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Date:   Sun, 18 Dec 2022 22:38:09 -0800
From:   Dan Li <ashimida.1990@gmail.com>
To:     Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Kees Cook <keescook@chromium.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Tom Rix <trix@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Marco Elver <elver@google.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Song Liu <song@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Uros Bizjak <ubizjak@gmail.com>,
        Kumar Kartikeya Dwivedi <memxor@gmail.com>,
        Juergen Gross <jgross@suse.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Borislav Petkov <bp@suse.de>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Aaron Tomlin <atomlin@redhat.com>,
        Kalesh Singh <kaleshsingh@google.com>,
        Yuntao Wang <ytcoode@gmail.com>,
        Changbin Du <changbin.du@intel.com>
Cc:     linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev,
        linux-hardening@vger.kernel.org
Subject: Re: [RFC/RFT] CFI: Add support for gcc CFI in aarch64
Message-ID: <20221219063809.xgd6jjio4f7j5ysw@ubuntu>
References: <20221219061758.23321-1-ashimida.1990@gmail.com>
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+ Cc: linux-hardening@vger.kernel.org
On 12/18, Dan Li wrote:
> Based on Sami's patch[1], this patch makes the corresponding kernel
> configuration of CFI available when compiling the kernel with the gcc[2].
> 
> The code after enabling cfi is as follows:
> 
> int (*p)(void);
> int func (int)
> {
> 	p();
> }
> 
> __cfi_func:
>         .4byte 0x439d3502
> func:
>         ......
>         adrp    x0, p
>         add     x0, x0, :lo12:p
>         mov     w1, 23592
>         movk    w1, 0x4601, lsl 16
>         cmp     w0, w1
>         beq     .L2
>         ......
>         bl      cfi_check_failed
> .L2:
>         blr     x19
>         ret
> 
> In the compiler part[4], there are some differences from Sami's
> implementation[3], mainly including: