hw-breakpoint: Attribute authorship of hw-breakpoint related files

Attribute authorship to developers of hw-breakpoint related
files.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan St

hw-breakpoint: Attribute authorship of hw-breakpoint related files

Attribute authorship to developers of hw-breakpoint related
files.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091123154713.GA5593@in.ibm.com>
[ v2: moved it to latest -tip ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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hw-breakpoints, x86: Fix modular KVM build

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

hw-breakpoints, x86: Fix modular KVM build

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 <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <1258114575-32655-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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hw-breakpoints: Fix broken a.out format dump

Fix the broken a.out format dump. For now we only dump the ptrace
breakpoints.

TODO: Dump every perf breakpoints for the current thread, not only
ptrace

hw-breakpoints: Fix broken a.out format dump

Fix the broken a.out format dump. For now we only dump the ptrace
breakpoints.

TODO: Dump every perf breakpoints for the current thread, not only
ptrace based ones.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>

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hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events

This patch rebase the implementation of the breakpoints API on top of
perf events instances.

Each breakpoints are now perf eve

hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf events

This patch rebase the implementation of the breakpoints API on top of
perf events instances.

Each breakpoints are now perf events that handle the
register scheduling, thread/cpu attachment, etc..

The new layering is now made as follows:

ptrace kgdb ftrace perf syscall
\ | / /
\ | / /
/
Core breakpoint API /
/
| /
| /

Breakpoints perf events

|
|

Breakpoints PMU ---- Debug Register constraints handling
(Part of core breakpoint API)
|
|

Hardware debug registers

Reasons of this rewrite:

- Use the centralized/optimized pmu registers scheduling,
implying an easier arch integration
- More powerful register handling: perf attributes (pinned/flexible
events, exclusive/non-exclusive, tunable period, etc...)

Impact:

- New perf ABI: the hardware breakpoints counters
- Ptrace breakpoints setting remains tricky and still needs some per
thread breakpoints references.

Todo (in the order):

- Support breakpoints perf counter events for perf tools (ie: implement
perf_bpcounter_event())
- Support from perf tools

Changes in v2:

- Follow the perf "event " rename
- The ptrace regression have been fixed (ptrace breakpoint perf events
weren't released when a task ended)
- Drop the struct hw_breakpoint and store generic fields in
perf_event_attr.
- Separate core and arch specific headers, drop
asm-generic/hw_breakpoint.h and create linux/hw_breakpoint.h
- Use new generic len/type for breakpoint
- Handle off case: when breakpoints api is not supported by an arch

Changes in v3:

- Fix broken CONFIG_KVM, we need to propagate the breakpoint api
changes to kvm when we exit the guest and restore the bp registers
to the host.

Changes in v4:

- Drop the hw_breakpoint_restore() stub as it is only used by KVM
- EXPORT_SYMBOL_GPL hw_breakpoint_restore() as KVM can be built as a
module
- Restore the breakpoints unconditionally on kvm guest exit:
TIF_DEBUG_THREAD doesn't anymore cover every cases of running
breakpoints and vcpu->arch.switch_db_regs might not always be
set when the guest used debug registers.
(Waiting for a reliable optimization)

Changes in v5:

- Split-up the asm-generic/hw-breakpoint.h moving to
linux/hw_breakpoint.h into a separate patch
- Optimize the breakpoints restoring while switching from kvm guest
to host. We only want to restore the state if we have active
breakpoints to the host, otherwise we don't care about messed-up
address registers.
- Add asm/hw_breakpoint.h to Kbuild
- Fix bad breakpoint type in trace_selftest.c

Changes in v6:

- Fix wrong header inclusion in trace.h (triggered a build
error with CONFIG_FTRACE_SELFTEST

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jan Kiszka <jan.kiszka@web.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>

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x86: hw_breakpoint.c arch_check_va_in_kernelspace and hw_breakpoint_handler should be static

arch_check_va_in_kernelspace() and hw_breakpoint_handler() is used only by same file so it should be stat

x86: hw_breakpoint.c arch_check_va_in_kernelspace and hw_breakpoint_handler should be static

arch_check_va_in_kernelspace() and hw_breakpoint_handler() is used only by same file so it should be static.

