Re: [PATCH v2 5/6] of/fdt: Remove custom __early_init_dt_declare_initrd() implementation

From: Rob Herring <robh+dt@kernel.org>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Frank Rowand <frowand.list@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Russell King <rmk+kernel@armlinux.org.uk>,
	aryabinin@virtuozzo.com, Andrey Konovalov <andreyknvl@google.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Laura Abbott <labbott@redhat.com>, Stefan Agner <stefan@agner.ch>,
	Johannes Weiner <hannes@cmpxchg.org>,
	ghackmann@android.com,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	chandan.vn@samsung.com,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>,
	devicetree@vger.kernel.org, rppt@linux.ibm.com,
	Russell King <linux@armlinux.org.uk>,
	Greentime Hu <green.hu@gmail.com>,
	deanbo422@gmail.com, gxt@pku.edu.cn,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	arcml <linux-snps-arc@lists.infradead.org>,
	Vineet Gupta <vgupta@synopsys.com>
Subject: Re: [PATCH v2 5/6] of/fdt: Remove custom __early_init_dt_declare_initrd() implementation
Date: Wed, 31 Oct 2018 07:29:47 -0500	[thread overview]
Message-ID: <CAL_JsqKynGpg5fgVes2UQprc0Re7-Yp2_jRYfyGxQdse9zro7g@mail.gmail.com> (raw)
In-Reply-To: <20181030230721.28429-6-f.fainelli@gmail.com>

On Tue, Oct 30, 2018 at 6:07 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>
> Now that ARM64 uses phys_initrd_start/phys_initrd_size, we can get rid
> of its custom __early_init_dt_declare_initrd() which causes a fair
> amount of objects rebuild when changing CONFIG_BLK_DEV_INITRD. In order
> to make sure ARM64 does not produce a BUG() when VM debugging is turned
> on though, we must avoid early calls to __va() which is what
> __early_init_dt_declare_initrd() does and wrap this around to avoid
> running that code on ARM64.
>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
>  arch/arm64/include/asm/memory.h | 8 --------
>  drivers/of/fdt.c                | 9 +++++++--
>  2 files changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index b96442960aea..dc3ca21ba240 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -168,14 +168,6 @@
>  #define IOREMAP_MAX_ORDER      (PMD_SHIFT)
>  #endif
>
> -#ifdef CONFIG_BLK_DEV_INITRD
> -#define __early_init_dt_declare_initrd(__start, __end)                 \
> -       do {                                                            \
> -               initrd_start = (__start);                               \
> -               initrd_end = (__end);                                   \
> -       } while (0)
> -#endif
> -
>  #ifndef __ASSEMBLY__
>
>  #include <linux/bitops.h>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index e34cb49231b5..f2b5becae96a 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -892,15 +892,20 @@ const void * __init of_flat_dt_match_machine(const void *default_match,
>  }
>
>  #ifdef CONFIG_BLK_DEV_INITRD
> -#ifndef __early_init_dt_declare_initrd
>  static void __early_init_dt_declare_initrd(unsigned long start,
>                                            unsigned long end)
>  {
> +       /* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
> +        * enabled since __va() is called too early. ARM64 does make use
> +        * of phys_initrd_start/phys_initrd_size so we can skip this
> +        * conversion.
> +        */
> +#if (!IS_ENABLED(CONFIG_ARM64))

Use 'if' not '#if'. Use C code rather than preprocessor whenever possible.

>         initrd_start = (unsigned long)__va(start);
>         initrd_end = (unsigned long)__va(end);
>         initrd_below_start_ok = 1;
> -}
>  #endif
> +}
>
>  /**
>   * early_init_dt_check_for_initrd - Decode initrd location from flat tree
> --
> 2.17.1
>