linux-kernel - Re: [PATCH v3 19/26] objtool: Implement noinstr validation

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Date:   Tue, 24 Mar 2020 16:41:52 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org, x86@...nel.org,
        mhiramat@...nel.org, mbenes@...e.cz, brgerst@...il.com
Subject: Re: [PATCH v3 19/26] objtool: Implement noinstr validation

On Tue, Mar 24, 2020 at 04:31:32PM +0100, Peter Zijlstra wrote:
> Validate that any call out of .noinstr.text is in between
> instr_begin() and instr_end() annotations.
> 
> This annotation is useful to ensure correct behaviour wrt tracing
> sensitive code like entry/exit and idle code. When we run code in a
> sensitive context we want a guarantee no unknown code is ran.
> 
> Since this validation relies on knowing the section of call
> destination symbols, we must run it on vmlinux.o instead of on
> individual object files.
> 
> Add two options:
> 
>  -d/--duplicate "duplicate validation for vmlinux"
>  -l/--vmlinux "vmlinux.o validation"
> 
> Where the latter auto-detects when objname ends with "vmlinux.o" and
> the former will force all validations, also those already done on
> !vmlinux object files.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>

-- 
Josh