Also fixed non-ANSI function declaration of function 'arch_uninstall_thread_hw_breakpoint'

Fixed following sparse warnings :
arch/x86/kernel/hw_breakpoint.c:124:42: warning: non-ANSI function declaration of function 'arch_uninstall_thread_hw_breakpoint'
arch/x86/kernel/hw_breakpoint.c:169:5: warning: symbol 'arch_check_va_in_kernelspace' was not declared. Should it be static?
arch/x86/kernel/hw_breakpoint.c:313:15: warning: symbol 'hw_breakpoint_handler' was not declared. Should it be static?

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1245230059.2662.4.camel@ht.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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hw-breakpoints: reset bits in dr6 after the corresponding exception is handled

This patch resets the bit in dr6 after the corresponding exception is
handled in code, so that we keep a clean track of

hw-breakpoints: reset bits in dr6 after the corresponding exception is handled

This patch resets the bit in dr6 after the corresponding exception is
handled in code, so that we keep a clean track of the current virtual debug
status register.

[ Impact: keep track of breakpoints triggering completion ]

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

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hw-breakpoints: x86 architecture implementation of Hardware Breakpoint interfaces

This patch introduces the arch-specific implementation of the generic
hardware breakpoints in kernel/hw_breakpoint.c

hw-breakpoints: x86 architecture implementation of Hardware Breakpoint interfaces

This patch introduces the arch-specific implementation of the generic
hardware breakpoints in kernel/hw_breakpoint.c inside x86 specific directories.
It contains functions which help to validate and serve requests using
Hardware Breakpoint registers on x86 processors.

[ fweisbec@gmail.com: fix conflict against kmemcheck ]

Original-patch-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

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x86/debug: Prevent data breakpoints on cpu_dr7

commit 3943abf2dbfae9ea4d2da05c1db569a0603f76da upstream.

local_db_save() is called at the start of exc_debug_kernel(), reads DR7 and

x86/debug: Prevent data breakpoints on cpu_dr7

commit 3943abf2dbfae9ea4d2da05c1db569a0603f76da upstream.

local_db_save() is called at the start of exc_debug_kernel(), reads DR7 and
disables breakpoints to prevent recursion.

When running in a guest (X86_FEATURE_HYPERVISOR), local_db_save() reads the
per-cpu variable cpu_dr7 to check whether a breakpoint is active or not
before it accesses DR7.

A data breakpoint on cpu_dr7 therefore results in infinite #DB recursion.

Disallow data breakpoints on cpu_dr7 to prevent that.

Fixes: 84b6a3491567a("x86/entry: Optimize local_db_save() for virt")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210204152708.21308-2-jiangshanlai@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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x86/debug: Prevent data breakpoints on __per_cpu_offset

commit c4bed4b96918ff1d062ee81fdae4d207da4fa9b0 upstream.

When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU GSBA

x86/debug: Prevent data breakpoints on __per_cpu_offset

commit c4bed4b96918ff1d062ee81fdae4d207da4fa9b0 upstream.

When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU GSBASE value
via __per_cpu_offset or pcpu_unit_offsets.

When a data breakpoint is set on __per_cpu_offset[cpu] (read-write
operation), the specific CPU will be stuck in an infinite #DB loop.

RCU will try to send an NMI to the specific CPU, but it is not working
either since NMI also relies on paranoid_entry(). Which means it's
undebuggable.

Fixes: eaad981291ee3("x86/entry/64: Introduce the FIND_PERCPU_BASE macro")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210204152708.21308-1-jiangshanlai@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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x86/debug: Fix DR6 handling

commit 9ad22e165994ccb64d85b68499eaef97342c175b upstream.

Tom reported that one of the GDB test-cases failed, and Boris bisected
it to commit:

x86/debug: Fix DR6 handling

commit 9ad22e165994ccb64d85b68499eaef97342c175b upstream.

