From: Peter Zijlstra <peterz@infradead.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Will Deacon <will@kernel.org>, Kees Cook <keescook@chromium.org>,
Arnd Bergmann <arnd@arndb.de>, Alexandre Ghiti <alex@ghiti.fr>,
Masahiro Yamada <masahiroy@kernel.org>,
Sami Tolvanen <samitolvanen@google.com>,
Peter Collingbourne <pcc@google.com>,
Krzysztof Kozlowski <krzk@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Stephen Boyd <sboyd@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH RFC] kprobes: Remove MODULES dependency
Date: Fri, 10 Jul 2020 12:49:10 +0200 [thread overview]
Message-ID: <20200710104910.GG4800@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200710103638.GA2614@linux.intel.com>
On Fri, Jul 10, 2020 at 01:36:38PM +0300, Jarkko Sakkinen wrote:
> Just so that I know (and learn), what did exactly disable optprobes?
So regular, old-skool style kprobe is:
- copy original instruction out
- replace instruction with breakpoint (int3 on x86)
- have exception handler return to the copied instruction with
single-step on
- have single step exception handler return to the original
instruction stream
which is 2 exceptions.
optprobes avoid the single-step by not only writing a single
instruction, but additionally placing a JMP instruction behind it such
that it will automagically continue in the original instruction stream.
This brings the requirement that the copied instruction is placed
within the JMP displacement of the regular kernel text (s32 on x86).
module_alloc() ensures the memory provided is within that range.
next prev parent reply other threads:[~2020-07-10 10:49 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 23:45 [PATCH RFC] kprobes: Remove MODULES dependency Jarkko Sakkinen
2020-07-10 9:03 ` Peter Zijlstra
2020-07-10 10:36 ` Jarkko Sakkinen
2020-07-10 10:49 ` Peter Zijlstra [this message]
2020-07-13 5:05 ` Jarkko Sakkinen
2020-07-13 10:17 ` Peter Zijlstra
2020-07-14 11:52 ` Masami Hiramatsu
2020-07-10 10:32 ` Masami Hiramatsu
2020-07-10 11:32 ` Peter Zijlstra
2020-07-10 13:04 ` Christoph Hellwig
2020-07-13 5:52 ` Jarkko Sakkinen
2020-07-10 13:18 ` Masami Hiramatsu
2020-07-10 13:22 ` Steven Rostedt
2020-07-13 5:55 ` Jarkko Sakkinen
2020-07-13 5:49 ` Jarkko Sakkinen
2020-07-14 11:45 ` Masami Hiramatsu
2020-07-10 15:51 ` Kees Cook
2020-07-13 5:56 ` Jarkko Sakkinen
2020-07-13 5:39 ` Jarkko Sakkinen
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