Commit graph

7 commits

Author SHA1 Message Date
Andi Kleen
2aae950b21 x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu
This implements new vDSO for x86-64.  The concept is similar
to the existing vDSOs on i386 and PPC.  x86-64 has had static
vsyscalls before,  but these are not flexible enough anymore.

A vDSO is a ELF shared library supplied by the kernel that is mapped into
user address space.  The vDSO mapping is randomized for each process
for security reasons.

Doing this was needed for clock_gettime, because clock_gettime
always needs a syscall fallback and having one at a fixed
address would have made buffer overflow exploits too easy to write.

The vdso can be disabled with vdso=0

It currently includes a new gettimeofday implemention and optimized
clock_gettime(). The gettimeofday implementation is slightly faster
than the one in the old vsyscall.  clock_gettime is significantly faster
than the syscall for CLOCK_MONOTONIC and CLOCK_REALTIME.

The new calls are generally faster than the old vsyscall.

Advantages over the old x86-64 vsyscalls:
- Extensible
- Randomized
- Cleaner
- Easier to virtualize (the old static address range previously causes
overhead e.g. for Xen because it has to create special page tables for it)

Weak points:
- glibc support still to be written

The VM interface is partly based on Ingo Molnar's i386 version.

Includes compile fix from Joachim Deguara

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 18:37:08 -07:00
Al Viro
f6a570333e [PATCH] severing module.h->sched.h
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2006-12-04 02:00:22 -05:00
David Woodhouse
75da736fb3 [PATCH] Fix 'make headers_check' on x86_64
On Tue, 2006-09-12 at 17:44 +0100, David Woodhouse wrote:
> asm-x86_64/elf.h requires asm/processor.h, which does not exist
> asm-x86_64/signal.h requires linux/linkage.h, which does not exist
> asm-x86_64/unistd.h requires linux/linkage.h, which does not exist
> asm-x86_64/vsyscall.h requires linux/seqlock.h, which does not exist

Again, move stuff which shouldn't be visible inside (mostly already existing)
#ifdef __KERNEL__.

This fixes a bunch of mislabelled and unlabelled #endifs in unistd.h and also
cleans that up to conform with what's visible on other architectures, since
the minimal fix for the error reported about would have involved a more
intrusive patch, renesting other ifdefs.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-16 12:54:32 -07:00
Andi Kleen
6ae53cd496 [PATCH] x86_64: Fix stack/mmap randomization for compat tasks
ia32_setup_arg_pages would ignore the passed in random stack top
and use its own static value.

Now it uses the 8bit of randomness native i386 would use too.

This indirectly fixes mmap randomization for 32bit processes too,
which depends on the stack randomization.

Should also give slightly better virtual cache colouring and
possibly better performance with HyperThreading.

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-30 20:31:05 -07:00
Andi Kleen
913bd90601 [PATCH] x86_64: Increase the variability of the process stack on 64bit architectures
8MB is not really very random, use 1GB (or more with larger page sizes)
instead.

Also use the low bits of the random generator output now instead of
throwing them away.

Only enabled on x86-64 right now. Other architectures need to add
a suitable STACK_RND_MASK

Cc: mingo@elte.hu
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25 09:10:52 -08:00
Tim Schmielau
8c65b4a604 [PATCH] fix remaining missing includes
Fix more include file problems that surfaced since I submitted the previous
fix-missing-includes.patch.  This should now allow not to include sched.h
from module.h, which is done by a followup patch.

Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 07:53:41 -08:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00