From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Lutomirski <luto@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Nicolai Stange <nstange@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Mimi Zohar <zohar@linux.ibm.com>, Juergen Gross <jgross@suse.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Nayna Jain <nayna@linux.ibm.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Joerg Roedel <jroedel@suse.de>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
live-patching@vger.kernel.org,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation
Date: Mon, 29 Apr 2019 13:16:10 -0700 [thread overview]
Message-ID: <CAHk-=wjyyKDv-WZLXZbVD=V05p2X7eg74z2SpR4TQTxN9JLq4Q@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
On Mon, Apr 29, 2019 at 12:02 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> If nmi were to break it, it would be a cpu bug. I'm pretty sure I've
> seen the "shadow stops even nmi" documented for some uarch, but as
> mentioned it's not necessarily the only way to guarantee the shadow.
In fact, the documentation is simply the official Intel instruction
docs for "STI":
The IF flag and the STI and CLI instructions do not prohibit the
generation of exceptions and NMI interrupts. NMI interrupts (and
SMIs) may be blocked for one macroinstruction following an STI.
note the "may be blocked". As mentioned, that's just one option for
not having NMI break the STI shadow guarantee, but it's clearly one
that Intel has done at times, and clearly even documents as having
done so.
There is absolutely no question that the sti shadow is real, and that
people have depended on it for _decades_. It would be a horrible
errata if the shadow can just be made to go away by randomly getting
an NMI or SMI.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: torvalds at linux-foundation.org (Linus Torvalds)
Subject: [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation
Date: Mon, 29 Apr 2019 13:16:10 -0700 [thread overview]
Message-ID: <CAHk-=wjyyKDv-WZLXZbVD=V05p2X7eg74z2SpR4TQTxN9JLq4Q@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
On Mon, Apr 29, 2019 at 12:02 PM Linus Torvalds
<torvalds at linux-foundation.org> wrote:
>
> If nmi were to break it, it would be a cpu bug. I'm pretty sure I've
> seen the "shadow stops even nmi" documented for some uarch, but as
> mentioned it's not necessarily the only way to guarantee the shadow.
In fact, the documentation is simply the official Intel instruction
docs for "STI":
The IF flag and the STI and CLI instructions do not prohibit the
generation of exceptions and NMI interrupts. NMI interrupts (and
SMIs) may be blocked for one macroinstruction following an STI.
note the "may be blocked". As mentioned, that's just one option for
not having NMI break the STI shadow guarantee, but it's clearly one
that Intel has done at times, and clearly even documents as having
done so.
There is absolutely no question that the sti shadow is real, and that
people have depended on it for _decades_. It would be a horrible
errata if the shadow can just be made to go away by randomly getting
an NMI or SMI.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: torvalds@linux-foundation.org (Linus Torvalds)
Subject: [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation
Date: Mon, 29 Apr 2019 13:16:10 -0700 [thread overview]
Message-ID: <CAHk-=wjyyKDv-WZLXZbVD=V05p2X7eg74z2SpR4TQTxN9JLq4Q@mail.gmail.com> (raw)
Message-ID: <20190429201610.DCWt_NR3ocYHUVW8sUuf2Cy-_wWyirkJ1GIAh8bsi1M@z> (raw)
In-Reply-To: <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
On Mon, Apr 29, 2019 at 12:02 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> If nmi were to break it, it would be a cpu bug. I'm pretty sure I've
> seen the "shadow stops even nmi" documented for some uarch, but as
> mentioned it's not necessarily the only way to guarantee the shadow.
In fact, the documentation is simply the official Intel instruction
docs for "STI":
The IF flag and the STI and CLI instructions do not prohibit the
generation of exceptions and NMI interrupts. NMI interrupts (and
SMIs) may be blocked for one macroinstruction following an STI.
note the "may be blocked". As mentioned, that's just one option for
not having NMI break the STI shadow guarantee, but it's clearly one
that Intel has done at times, and clearly even documents as having
done so.
There is absolutely no question that the sti shadow is real, and that
people have depended on it for _decades_. It would be a horrible
errata if the shadow can just be made to go away by randomly getting
an NMI or SMI.
