Hi Matt,
Thanks for your review!
On Thu, Jul 30, 2015 at 04:37:42PM +0100, Matt Fleming wrote:
> On Thu, 2015-07-16 at 22:25 +0800, Lee, Chun-Yi wrote:
> > This patch adds the codes for generating random number array as the
> > HMAC key that will used by later EFI stub codes.
> >
> > The original codes in efi_random copied from aslr and add the codes
> > to accept input entropy and EFI debugging. In later patch will add
> > the codes to get random number by EFI protocol. The separate codes
> > can avoid impacting aslr function.
> >
> > Signed-off-by: Lee, Chun-Yi <jlee@xxxxxxxx>
> > ---
> > arch/x86/boot/compressed/Makefile | 1 +
> > arch/x86/boot/compressed/efi_random.c | 88 +++++++++++++++++++++++++++++++++++
> > arch/x86/boot/compressed/misc.c | 4 +-
> > arch/x86/boot/compressed/misc.h | 2 +-
> > 4 files changed, 92 insertions(+), 3 deletions(-)
> > create mode 100644 arch/x86/boot/compressed/efi_random.c
>
> [...]
>
> > +static unsigned long get_random_long(unsigned long entropy,
> > + struct boot_params *boot_params,
> > + efi_system_table_t *sys_table)
> > +{
> > +#ifdef CONFIG_X86_64
> > + const unsigned long mix_const = 0x5d6008cbf3848dd3UL;
> > +#else
> > + const unsigned long mix_const = 0x3f39e593UL;
> > +#endif
> > + unsigned long raw, random;
> > + bool use_i8254 = true;
> > +
> > + efi_printk(sys_table, " EFI random");
>
> Probably want to remove these efi_printk()s from the final version ;-)
>
OK, I will remove those log.
> > + if (entropy)
> > + random = entropy;
> > + else
> > + random = get_random_boot(boot_params);
> > +
> > + if (rdrand_feature()) {
> > + efi_printk(sys_table, " RDRAND");
> > + if (rdrand_long(&raw)) {
> > + random ^= raw;
> > + use_i8254 = false;
> > + }
> > + }
> > +
> > + if (rdtsc_feature()) {
> > + efi_printk(sys_table, " RDTSC");
> > + rdtscll(raw);
> > +
> > + random ^= raw;
> > + use_i8254 = false;
> > + }
> > +
> > + if (use_i8254) {
> > + efi_printk(sys_table, " i8254");
> > + random ^= i8254();
> > + }
> > +
> > + /* Circular multiply for better bit diffusion */
> > + asm("mul %3"
> > + : "=a" (random), "=d" (raw)
> > + : "a" (random), "rm" (mix_const));
> > + random += raw;
> > +
> > + efi_printk(sys_table, "...\n");
> > +
> > + return random;
> > +}
> > +
> > +void efi_get_random_key(efi_system_table_t *sys_table,
> > + struct boot_params *params, u8 key[], int size)
> > +{
>
> I would think that the size of the key array should be unsigned.
>
I will change size to unsigned int.
Thanks
Joey Lee
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