fs: create helper file_user_path() for user displayed mapped file path

Overlayfs uses backing files with "fake" overlayfs f_path and "real"
underlying f_inode, in order to use underlying inode aops for mapped
files and to display the overlayfs path in /proc/<pid>/maps.

In preparation for storing the overlayfs "fake" path instead of the
underlying "real" path in struct backing_file, define a noop helper
file_user_path() that returns f_path for now.

Use the new helper in procfs and kernel logs whenever a path of a
mapped file is displayed to users.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231009153712.1566422-3-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

ARC: pt_regs: create seperate type for ecr

Reduces duplication in each ISA specific pt_regs

Tested-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308151342.ROQ9Urvv-lkp@intel.com
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

arch/arc/kernel/troubleshoot: use vma_lookup() instead of find_vma()

Use vma_lookup() to find the VMA at a specific address. As vma_lookup()
will return NULL if the address is not within any VMA, the start address
no longer needs to be validated.

Link: https://lkml.kernel.org/r/20210521174745.2219620-4-Liam.Howlett@Oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ARC: show_regs: fix r12 printing and simplify

when working on ARC64, spotted an issue in ARCv2 reg file printing.
print_reg_file() assumes contiguous reg-file whereas in ARCv2 they are
not: r12 comes before r0-r11 due to hardware auto-save. Apparently this
issue has been present since v2 port submission.

To avoid bolting hacks for this discontinuity while looping through
pt_regs, just ditching the loop and print pt_regs directly.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

mmap locking API: use coccinelle to convert mmap_sem rwsem call sites

This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arc: add show_stack_loglvl()

Currently, the log-level of show_stack() depends on a platform
realization. It creates situations where the headers are printed with
lower log level or higher than the stacktrace (depending on a platform or
user).

Furthermore, it forces the logic decision from user to an architecture
side. In result, some users as sysrq/kdb/etc are doing tricks with
temporary rising console_loglevel while printing their messages. And in
result it not only may print unwanted messages from other CPUs, but also
omit printing at all in the unlucky case where the printk() was deferred.

Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems an easier
approach than introducing more printk buffers. Also, it will consolidate
printings with headers.

Introduce show_stack_loglvl(), that eventually will substitute
show_stack().

As a good side-effect header "Stack Trace:" is now printed with the same
log level as the rest of backtrace.

[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Link: http://lkml.kernel.org/r/20200418201944.482088-4-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ARC: show_regs: avoid extra line of output

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: show_regs: reduce lines of output

Before
------

| CPU: 1 PID: 29061 Comm: tst-dynarray-at Not tainted 5.6.0-rc1-00002-g941fcc018ca6-dirty #12
|
| [ECR ]: 0x00090000 =>
| [EFA ]: 0x00000000
| [ERET ]: 0x2004aa6c
| @off 0x2aa6c in [/lib/libc-2.31.9000.so]
VMA: 0x20020000 to 0x20122000
| [STAT32]: 0x80080a82 [IE U ]
| BTA: 0x2004aa18 SP: 0x5ffff8a8 FP: 0x5ffff8fc
| LPS: 0x2008788e LPE: 0x20087896 LPC: 0x00000000
| r00: 0x00000000 r01: 0x5ffff8a8 r02: 0x00000000
| r03: 0x00000008 r04: 0xffffffff r05: 0x00000000
| r06: 0x00000000 r07: 0x00000000 r08: 0x00000087
| r09: 0x00000000 r10: 0x2010691c r11: 0x00000020
| r12: 0x2003b214 r13: 0x5ffff8a8 r14: 0x20126e68
| r15: 0x2001f26c r16: 0x2012a000 r17: 0x00000001
| r18: 0x5ffff8fc r19: 0x00000000 r20: 0x5ffff948
| r21: 0x00000001 r22: 0xffffffff r23: 0x5fffff8c
| r24: 0x4008c2a8 r25: 0x2001f6e0

