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From: Heiko Carstens <hca@linux.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Ingo Molnar <mingo@redhat.com>,
	"Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"live-patching@vger.kernel.org" <live-patching@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>
Subject: Re: [PATCH v1 0/5] Implement livepatch on PPC32
Date: Tue, 14 Dec 2021 15:25:57 +0100	[thread overview]
Message-ID: <YbipdU5X4HNDWIni@osiris> (raw)
In-Reply-To: <fc3099b8-9f12-3e47-08a0-05abc37a0482@csgroup.eu>

On Mon, Dec 13, 2021 at 05:50:52PM +0000, Christophe Leroy wrote:
> Le 13/12/2021 à 18:33, Steven Rostedt a écrit :
> > On Mon, 13 Dec 2021 17:30:48 +0000
> > Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
> > 
> >> Thanks, I will try that.
> >>
> >> I can't find ftrace_graph_func() in s390. Does it mean that s390 doesn't
> >> have a working function tracer anymore ?
> >>
> >> I see your commit 0c0593b45c9b4 ("x86/ftrace: Make function graph use
> >> ftrace directly") is dated 8 Oct 2021 while 5740a7c71ab6 ("s390/ftrace:
> >> add HAVE_DYNAMIC_FTRACE_WITH_ARGS support") is 4 Oct 2021.
> > 
> > Hmm, maybe not. I can't test it.
> > 
> > This needs to be fixed if that's the case.
> > 
> > Thanks for bringing it up!

It still works, we run the full ftrace/kprobes selftests from the
kernel every day on multiple machines with several kernels (besides
other Linus' tree, but also linux-next). That said, I wanted to change
s390's code follow what x86 is currently doing anyway.

One thing to note: commit 5740a7c71ab6 ("s390/ftrace: add
HAVE_DYNAMIC_FTRACE_WITH_ARGS support") looks only that simple because
ftrace_caller _and_ ftrace_regs_caller used to save all register
contents into the pt_regs structure, which never was a requirement,
but implicitly fulfills the HAVE_DYNAMIC_FTRACE_WITH_ARGS
requirements.
Not sure if powerpc passes enough register contents via pt_regs for
HAVE_DYNAMIC_FTRACE_WITH_ARGS though. Might be something to check?

WARNING: multiple messages have this Message-ID (diff)
From: Heiko Carstens <hca@linux.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	Jiri Kosina <jikos@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	"live-patching@vger.kernel.org" <live-patching@vger.kernel.org>,
	"Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Miroslav Benes <mbenes@suse.cz>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v1 0/5] Implement livepatch on PPC32
Date: Tue, 14 Dec 2021 15:25:57 +0100	[thread overview]
Message-ID: <YbipdU5X4HNDWIni@osiris> (raw)
In-Reply-To: <fc3099b8-9f12-3e47-08a0-05abc37a0482@csgroup.eu>

On Mon, Dec 13, 2021 at 05:50:52PM +0000, Christophe Leroy wrote:
> Le 13/12/2021 à 18:33, Steven Rostedt a écrit :
> > On Mon, 13 Dec 2021 17:30:48 +0000
> > Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
> > 
> >> Thanks, I will try that.
> >>
> >> I can't find ftrace_graph_func() in s390. Does it mean that s390 doesn't
> >> have a working function tracer anymore ?
> >>
> >> I see your commit 0c0593b45c9b4 ("x86/ftrace: Make function graph use
> >> ftrace directly") is dated 8 Oct 2021 while 5740a7c71ab6 ("s390/ftrace:
> >> add HAVE_DYNAMIC_FTRACE_WITH_ARGS support") is 4 Oct 2021.
> > 
> > Hmm, maybe not. I can't test it.
> > 
> > This needs to be fixed if that's the case.
> > 
> > Thanks for bringing it up!

It still works, we run the full ftrace/kprobes selftests from the
kernel every day on multiple machines with several kernels (besides
other Linus' tree, but also linux-next). That said, I wanted to change
s390's code follow what x86 is currently doing anyway.

