From: Andy Lutomirski <luto@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
live-patching@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Jiri Slaby <jslaby@suse.cz>, Ingo Molnar <mingo@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH v2 6/8] x86/entry: add unwind hint annotations
Date: Fri, 30 Jun 2017 08:44:40 -0700 [thread overview]
Message-ID: <CALCETrWgHQ93G8B8yyX2Ok_rBVJxfsm_2jPAcKS7iUfcHH3NFA@mail.gmail.com> (raw)
In-Reply-To: <20170630131148.yszdjakekrwqlf6k@treble>
On Fri, Jun 30, 2017 at 6:11 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Thu, Jun 29, 2017 at 10:41:44PM -0700, Andy Lutomirski wrote:
>> On Thu, Jun 29, 2017 at 10:05 PM, Andy Lutomirski <luto@kernel.org> wrote:
>> > Hmm. There's another option that might be considerably nicer, though:
>> > put the IRQ stack at a known (at link time) position *in percpu
>> > space*. (Presumably it already is -- I haven't checked.) Then we do:
>> >
>> > .macro ENTER_IRQ_STACK old_rsp
>> > DEBUG_ENTRY_ASSERT_IRQS_OFF
>> > movq %rsp, \old_rsp
>> > incl PER_CPU_VAR(irq_count)
>> >
>> > /*
>> > * Right now, if we just incremented irq_count to zero, we've
>> > * claimed the IRQ stack but we haven't switched to it yet.
>> > * Anything that can interrupt us here without using IST
>> > * must be *extremely* careful to limit its stack usage.
>> > */
>> > jnz .Lpush_old_rsp_\@
>> > movq \old_rsp, PER_CPU_VAR(top_word_in_irq_stack)
>> > movq PER_CPU_VAR(irq_stack_ptr), %rsp
>> > .Lpush_old_rsp_\@:
>> > pushq \old_rsp
>> > .endm
>> >
>>
>> How about the two commits here (well, soon to be there once gitweb catches up):
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_irq_stack&id=0f56a55bb133cd53ccb78ca51378086296618322
>>
>> If you like them, want to add them to your series?
>
> The second patch looks good to me, thanks. I can pick up the patches.
>
> A few comments about the first patch:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_irq_stack&id=3e2aa2102cc1c5e60d4a8637bff78d0478a55059
>
> - It uses a '693:' label instead of '.Lirqs_off_\@:'
Touché!
>
> - There's a comment I don't follow:
>
> "Anything that can interrupt us here without using IST must be
> *extremely* careful to limit its stack usage."
>
> What specifically could interrupt there without using IST?
#DB, later on in the series. I'll update the comment.
>
> - Since do_softirq_own_stack() is a callable function, I think it still
> needs to save rbp.
Whoops.
>
> - Why change the "jmp error_exit" to "ret" in
> xen_do_hypervisor_callback()?
To match the other change I made there. I removed both.
next prev parent reply other threads:[~2017-06-30 15:45 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-28 15:11 [PATCH v2 0/8] x86: undwarf unwinder Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 1/8] objtool: move checking code to check.c Josh Poimboeuf
2017-06-30 13:12 ` [tip:core/objtool] objtool: Move " tip-bot for Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 2/8] objtool, x86: add several functions and files to the objtool whitelist Josh Poimboeuf
2017-06-30 13:12 ` [tip:core/objtool] objtool, x86: Add " tip-bot for Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 3/8] objtool: stack validation 2.0 Josh Poimboeuf
2017-06-30 8:32 ` Ingo Molnar
2017-06-30 13:23 ` Josh Poimboeuf
2017-06-30 13:26 ` Josh Poimboeuf
2017-06-30 14:09 ` [PATCH] objtool: silence warnings for functions which use iret Josh Poimboeuf
2017-06-30 17:49 ` [tip:core/objtool] objtool: Silence warnings for functions which use IRET tip-bot for Josh Poimboeuf
2017-06-30 13:13 ` [tip:core/objtool] objtool: Implement stack validation 2.0 tip-bot for Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 4/8] objtool: add undwarf debuginfo generation Josh Poimboeuf
2017-06-29 7:14 ` Ingo Molnar
2017-06-29 13:40 ` Josh Poimboeuf
2017-06-29 7:25 ` Ingo Molnar
2017-06-29 14:04 ` Josh Poimboeuf
2017-06-29 14:46 ` Ingo Molnar
2017-06-29 15:06 ` Josh Poimboeuf
2017-07-06 20:36 ` Josh Poimboeuf
2017-07-07 9:44 ` Ingo Molnar
2017-07-11 2:58 ` Josh Poimboeuf
2017-07-11 8:40 ` Ingo Molnar
2017-06-28 15:11 ` [PATCH v2 5/8] objtool, x86: add facility for asm code to provide unwind hints Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 6/8] x86/entry: add unwind hint annotations Josh Poimboeuf
2017-06-29 17:53 ` Josh Poimboeuf
2017-06-29 18:50 ` Andy Lutomirski
2017-06-29 19:05 ` Josh Poimboeuf
2017-06-29 21:09 ` Andy Lutomirski
2017-06-29 21:41 ` Josh Poimboeuf
2017-06-29 22:59 ` Andy Lutomirski
2017-06-30 2:12 ` Josh Poimboeuf
2017-06-30 5:05 ` Andy Lutomirski
2017-06-30 5:41 ` Andy Lutomirski
2017-06-30 13:11 ` Josh Poimboeuf
2017-06-30 15:44 ` Andy Lutomirski [this message]
2017-06-30 15:55 ` Josh Poimboeuf
2017-06-30 15:56 ` Andy Lutomirski
2017-06-30 16:16 ` Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 7/8] x86/asm: add unwind hint annotations to sync_core() Josh Poimboeuf
2017-06-28 15:11 ` [PATCH v2 8/8] x86/unwind: add undwarf unwinder Josh Poimboeuf
2017-06-29 7:55 ` [PATCH v2 0/8] x86: " Ingo Molnar
2017-06-29 14:12 ` Josh Poimboeuf
2017-06-29 19:13 ` Josh Poimboeuf
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