Hi Pavel, Thanks for your review.
On Tue, Jul 28, 2015 at 02:01:12PM +0200, Pavel Machek wrote: > Hi! > > > 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 <[email protected]> > > > +#define X86_FEATURE_EDX_TSC (1 << 4) > > +#define X86_FEATURE_ECX_RDRAND (1 << 30) > > Can you pull it from existing includes somewhere? > I didn't see similar definition in header. > > +static bool rdrand_feature(void) > > +{ > > + return (cpuid_ecx(0x1) & X86_FEATURE_ECX_RDRAND); > > +} > > + > > +static bool rdtsc_feature(void) > > +{ > > + return (cpuid_edx(0x1) & X86_FEATURE_EDX_TSC); > > +} > > Are these helpers neccessary? I will try to simplify it. > > > + 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; > > + } > > You'll do two (expensive) cpuids calls here. > I will try to avoid call cpuid many times. Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
