linux.git/arch/sh/kernel/kgdb.c, branch v5.4.252

Merge tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux

2019-01-01T23:38:14+00:00

Pull kgdb updates from Daniel Thompson:
 "Mostly clean ups although while Doug's was chasing down a odd lockdep
  warning he also did some work to improved debugger resilience when
  some CPUs fail to respond to the round up request.

  The main changes are:

   - Fixing a lockdep warning on architectures that cannot use an NMI
     for the round up plus related changes to make CPU round up and all
     CPU backtrace more resilient.

   - Constify the arch ops tables

   - A couple of other small clean ups

  Two of the three patchsets here include changes that spill over into
  arch/. Changes in the arch space are relatively narrow in scope (and
  directly related to kgdb). Didn't get comprehensive acks but all
  impacted maintainers were Cc:ed in good time"

* tag 'kgdb-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux:
  kgdb/treewide: constify struct kgdb_arch arch_kgdb_ops
  mips/kgdb: prepare arch_kgdb_ops for constness
  kdb: use bool for binary state indicators
  kdb: Don't back trace on a cpu that didn't round up
  kgdb: Don't round up a CPU that failed rounding up before
  kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()
  kgdb: Remove irq flags from roundup

kgdb/treewide: constify struct kgdb_arch arch_kgdb_ops

2018-12-30T08:33:06+00:00

checkpatch.pl reports the following:

  WARNING: struct kgdb_arch should normally be const
  #28: FILE: arch/mips/kernel/kgdb.c:397:
  +struct kgdb_arch arch_kgdb_ops = {

This report makes sense, as all other ops struct, this
one should also be const. This patch does the change.

Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Cc: Richard Kuo 
Cc: Michal Simek 
Cc: Ralf Baechle 
Cc: Paul Burton 
Cc: James Hogan 
Cc: Ley Foon Tan 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: x86@kernel.org
Acked-by: Daniel Thompson 
Acked-by: Paul Burton 
Signed-off-by: Christophe Leroy 
Acked-by: Borislav Petkov 
Acked-by: Michael Ellerman  (powerpc)
Signed-off-by: Daniel Thompson

kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()

2018-12-30T08:28:02+00:00

When I had lockdep turned on and dropped into kgdb I got a nice splat
on my system.  Specifically it hit:
  DEBUG_LOCKS_WARN_ON(current->hardirq_context)

Specifically it looked like this:
  sysrq: SysRq : DEBUG
  ------------[ cut here ]------------
  DEBUG_LOCKS_WARN_ON(current->hardirq_context)
  WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 lockdep_hardirqs_on+0xf0/0x160
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27
  pstate: 604003c9 (nZCv DAIF +PAN -UAO)
  pc : lockdep_hardirqs_on+0xf0/0x160
  ...
  Call trace:
   lockdep_hardirqs_on+0xf0/0x160
   trace_hardirqs_on+0x188/0x1ac
   kgdb_roundup_cpus+0x14/0x3c
   kgdb_cpu_enter+0x53c/0x5cc
   kgdb_handle_exception+0x180/0x1d4
   kgdb_compiled_brk_fn+0x30/0x3c
   brk_handler+0x134/0x178
   do_debug_exception+0xfc/0x178
   el1_dbg+0x18/0x78
   kgdb_breakpoint+0x34/0x58
   sysrq_handle_dbg+0x54/0x5c
   __handle_sysrq+0x114/0x21c
   handle_sysrq+0x30/0x3c
   qcom_geni_serial_isr+0x2dc/0x30c
  ...
  ...
  irq event stamp: ...45
  hardirqs last  enabled at (...44): [...] __do_softirq+0xd8/0x4e4
  hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130
  softirqs last  enabled at (...42): [...] _local_bh_enable+0x2c/0x34
  softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100
  ---[ end trace adf21f830c46e638 ]---

Looking closely at it, it seems like a really bad idea to be calling
local_irq_enable() in kgdb_roundup_cpus().  If nothing else that seems
like it could violate spinlock semantics and cause a deadlock.

Instead, let's use a private csd alongside
smp_call_function_single_async() to round up the other CPUs.  Using
smp_call_function_single_async() doesn't require interrupts to be
enabled so we can remove the offending bit of code.

In order to avoid duplicating this across all the architectures that
use the default kgdb_roundup_cpus(), we'll add a "weak" implementation
to debug_core.c.

