linux.git/arch/arm/kernel/hw_breakpoint.c, branch v5.8

ARM: 8986/1: hw_breakpoint: Don't invoke overflow handler on uaccess watchpoints

2020-07-21T15:32:54+00:00

Unprivileged memory accesses generated by the so-called "translated"
instructions (e.g. LDRT) in kernel mode can cause user watchpoints to fire
unexpectedly. In such cases, the hw_breakpoint logic will invoke the user
overflow handler which will typically raise a SIGTRAP back to the current
task. This is futile when returning back to the kernel because (a) the
signal won't have been delivered and (b) userspace can't handle the thing
anyway.

Avoid invoking the user overflow handler for watchpoints triggered by
kernel uaccess routines, and instead single-step over the faulting
instruction as we would if no overflow handler had been installed.

Cc: 
Fixes: f81ef4a920c8 ("ARM: 6356/1: hw-breakpoint: add ARM backend for the hw-breakpoint framework")
Reported-by: Luis Machado 
Tested-by: Luis Machado 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 8927/1: ARM/hw_breakpoint: add more ARMv8 debug architecture versions support

2019-11-15T22:21:08+00:00

When ARMv8 cores are used in AArch32 mode, arch_hw_breakpoint_init()
in arch/arm/kernel/hw_breakpoint.c will be used.

From ARMv8 specification, v8 debug architecture versions defined:
* 0110 ARMv8, v8 Debug architecture.
* 0111 ARMv8.1, v8 Debug architecture, with Virtualization Host
  Extensions.
* 1000 ARMv8.2, v8.2 Debug architecture.
* 1001 ARMv8.4, v8.4 Debug architecture.

So missing ARMv8.1/ARMv8.2/ARMv8.4 cases will cause
enable_monitor_mode() returns -ENODEV,and eventually
arch_hw_breakpoint_init() will fail.

Signed-off-by: Candle Sun 
Signed-off-by: Nianfu Bai 
Signed-off-by: Russell King

ARM/hw_breakpoint: Mark expected switch fall-throughs

2019-08-10T00:45:01+00:00

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_arch_parse':
arch/arm/kernel/hw_breakpoint.c:609:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
      ^
arch/arm/kernel/hw_breakpoint.c:611:2: note: here
  case 3:
  ^~~~
arch/arm/kernel/hw_breakpoint.c:613:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
      ^
arch/arm/kernel/hw_breakpoint.c:615:2: note: here
  default:
  ^~~~~~~
arch/arm/kernel/hw_breakpoint.c: In function 'arch_build_bp_info':
arch/arm/kernel/hw_breakpoint.c:544:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if ((hw->ctrl.type != ARM_BREAKPOINT_EXECUTE)
      ^
arch/arm/kernel/hw_breakpoint.c:547:2: note: here
  default:
  ^~~~~~~
In file included from include/linux/kernel.h:11,
                 from include/linux/list.h:9,
                 from include/linux/preempt.h:11,
                 from include/linux/hardirq.h:5,
                 from arch/arm/kernel/hw_breakpoint.c:16:
arch/arm/kernel/hw_breakpoint.c: In function 'hw_breakpoint_pending':
include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:136:2: note: in expansion of macro 'unlikely'
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
arch/arm/kernel/hw_breakpoint.c:863:3: note: in expansion of macro 'WARN'
   WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n");
   ^~~~
arch/arm/kernel/hw_breakpoint.c:864:2: note: here
  case ARM_ENTRY_SYNC_WATCHPOINT:
  ^~~~
arch/arm/kernel/hw_breakpoint.c: In function 'core_has_os_save_restore':
arch/arm/kernel/hw_breakpoint.c:910:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (oslsr & ARM_OSLSR_OSLM0)
      ^
arch/arm/kernel/hw_breakpoint.c:912:2: note: here
  default:
  ^~~~~~~

Reported-by: Stephen Rothwell 
Reviewed-by: Kees Cook 
Signed-off-by: Gustavo A. R. Silva

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333

2019-06-05T15:37:06+00:00

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 version 2 as
  published by the free software foundation 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-only

has been chosen to replace the boilerplate/reference in 136 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexios Zavras 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000436.384967451@linutronix.de
Signed-off-by: Greg Kroah-Hartman

perf/arch/arm: Implement hw_breakpoint_arch_parse()

2018-06-26T07:07:56+00:00

Migrate to the new API in order to remove arch_validate_hwbkpt_settings()
that clumsily mixes up architecture validation and commit.

