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From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 4/9] arm64: head.S: move KASLR processing out of __enable_mmu()
Date: Wed, 24 Aug 2016 21:46:54 +0100	[thread overview]
Message-ID: <20160824204654.GA1775@remoulade> (raw)
In-Reply-To: <20160824203609.GA1642@remoulade>

On Wed, Aug 24, 2016 at 09:36:10PM +0100, Mark Rutland wrote:
> On Wed, Aug 24, 2016 at 04:36:01PM +0200, Ard Biesheuvel wrote:
> > +__primary_switch:
> > +#ifdef CONFIG_RANDOMIZE_BASE
> > +	mov	x19, x0				// preserve new SCTLR_EL1 value
> > +	mrs	x20, sctlr_el1			// preserve old SCTLR_EL1 value
> > +#endif
> > +
> > +	adr	x27, 0f
> > +	b	__enable_mmu
> 
> As we do elsewhere, it's probably worth a comment on the line with the ADR into
> x27, mentioning that __enable_mmu will branch there.
> 
> ... or perhaps we should just have __enable_mmu return to the LR like a normal
> AAPCS function, place the switch routines in the idmap, and use the idiomatic
> sequence:
> 
> __thing_switch:
> 	bl	__enable_mmu
> 	ldr	xN, =__thing
> 	blr	xN

... and now I see that this is what subsequent patches do ;)

Is it possible to first AAPCS-ify __enable_mmu (with shuffling of callers as
above) in one patch, prior to this? That would avoid introducing the unusual 0f
label above, and the temporary x30 usage in a subsequent patch.

Thanks,
Mark.

  parent reply	other threads:[~2016-08-24 20:46 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-24 14:35 [PATCH v2 0/9] arm64: clean up early boot function calls Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 1/9] arm64: kernel: get rid of x25 and x26 with 'global' scope Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 2/9] arm64: kernel: fix style issues in sleep.S Ard Biesheuvel
2016-08-24 16:13   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 3/9] arm64: kernel: use ordinary return/argument register for el2_setup() Ard Biesheuvel
2016-08-24 16:20   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 4/9] arm64: head.S: move KASLR processing out of __enable_mmu() Ard Biesheuvel
2016-08-24 20:36   ` Mark Rutland
2016-08-24 20:44     ` Ard Biesheuvel
2016-08-24 20:46     ` Mark Rutland [this message]
2016-08-25 13:59       ` Ard Biesheuvel
2016-08-30 10:24         ` Mark Rutland
2016-08-30 13:45   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 5/9] arm64: kernel: use x30 for __enable_mmu return address Ard Biesheuvel
2016-08-24 14:36 ` [PATCH v2 6/9] arm64: call __enable_mmu as an ordinary function for secondary/resume Ard Biesheuvel
2016-08-30 14:07   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 7/9] arm64: kernel: drop use of x24 from primary boot path Ard Biesheuvel
2016-08-30 14:26   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 8/9] arm64: head.S: use ordinary stack frame for __primary_switched() Ard Biesheuvel
2016-08-30 14:38   ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 9/9] arm64: head.S: document the use of callee saved registers Ard Biesheuvel
2016-08-30 14:43   ` Mark Rutland
2016-08-30 14:48 ` [PATCH v2 0/9] arm64: clean up early boot function calls Mark Rutland
2016-08-30 14:50   ` Ard Biesheuvel

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