linux-kernel - Re: [PATCH] arch: x86: boot: compressed: eboot: fix cast warnings on 32b platforms

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Message-ID: <20121226080019.GB11555@liondog.tnic>
Date:	Wed, 26 Dec 2012 09:00:19 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Stefan Hasko <hasko.stevo@...il.com>
Cc:	Matt Fleming <matt.fleming@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arch: x86: boot: compressed: eboot: fix cast warnings on
 32b platforms

On Sat, Dec 22, 2012 at 11:23:25AM +0100, Stefan Hasko wrote:
> Fixed different size cast warnings in function setup_efi_pci
> 
> Signed-off-by: Stefan Hasko <hasko.stevo@...il.com>

You might want to add the actual compiler warnings to the commit
message:

arch/x86/boot/compressed/eboot.c: In function ‘setup_efi_pci’:
arch/x86/boot/compressed/eboot.c:259:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
arch/x86/boot/compressed/eboot.c:262:10: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
arch/x86/boot/compressed/eboot.c:348:17: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
arch/x86/boot/compressed/eboot.c:350:29: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]

And yes, I see them in all{mod,yes}config builds here too. The issue,
AFAICT, is that setup_data is __u64 to obviously accomodate 8-byte
pointers on x86-64 but on 32-bit they're half the size. And we obviously
cannot change struct setup_data since this is an ABI so I'd guess the
casts to native pointer sizes are ok. So

Acked-by: Borislav Petkov <bp@...en8.de>

> ---
>  arch/x86/boot/compressed/eboot.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index b1942e2..dd99fca 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -256,10 +256,10 @@ static efi_status_t setup_efi_pci(struct boot_params *params)
>  	int i;
>  	struct setup_data *data;
>  
> -	data = (struct setup_data *)params->hdr.setup_data;
> +	data = (struct setup_data *)(uintptr_t)params->hdr.setup_data;
>  
>  	while (data && data->next)
> -		data = (struct setup_data *)data->next;
> +		data = (struct setup_data *)(uintptr_t)data->next;
>  
>  	status = efi_call_phys5(sys_table->boottime->locate_handle,
>  				EFI_LOCATE_BY_PROTOCOL, &pci_proto,
> @@ -345,9 +345,9 @@ static efi_status_t setup_efi_pci(struct boot_params *params)
>  		memcpy(rom->romdata, pci->romimage, pci->romsize);
>  
>  		if (data)
> -			data->next = (uint64_t)rom;
> +			data->next = (uintptr_t)rom;
>  		else
> -			params->hdr.setup_data = (uint64_t)rom;
> +			params->hdr.setup_data = (uintptr_t)rom;
>  
>  		data = (struct setup_data *)rom;
>  
> -- 
> 1.7.10.4

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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