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Date: Wed, 31 Aug 2022 11:23:34 -0700
From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: linux-kernel@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [PATCH v4 16/21] objtool: Disable CFI warnings
Message-ID: <202208311123.CFD2B1B9@keescook>
References: <20220830233129.30610-1-samitolvanen@google.com>
 <20220830233129.30610-17-samitolvanen@google.com>
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On Tue, Aug 30, 2022 at 04:31:24PM -0700, Sami Tolvanen wrote:
> The __cfi_ preambles contain a mov instruction that embeds the KCFI
> type identifier in the following format:
> 
>   ; type preamble
>   __cfi_function:
>     mov <id>, %eax
>   function:
>     ...
> 
> While the preamble symbols are STT_FUNC and contain valid
> instructions, they are never executed and always fall through. Skip
> the warning for them.
> 
> .kcfi_traps sections point to CFI traps in text sections. Also skip
> the warning about them referencing !ENDBR instructions.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

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Date: Wed, 31 Aug 2022 11:23:34 -0700
From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: linux-kernel@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [PATCH v4 16/21] objtool: Disable CFI warnings
Message-ID: <202208311123.CFD2B1B9@keescook>
References: <20220830233129.30610-1-samitolvanen@google.com>
 <20220830233129.30610-17-samitolvanen@google.com>
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On Tue, Aug 30, 2022 at 04:31:24PM -0700, Sami Tolvanen wrote:
> The __cfi_ preambles contain a mov instruction that embeds the KCFI
> type identifier in the following format:
> 
>   ; type preamble
>   __cfi_function:
>     mov <id>, %eax
>   function:
>     ...
> 
> While the preamble symbols are STT_FUNC and contain valid
> instructions, they are never executed and always fall through. Skip
> the warning for them.
> 
> .kcfi_traps sections point to CFI traps in text sections. Also skip
> the warning about them referencing !ENDBR instructions.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

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