Re: [PATCH v6 03/18] khwasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_HW

From: Andrey Konovalov <andreyknvl@google.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Alexander Potapenko <glider@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
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	Andrew Morton <akpm@linux-foundation.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Dave Martin <dave.martin@arm.com>,
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	"Eric W . Biederman" <ebiederm@xmission.com>,
	Ingo Molnar <mingo@kernel.org>,
	Paul Lawrence <paullawrence@google.com>,
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	Chintan Pandya <cpandya@codeaurora.org>,
	Vishwath Mohan <vishwath@google.com>
Subject: Re: [PATCH v6 03/18] khwasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_HW
Date: Mon, 17 Sep 2018 20:42:36 +0200	[thread overview]
Message-ID: <CAAeHK+yvVgV6LA8PgJz6ysCo+X38tCyLrMVhKOe08tFyZP_F0Q@mail.gmail.com> (raw)
In-Reply-To: <CACT4Y+baDKvmpKJ4SKoEuZG4ir2xRGscQ7Ro4hkVAX3jwiWnFg@mail.gmail.com>

On Wed, Sep 12, 2018 at 4:47 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Wed, Aug 29, 2018 at 1:35 PM, Andrey Konovalov <andreyknvl@google.com> wrote:

>>
>>  #define __no_sanitize_address __attribute__((no_sanitize("address")))
>> +#define __no_sanitize_hwaddress __attribute__((no_sanitize("hwaddress")))
>
> It seems that it would be better to have just 1 attribute for both types.
> Currently __no_sanitize_address is used just in a single place. But if
> it ever used more, people will need to always spell both which looks
> unnecessary, or, worse will only fix asan but forget about khwasan.
>
> If we do just:
>
> #define __no_sanitize_address __attribute__((no_sanitize("address",
> "hwaddress")))
>
> Then we don't need any changes in compiler-gcc.h nor in compiler.h,
> and no chance or forgetting one of them.

Will do in v7.

>>  config KASAN
>> -       bool "KASan: runtime memory debugger"
>> +       bool "KASAN: runtime memory debugger"
>> +       help
>> +         Enables KASAN (KernelAddressSANitizer) - runtime memory debugger,
>> +         designed to find out-of-bounds accesses and use-after-free bugs.
>
> Perhaps also give link to Documentation/dev-tools/kasan.rst while we are here.

Will do in v7.

>
>> +
>> +choice
>> +       prompt "KASAN mode"
>> +       depends on KASAN
>> +       default KASAN_GENERIC
>> +       help
>> +         KASAN has two modes: KASAN (a classic version, similar to userspace
>
> In these few sentences we call the old mode with 3 different terms:
> "generic", "classic" and "KASAN" :)
> This is somewhat confusing. Let's call it "generic" throughout (here
> and in the docs patch). "Generic" as in "supported on multiple arch
> and not-dependent on hardware features". "Classic" makes sense for
> people who knew KASAN before, but for future readers in won't make
> sense.

Will use "generic" in v7.

>>
>> +if HAVE_ARCH_KASAN_HW
>
> This choice looks somewhat weird on non-arm64. It's kinda a choice
> menu, but one can't really choose anything. Should we put the whole
> choice under HAVE_ARCH_KASAN_HW, and just select KASAN_GENERIC
> otherwise? I don't know what't the practice here. Andrey R?

I think having one option that is auto selected is fine.

>> +config KASAN_HW
>> +       bool "KHWASAN: the hardware assisted mode"

Do we need a hyphen here? hardware-assisted?

Yes, will fix in v7.