Tom reported that one of the GDB test-cases failed, and Boris bisected
it to commit:

d53d9bc0cf78 ("x86/debug: Change thread.debugreg6 to thread.virtual_dr6")

The debugging session led us to commit:

6c0aca288e72 ("x86: Ignore trap bits on single step exceptions")

It turns out that TF and data breakpoints are both traps and will be
merged, while instruction breakpoints are faults and will not be merged.
This means 6c0aca288e72 is wrong, only TF and instruction breakpoints
need to be excluded while TF and data breakpoints can be merged.

[ bp: Massage commit message. ]

Fixes: d53d9bc0cf78 ("x86/debug: Change thread.debugreg6 to thread.virtual_dr6")
Fixes: 6c0aca288e72 ("x86: Ignore trap bits on single step exceptions")
Reported-by: Tom de Vries <tdevries@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/YBMAbQGACujjfz%2Bi@hirez.programming.kicks-ass.net
Link: https://lkml.kernel.org/r/20210128211627.GB4348@worktop.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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x86/debug: Change thread.debugreg6 to thread.virtual_dr6

Current usage of thread.debugreg6 is convoluted at best. It starts life as
a copy of the hardware DR6 value, but then various bit

x86/debug: Change thread.debugreg6 to thread.virtual_dr6

Current usage of thread.debugreg6 is convoluted at best. It starts life as
a copy of the hardware DR6 value, but then various bits are cleared and
set.

Replace this with a new variable thread.virtual_dr6 that is initialized to
0 when DR6 is read and only gains bits, at the same time the actual (on
stack) dr6 value which is read from the hardware only gets bits cleared.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.415372940@infradead.org

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x86/debug: Support negative polarity DR6 bits

DR6 has a whole bunch of bits that have negative polarity; they were
architecturally reserved and defined to be 1 and are now getting used.

x86/debug: Support negative polarity DR6 bits

DR6 has a whole bunch of bits that have negative polarity; they were
architecturally reserved and defined to be 1 and are now getting used.
Since they're 1 by default, 0 becomes the signal value.

Handle this by xor'ing the read DR6 value by the reserved mask, this
will flip them around such that 1 is the signal value (positive
polarity).

Current Linux doesn't yet support any of these bits, but there's two
defined:

- DR6[11] Bus Lock Debug Exception (ISEr39)
- DR6[16] Restricted Transactional Memory (SDM)

Update ptrace_{set,get}_debugreg() to provide/consume the value in
architectural polarity. Although afaict ptrace_set_debugreg(6) is
pointless, the value is not consumed anywhere.

Change hw_breakpoint_restore() to alway write the DR6_RESERVED value
to DR6, again, no consumer for that write.

Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.354220797@infradead.org

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x86/debug: Simplify hw_breakpoint_handler()

This is called with interrupts disabled, there's no point in using
get_cpu() and per_cpu().

Signed-off-by: Peter Zijlstra (Intel) <pe

x86/debug: Simplify hw_breakpoint_handler()

This is called with interrupts disabled, there's no point in using
get_cpu() and per_cpu().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.292906672@infradead.org

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x86/debug: Remove aout_dump_debugregs()

Unused remnants for the bit-bucket.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@lin

x86/debug: Remove aout_dump_debugregs()

Unused remnants for the bit-bucket.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20200902133201.233022474@infradead.org

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treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

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x86/entry: Optimize local_db_save() for virt

Because DRn access is 'difficult' with virt; but the DR7 read is cheaper
than a cacheline miss on native, add a virt specific fast path to

x86/entry: Optimize local_db_save() for virt

Because DRn access is 'difficult' with virt; but the DR7 read is cheaper
than a cacheline miss on native, add a virt specific fast path to
local_db_save(), such that when breakpoints are not in use to avoid
touching DRn entirely.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.187833200@infradead.org

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x86/hw_breakpoint: Prevent data breakpoints on user_pcid_flush_mask

The per-CPU user_pcid_flush_mask is used in the low level entry code. A
data breakpoint can cause #DB recursion.

x86/hw_breakpoint: Prevent data breakpoints on user_pcid_flush_mask

The per-CPU user_pcid_flush_mask is used in the low level entry code. A
data breakpoint can cause #DB recursion.