Linus
next prev parent reply other threads:[~2019-04-29 20:23 UTC|newest]
Thread overview: 192+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-27 10:06 [PATCH 0/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation Nicolai Stange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` nstange
2019-04-27 10:06 ` [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member Nicolai Stange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` nstange
2019-04-28 17:41 ` Andy Lutomirski
2019-04-28 17:41 ` Andy Lutomirski
2019-04-28 17:41 ` luto
2019-04-28 17:51 ` Steven Rostedt
2019-04-28 17:51 ` Steven Rostedt
2019-04-28 17:51 ` rostedt
2019-04-28 18:08 ` Andy Lutomirski
2019-04-28 18:08 ` Andy Lutomirski
2019-04-28 18:08 ` luto
2019-04-28 19:43 ` Steven Rostedt
2019-04-28 19:43 ` Steven Rostedt
2019-04-28 19:43 ` rostedt
2019-04-28 20:56 ` Andy Lutomirski
2019-04-28 20:56 ` Andy Lutomirski
2019-04-28 20:56 ` luto
2019-04-28 21:22 ` Nicolai Stange
2019-04-28 21:22 ` Nicolai Stange
2019-04-28 21:22 ` nstange
2019-04-28 23:27 ` Andy Lutomirski
2019-04-28 23:27 ` Andy Lutomirski
2019-04-28 23:27 ` luto
2019-04-27 10:06 ` [PATCH 2/4] ftrace: drop 'static' qualifier from ftrace_ops_list_func() Nicolai Stange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` nstange
2019-04-27 10:06 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation Nicolai Stange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` nstange
2019-04-27 10:26 ` Peter Zijlstra
2019-04-27 10:26 ` Peter Zijlstra
2019-04-27 10:26 ` peterz
2019-04-28 17:38 ` Steven Rostedt
2019-04-28 17:38 ` Steven Rostedt
2019-04-28 17:38 ` rostedt
2019-04-29 18:06 ` Linus Torvalds
2019-04-29 18:06 ` Linus Torvalds
2019-04-29 18:06 ` torvalds
2019-04-29 18:22 ` Linus Torvalds
2019-04-29 18:22 ` Linus Torvalds
2019-04-29 18:22 ` torvalds
2019-04-29 18:42 ` Andy Lutomirski
2019-04-29 18:42 ` Andy Lutomirski
2019-04-29 18:42 ` luto
[not found] ` <CAHk-=whtt4K2f0KPtG-4Pykh3FK8UBOjD8jhXCUKB5nWDj_YRA@mail.gmail.com>
2019-04-29 18:56 ` Andy Lutomirski
2019-04-29 18:56 ` Andy Lutomirski
2019-04-29 18:56 ` luto
[not found] ` <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
[not found] ` <CAHk-=whay7eN6+2gZjY-ybRbkbcqAmgrLwwszzHx8ws3c=S-MA@mail.gmail.com>
2019-04-29 19:24 ` Andy Lutomirski
2019-04-29 19:24 ` Andy Lutomirski
2019-04-29 19:24 ` luto
2019-04-29 20:07 ` Linus Torvalds
2019-04-29 20:07 ` Linus Torvalds
2019-04-29 20:07 ` torvalds
2019-04-30 13:56 ` Peter Zijlstra
2019-04-30 13:56 ` Peter Zijlstra
2019-04-30 13:56 ` peterz
2019-04-30 16:06 ` Linus Torvalds
2019-04-30 16:06 ` Linus Torvalds
2019-04-30 16:06 ` torvalds
2019-04-30 16:33 ` Andy Lutomirski
2019-04-30 16:33 ` Andy Lutomirski
2019-04-30 16:33 ` luto
2019-04-30 17:03 ` Steven Rostedt
2019-04-30 17:03 ` Steven Rostedt
2019-04-30 17:03 ` rostedt
2019-04-30 17:20 ` Steven Rostedt
2019-04-30 17:20 ` Steven Rostedt
2019-04-30 17:20 ` rostedt
2019-04-30 17:49 ` [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler Steven Rostedt
2019-04-30 17:49 ` Steven Rostedt
2019-04-30 17:49 ` rostedt
2019-04-30 18:33 ` Linus Torvalds
2019-04-30 18:33 ` Linus Torvalds
2019-04-30 18:33 ` torvalds
2019-04-30 19:00 ` Steven Rostedt
2019-04-30 19:00 ` Steven Rostedt
2019-04-30 19:00 ` rostedt
2019-04-30 21:08 ` Steven Rostedt
2019-04-30 21:08 ` Steven Rostedt
2019-04-30 21:08 ` rostedt
2019-05-01 13:11 ` Peter Zijlstra
2019-05-01 13:11 ` Peter Zijlstra
2019-05-01 13:11 ` peterz
2019-05-01 18:58 ` Steven Rostedt
2019-05-01 18:58 ` Steven Rostedt
2019-05-01 18:58 ` rostedt