Looking at all the people who previously had copies of this code,
there were a few variants.  I've attempted to keep the variants
working like they used to.  Specifically:
* For arch/arc we passed NULL to kgdb_nmicallback() instead of
  get_irq_regs().
* For arch/mips there was a bit of extra code around
  kgdb_nmicallback()

NOTE: In this patch we will still get into trouble if we try to round
up a CPU that failed to round up before.  We'll try to round it up
again and potentially hang when we try to grab the csd lock.  That's
not new behavior but we'll still try to do better in a future patch.

Suggested-by: Daniel Thompson 
Signed-off-by: Douglas Anderson 
Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Richard Kuo 
Cc: Ralf Baechle 
Cc: Paul Burton 
Cc: James Hogan 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Yoshinori Sato 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Acked-by: Will Deacon 
Signed-off-by: Daniel Thompson

kgdb: Remove irq flags from roundup

2018-12-30T08:24:21+00:00

The function kgdb_roundup_cpus() was passed a parameter that was
documented as:

> the flags that will be used when restoring the interrupts. There is
> local_irq_save() call before kgdb_roundup_cpus().

Nobody used those flags.  Anyone who wanted to temporarily turn on
interrupts just did local_irq_enable() and local_irq_disable() without
looking at them.  So we can definitely remove the flags.

Signed-off-by: Douglas Anderson 
Cc: Vineet Gupta 
Cc: Russell King 
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Richard Kuo 
Cc: Ralf Baechle 
Cc: Paul Burton 
Cc: James Hogan 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Yoshinori Sato 
Cc: Rich Felker 
Cc: "David S. Miller" 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Acked-by: Will Deacon 
Signed-off-by: Daniel Thompson

sh: kernel: convert to SPDX identifiers

2018-12-28T20:11:45+00:00

Update license to use SPDX-License-Identifier instead of verbose license
text.

Link: http://lkml.kernel.org/r/8736rccswn.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Kuninori Morimoto 
Reviewed-by: Simon Horman 
Cc: Rich Felker 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:36+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

arch/sh/kernel/kgdb.c: add missing #include

2014-01-22T00:19:42+00:00

  arch/sh/kernel/kgdb.c: In function 'sleeping_thread_to_gdb_regs':
  arch/sh/kernel/kgdb.c:225:32: error: implicit declaration of function 'task_stack_page' [-Werror=implicit-function-declaration]
  arch/sh/kernel/kgdb.c:242:23: error: dereferencing pointer to incomplete type
  arch/sh/kernel/kgdb.c:243:22: error: dereferencing pointer to incomplete type
  arch/sh/kernel/kgdb.c: In function 'singlestep_trap_handler':
  arch/sh/kernel/kgdb.c:310:27: error: 'SIGTRAP' undeclared (first use in this function)
  arch/sh/kernel/kgdb.c:310:27: note: each undeclared identifier is reported only once for each function it appears in

This was introduced by commit 16559ae48c76 ("kgdb: remove #include
 from kgdb.h").

[geert@linux-m68k.org: reworded and reformatted]
Signed-off-by: Wanlong Gao 
Signed-off-by: Geert Uytterhoeven 
Reported-by: Fengguang Wu 
Acked-by: Greg Kroah-Hartman 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sh: kgdb: Fix up NULL pointer deref by kgdb_nmicallback.

2012-04-10T05:22:39+00:00

kgdb_nmicallback expects valid register state, so just fetch the register
state with get_irq_regs() as on other platforms.

Signed-off-by: Paul Mundt

sh: kgdb: Fill out sleeping_thread_to_gdb_regs() state.

2012-04-10T05:00:30+00:00

Presently we're using a pretty dumbed-down implementation that copies
over register state visible from the thread info, leaving the bulk of the
switch_to state uncopied.

Given that we're also depending on register bank toggling for switch_to
optimization we ought to also explicitly zero out the GP regs that reside
in an alternate bank in order to prevent handing back garbage.

There are a few extra registers that we have state for in switch_to, so
copy those over while we're at it.

Signed-off-by: Paul Mundt

sh: kgdb: Individual register get/set support.

2012-04-10T04:42:56+00:00

This updates sh following the generic kgdb changes adding support
for individual register get/set for kgdb/kdb use.

Signed-off-by: Paul Mundt