86/asm/entry: Move the compat syscall entry code " Ingo Molnar
2015-06-03 17:04 ` Andy Lutomirski
2015-06-03 17:11 ` Ingo Molnar
2015-06-03 16:59 ` [PATCH 3/7] x86/asm/entry, x86/vdso: Move the vDSO code to arch/x86/entry/vdso/ Ingo Molnar
2015-06-03 17:05 ` Andy Lutomirski
2015-06-03 16:59 ` [PATCH 4/7] x86/asm/entry: Move the 'thunk' functions to arch/x86/entry/ Ingo Molnar
2015-06-03 16:59 ` [PATCH 5/7] x86/asm/entry: Move arch/x86/include/asm/calling.h " Ingo Molnar
2015-06-03 16:59 ` [PATCH 6/7] x86/asm/entry: Move the arch/x86/syscalls/ definitions to arch/x86/entry/syscalls/ Ingo Molnar
2015-06-03 16:59 ` [PATCH 7/7] x86/asm/entry: Move the vsyscall code to arch/x86/entry/vsyscall/ Ingo Molnar
2015-06-03 17:03 ` [RFC PATCH 0/7] x86/entry: Create a home for the x86 entry code in arch/x86/entry/ H. Peter Anvin
2015-06-03 17:11 ` Ingo Molnar
2015-06-03 17:13 ` Andy Lutomirski
2015-06-03 17:16 ` Ingo Molnar
2015-06-03 17:21 ` Ingo Molnar
2015-06-03 17:23 ` Andy Lutomirski
2015-06-03 17:29 ` Ingo Molnar
2015-06-03 17:22 ` Andy Lutomirski
2015-06-03 18:04 ` H. Peter Anvin
2015-06-03 18:18 ` H. Peter Anvin [this message]
2015-06-03 17:07 ` Andy Lutomirski
2015-06-03 17:08 ` Andy Lutomirski
2015-06-03 17:13 ` Ingo Molnar
2015-06-03 18:02 ` H. Peter Anvin
2015-06-05 7:37 ` Ingo Molnar
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