From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org,
mhiramat@kernel.org, mbenes@suse.cz,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2] objtool,ftrace: Implement UNWIND_HINT_RET_OFFSET
Date: Wed, 1 Apr 2020 17:38:10 +0200 [thread overview]
Message-ID: <20200401153810.GV20696@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200401143916.h5keq55yabetyv5u@treble>
On Wed, Apr 01, 2020 at 09:39:16AM -0500, Josh Poimboeuf wrote:
> On Wed, Apr 01, 2020 at 04:22:26PM +0200, Peter Zijlstra wrote:
> > > > @@ -366,6 +367,13 @@ create_trampoline(struct ftrace_ops *ops
> > > > if (WARN_ON(ret < 0))
> > > > goto fail;
> > > >
> > > > + if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
> > > > + ip = ftrace_regs_caller_ret;
> > > > + ret = probe_kernel_read(ip, (void *)retq, RET_SIZE);
> > > > + if (WARN_ON(ret < 0))
> > > > + goto fail;
> > > > + }
> > > > +
> Right, but 'ip' needs to point to the trampoline's version of
> 'ftrace_regs_caller_ret', not the original ftrace_64 version.
Duh,
ip = trampline + (ftrace_regs_caller_ret - ftrace_regs_caller);
it is.
Luckily this would've triggerd a splat the first time I'd have actually
booted this, because the regular text is RO, while the trampoline is
still RW here. Still, good spotting.
next prev parent reply other threads:[~2020-04-01 15:38 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 17:45 [PATCH v4 00/13] objtool: vmlinux.o and moinstr validation Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 01/13] objtool: Remove CFI save/restore special case Peter Zijlstra
2020-03-26 11:30 ` Peter Zijlstra
2020-03-26 12:58 ` Peter Zijlstra
2020-03-26 13:44 ` Josh Poimboeuf
2020-03-26 15:38 ` Peter Zijlstra
2020-03-27 4:19 ` Josh Poimboeuf
2020-03-26 14:44 ` Miroslav Benes
2020-03-26 15:04 ` Miroslav Benes
2020-03-26 13:00 ` Peter Zijlstra
2020-03-26 13:56 ` Josh Poimboeuf
2020-03-26 15:49 ` Peter Zijlstra
2020-03-26 19:57 ` Peter Zijlstra
2020-03-27 1:00 ` Josh Poimboeuf
2020-03-30 17:02 ` Peter Zijlstra
2020-03-30 19:02 ` Josh Poimboeuf
2020-03-30 20:02 ` Peter Zijlstra
2020-03-30 20:29 ` Peter Zijlstra
2020-03-31 11:16 ` [RFC][PATCH] objtool,ftrace: Implement UNWIND_HINT_RET_OFFSET Peter Zijlstra
2020-03-31 15:31 ` Steven Rostedt
2020-03-31 16:06 ` [RFC][PATCH] x86,ftrace: Shrink ftrace_regs_caller() by one byte Peter Zijlstra
2020-03-31 19:58 ` [RFC][PATCH] objtool,ftrace: Implement UNWIND_HINT_RET_OFFSET Peter Zijlstra
2020-03-31 20:26 ` Josh Poimboeuf
2020-03-31 20:23 ` Josh Poimboeuf
2020-03-31 20:40 ` Peter Zijlstra
2020-03-31 21:07 ` Peter Zijlstra
2020-03-31 21:17 ` Josh Poimboeuf
2020-03-31 21:20 ` Josh Poimboeuf
2020-03-31 22:27 ` [PATCH v2] " Peter Zijlstra
2020-04-01 14:14 ` Josh Poimboeuf
2020-04-01 14:22 ` Peter Zijlstra
2020-04-01 14:39 ` Josh Poimboeuf
2020-04-01 15:38 ` Peter Zijlstra [this message]
2020-04-01 15:39 ` Steven Rostedt
2020-04-01 15:43 ` Julien Thierry
2020-04-01 17:09 ` Peter Zijlstra
2020-04-01 17:33 ` Steven Rostedt
2020-04-01 17:45 ` Peter Zijlstra
2020-04-01 18:20 ` Steven Rostedt
2020-04-01 20:20 ` Peter Zijlstra
2020-04-01 17:37 ` Josh Poimboeuf
2020-04-02 6:41 ` Julien Thierry
2020-04-02 6:56 ` Julien Thierry
2020-04-02 7:50 ` Peter Zijlstra
2020-04-02 8:16 ` Julien Thierry
2020-04-02 8:17 ` Peter Zijlstra
2020-04-02 8:29 ` Julien Thierry
2020-04-02 8:58 ` Miroslav Benes
2020-03-25 17:45 ` [PATCH v4 02/13] objtool: Factor out CFI hints Peter Zijlstra
2020-03-25 18:26 ` Miroslav Benes
2020-03-25 19:41 ` Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 03/13] objtool: Rename struct cfi_state Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 04/13] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 05/13] objtool: Implement noinstr validation Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 06/13] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 07/13] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 08/13] objtool: Detect loading function pointers across noinstr Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 09/13] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 10/13] objtool: Avoid iterating !text section symbols Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 11/13] objtool: Rearrange validate_section() Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 12/13] objtool: Add STT_NOTYPE noinstr validation Peter Zijlstra
2020-03-25 17:45 ` [PATCH v4 13/13] objtool: Also consider .entry.text as noinstr Peter Zijlstra
2020-03-25 19:03 ` [PATCH v4 00/13] objtool: vmlinux.o and moinstr validation Miroslav Benes
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