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Date: Fri, 31 Jul 2015 17:58:54 +0800
From: joeyli <jlee@...e.com>
To: Pavel Machek <pavel@....cz>
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@...k.pl>,
Matthew Garrett <matthew.garrett@...ula.com>,
Len Brown <len.brown@...el.com>,
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>
Subject: Re: [RFC PATCH 05/16] x86/efi: Get entropy through EFI random number
generator protocol
On Tue, Jul 28, 2015 at 02:28:53PM +0200, Pavel Machek wrote:
> On Thu 2015-07-16 22:25:19, 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 | 193 ++++++++++++++++++++++++++++++++++
> > include/linux/efi.h | 46 ++++++++
> > 2 files changed, 239 insertions(+)
> >
> > diff --git a/arch/x86/boot/compressed/efi_random.c b/arch/x86/boot/compressed/efi_random.c
> > index bdb2d46..1f5c63d 100644
> > --- a/arch/x86/boot/compressed/efi_random.c
> > +++ b/arch/x86/boot/compressed/efi_random.c
> > @@ -2,6 +2,191 @@
> >
> > #include <linux/efi.h>
> > #include <asm/archrandom.h>
> > +#include <asm/efi.h>
> > +
> > +static efi_status_t efi_locate_rng(efi_system_table_t *sys_table,
> > + void ***rng_handle)
> > +{
> > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
> > + unsigned long size = 0;
> > + efi_status_t status;
> > +
> > + status = efi_call_early(locate_handle,
> > + EFI_LOCATE_BY_PROTOCOL,
> > + &rng_proto, NULL, &size, *rng_handle);
> > +
> > + if (status == EFI_BUFFER_TOO_SMALL) {
> > + status = efi_call_early(allocate_pool,
> > + EFI_LOADER_DATA,
> > + size, (void **)rng_handle);
> > +
> > + if (status != EFI_SUCCESS) {
> > + efi_printk(sys_table, " Failed to alloc mem for rng_handle");
> > + return status;
> > + }
> > +
> > + status = efi_call_early(locate_handle,
> > + EFI_LOCATE_BY_PROTOCOL, &rng_proto,
> > + NULL, &size, *rng_handle);
> > + }
> > +
> > + if (status != EFI_SUCCESS) {
> > + efi_printk(sys_table, " Failed to locateEFI_RNG_PROTOCOL");
>
> missing \n?
>
Originally those logs just follow a "EFI random" as a complete line. After
removed "EFI random", I will add "\n" back to those log.
> > + goto free_handle;
>
> You use that label exactly once, no need for goto
>
OK, I will remove free_handle label.
> > +static bool efi_rng_supported32(efi_system_table_t *sys_table, void **rng_handle)
> > +{
> > + const struct efi_config *efi_early = __efi_early();
> > + efi_rng_protocol_32 *rng = NULL;
> ...> +static bool efi_rng_supported64(efi_system_table_t *sys_table, void **rng_handle)
> > +{
> > + const struct efi_config *efi_early = __efi_early();
> > + efi_rng_protocol_64 *rng = NULL;
> > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
> ...
> > +static unsigned long efi_get_rng32(efi_system_table_t *sys_table,
> > + void **rng_handle)
> > +{
> > + const struct efi_config *efi_early = __efi_early();
> > + efi_rng_protocol_32 *rng = NULL;
> > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
> ...
> > +static unsigned long efi_get_rng64(efi_system_table_t *sys_table,
> > + void **rng_handle)
> > +{
> > + const struct efi_config *efi_early = __efi_early();
> > + efi_rng_protocol_64 *rng = NULL;
> > + efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
>
> Can you do something to avoid each function having two very similar
> versions of these functions?
>
They are similar but I want follow the style in eboot.c.
On the other hand, it's earlier to locate problem on 32-bit or 64-bit EFI.
So, I will keep the above codes.
> > + if (status != EFI_SUCCESS) {
> > + efi_printk(sys_table, " Failed to get RNG value ");
> > + efi_printk(sys_table, efi_status_to_str(status));
>
> Yep. You definitely have \n problems here.
Thanks, I will add \n here also.
>
> > --- 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 don't typedef structs usually...
>
> Make it union so you can have just one
>
I want to follow the style as efi_pci_io_protocolxxx in efi.h.
So I will keep it.
> > +static inline char *efi_status_to_str(efi_status_t status)
> > +{
> > + char *str;
> > +
>
> Are you sure you want this inlined?
>
It's inlined because in header file.
Currently it's only used by efi_random.c, I will move it to efi_random.
> > + switch (status) {
> > + case EFI_SUCCESS:
> > + str = "EFI_SUCCESS";
> > + break;
>
> Can you use macros to reduce code duplication here?
> Pavel
I will try to reduce duplicate code.
Thanks
Joey Lee
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