After
-----

| CPU: 1 PID: 29061 Comm: tst-dynarray-at Not tainted 5.6.0-rc1-00002-g941fcc018ca6-dirty #12
| @off 0x2aa6c in [/lib/libc-2.31.9000.so] VMA: 0x20020000 to 0x20122000
| ECR: 0x00090000 EFA: 0x00000000 ERET: 0x2004aa6c
| STAT32: 0x80080a82 [IE U ] BTA: 0x2004aa18
| BLK: 0x2003b214 SP: 0x5ffff8a8 FP: 0x5ffff8fc
| LPS: 0x2008788e LPE: 0x20087896 LPC: 0x00000000
| r00: 0x00000000 r01: 0x5ffff8a8 r02: 0x00000000
| r03: 0x00000008 r04: 0xffffffff r05: 0x00000000
| r06: 0x00000000 r07: 0x00000000 r08: 0x00000087
| r09: 0x00000000 r10: 0x2010691c r11: 0x00000020
| r12: 0x2003b214 r13: 0x5ffff8a8 r14: 0x20126e68
| r15: 0x2001f26c r16: 0x2012a000 r17: 0x00000001
| r18: 0x5ffff8fc r19: 0x00000000 r20: 0x5ffff948
| r21: 0x00000001 r22: 0xffffffff r23: 0x5fffff8c
| r24: 0x4008c2a8 r25: 0x2001f6e0 BTA: 0x2004aa18

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 332

Based on 2 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

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
publishhed by the free software foundation

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 48 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000436.292339952@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARCv2: Add explcit unaligned access support (and ability to disable too)

As of today we enable unaligned access unconditionally on ARCv2.
Do this under a Kconfig option to allow disable it for test, benchmarking
etc. Also while at it

- Select HAVE_EFFICIENT_UNALIGNED_ACCESS
- Although gcc defaults to unaligned access (since GNU 2018.03), add the
right toggles for enabling or disabling as appropriate
- update bootlog to prints both HW feature status (exists, enabled/disabled)
and SW status (used / not used).
- wire up the relaxed memcpy for unaligned access

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: squashed patches, handle gcc -mno-unaligned-access quick]

ARC: show_regs: lockdep: re-enable preemption

signal handling core calls show_regs() with preemption disabled which
on ARC takes mmap_sem for mm/vma access, causing lockdep splat.

| [ARCLinux]# ./segv-null-ptr
| potentially unexpected fatal signal 11.
| BUG: sleeping function called from invalid context at kernel/fork.c:1011
| in_atomic(): 1, irqs_disabled(): 0, pid: 70, name: segv-null-ptr
| no locks held by segv-null-ptr/70.
| CPU: 0 PID: 70 Comm: segv-null-ptr Not tainted 4.18.0+ #69
|
| Stack Trace:
| arc_unwind_core+0xcc/0x100
| ___might_sleep+0x17a/0x190
| mmput+0x16/0xb8
| show_regs+0x52/0x310
| get_signal+0x5ee/0x610
| do_signal+0x2c/0x218
| resume_user_mode_begin+0x90/0xd8

Workaround by re-enabling preemption temporarily.

Note that the preemption disabling in core code around show_regs()
was introduced by commit 3a9f84d354ce ("signals, debug: fix BUG: using
smp_processor_id() in preemptible code in print_fatal_signal()")

to silence a differnt lockdep seen on x86 bakc in 2009.

Cc: <stable@vger.kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: show_regs: lockdep: avoid page allocator...

and use smaller/on-stack buffer instead

The motivation for this change was lockdep splat like below.

| potentially unexpected fatal signal 11.
| BUG: sleeping function called from invalid context at ../mm/page_alloc.c:4317
| in_atomic(): 1, irqs_disabled(): 0, pid: 57, name: segv
| no locks held by segv/57.
| Preemption disabled at:
| [<8182f17e>] get_signal+0x4a6/0x7c4
| CPU: 0 PID: 57 Comm: segv Not tainted 4.17.0+ #23
|
| Stack Trace:
| arc_unwind_core.constprop.1+0xd0/0xf4
| __might_sleep+0x1f6/0x234
| __get_free_pages+0x174/0xca0
| show_regs+0x22/0x330
| get_signal+0x4ac/0x7c4 # print_fatal_signals() -> preempt_disable()
| do_signal+0x30/0x224
| resume_user_mode_begin+0x90/0xd8

So signal handling core calls show_regs() with preemption disabled but
an ensuing GFP_KERNEL page allocator call is flagged by lockdep.

We could have switched to GFP_NOWAIT, but turns out that is not enough
anways and eliding page allocator call leads to less code and
instruction traces to sift thru when debugging pesky crashes.

FWIW, this patch doesn't cure the lockdep splat (which next patch does).

Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: cleanup show_faulting_vma()

- Remove unused variables
- check return value of file_path

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

get rid of pointless includes of fs_struct.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ARC: handle gcc generated __builtin_trap()

gcc toggle -fisolate-erroneous-paths-dereference (default at -O2
onwards) isolates faulty code paths such as null pointer access, divide
by zero etc by emitting __builtin_trap()

Newer ARC gcc generates TRAP_S 5 instruction which needs to be handled
and treated like any other unexpected exception
- user mode : task terminated with a SEGV
- kernel mode: die() called after register and stack dump

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

mm: treewide: remove GFP_TEMPORARY allocation flag

GFP_TEMPORARY was introduced by commit e12ba74d8ff3 ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE. It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation. As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag. How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory. So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification. I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring. This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse. Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL. Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic. It
seems to be a heuristic without any measured advantage for most (if not
all) its current users. The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers. So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ARC: Show fault information passed to show_kernel_fault_diag()

Currently we pass a string argument to show_kernel_fault_diag() which
describes the reason for the fault. This is not being used so just
add a pr_info() which outputs the fault information.

With this change we get from:

|
| Path: /bin/busybox
| CPU: 0 PID: 92 Comm: modprobe Not tainted 4.12.0-rc6 #30
| task: 9a254780 task.stack: 9a212000
|
| [ECR ]: 0x00200400 => Other Fatal Err
|

to:

|
| Unhandled Machine Check Exception
| Path: /bin/busybox
| CPU: 0 PID: 92 Comm: modprobe Not tainted 4.12.0-rc6 #37
| task: 9a240780 task.stack: 9a226000
|
|[ECR ]: 0x00200400 => Machine Check (Other Fatal Err)
|

Which can help debugging.

Cc: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>

We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> 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 <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>

We are going to split <linux/sched/mm.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/mm.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

The APIs that are going to be moved first are:

mm_alloc()
__mmdrop()
mmdrop()
mmdrop_async_fn()
mmdrop_async()
mmget_not_zero()
mmput()
mmput_async()
get_task_mm()
mm_access()
mm_release()

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

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

ARC: mm: retire ARC_DBG_TLB_MISS_COUNT...

... given that we have perf counters abel to do the same thing non
intrusively

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Fix typos

Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: fix unused var wanring

Fixes: 9bf39ab2adaf ("vfs: add file_path() helper")
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

vfs: add file_path() helper

Turn
d_path(&file->f_path, ...);
into
file_path(file, ...);

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ARCv2: Support for ARCv2 ISA and HS38x cores

The notable features are:
- SMP configurations of upto 4 cores with coherency
- Optional L2 Cache and IO-Coherency
- Revised Interrupt Architecture (multiple priorites, reg banks,
auto stack switch, auto regfile save/restore)
- MMUv4 (PIPT dcache, Huge Pages)
- Instructions for
* 64bit load/store: LDD, STD
* Hardware assisted divide/remainder: DIV, REM
* Function prologue/epilogue: ENTER_S, LEAVE_S
* IRQ enable/disable: CLRI, SETI
* pop count: FFS, FLS
* SETcc, BMSKN, XBFU...

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arc: do not export symbols in troubleshoot.c

print_task_path_n_nm() is local to this file, its only user being
show_regs(). Mark the function static and avoid the EXPORT_SYMBOL.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Vineet Gupta <vgupta@synoipsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arc: call find_vma with the mmap_sem held

Performing vma lookups without taking the mm->mmap_sem is asking for
trouble. While doing the search, the vma in question can be modified or
even removed before returning to the caller. Take the lock (shared) in
order to avoid races while iterating through the vmacache and/or rbtree.

[akpm@linux-foundation.org: CSE current->active_mm, per Vineet]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

more open-coded file_inode() calls

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ARC: Remove explicit passing around of ECR

With ECR now part of pt_regs

* No need to propagate from lowest asm handlers as arg
* No need to save it in tsk->thread.cause_code
* Avoid bit chopping to access the bit-fields

More code consolidation, cleanup

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: pt_regs update #5: Use real ECR for pt_regs->event vs. synth values

pt_regs->event was set with artificial values to identify the low level
system event (syscall trap / breakpoint trap / exceptions / interrupts)

With r8 saving out of the way, the full word can be used to save real
ECR (Exception Cause Register) which helps idenify the event naturally,
including additional info such as cause code, param.
Only for Interrupts, where ECR is not applicable, do we resort to
synthetic non ECR values.

SAVE_ALL_TRAP/EXCEPTIONS can now be merged as they both use ECR with
different runtime values.

The ptrace helpers now use the sub-fields of ECR to distinguish the
events (e.g. vector 0x25 is trap, param 0 is syscall...)

