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Subject: Re: [PATCH 4/4] kprobes: Remove core dependency on modules
From: Jarkko Sakkinen <jarkko@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>, Mark Rutland
 <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org, agordeev@linux.ibm.com, 
 anil.s.keshavamurthy@intel.com, aou@eecs.berkeley.edu, bp@alien8.de, 
 catalin.marinas@arm.com, dave.hansen@linux.intel.com, davem@davemloft.net, 
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  naveen.n.rao@linux.ibm.com, palmer@dabbelt.com, paul.walmsley@sifive.com, 
 tglx@linutronix.de, will@kernel.org
Date: Wed, 27 Mar 2024 15:23:24 +0200
In-Reply-To: <20240327090155.873f1ed32700dbdb75f8eada@kernel.org>
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On Wed, 2024-03-27 at 09:01 +0900, Masami Hiramatsu wrote:
> On Tue, 26 Mar 2024 17:38:18 +0000
> Mark Rutland <mark.rutland@arm.com> wrote:
>=20
> > On Tue, Mar 26, 2024 at 07:13:51PM +0200, Jarkko Sakkinen wrote:
> > > On Tue Mar 26, 2024 at 6:36 PM EET, Mark Rutland wrote:
> >=20
> > > > +#ifdef CONFIG_MODULES
> > > > =C2=A0	/* Check if 'p' is probing a module. */
> > > > =C2=A0	*probed_mod =3D __module_text_address((unsigned long) p-
> > > > >addr);
> > > > =C2=A0	if (*probed_mod) {
> > > > @@ -1605,6 +1606,8 @@ static int
> > > > check_kprobe_address_safe(struct kprobe *p,
> > > > =C2=A0			ret =3D -ENOENT;
> > > > =C2=A0		}
> > > > =C2=A0	}
> > > > +#endif
> > >=20
> > > This can be scoped a bit more (see v7 of my patch set).
> >=20
> > > > +#ifdef CONFIG_MODULES
> > > > =C2=A0static nokprobe_inline bool trace_kprobe_module_exist(struct
> > > > trace_kprobe *tk)
> > > > =C2=A0{
> > > > =C2=A0	char *p;
> > > > @@ -129,6 +130,9 @@ static nokprobe_inline bool
> > > > trace_kprobe_module_exist(struct trace_kprobe *tk)
> > > > =C2=A0
> > > > =C2=A0	return ret;
> > > > =C2=A0}
> > > > +#else
> > > > +#define trace_kprobe_module_exist(tk) false /* aka a module
> > > > never exists */
> > > > +#endif /* CONFIG_MODULES */
> > > > =C2=A0
> > > > =C2=A0static bool trace_kprobe_is_busy(struct dyn_event *ev)
> > > > =C2=A0{
> > > > @@ -670,6 +674,7 @@ static int register_trace_kprobe(struct
> > > > trace_kprobe *tk)
> > > > =C2=A0	return ret;
> > > > =C2=A0}
> > > > =C2=A0
> > > > +#ifdef CONFIG_MODULES
> > > > =C2=A0/* Module notifier call back, checking event on the module */
> > > > =C2=A0static int trace_kprobe_module_callback(struct notifier_block
> > > > *nb,
> > > > =C2=A0				=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long val, v=
oid
> > > > *data)
> > > > @@ -699,6 +704,9 @@ static int
> > > > trace_kprobe_module_callback(struct notifier_block *nb,
> > > > =C2=A0
> > > > =C2=A0	return NOTIFY_DONE;
> > > > =C2=A0}
> > > > +#else
> > > > +#define trace_kprobe_module_callback (NULL)
> > > > +#endif /* CONFIG_MODULES */
> > >=20
> > > The last two CONFIG_MODULES sections could be combined. This was
> > > also in
> > > v7.
> >=20
> > > Other than lgtm.
> >=20
> > Great! I've folded your v7 changes in, and pushed that out to:
> >=20
> > =C2=A0
> > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=
=3Dkprobes/without-modules
> >=20
> > I'll hold off sending that out to the list until other folk have
> > had a chance
> > to comment.
>=20
> Yeah, the updated one looks good to me too.
>=20
> Thanks!

Yeah, I'm also planning to test this with x86 instrumenting sgx_* calls
as I need to test the cgroups support for it so can help with the
coverage both RISC-V and x86 (as I find a good time slot).

BR, Jarkko