Protect the full cpu_tlbstate structure for simplicity.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-5-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.955117574@infradead.org

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x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw

cpu_tss_rw is not directly referenced by hardware, but cpu_tss_rw is
accessed in CPU entry code, especially when #DB shi

x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw

cpu_tss_rw is not directly referenced by hardware, but cpu_tss_rw is
accessed in CPU entry code, especially when #DB shifts its stacks.

If a data breakpoint would be set on cpu_tss_rw.x86_tss.ist[IST_INDEX_DB],
it would cause recursive #DB ending up in a double fault.

Add it to the list of protected items.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-4-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.897976479@infradead.org

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x86/hw_breakpoint: Prevent data breakpoints on direct GDT

A data breakpoint on the GDT can be fatal and must be avoided. The GDT in
the CPU entry area is already protected, but not the

x86/hw_breakpoint: Prevent data breakpoints on direct GDT

A data breakpoint on the GDT can be fatal and must be avoided. The GDT in
the CPU entry area is already protected, but not the direct GDT.

Add the necessary protection.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-3-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.840953950@infradead.org

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x86/hw_breakpoint: Add within_area() to check data breakpoints

Add a within_area() helper to checking whether the data breakpoints overlap
with cpu_entry_area.

It will be used t

x86/hw_breakpoint: Add within_area() to check data breakpoints

Add a within_area() helper to checking whether the data breakpoints overlap
with cpu_entry_area.

It will be used to completely prevent data breakpoints on GDT, IDT, or TSS.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-2-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.784524504@infradead.org

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x86/db: Split out dr6/7 handling

DR6/7 should be handled before nmi_enter() is invoked and restore after
nmi_exit() to minimize the exposure.

Split it out into helper inlines an

x86/db: Split out dr6/7 handling

DR6/7 should be handled before nmi_enter() is invoked and restore after
nmi_exit() to minimize the exposure.

Split it out into helper inlines and bring it into the correct order.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135314.808628211@linutronix.de

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x86/hw_breakpoint: Prevent data breakpoints on cpu_entry_area

A data breakpoint near the top of an IST stack will cause unrecoverable
recursion. A data breakpoint on the GDT, IDT, or TS

x86/hw_breakpoint: Prevent data breakpoints on cpu_entry_area

A data breakpoint near the top of an IST stack will cause unrecoverable
recursion. A data breakpoint on the GDT, IDT, or TSS is terrifying.
Prevent either of these from happening.

Co-developed-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134058.272448010@linutronix.de

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it u

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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x86/hw_breakpoints: Make default case in hw_breakpoint_arch_parse() return an error

When building with -Wsometimes-uninitialized, Clang warns:

arch/x86/kernel/hw_breakpoint.c:355:2:

x86/hw_breakpoints: Make default case in hw_breakpoint_arch_parse() return an error

When building with -Wsometimes-uninitialized, Clang warns:

arch/x86/kernel/hw_breakpoint.c:355:2: warning: variable 'align' is used
uninitialized whenever switch default is taken
[-Wsometimes-uninitialized]

The default cannot be reached because arch_build_bp_info() initializes
hw->len to one of the specified cases. Nevertheless the warning is valid
and returning -EINVAL makes sure that this cannot be broken by future
modifications.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: clang-built-linux@googlegroups.com
Link: https://github.com/ClangBuiltLinux/linux/issues/392
Link: https://lkml.kernel.org/r/20190307212756.4648-1-natechancellor@gmail.com

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x86/hw_breakpoints, kprobes: Remove kprobes ifdeffery

Remove the ifdeffery in the breakpoint parsing arch_build_bp_info() by
adding a within_kprobe_blacklist() stub for the !CONFIG_KPROB

x86/hw_breakpoints, kprobes: Remove kprobes ifdeffery

Remove the ifdeffery in the breakpoint parsing arch_build_bp_info() by
adding a within_kprobe_blacklist() stub for the !CONFIG_KPROBES case.

It is returning true when kprobes are not enabled to mean that any
address is within the kprobes blacklist on such kernels and thus not
allow kernel breakpoints on non-kprobes kernels.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190127131237.4557-1-bp@alien8.de

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