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From: Mark Rutland <mark.rutland@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, keescook@chromium.org,
	ard.biesheuvel@linaro.org, matt@codeblueprint.co.uk,
	kernel-hardening@lists.openwall.com, will.deacon@arm.com,
	linux-kernel@vger.kernel.org, luto@amacapital.net,
	james.morse@arm.com, labbott@redhat.com
Subject: Re: [PATCH 05/14] arm64: clean up THREAD_* definitions
Date: Mon, 14 Aug 2017 14:10:24 +0100	[thread overview]
Message-ID: <20170814131023.GA23428@leverpostej> (raw)
In-Reply-To: <20170814115958.dqg2xrobls4jcgx3@armageddon.cambridge.arm.com>

On Mon, Aug 14, 2017 at 12:59:59PM +0100, Catalin Marinas wrote:
> On Mon, Aug 07, 2017 at 07:35:56PM +0100, Mark Rutland wrote:
> > Currently we define THREAD_SIZE and THREAD_SIZE order separately, with
> 
> s/THREAD_SIZE order/THREAD_SIZE_ORDER/

Whoops; I'll fix that up now.

> > +#define THREAD_SHIFT		14
> > +
> > +#if THREAD_SHIFT >= PAGE_SHIFT
> > +#define THREAD_SIZE_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
> > +#endif
> > +
> > +#define THREAD_SIZE		(UL(1) << THREAD_SHIFT)
> 
> I haven't tried the series to this patch but it seems to me that
> THREAD_SIZE_ORDER is undefined for a PAGE_SHIFT of 16. 

That is already the case without these patches, as we have:

#ifdef CONFIG_ARM64_4K_PAGES
#define THREAD_SIZE_ORDER       2
#elif defined(CONFIG_ARM64_16K_PAGES)
#define THREAD_SIZE_ORDER       0
#endif

... this is also deliberate, as we'd need an order of -2 with 16K stacks and
64K pages, and this doesn't make sense.

THREAD_SIZE_ORDER only matters if THREAD_SIZE >= PAGE_SIZE (or if we're using a
VMAP'd stack). For 64K pages && VMAP_STACK, we'll use a 64K stack, avoiding the
problem.

Thanks,
Mark.

  reply	other threads:[~2017-08-14 13:12 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-07 18:35 [PATCH 00/14] arm64: VMAP_STACK support Mark Rutland
2017-08-07 18:35 ` [PATCH 01/14] arm64: remove __die()'s stack dump Mark Rutland
2017-08-07 18:35 ` [PATCH 02/14] fork: allow arch-override of VMAP stack alignment Mark Rutland
2017-08-07 18:35 ` [PATCH 03/14] arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP Mark Rutland
2017-08-07 18:35 ` [PATCH 04/14] arm64: factor out PAGE_* and CONT_* definitions Mark Rutland
2017-08-07 18:35 ` [PATCH 05/14] arm64: clean up THREAD_* definitions Mark Rutland
2017-08-14 11:59   ` Catalin Marinas
2017-08-14 13:10     ` Mark Rutland [this message]
2017-08-07 18:35 ` [PATCH 06/14] arm64: clean up irq stack definitions Mark Rutland
2017-08-07 18:35 ` [PATCH 07/14] arm64: move SEGMENT_ALIGN to <asm/memory.h> Mark Rutland
2017-08-07 18:35 ` [PATCH 08/14] efi/arm64: add EFI_KIMG_ALIGN Mark Rutland
2017-08-07 18:36 ` [PATCH 09/14] arm64: factor out entry stack manipulation Mark Rutland
2017-08-07 18:36 ` [PATCH 10/14] arm64: assembler: allow adr_this_cpu to use the stack pointer Mark Rutland
2017-08-14 17:13   ` Catalin Marinas
2017-08-14 17:42     ` Mark Rutland
2017-08-07 18:36 ` [PATCH 11/14] arm64: use an irq " Mark Rutland
2017-08-07 18:36 ` [PATCH 12/14] arm64: add basic VMAP_STACK support Mark Rutland
2017-08-07 18:36 ` [PATCH 13/14] arm64: add on_accessible_stack() Mark Rutland
2017-08-07 18:36 ` [PATCH 14/14] arm64: add VMAP_STACK overflow detection Mark Rutland
2017-08-14 15:32   ` Will Deacon
2017-08-14 17:25     ` Mark Rutland
2017-08-15 11:10   ` Catalin Marinas
2017-08-15 11:19     ` Mark Rutland

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