From: Balbir Singh <bsingharora@gmail.com>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
Jiri Kosina <jkosina@suse.cz>,
linux-kernel@vger.kernel.org, Torsten Duwe <duwe@lst.de>,
live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: ppc64le reliable stack unwinder and scheduled tasks
Date: Sun, 13 Jan 2019 23:33:56 +1100 [thread overview]
Message-ID: <20190113123356.GA26056@350D> (raw)
In-Reply-To: <20190112084541.GK14180@gate.crashing.org>
On Sat, Jan 12, 2019 at 02:45:41AM -0600, Segher Boessenkool wrote:
> On Sat, Jan 12, 2019 at 12:09:14PM +1100, Balbir Singh wrote:
> > Could you please define interesting frame on top a bit more? Usually
> > the topmost return address is in LR
>
> There is no reliable way (other than DWARF unwind info) to find out where
> the value of LR at function entry currently lives (if anywhere). It may or
> may not be still available in LR, it may or may not be saved to the return
> stack slot. It can also live in some GPR, or in some other stack slot.
>
> (The same is true for all other registers).
>
> The only thing the ABI guarantees you is that you can find all stack frames
> via the back chain. If you want more you can use some heuristics and do
> some heroics (like GDB does), but this is not fully reliable. Using DWARF
> unwind info is, but that requires big tables.
>
Thanks, so are you suggesting that a reliable stack is not possible on
ppc64le? Even with the restricted scope of the kernel?
Balbir Singh.
next prev parent reply other threads:[~2019-01-13 12:36 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-10 21:14 ppc64le reliable stack unwinder and scheduled tasks Joe Lawrence
2019-01-10 21:14 ` Joe Lawrence
2019-01-11 0:00 ` Nicolai Stange
2019-01-11 0:00 ` Nicolai Stange
2019-01-11 1:08 ` Joe Lawrence
2019-01-11 1:08 ` Joe Lawrence
2019-01-11 7:51 ` Nicolai Stange
2019-01-11 7:51 ` Nicolai Stange
2019-01-14 4:09 ` Joe Lawrence
2019-01-14 4:09 ` Joe Lawrence
2019-01-14 7:21 ` Nicolai Stange
2019-01-14 7:21 ` Nicolai Stange
2019-01-14 16:46 ` Joe Lawrence
2019-01-14 16:46 ` Joe Lawrence
2019-01-14 17:09 ` Josh Poimboeuf
2019-01-14 17:09 ` Josh Poimboeuf
2019-01-14 17:54 ` Joe Lawrence
2019-01-14 17:54 ` Joe Lawrence
2019-01-12 1:09 ` Balbir Singh
2019-01-12 1:09 ` Balbir Singh
2019-01-12 8:45 ` Segher Boessenkool
2019-01-13 12:33 ` Balbir Singh [this message]
2019-01-13 13:05 ` Torsten Duwe
2019-01-13 13:05 ` Torsten Duwe
2019-01-17 14:52 ` Segher Boessenkool
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