From: Denys Vlasenko <vda.linux@googlemail.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-mm <linux-mm@kvack.org>, Andi Kleen <andi@firstfloor.org>,
Christoph Hellwig <hch@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Roland McGrath <roland@hack.frob.com>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Anton Arapov <anton@redhat.com>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Jim Keniston <jkenisto@linux.vnet.ibm.com>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH v9 3.2 1/9] uprobes: Install and remove breakpoints.
Date: Wed, 25 Jan 2012 15:39:19 +0100 [thread overview]
Message-ID: <CAK1hOcMVQN4sQjMnV3YBtd6hi8ZtbxPuguVHGxGgSPGn2scsNQ@mail.gmail.com> (raw)
In-Reply-To: <20120110114831.17610.88468.sendpatchset@srdronam.in.ibm.com>
On Tue, Jan 10, 2012 at 12:48 PM, Srikar Dronamraju
<srikar@linux.vnet.ibm.com> wrote:
> +/*
> + * opcodes we'll probably never support:
> + * 6c-6d, e4-e5, ec-ed - in
> + * 6e-6f, e6-e7, ee-ef - out
> + * cc, cd - int3, int
I imagine desire to set a breakpoint on int 0x80 will be rather typical.
(Same for sysenter).
> + * cf - iret
Iret does work. Test program for 32-bit x86:
/* gcc -nostartfiles -nostdlib -o iret iret.S */
_start: .globl _start
pushf
push %cs
push $_e
iret /* will this jump to _e? Yes! */
hlt /* segv if reached */
_e: movl $42, %ebx
movl $1, %eax
int $0x80
I guess supporting probes in weird stuff like ancient DOS emulators
(they actually use iret) is not important.
OTOH iret doesn't seem to be too hard: if it fails (bad cs/eflags
on stack), then the location of iret instruction per se is not
terribly important.
If it works, then you need to be careful to not mess up eip,
same as you already do with ordinary [l]ret, nothing more.
Come to think of it, why do you bother checking for
invalid instructions? What can happen if you would just copy
and run all instructions? You already are prepared to handle
exceptions, right?
--
vda
next prev parent reply other threads:[~2012-01-25 14:39 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-10 11:48 [PATCH v9 3.2 0/9] Uprobes patchset with perf probe support Srikar Dronamraju
2012-01-10 11:48 ` [PATCH v9 3.2 1/9] uprobes: Install and remove breakpoints Srikar Dronamraju
2012-01-25 14:39 ` Denys Vlasenko [this message]
2012-01-25 16:31 ` Oleg Nesterov
2012-01-25 15:13 ` Denys Vlasenko
2012-01-25 15:32 ` Denys Vlasenko
2012-01-26 14:14 ` Masami Hiramatsu
2012-01-26 18:28 ` Denys Vlasenko
2012-01-30 9:51 ` Masami Hiramatsu
2012-01-26 13:38 ` Masami Hiramatsu
2012-01-26 13:45 ` Masami Hiramatsu
2012-01-10 11:48 ` [PATCH v9 3.2 2/9] uprobes: handle breakpoint and signal step exception Srikar Dronamraju
2012-01-18 8:39 ` Anton Arapov
2012-01-18 9:02 ` Srikar Dronamraju
2012-01-18 10:18 ` Mike Frysinger
2012-01-18 10:47 ` Srikar Dronamraju
2012-01-18 11:01 ` Mike Frysinger
2012-01-20 22:57 ` Mike Frysinger
2012-01-25 8:12 ` Srikar Dronamraju
2012-01-10 11:48 ` [PATCH v9 3.2 3/9] uprobes: slot allocation Srikar Dronamraju
2012-01-10 11:49 ` [PATCH v9 3.2 4/9] uprobes: counter to optimize probe hits Srikar Dronamraju
2012-01-10 11:49 ` [PATCH v9 3.2 5/9] tracing: modify is_delete, is_return from ints to bool Srikar Dronamraju
2012-01-10 11:49 ` [PATCH v9 3.2 6/9] tracing: Extract out common code for kprobes/uprobes traceevents Srikar Dronamraju
2012-01-10 11:49 ` [PATCH v9 3.2 7/9] tracing: uprobes trace_event interface Srikar Dronamraju
2012-01-16 13:11 ` Jiri Olsa
2012-01-16 14:45 ` Srikar Dronamraju
2012-01-16 15:33 ` Jiri Olsa
2012-01-16 16:41 ` Srikar Dronamraju
2012-01-17 9:28 ` Ingo Molnar
2012-01-17 10:22 ` Srikar Dronamraju
2012-01-17 10:59 ` Ingo Molnar
2012-01-17 11:03 ` Srikar Dronamraju
2012-01-17 11:22 ` Ingo Molnar
2012-01-17 11:57 ` Srikar Dronamraju
2012-01-17 12:23 ` Ingo Molnar
2012-01-17 12:27 ` Ingo Molnar
2012-01-17 12:11 ` Ingo Molnar
2012-01-17 12:21 ` Ingo Molnar
2012-01-18 10:07 ` Srikar Dronamraju
2012-01-10 11:49 ` [PATCH v9 3.2 8/9] perf: rename target_module to target Srikar Dronamraju
2012-01-16 8:34 ` [PATCH v9 3.2 0/9] Uprobes patchset with perf probe support Ingo Molnar
2012-01-16 15:17 ` Srikar Dronamraju
2012-01-17 9:39 ` Ingo Molnar
2012-01-25 14:11 ` Peter Zijlstra
2012-01-26 11:10 ` Ingo Molnar
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