Signed-off-by: Frederic Weisbecker 
Acked-by: Mark Rutland 
Cc: Alexander Shishkin 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Benjamin Herrenschmidt 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: Jiri Olsa 
Cc: Joel Fernandes 
Cc: Linus Torvalds 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Rich Felker 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Link: http://lkml.kernel.org/r/1529981939-8231-6-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar

perf/hw_breakpoint: Pass arch breakpoint struct to arch_check_bp_in_kernelspace()

2018-06-26T07:07:54+00:00

We can't pass the breakpoint directly on arch_check_bp_in_kernelspace()
anymore because its architecture internal datas (struct arch_hw_breakpoint)
are not yet filled by the time we call the function, and most
implementation need this backend to be up to date. So arrange the
function to take the probing struct instead.

Signed-off-by: Frederic Weisbecker 
Cc: Alexander Shishkin 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Benjamin Herrenschmidt 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: Jiri Olsa 
Cc: Joel Fernandes 
Cc: Linus Torvalds 
Cc: Mark Rutland 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Rich Felker 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Link: http://lkml.kernel.org/r/1529981939-8231-3-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar

ARM: 8733/1: hw_breakpoint: Mark variables as __ro_after_init

2017-12-17T22:16:20+00:00

core_num_brps, core_num_wrps, debug_arch, has_ossr,
max_watchpoint_len are setup once while init stage,
and never changed after that.
so it is good candidate for __ro_after_init.

Reviewed-by: Kees Cook 
Signed-off-by: Jinbum Park 
Signed-off-by: Russell King

ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init

2017-06-20T10:25:22+00:00

Recent change to use cpuhp_setup_state_cpuslocked() with commit
fe2a5cd8aa03 ("ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()")
missed to change the related paired cpuhp_remove_state_nocalls_cpuslocked().

Now if arch_hw_breakpoint_init() fails, we get "WARNING: possible recursive
locking detected" on the exit path.

Fixes: fe2a5cd8aa03 ("ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()")
Signed-off-by: Tony Lindgren 
Acked-by: Sebastian Andrzej Siewior 
Cc: Mark Rutland 
Cc: linux-omap@vger.kernel.org
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Steven Rostedt 
Cc: Russell King 
Cc: "Paul E . McKenney" 
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170616082238.15553-1-tony@atomide.com
Signed-off-by: Thomas Gleixner

ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()

2017-05-26T08:10:40+00:00

arch_hw_breakpoint_init() holds get_online_cpus() while registerring the
hotplug callbacks.

cpuhp_setup_state() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use cpuhp_setup_state_cpuslocked() to avoid the nested call. Convert
*_online_cpus() to the new interfaces while at it.

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Thomas Gleixner 
Acked-by: Ingo Molnar 
Acked-by: Mark Rutland 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Steven Rostedt 
Cc: Russell King 
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170524081548.170940729@linutronix.de

ARM: 8634/1: hw_breakpoint: blacklist Scorpion CPUs

2017-01-10T23:32:26+00:00

On APQ8060, the kernel crashes in arch_hw_breakpoint_init, taking an
undefined instruction trap within write_wb_reg. This is because Scorpion
CPUs erroneously appear to set DBGPRSR.SPD when WFI is issued, even if
the core is not powered down. When DBGPRSR.SPD is set, breakpoint and
watchpoint registers are treated as undefined.

It's possible to trigger similar crashes later on from userspace, by
requesting the kernel to install a breakpoint or watchpoint, as we can
go idle at any point between the reset of the debug registers and their
later use. This has always been the case.

Given that this has always been broken, no-one has complained until now,
and there is no clear workaround, disable hardware breakpoints and
watchpoints on Scorpion to avoid these issues.

Signed-off-by: Mark Rutland 
Reported-by: Linus Walleij 
Reviewed-by: Stephen Boyd 
Acked-by: Will Deacon 
Cc: Russell King 
Cc: stable@vger.kernel.org
Signed-off-by: Russell King