From: Josh Poimboeuf <jpoimboe@redhat.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, Jiri Slaby <jslaby@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
live-patching@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>,
Andy Lutomirski <luto@kernel.org>, Jiri Kosina <jikos@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 7/7] DWARF: add the config option
Date: Fri, 19 May 2017 16:35:56 -0500 [thread overview]
Message-ID: <20170519213556.pv5kxocfprfkloay@treble> (raw)
In-Reply-To: <20170519212913.otir6mlujoxoy3ha@treble>
On Fri, May 19, 2017 at 04:29:13PM -0500, Josh Poimboeuf wrote:
> > How are you handling control flow?
>
> Control flow of what?
>
> > > Here's the struct in its current state:
> > >
> > > #define UNDWARF_REG_UNDEFINED 0
> > > #define UNDWARF_REG_CFA 1
> > > #define UNDWARF_REG_SP 2
> > > #define UNDWARF_REG_FP 3
> > > #define UNDWARF_REG_SP_INDIRECT 4
> > > #define UNDWARF_REG_FP_INDIRECT 5
> > > #define UNDWARF_REG_R10 6
> > > #define UNDWARF_REG_DI 7
> > > #define UNDWARF_REG_DX 8
> > >
> >
> > Why only those registers? Also, if you have the option I would really
> > suggest using the actual x86 register numbers (ax, ex, dx, bx, sp, bp,
> > si, di, r8-r15 in that order.)
>
> Those are the only registers which are ever needed as the base for
> finding the previous stack frame. 99% of the time it's sp or bp, the
> other registers are needed for aligned stacks and entry code.
>
> Using the actual register numbers isn't an option because I don't need
> them all and they need to fit in a small number of bits.
>
> This construct might be useful for other arches, which is why I called
> it "FP" instead of "BP". But then I ruined that with the last 3 :-)
BTW, here's the link to the unwinder code if you're interested:
https://github.com/jpoimboe/linux/blob/undwarf/arch/x86/kernel/unwind_undwarf.c
--
Josh
next prev parent reply other threads:[~2017-05-19 21:36 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 12:21 [PATCH 1/7] DWARF: add option to preserve unwind info Jiri Slaby
2017-05-05 12:21 ` [PATCH 2/7] DWARF: EH-frame based stack unwinding Jiri Slaby
2017-05-05 12:21 ` [PATCH 3/7] vmlinux.lds: preserve eh_frame for DWARF unwinder Jiri Slaby
2017-05-05 12:21 ` [PATCH 4/7] DWARF: initialize structures for kernel and modules Jiri Slaby
2017-05-05 12:21 ` [PATCH 5/7] unwinder: show_stack, check also ret_addr_p's contents Jiri Slaby
2017-05-05 12:21 ` [PATCH 6/7] unwinder: plug in the DWARF unwinder Jiri Slaby
2017-05-05 12:22 ` [PATCH 7/7] DWARF: add the config option Jiri Slaby
2017-05-05 19:57 ` Linus Torvalds
2017-05-06 7:19 ` Ingo Molnar
2017-05-10 7:46 ` Jiri Slaby
2017-05-06 14:24 ` Jiri Kosina
2017-05-07 16:55 ` Josh Poimboeuf
2017-05-07 17:59 ` Ingo Molnar
2017-05-07 18:08 ` hpa
2017-05-07 21:48 ` Josh Poimboeuf
2017-05-08 7:50 ` Vojtech Pavlik
2017-05-08 13:14 ` Josh Poimboeuf
2017-05-08 5:35 ` Andy Lutomirski
2017-05-08 6:15 ` Ingo Molnar
2017-05-08 14:40 ` Josh Poimboeuf
2017-05-08 18:57 ` hpa
2017-05-09 0:21 ` Andy Lutomirski
2017-05-09 1:38 ` Josh Poimboeuf
2017-05-09 2:31 ` Andy Lutomirski
2017-05-09 3:38 ` Josh Poimboeuf
2017-05-09 10:00 ` hpa
2017-05-09 14:58 ` Josh Poimboeuf
2017-05-09 16:46 ` H.J. Lu
2017-05-10 8:15 ` Jiri Slaby
2017-05-10 13:09 ` Josh Poimboeuf
2017-05-10 16:23 ` H.J. Lu
2017-05-09 18:47 ` Jiri Kosina
2017-05-09 19:22 ` Josh Poimboeuf
2017-05-10 8:32 ` Jiri Slaby
2017-05-10 13:13 ` Josh Poimboeuf
2017-05-23 7:07 ` Peter Zijlstra
2017-05-23 7:27 ` Ingo Molnar
2017-05-19 20:53 ` Josh Poimboeuf
2017-05-19 20:57 ` H. Peter Anvin
2017-05-19 20:59 ` H. Peter Anvin
2017-05-19 21:29 ` Josh Poimboeuf
2017-05-19 21:35 ` Josh Poimboeuf [this message]
2017-05-20 5:23 ` Andy Lutomirski
2017-05-20 16:20 ` Josh Poimboeuf
2017-05-20 17:19 ` Josh Poimboeuf
2017-05-20 20:01 ` H.J. Lu
2017-05-20 21:58 ` Andy Lutomirski
2017-05-20 22:20 ` H.J. Lu
2017-05-22 11:34 ` Jiri Kosina
2017-05-22 14:39 ` H.J. Lu
2017-05-22 21:07 ` H. Peter Anvin
2017-05-22 21:37 ` H. Peter Anvin
2017-05-22 22:11 ` Josh Poimboeuf
2017-05-20 20:16 ` Linus Torvalds
2017-05-20 21:56 ` Andy Lutomirski
2017-05-20 23:00 ` Linus Torvalds
2017-05-20 23:29 ` Linus Torvalds
2017-05-26 6:54 ` Jiri Slaby
2017-05-26 11:29 ` Jiri Slaby
2017-05-26 12:14 ` Josh Poimboeuf
2017-05-22 11:12 ` Ingo Molnar
2017-05-22 21:16 ` H. Peter Anvin
2017-05-22 23:23 ` Jiri Kosina
2017-05-23 5:49 ` Ingo Molnar
2017-05-26 19:16 ` hpa
2017-05-28 9:12 ` Ingo Molnar
2017-05-10 7:39 ` Jiri Slaby
2017-05-10 12:42 ` Josh Poimboeuf
2017-05-10 12:47 ` Jiri Slaby
2017-05-10 18:11 ` Linus Torvalds
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