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Date:   Wed, 10 Jun 2020 13:03:27 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Alexander Popov <alex.popov@linux.com>
Cc:     Emese Revfy <re.emese@gmail.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Jessica Yu <jeyu@kernel.org>,
        Sven Schnelle <svens@stackframe.org>,
        Iurii Zaikin <yzaikin@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
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Subject: Re: [PATCH 2/5] gcc-plugins/stackleak: Use asm instrumentation to
 avoid useless register saving
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On Wed, Jun 10, 2020 at 06:47:14PM +0300, Alexander Popov wrote:
> On 09.06.2020 21:46, Kees Cook wrote:
> The inline asm statement that is used for instrumentation is arch-specific.
> Trying to add
>   asm volatile("call stackleak_track_stack")
> in gcc plugin on aarch64 makes gcc break spectacularly.

Ah! Thank you, that eluded my eyes. :)

> I pass the target arch name to the plugin and check it explicitly to avoid that.
> 
> Moreover, I'm going to create a gcc enhancement request for supporting
> no_caller_saved_registers attribute on aarch64.

For arm64 right now it looks like the plugin will just remain
"inefficient" in these cleanup, as before, yes?

-- 
Kees Cook