Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 8 May 2019 14:04:16 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Nicolai Stange <nstange@suse.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Jiri Kosina <jikos@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        Shuah Khan <shuah@kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Juergen Gross <jgross@suse.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nayna Jain <nayna@linux.ibm.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Joerg Roedel <jroedel@suse.de>,
        linux-kselftest@vger.kernel.org,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 2/4] x86/kprobes: Fix frame pointer annotations
Message-ID: <20190508120416.GL2589@hirez.programming.kicks-ass.net>
References: <20190508074901.982470324@infradead.org>
 <20190508080612.721269814@infradead.org>
 <20190508115416.nblx7c2kocidpytm@treble>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190508115416.nblx7c2kocidpytm@treble>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, May 08, 2019 at 06:54:16AM -0500, Josh Poimboeuf wrote:
> On Wed, May 08, 2019 at 09:49:03AM +0200, Peter Zijlstra wrote:
> > The kprobe trampolines have a FRAME_POINTER annotation that makes no
> > sense. It marks the frame in the middle of pt_regs, at the place of
> > saving BP.
> > 
> > Change it to mark the pt_regs frame as per the ENCODE_FRAME_POINTER
> > from the respective entry_*.S.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > ---
> >  arch/x86/kernel/kprobes/common.h |   32 +++++++++++++++++++++++---------
> >  1 file changed, 23 insertions(+), 9 deletions(-)
> > 
> > --- a/arch/x86/kernel/kprobes/common.h
> > +++ b/arch/x86/kernel/kprobes/common.h
> > @@ -6,14 +6,15 @@
> >  
> >  #include <asm/asm.h>
> >  
> > +#ifdef CONFIG_X86_64
> > +
> >  #ifdef CONFIG_FRAME_POINTER
> > -# define SAVE_RBP_STRING "	push %" _ASM_BP "\n" \
> > -			 "	mov  %" _ASM_SP ", %" _ASM_BP "\n"
> > +#define ENCODE_FRAME_POINTER			\
> > +	"	leaq 1(%rsp), %rbp\n"
> >  #else
> > -# define SAVE_RBP_STRING "	push %" _ASM_BP "\n"
> > +#define ENCODE_FRAME_POINTER
> >  #endif
> 
> > +#ifdef CONFIG_FRAME_POINTER
> > +#define ENCODE_FRAME_POINTER			\
> > +	"	movl %esp, %ebp\n"		\
> > +	"	andl $0x7fffffff, %ebp\n"
> > +#else
> > +#define ENCODE_FRAME_POINTER
> > +#endif
> 
> We should put these macros in a header file somewhere (including
> stringified versions).

Probably a good idea. I'll frob them into asm/frame.h.

Do the x86_64 variants also want some ORC annotation?