The following benefits will follow:

(1) This centralizes the location of where ECR is saved and will allow
the cleanup of task->thread.cause_code ECR placeholder which is set
in non-uniform way. Then ARC VM code can safely rely on it being
there for purpose of finer grained VM_EXEC dcache flush (based on
exec fault: I-TLB Miss)

(2) Further, ECR being passed around from low level handlers as arg can
be eliminated as it is part of standard reg-file in pt_regs

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: Reduce Code for ECR printing

Cause codes are same for D-TLB-Miss and Prot-V

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: Debug/crash-printing Improvements

* Remove the line-break between scratch/callee-regs (sneaked in when we
converted from printk to pr_*

* Use %pS to print the symbol names of faulting PC (ret pseudo register)
and BLINK (call return register)

* Don't print user-vma for a kernel crash (only do it for
print-fatal-signals based regfile dump)

* Verbose print the Interrupt/Exception Enable/Active state

* for main executable link address is 0x10000 based (vs. 0) thus offset
of faulting PC needs to be adjusted

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arc, print-fatal-signals: reduce duplicated information

After the recent generic debug info on dump_stack() and friends, arc
is printing duplicate information on debug dumps.

[ARCLinux]$ ./crash
crash/50: potentially unexpected fatal signal 11. <-- [1]
/sbin/crash, TGID 50 <-- [2]
Pid: 50, comm: crash Not tainted 3.9.0-rc4+ #132 <-- [3]
...

Remove them.

[tj@kernel.org: updated patch desc]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dump_stack: unify debug information printed by show_regs()

show_regs() is inherently arch-dependent but it does make sense to print
generic debug information and some archs already do albeit in slightly
different forms. This patch introduces a generic function to print debug
information from show_regs() so that different archs print out the same
information and it's much easier to modify what's printed.

show_regs_print_info() prints out the same debug info as dump_stack()
does plus task and thread_info pointers.

* Archs which didn't print debug info now do.

alpha, arc, blackfin, c6x, cris, frv, h8300, hexagon, ia64, m32r,
metag, microblaze, mn10300, openrisc, parisc, score, sh64, sparc,
um, xtensa

* Already prints debug info. Replaced with show_regs_print_info().
The printed information is superset of what used to be there.

arm, arm64, avr32, mips, powerpc, sh32, tile, unicore32, x86

* s390 is special in that it used to print arch-specific information
along with generic debug info. Heiko and Martin think that the
arch-specific extra isn't worth keeping s390 specfic implementation.
Converted to use the generic version.

Note that now all archs print the debug info before actual register
dumps.

An example BUG() dump follows.

kernel BUG at /work/os/work/kernel/workqueue.c:4841!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #7
Hardware name: empty empty/S3992, BIOS 080011 10/26/2007
task: ffff88007c85e040 ti: ffff88007c860000 task.ti: ffff88007c860000
RIP: 0010:[<ffffffff8234a07e>] [<ffffffff8234a07e>] init_workqueues+0x4/0x6
RSP: 0000:ffff88007c861ec8 EFLAGS: 00010246
RAX: ffff88007c861fd8 RBX: ffffffff824466a8 RCX: 0000000000000001
RDX: 0000000000000046 RSI: 0000000000000001 RDI: ffffffff8234a07a
RBP: ffff88007c861ec8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8234a07a
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffff88015f7ff000 CR3: 00000000021f1000 CR4: 00000000000007f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Stack:
ffff88007c861ef8 ffffffff81000312 ffffffff824466a8 ffff88007c85e650
0000000000000003 0000000000000000 ffff88007c861f38 ffffffff82335e5d
ffff88007c862080 ffffffff8223d8c0 ffff88007c862080 ffffffff81c47760
Call Trace:
[<ffffffff81000312>] do_one_initcall+0x122/0x170
[<ffffffff82335e5d>] kernel_init_freeable+0x9b/0x1c8
[<ffffffff81c47760>] ? rest_init+0x140/0x140
[<ffffffff81c4776e>] kernel_init+0xe/0xf0
[<ffffffff81c6be9c>] ret_from_fork+0x7c/0xb0
[<ffffffff81c47760>] ? rest_init+0x140/0x140
...

v2: Typo fix in x86-32.

v3: CPU number dropped from show_regs_print_info() as
dump_stack_print_info() has been updated to print it. s390
specific implementation dropped as requested by s390 maintainers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com> [tile bits]
Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon bits]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ARC: Diagnostics: show_regs() etc

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

ARC: Last bits (stubs) to get to a running kernel with UART

This was part of port buildup strategy from Arnd to have a minimal kernel
at first and then add optional features (stacktracing, ptrace, smp,
kprobes, oprofile....)

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>