2019-05-01 19:03 ` Peter Zijlstra
2019-05-01 19:03 ` Peter Zijlstra
2019-05-01 19:03 ` peterz
2019-05-01 19:03 ` Linus Torvalds
2019-05-01 19:03 ` Linus Torvalds
2019-05-01 19:03 ` torvalds
2019-05-01 19:13 ` Peter Zijlstra
2019-05-01 19:13 ` Peter Zijlstra
2019-05-01 19:13 ` peterz
2019-05-01 19:13 ` Steven Rostedt
2019-05-01 19:13 ` Steven Rostedt
2019-05-01 19:13 ` rostedt
2019-05-01 19:33 ` Jiri Kosina
2019-05-01 19:33 ` Jiri Kosina
2019-05-01 19:33 ` jikos
2019-05-01 19:41 ` Peter Zijlstra
2019-05-01 19:41 ` Peter Zijlstra
2019-05-01 19:41 ` peterz
2019-04-30 21:53 ` [RFC][PATCH v2] " Steven Rostedt
2019-04-30 21:53 ` Steven Rostedt
2019-04-30 21:53 ` rostedt
2019-05-01 1:35 ` Steven Rostedt
2019-05-01 1:35 ` Steven Rostedt
2019-05-01 1:35 ` rostedt
2019-05-01 1:58 ` Linus Torvalds
2019-05-01 1:58 ` Linus Torvalds
2019-05-01 1:58 ` torvalds
2019-05-01 8:26 ` Nicolai Stange
2019-05-01 8:26 ` Nicolai Stange
2019-05-01 8:26 ` nstange
2019-05-01 13:22 ` Steven Rostedt
2019-05-01 13:22 ` Steven Rostedt
2019-05-01 13:22 ` rostedt
2019-04-29 20:16 ` Linus Torvalds [this message]
2019-04-29 20:16 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation Linus Torvalds
2019-04-29 20:16 ` torvalds
2019-04-29 22:08 ` Sean Christopherson
2019-04-29 22:08 ` Sean Christopherson
2019-04-29 22:08 ` sean.j.christopherson
2019-04-29 22:22 ` Linus Torvalds
2019-04-29 22:22 ` Linus Torvalds
2019-04-29 22:22 ` torvalds
2019-04-30 0:08 ` Sean Christopherson
2019-04-30 0:08 ` Sean Christopherson
2019-04-30 0:08 ` sean.j.christopherson
2019-04-30 0:45 ` Sean Christopherson
2019-04-30 0:45 ` Sean Christopherson
2019-04-30 0:45 ` sean.j.christopherson
2019-04-30 2:26 ` Linus Torvalds
2019-04-30 2:26 ` Linus Torvalds
2019-04-30 2:26 ` torvalds
2019-04-30 10:40 ` Peter Zijlstra
2019-04-30 10:40 ` Peter Zijlstra
2019-04-30 10:40 ` peterz
2019-04-30 11:17 ` Jiri Kosina
2019-04-30 11:17 ` Jiri Kosina
2019-04-30 11:17 ` jikos
2019-04-29 22:06 ` Linus Torvalds
2019-04-29 22:06 ` Linus Torvalds
2019-04-29 22:06 ` torvalds
2019-04-30 11:18 ` Peter Zijlstra
2019-04-30 11:18 ` Peter Zijlstra
2019-04-30 11:18 ` peterz
2019-04-29 18:52 ` Steven Rostedt
2019-04-29 18:52 ` Steven Rostedt
2019-04-29 18:52 ` rostedt
[not found] ` <CAHk-=wjm93jLtVxTX4HZs6K4k1Wqh3ujjmapqaYtcibVk_YnzQ@mail.gmail.com>
2019-04-29 19:07 ` Steven Rostedt
2019-04-29 19:07 ` Steven Rostedt
2019-04-29 19:07 ` rostedt
2019-04-29 20:06 ` Linus Torvalds
2019-04-29 20:06 ` Linus Torvalds
2019-04-29 20:06 ` torvalds
2019-04-29 20:20 ` Linus Torvalds
2019-04-29 20:20 ` Linus Torvalds
2019-04-29 20:20 ` torvalds
2019-04-29 20:30 ` Steven Rostedt
2019-04-29 20:30 ` Steven Rostedt
2019-04-29 20:30 ` rostedt
2019-04-29 21:38 ` Linus Torvalds
2019-04-29 21:38 ` Linus Torvalds
2019-04-29 21:38 ` torvalds
2019-04-29 22:07 ` Steven Rostedt
2019-04-29 22:07 ` Steven Rostedt
2019-04-29 22:07 ` rostedt
2019-04-30 9:24 ` Nicolai Stange
2019-04-30 9:24 ` Nicolai Stange
2019-04-30 9:24 ` nstange
2019-04-30 10:46 ` Peter Zijlstra
2019-04-30 10:46 ` Peter Zijlstra
2019-04-30 10:46 ` peterz
2019-04-30 13:44 ` Steven Rostedt
2019-04-30 13:44 ` Steven Rostedt
2019-04-30 13:44 ` rostedt
2019-04-30 14:20 ` Peter Zijlstra
2019-04-30 14:20 ` Peter Zijlstra
2019-04-30 14:20 ` peterz
2019-04-30 14:36 ` Steven Rostedt
2019-04-30 14:36 ` Steven Rostedt
2019-04-30 14:36 ` rostedt
2019-04-27 10:06 ` [PATCH 4/4] selftests/livepatch: add "ftrace a live patched function" test Nicolai Stange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` nstange
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