linux-kernel - Re: [PATCH v2 05/16] x86/efi: Get entropy through EFI random number generator protocol

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Date:	Thu, 27 Aug 2015 12:51:10 +0800
From:	joeyli <jlee@...e.com>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Josh Boyer <jwboyer@...hat.com>,
	Vojtech Pavlik <vojtech@...e.cz>,
	Matt Fleming <matt.fleming@...el.com>,
	Jiri Kosina <jkosina@...e.cz>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v2 05/16] x86/efi: Get entropy through EFI random number
 generator protocol

On Thu, Aug 20, 2015 at 03:47:06PM +0100, Matt Fleming wrote:
> On Tue, 11 Aug, at 02:16:25PM, Lee, Chun-Yi wrote:
> > To grab random numbers through EFI protocol as one of the entropies
> > source of swsusp key, this patch adds the logic for accessing EFI RNG
> > (random number generator) protocol that's introduced since UEFI 2.4.
> > 
> > Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
> > ---
> >  arch/x86/boot/compressed/efi_random.c | 209 ++++++++++++++++++++++++++++++++++
> >  include/linux/efi.h                   |  13 +++
> >  2 files changed, 222 insertions(+)
> 
> [...]
> 
> Most of this looks good.
> 
> > +static unsigned long efi_get_rng(efi_system_table_t *sys_table)
> > +{
> > +	const struct efi_config *efi_early = __efi_early();
> > +	unsigned long random = 0;
> > +	efi_status_t status;
> > +	void **rng_handle = NULL;
> > +
> > +	status = efi_locate_rng(sys_table, &rng_handle);
> > +	if (status != EFI_SUCCESS)
> > +		return 0;
> > +
> > +	if (efi_early->is64)
> > +		random = efi_get_rng64(sys_table, rng_handle);
> > +	else
> > +		random = efi_get_rng32(sys_table, rng_handle);
> > +
> > +	efi_call_early(free_pool, rng_handle);
> > +
> > +	return random;
> > +}
>   
> I think this function is named particularly poorly in the UEFI spec
> (GetRNG), can we maybe make this efi_get_rng_number(),
> efi_get_rng_value() or efi_get_rng_long() to match the existing
> naming?
>

Thanks for your suggestion, I will change the naming of functions.
 
> > diff --git a/include/linux/efi.h b/include/linux/efi.h
> > index 85ef051..8914d60 100644
> > --- a/include/linux/efi.h
> > +++ b/include/linux/efi.h
> > @@ -427,6 +427,16 @@ typedef struct {
> >  #define EFI_PCI_IO_ATTRIBUTE_VGA_PALETTE_IO_16 0x20000
> >  #define EFI_PCI_IO_ATTRIBUTE_VGA_IO_16 0x40000
> >  
> > +typedef struct {
> > +	u32 get_info;
> > +	u32 get_rng;
> > +} efi_rng_protocol_32;
> > +
> > +typedef struct {
> > +	u64 get_info;
> > +	u64 get_rng;
> > +} efi_rng_protocol_64;
> > +
> 
> We've been kinda slack with the naming conventions in efi.h but these
> should really both be 'efi_rng_protocol_*_t'.
> 

I will also change the name of struct here. 

> -- 
> Matt Fleming, Intel Open Source Technology Center


Thanks a lot!
Joey Lee
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