From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: 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 11:16:07 -0500 [thread overview]
Message-ID: <20170630161607.mruu2bnp7okwpq7b@treble> (raw)
In-Reply-To: <CALCETrX0rmb4F9Kco1oz6zDqs45aowRWXX6B-B_f1G+Ck+XQ0Q@mail.gmail.com>
On Fri, Jun 30, 2017 at 08:56:09AM -0700, Andy Lutomirski wrote:
> On Fri, Jun 30, 2017 at 8:55 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Fri, Jun 30, 2017 at 08:44:40AM -0700, Andy Lutomirski wrote:
> >> > 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.
> >
> > One more thing I forgot to mention: if you could use r10 instead of r11,
> > that would be helpful because it means one less register undwarf needs
> > to know about. (It already deals with r10 because of GCC stack
> > realignment).
>
> I'll let you figure that one out :)
>
> (Although I think I agree with hpa: why not let it support all regs?
> Or am I missing something still?)
Sure, it can support all regs, but as the code is structured now, doing
so means adding more switch cases, e.g.:
https://github.com/jpoimboe/linux/blob/undwarf-v2/arch/x86/kernel/unwind_undwarf.c#L388
And that makes the balrog angry!
--
Josh
next prev parent reply other threads:[~2017-06-30 16:16 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
2017-06-30 15:55 ` Josh Poimboeuf
2017-06-30 15:56 ` Andy Lutomirski
2017-06-30 16:16 ` Josh Poimboeuf [this message]
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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