One thing to note: commit 5740a7c71ab6 ("s390/ftrace: add
HAVE_DYNAMIC_FTRACE_WITH_ARGS support") looks only that simple because
ftrace_caller _and_ ftrace_regs_caller used to save all register
contents into the pt_regs structure, which never was a requirement,
but implicitly fulfills the HAVE_DYNAMIC_FTRACE_WITH_ARGS
requirements.
Not sure if powerpc passes enough register contents via pt_regs for
HAVE_DYNAMIC_FTRACE_WITH_ARGS though. Might be something to check?

  parent reply	other threads:[~2021-12-14 14:26 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-28 12:24 [PATCH v1 0/5] Implement livepatch on PPC32 Christophe Leroy
2021-10-28 12:24 ` Christophe Leroy
2021-10-28 12:24 ` [PATCH v1 1/5] livepatch: Fix build failure on 32 bits processors Christophe Leroy
2021-10-28 12:24   ` Christophe Leroy
2021-11-08  9:47   ` Petr Mladek
2021-11-08  9:47     ` Petr Mladek
2021-10-28 12:24 ` [PATCH v1 2/5] powerpc/ftrace: No need to read LR from stack in _mcount() Christophe Leroy
2021-10-28 12:24   ` Christophe Leroy
2021-10-28 12:24 ` [PATCH v1 3/5] powerpc/ftrace: Add module_trampoline_target() for PPC32 Christophe Leroy
2021-10-28 12:24   ` Christophe Leroy
2021-10-28 12:24 ` [PATCH v1 4/5] powerpc/ftrace: Activate HAVE_DYNAMIC_FTRACE_WITH_REGS on PPC32 Christophe Leroy
2021-10-28 12:24   ` Christophe Leroy
2021-10-28 12:24 ` [PATCH v1 5/5] powerpc/ftrace: Add support for livepatch to PPC32 Christophe Leroy
2021-10-28 12:24   ` Christophe Leroy
2021-11-08 10:01   ` Petr Mladek
2021-11-08 10:01     ` Petr Mladek
2021-10-28 13:35 ` [PATCH v1 0/5] Implement livepatch on PPC32 Steven Rostedt
2021-10-28 13:35   ` Steven Rostedt
2021-12-13 14:39   ` Christophe Leroy
2021-12-13 14:39     ` Christophe Leroy
2021-12-13 17:15     ` Steven Rostedt
2021-12-13 17:15       ` Steven Rostedt
2021-12-13 17:30       ` Christophe Leroy
2021-12-13 17:30         ` Christophe Leroy
2021-12-13 17:33         ` Steven Rostedt
2021-12-13 17:33           ` Steven Rostedt
2021-12-13 17:50           ` Christophe Leroy
2021-12-13 17:50             ` Christophe Leroy
2021-12-13 18:54             ` Steven Rostedt
2021-12-13 18:54               ` Steven Rostedt
2021-12-13 19:33               ` Christophe Leroy
2021-12-13 19:33                 ` Christophe Leroy
2021-12-13 19:46                 ` Steven Rostedt
2021-12-13 19:46                   ` Steven Rostedt
2021-12-14  6:09                   ` Christophe Leroy
2021-12-14  6:09                     ` Christophe Leroy
2021-12-14  7:35                     ` Christophe Leroy
2021-12-14  7:35                       ` Christophe Leroy
2021-12-14 14:01                       ` Steven Rostedt
2021-12-14 14:01                         ` Steven Rostedt
2021-12-18 16:12                         ` Christophe Leroy
2021-12-18 16:12                           ` Christophe Leroy
2021-12-14 14:25             ` Heiko Carstens [this message]
2021-12-14 14:25               ` Heiko Carstens
2021-12-14 15:12               ` Christophe Leroy
2021-12-14 15:12                 ` Christophe Leroy
2021-11-01 14:50 ` Miroslav Benes
2021-11-01 14:50   ` Miroslav Benes
2021-11-24 22:34 ` Michael Ellerman
2021-11-25  5:49   ` Christophe Leroy
2021-12-07 13:26 ` Michael Ellerman
2021-12-07 13:26   ` Michael Ellerman

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