From: Miroslav Benes <mbenes@suse.cz>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Borislav Petkov <bp@suse.de>, Dave Hansen <dave.hansen@intel.com>,
x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
live-patching@vger.kernel.org
Subject: Re: [GIT PULL] x86/urgent for v5.11-rc7
Date: Tue, 9 Feb 2021 09:32:34 +0100 (CET) [thread overview]
Message-ID: <alpine.LSU.2.21.2102090927230.31501@pobox.suse.cz> (raw)
In-Reply-To: <20210208111546.5e01c3fb@gandalf.local.home>
On Mon, 8 Feb 2021, Steven Rostedt wrote:
> On Mon, 8 Feb 2021 16:47:05 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > > /*
> > > * Convert a function address into the appropriate ftrace location.
> > > *
> > > * Usually this is just the address of the function, but on some architectures
> > > * it's more complicated so allow them to provide a custom behaviour.
> > > */
> > > #ifndef klp_get_ftrace_location
> > > static unsigned long klp_get_ftrace_location(unsigned long faddr)
> > > {
> > > return faddr;
> > > }
> > > #endif
powerpc has this
static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
{
/*
* Live patch works only with -mprofile-kernel on PPC. In this case,
* the ftrace location is always within the first 16 bytes.
*/
return ftrace_location_range(faddr, faddr + 16);
}
> > I suppose the trivial fix is to see if it points to endbr64 and if so,
> > increment the addr by the length of that.
>
> I thought of that too. But one thing that may be possible, is to use
> kallsym. I believe you can get the range of a function (start and end of
> the function) from kallsyms. Then ask ftrace for the addr in that range
> (there should only be one).
And we can do this if a hard-coded value live above is not welcome. If I
remember correctly, we used to have exactly this in the old versions of
kGraft. We walked through all ftrace records, called
kallsyms_lookup_size_offset() on every record's ip and if the offset+ip
matched faddr (in this case), we returned the ip.
Miroslav
next prev parent reply other threads:[~2021-02-09 8:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210207104022.GA32127@zn.tnic>
[not found] ` <CAHk-=widXSyJ8W3vRrqO-zNP12A+odxg2J2_-oOUskz33wtfqA@mail.gmail.com>
[not found] ` <20210207175814.GF32127@zn.tnic>
[not found] ` <CAHk-=wi5z9S7x94SKYNj6qSHBqz+OD76GW=MDzo-KN2Fzm-V4Q@mail.gmail.com>
[not found] ` <20210207224540.ercf5657pftibyaw@treble>
[not found] ` <20210208100206.3b74891e@gandalf.local.home>
2021-02-08 15:33 ` [GIT PULL] x86/urgent for v5.11-rc7 Josh Poimboeuf
2021-02-08 15:47 ` Peter Zijlstra
2021-02-08 16:15 ` Steven Rostedt
2021-02-09 8:32 ` Miroslav Benes [this message]
2021-02-09 14:49 ` Steven Rostedt
2021-02-09 15:16 ` Miroslav Benes
2021-02-09 16:45 ` Alexei Starovoitov
2021-02-09 16:55 ` Andy Lutomirski
2021-02-09 18:09 ` Linus Torvalds
2021-02-09 18:26 ` Andy Lutomirski
2021-02-09 18:39 ` Linus Torvalds
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LSU.2.21.2102090927230.31501@pobox.suse.cz \
--to=mbenes@suse.cz \
--cc=ast@kernel.org \
--cc=bp@suse.de \
--cc=dave.hansen@intel.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).