linux-toradex.git/arch/x86/include/asm/debugreg.h, branch v4.4.87

perf/x86/amd: AMD support for bp_len > HW_BREAKPOINT_LEN_8

2014-12-03T14:14:26+00:00

Implement hardware breakpoint address mask for AMD Family 16h and
above processors. CPUID feature bit indicates hardware support for
DRn_ADDR_MASK MSRs. These masks further qualify DRn/DR7 hardware
breakpoint addresses to allow matching of larger addresses ranges.

Valuable advice and pseudo code from Oleg Nesterov 

Signed-off-by: Jacob Shin 
Signed-off-by: Suravee Suthikulpanit 
Acked-by: Jiri Olsa 
Reviewed-by: Oleg Nesterov 
Cc: Arnaldo Carvalho de Melo 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: xiakaixu 
Signed-off-by: Frederic Weisbecker

x86: Replace __get_cpu_var uses

2014-08-26T17:45:49+00:00

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

Cc: Thomas Gleixner 
Cc: x86@kernel.org
Acked-by: H. Peter Anvin 
Acked-by: Ingo Molnar 
Signed-off-by: Christoph Lameter 
Signed-off-by: Tejun Heo

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: relocate get/set debugreg fcns to include/asm/debugreg.

2012-02-28T22:48:04+00:00

Since we already have a debugreg.h header file, move the
assoc. get/set functions to it.  In addition to it being the
logical home for them, it has a secondary advantage.  The
functions that are moved use BUG().  So we really need to
have linux/bug.h in scope.  But asm/processor.h is used about
600 times, vs. only about 15 for debugreg.h -- so adding bug.h
to the latter reduces the amount of time we'll be processing
it during a compile.

Signed-off-by: Paul Gortmaker 
Acked-by: Ingo Molnar 
CC: Thomas Gleixner 
CC: "H. Peter Anvin"

x86: Add counter when debug stack is used with interrupts enabled

2011-12-21T20:38:56+00:00

Mathieu Desnoyers pointed out a case that can cause issues with
NMIs running on the debug stack:

  int3 -> interrupt -> NMI -> int3

Because the interrupt changes the stack, the NMI will not see that
it preempted the debug stack. Looking deeper at this case,
interrupts only happen when the int3 is from userspace or in
an a location in the exception table (fixup).

  userspace -> int3 -> interurpt -> NMI -> int3

All other int3s that happen in the kernel should be processed
without ever enabling interrupts, as the do_trap() call will
panic the kernel if it is called to process any other location
within the kernel.

Adding a counter around the sections that enable interrupts while
using the debug stack allows the NMI to also check that case.
If the NMI sees that it either interrupted a task using the debug
stack or the debug counter is non-zero, then it will have to
change the IDT table to make the int3 not change stacks (which will
corrupt the stack if it does).

Note, I had to move the debug_usage functions out of processor.h
and into debugreg.h because of the static inlined functions to
inc and dec the debug_usage counter. __get_cpu_var() requires
smp.h which includes processor.h, and would fail to build.

Link: http://lkml.kernel.org/r/1323976535.23971.112.camel@gandalf.stny.rr.com

Reported-by: Mathieu Desnoyers 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: H. Peter Anvin 
Cc: Thomas Gleixner 
Cc: Paul Turner 
Cc: Frederic Weisbecker 
Signed-off-by: Steven Rostedt

x86: Use this_cpu_ops to optimize code

2010-12-30T11:20:28+00:00

Go through x86 code and replace __get_cpu_var and get_cpu_var
instances that refer to a scalar and are not used for address
determinations.

Cc: Yinghai Lu 
Cc: Ingo Molnar 
Acked-by: Tejun Heo 
Acked-by: "H. Peter Anvin" 
Signed-off-by: Christoph Lameter 
Signed-off-by: Tejun Heo

x86/debug: Clear reserved bits of DR6 in do_debug()

2010-01-29T01:26:10+00:00

Clear the reserved bits from the stored copy of debug status
register (DR6).
This will help easy bitwise operations such as quick testing
of a debug event origin.

Signed-off-by: K.Prasad 
Cc: Roland McGrath 
Cc: Jan Kiszka 
Cc: Alan Stern 
Cc: Ingo Molnar 
LKML-Reference: <20100128111401.GB13935@in.ibm.com>
Signed-off-by: Frederic Weisbecker

x86: Rename global percpu symbol dr7 to cpu_dr7

2009-11-25T13:30:04+00:00

Percpu symbols now occupy the same namespace as other global
symbols and as such short global symbols without subsystem
prefix tend to collide with local variables.  dr7 percpu
variable used by x86 was hit by this. Rename it to cpu_dr7.

The rename also makes it more consistent with its fellow
cpu_debugreg percpu variable.

Signed-off-by: Tejun Heo 
Cc: Frederic Weisbecker 
Cc: Peter Zijlstra 
Cc: Rusty Russell 
Cc: Christoph Lameter 
Cc: Linus Torvalds ,
Cc: Andrew Morton 
LKML-Reference: <20091125115856.GA17856@elte.hu>
Signed-off-by: Ingo Molnar 
Reported-by: Stephen Rothwell

hw-breakpoints, x86: Fix modular KVM build

2009-11-14T14:32:53+00:00

This build error:

arch/x86/kvm/x86.c:3655: error: implicit declaration of function 'hw_breakpoint_restore'

Happens because in the CONFIG_KVM=m case there's no 'CONFIG_KVM' define
in the kernel - it's CONFIG_KVM_MODULE in that case.

Make the prototype available unconditionally.

Cc: Frederic Weisbecker 
Cc: Prasad 
LKML-Reference: <1258114575-32655-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar

hw-breakpoints: Wrap in the KVM breakpoint active state check

2009-11-10T10:23:43+00:00

Wrap in the cpu dr7 check that tells if we have active
breakpoints that need to be restored in the cpu.

This wrapper makes the check more self-explainable and also
reusable for any further other uses.

Reported-by: Jan Kiszka 
Signed-off-by: Frederic Weisbecker 
Cc: Avi Kivity 
Cc: "K. Prasad"