From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Miroslav Benes <mbenes@suse.cz>,
Nick Desaulniers <ndesaulniers@google.com>,
Julien Thierry <jthierry@redhat.com>,
Kees Cook <keescook@chromium.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] objtool: Change REG_SP_INDIRECT
Date: Wed, 3 Feb 2021 15:49:02 +0100 [thread overview]
Message-ID: <YBq33lMgoUOnCXPW@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210203144215.4ledy6srx7zwfxde@treble>
On Wed, Feb 03, 2021 at 08:42:15AM -0600, Josh Poimboeuf wrote:
> On Wed, Feb 03, 2021 at 01:02:23PM +0100, Peter Zijlstra wrote:
> > Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
> > change it to mean (%rsp) + offset.
> >
> > This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
> > and thus needs to retain the current (%rbp + offset).
>
> Offset is going to be zero, should it not work either way?
For DRAP? I couldn't tell in a hurry. I'm ever quite clear on how DRAP
works. Some day, when I figure it out, i'll write a comment.
Anyway, if it's always 0 for DRAP, then yes, I'll change both.
next prev parent reply other threads:[~2021-02-03 14:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 12:02 [PATCH 0/5] objtool: The stack swizzle again Peter Zijlstra
2021-02-03 12:02 ` [PATCH 1/5] objtool: Change REG_SP_INDIRECT Peter Zijlstra
2021-02-03 14:42 ` Josh Poimboeuf
2021-02-03 14:49 ` Peter Zijlstra [this message]
2021-02-03 14:55 ` Josh Poimboeuf
2021-02-03 12:02 ` [PATCH 2/5] objtool: More consistent use of arch_callee_saved_reg() Peter Zijlstra
2021-02-03 12:02 ` [PATCH 3/5] objtool: Prepare for scratch regs Peter Zijlstra
2021-02-03 12:02 ` [PATCH 4/5] objtool,x86: Additionally decode: mov %rsp, (%reg) Peter Zijlstra
2021-02-03 12:02 ` [PATCH 5/5] objtool: Support stack-swizzle Peter Zijlstra
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