From: David Laight <David.Laight@ACULAB.COM>
To: "'Reshetova, Elena'" <elena.reshetova@intel.com>,
Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
"Eric Biggers" <ebiggers3@gmail.com>,
"ebiggers@google.com" <ebiggers@google.com>,
"herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
Peter Zijlstra <peterz@infradead.org>,
"keescook@chromium.org" <keescook@chromium.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
"jannh@google.com" <jannh@google.com>,
"Perla, Enrico" <enrico.perla@intel.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: RE: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall
Date: Fri, 3 May 2019 16:40:53 +0000 [thread overview]
Message-ID: <e4fbad8c51284a0583b98c52de4a207d@AcuMS.aculab.com> (raw)
In-Reply-To: <2236FBA76BA1254E88B949DDB74E612BA4C6F523@IRSMSX102.ger.corp.intel.com>
From: Reshetova, Elena
> Sent: 03 May 2019 17:17
...
> rdrand (calling every 8 syscalls): Simple syscall: 0.0795 microseconds
You could try something like:
u64 rand_val = cpu_var->syscall_rand
while (unlikely(rand_val == 0))
rand_val = rdrand64();
stack_offset = rand_val & 0xff;
rand_val >>= 6;
if (likely(rand_val >= 4))
cpu_var->syscall_rand = rand_val;
else
cpu_var->syscall_rand = rdrand64();
return stack_offset;
That gives you 10 system calls per rdrand instruction
and mostly takes the latency out of line.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-05-03 16:41 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-15 6:09 [PATCH] x86/entry/64: randomize kernel stack offset upon syscall Elena Reshetova
2019-04-15 7:25 ` Ingo Molnar
2019-04-15 8:44 ` Reshetova, Elena
2019-04-16 7:34 ` Ingo Molnar
2019-04-16 11:10 ` Reshetova, Elena
2019-04-16 12:08 ` Peter Zijlstra
2019-04-16 12:45 ` David Laight
2019-04-16 15:43 ` Theodore Ts'o
2019-04-16 16:07 ` Peter Zijlstra
2019-04-16 16:47 ` Reshetova, Elena
2019-04-17 9:28 ` David Laight
2019-04-17 15:15 ` Theodore Ts'o
2019-04-17 15:40 ` Kees Cook
2019-04-17 15:53 ` David Laight
2019-04-24 11:42 ` Reshetova, Elena
2019-04-24 13:33 ` David Laight
2019-04-25 11:23 ` Reshetova, Elena
2019-04-26 11:33 ` Reshetova, Elena
2019-04-26 14:01 ` Theodore Ts'o
2019-04-26 17:44 ` Eric Biggers
2019-04-26 18:02 ` Theodore Ts'o
2019-04-27 13:59 ` Andy Lutomirski
2019-04-29 8:04 ` Reshetova, Elena
2019-04-26 18:34 ` Andy Lutomirski
2019-04-29 7:46 ` Reshetova, Elena
2019-04-29 16:08 ` Andy Lutomirski
2019-04-30 17:51 ` Reshetova, Elena
2019-04-30 18:01 ` Kees Cook
2019-05-01 8:23 ` David Laight
2019-05-02 8:07 ` Reshetova, Elena
2019-05-01 8:41 ` David Laight
2019-05-01 23:33 ` Andy Lutomirski
2019-05-02 8:15 ` Reshetova, Elena
2019-05-02 9:23 ` David Laight
2019-05-02 14:47 ` Andy Lutomirski
2019-05-02 15:08 ` Ingo Molnar
2019-05-02 16:32 ` Andy Lutomirski
2019-05-02 16:43 ` Ingo Molnar
2019-05-03 16:40 ` Andy Lutomirski
2019-05-02 16:34 ` David Laight
2019-05-02 16:45 ` Ingo Molnar
2019-05-03 16:17 ` Reshetova, Elena
2019-05-03 16:40 ` David Laight [this message]
2019-05-03 19:10 ` Linus Torvalds
2019-05-06 6:47 ` Reshetova, Elena
2019-05-06 7:01 ` Reshetova, Elena
2019-05-08 11:18 ` Reshetova, Elena
2019-05-08 11:32 ` Ingo Molnar
2019-05-08 13:22 ` Reshetova, Elena
2019-05-09 5:59 ` Ingo Molnar
2019-05-09 7:01 ` Reshetova, Elena
2019-05-09 8:43 ` Ingo Molnar
2019-05-11 22:45 ` Andy Lutomirski
2019-05-12 0:12 ` Kees Cook
2019-05-12 8:02 ` Ingo Molnar
2019-05-12 14:33 ` Kees Cook
2019-05-28 12:28 ` Reshetova, Elena
2019-05-28 13:33 ` Theodore Ts'o
2019-05-29 10:13 ` Reshetova, Elena
2019-05-29 10:51 ` David Laight
2019-05-29 18:35 ` Kees Cook
2019-05-29 18:37 ` Kees Cook
2019-07-29 11:41 ` Reshetova, Elena
2019-07-30 18:07 ` Kees Cook
2019-08-01 6:35 ` Reshetova, Elena
2019-05-09 7:03 ` Reshetova, Elena
2019-05-06 7:32 ` Reshetova, Elena
2019-04-29 7:49 ` Reshetova, Elena
2019-04-26 17:37 ` Edgecombe, Rick P
2019-04-17 6:24 ` Ingo Molnar
2019-04-16 18:19 ` Reshetova, Elena
[not found] <20190408061358.21288-1-elena.reshetova@intel.com>
2019-04-08 12:49 ` Josh Poimboeuf
2019-04-08 13:30 ` Reshetova, Elena
2019-04-08 16:21 ` Kees Cook
2019-04-10 8:26 ` Ingo Molnar
2019-04-10 9:00 ` Reshetova, Elena
2019-04-10 10:17 ` Ingo Molnar
2019-04-10 10:24 ` Reshetova, Elena
2019-04-10 14:52 ` Andy Lutomirski
2019-04-12 5:36 ` Reshetova, Elena
2019-04-12 21:16 ` Andy Lutomirski
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