linux-toradex.git/arch/x86/include/asm/vsyscall.h, branch v4.3.1

x86_64,vsyscall: Make vsyscall emulation configurable

2014-11-03T20:44:57+00:00

This adds CONFIG_X86_VSYSCALL_EMULATION, guarded by CONFIG_EXPERT.
Turning it off completely disables vsyscall emulation, saving ~3.5k
for vsyscall_64.c, 4k for vsyscall_emu_64.S (the fake vsyscall
page), some tiny amount of core mm code that supports a gate area,
and possibly 4k for a wasted pagetable.  The latter is because the
vsyscall addresses are misaligned and fit poorly in the fixmap.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Josh Triplett 
Cc: Konrad Rzeszutek Wilk 
Link: http://lkml.kernel.org/r/406db88b8dd5f0cbbf38216d11be34bbb43c7eae.1414618407.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner

x86,vdso: Use LSL unconditionally for vgetcpu

2014-11-03T12:41:53+00:00

LSL is faster than RDTSCP and works everywhere; there's no need to
switch between them depending on CPU.

Signed-off-by: Andy Lutomirski 
Cc: Andi Kleen 
Link: http://lkml.kernel.org/r/72f73d5ec4514e02bba345b9759177ef03742efb.1414706021.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner

UAPI: (Scripted) Disintegrate arch/x86/include/asm

2012-12-14T22:37:13+00:00

Signed-off-by: David Howells 
Acked-by: Arnd Bergmann 
Acked-by: Thomas Gleixner 
Acked-by: Michael Kerrisk 
Acked-by: Paul E. McKenney 
Acked-by: Dave Jones

x86: vdso: pvclock gettime support

2012-11-28T01:29:11+00:00

Improve performance of time system calls when using Linux pvclock,
by reading time info from fixmap visible copy of pvclock data.

Originally from Jeremy Fitzhardinge.

Signed-off-by: Marcelo Tosatti

x86-64: Rework vsyscall emulation and add vsyscall= parameter

2011-08-11T00:26:46+00:00

There are three choices:

vsyscall=native: Vsyscalls are native code that issues the
corresponding syscalls.

vsyscall=emulate (default): Vsyscalls are emulated by instruction
fault traps, tested in the bad_area path.  The actual contents of
the vsyscall page is the same as the vsyscall=native case except
that it's marked NX.  This way programs that make assumptions about
what the code in the page does will not be confused when they read
that code.

vsyscall=none: Trying to execute a vsyscall will segfault.

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/8449fb3abf89851fd6b2260972666a6f82542284.1312988155.git.luto@mit.edu
Signed-off-by: H. Peter Anvin

x86-64: Move vread_tsc and vread_hpet into the vDSO

2011-07-15T00:57:05+00:00

The vsyscall page now consists entirely of trap instructions.

Cc: John Stultz 
Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/637648f303f2ef93af93bae25186e9a1bea093f5.1310639973.git.luto@mit.edu
Signed-off-by: H. Peter Anvin

x86-64: Improve vsyscall emulation CS and RIP handling

2011-07-13T18:22:55+00:00

Three fixes here:
 - Send SIGSEGV if called from compat code or with a funny CS.
 - Don't BUG on impossible addresses.
 - Add a missing local_irq_disable.

This patch also removes an unused variable.

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/6fb2b13ab39b743d1e4f466eef13425854912f7f.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin

x86-64: Emulate legacy vsyscalls

2011-06-07T08:02:35+00:00

There's a fair amount of code in the vsyscall page.  It contains
a syscall instruction (in the gettimeofday fallback) and who
knows what will happen if an exploit jumps into the middle of
some other code.

Reduce the risk by replacing the vsyscalls with short magic
incantations that cause the kernel to emulate the real
vsyscalls. These incantations are useless if entered in the
middle.

This causes vsyscalls to be a little more expensive than real
syscalls.  Fortunately sensible programs don't use them.
The only exception is time() which is still called by glibc
through the vsyscall - but calling time() millions of times
per second is not sensible. glibc has this fixed in the
development tree.

This patch is not perfect: the vread_tsc and vread_hpet
functions are still at a fixed address.  Fixing that might
involve making alternative patching work in the vDSO.

Signed-off-by: Andy Lutomirski 
Acked-by: Linus Torvalds 
Cc: Jesper Juhl 
Cc: Borislav Petkov 
Cc: Arjan van de Ven 
Cc: Jan Beulich 
Cc: richard -rw- weinberger 
Cc: Mikael Pettersson 
Cc: Andi Kleen 
Cc: Brian Gerst 
Cc: Louis Rilling 
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/e64e1b3c64858820d12c48fa739efbd1485e79d5.1307292171.git.luto@mit.edu
[ Removed the CONFIG option - it's simpler to just do it unconditionally. Tidied up the code as well. ]
Signed-off-by: Ingo Molnar

x86-64: Clean up vdso/kernel shared variables

2011-05-24T12:51:28+00:00

Variables that are shared between the vdso and the kernel are
currently a bit of a mess.  They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.

This changes them all to use a common mechanism.  All of them are
delcared in vvar.h with a fixed address (validated by the linker
script).  In the kernel (as before), they look like ordinary
read-write variables.  In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.

The vdso is now loaded verbatim into memory without any fixups.  As a
side bonus, access from the vdso is faster because a level of
indirection is removed.

While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.

Signed-off-by: Andy Lutomirski 
Cc: Andi Kleen 
Cc: Linus Torvalds 
Cc: "David S. Miller" 
Cc: Eric Dumazet 
Cc: Peter Zijlstra 
Cc: Borislav Petkov 
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner

x86: Fix ASM_X86__ header guards

2008-10-23T05:55:23+00:00

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin