Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1712195
| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: early x86 unseeded randomness |
| Date | 2017-08-15 15:50 +0200 |
| Message-ID | <ueKoh-1VC-15@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <ueyZR-3cJ-31@gated-at.bofh.it> <ueDPQ-6jk-7@gated-at.bofh.it> <ueELT-6RV-1@gated-at.bofh.it> <ueHA6-bQ-17@gated-at.bofh.it> <ueKoh-1VC-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, 15 Aug 2017, Borislav Petkov wrote:
> On Tue, Aug 15, 2017 at 12:47:36PM +0200, Thomas Gleixner wrote:
> > 8<-------------------
> >
> > --- a/arch/x86/kernel/tsc.c
> > +++ b/arch/x86/kernel/tsc.c
> > @@ -1360,3 +1360,19 @@ unsigned long calibrate_delay_is_known(v
> > return 0;
> > }
> > #endif
> > +
> > +u64 __init tsc_early_random(void)
> > +{
> > + u64 uninitialized_var(res);
> > + int i;
> > +
> > + if (!boot_cpu_has(X86_FEATURE_TSC))
> > + return res;
> > +
> > + res ^= rdtsc();
> > + for (i = 0; i < BITS_PER_LONG; i++) {
> > + res ^= ((rdtsc() & 0x04) >> 2) << i;
> > + udelay(2);
> > + }
> > + return res;
> > +}
>
> Something like this is exactly what I was aiming at with my dumb patch.
> We could use this for early boot randomness on x86.
>
> Should I turn it into proper patches or you want to?
Go ahead. What you actually want to do is to replace boot_cpu_has() with a
real cpuid() check because boot_cpu_has() is not initialized on real early
boot.
Thanks,
tglx
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 19:40 +0200
Re: early x86 unseeded randomness Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-14 19:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 20:10 +0200
Re: early x86 unseeded randomness Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-14 20:20 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-14 21:10 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 03:40 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 08:50 +0200
Re: early x86 unseeded randomness Ingo Molnar <mingo@kernel.org> - 2017-08-15 09:50 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 10:10 +0200
Re: early x86 unseeded randomness Ingo Molnar <mingo@kernel.org> - 2017-08-15 10:10 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 14:20 +0200
Re: early x86 unseeded randomness Willy Tarreau <w@1wt.eu> - 2017-08-15 15:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 12:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 15:50 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 15:50 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-15 16:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 16:50 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 17:30 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-15 19:40 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-16 05:40 +0200
Re: early x86 unseeded randomness Thomas Gleixner <tglx@linutronix.de> - 2017-08-16 11:20 +0200
Re: early x86 unseeded randomness Will Deacon <will.deacon@arm.com> - 2017-08-16 12:00 +0200
Re: early x86 unseeded randomness Theodore Ts'o <tytso@mit.edu> - 2017-08-16 05:30 +0200
Re: early x86 unseeded randomness Borislav Petkov <bp@alien8.de> - 2017-08-15 17:30 +0200
Re: early x86 unseeded randomness Michael Ellerman <mpe@ellerman.id.au> - 2017-08-15 14:50 +0200
csiph-web