ARM: 9258/1: stacktrace: Make stack walk callback consistent with generic code

As with the generic arch_stack_walk() code the ARM stack walk code takes
a callback that is called per stack frame. Currently the ARM code always
passes a struct stackframe to the callback and the generic code just
passes the pc, however none of the users ever reference anything in the
struct other than the pc value. The ARM code also uses a return type of
int while the generic code uses a return type of bool though in both
cases the return value is a boolean value and the sense is inverted
between the two.

In order to reduce code duplication when ARM is converted to use
arch_stack_walk() change the signature and return sense of the ARM
specific callback to match that of the generic code.

Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Linus Waleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

ARM: 9234/1: stacktrace: Avoid duplicate saving of exception PC value

Because an exception stack frame is not created in the exception entry,
save_trace() does special handling for the exception PC, but this is
only needed when CONFIG_FRAME_POINTER_UNWIND=y. When
CONFIG_ARM_UNWIND=y, unwind annotations have been added to the exception
entry and save_trace() will repeatedly save the exception PC:

[0x7f000090] hrtimer_hander+0x8/0x10 [hrtimer]
[0x8019ec50] __hrtimer_run_queues+0x18c/0x394
[0x8019f760] hrtimer_run_queues+0xbc/0xd0
[0x8019def0] update_process_times+0x34/0x80
[0x801ad2a4] tick_periodic+0x48/0xd0
[0x801ad3dc] tick_handle_periodic+0x1c/0x7c
[0x8010f2e0] twd_handler+0x30/0x40
[0x80177620] handle_percpu_devid_irq+0xa0/0x23c
[0x801718d0] generic_handle_domain_irq+0x24/0x34
[0x80502d28] gic_handle_irq+0x74/0x88
[0x8085817c] generic_handle_arch_irq+0x58/0x78
[0x80100ba8] __irq_svc+0x88/0xc8
[0x80108114] arch_cpu_idle+0x38/0x3c
[0x80108114] arch_cpu_idle+0x38/0x3c <==== duplicate saved exception PC
[0x80861bf8] default_idle_call+0x38/0x130
[0x8015d5cc] do_idle+0x150/0x214
[0x8015d978] cpu_startup_entry+0x18/0x1c
[0x808589c0] rest_init+0xd8/0xdc
[0x80c00a44] arch_post_acpi_subsys_init+0x0/0x8

We can move the special handling of the exception PC in save_trace() to
the unwind_frame() of the frame pointer unwinder.

Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Linus Waleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

ARM: 9224/1: Dump the stack traces based on the parameter 'regs' of show_regs()

Function show_regs() is usually called in interrupt handler or exception
handler, it prints the registers specified by the parameter 'regs', then
dump the stack traces. Although not explicitly documented, dump the stack
traces based on'regs' seems to make the most sense. Although dump_stack()
can finally dump the desired content, because 'regs' are saved by the
entry of current interrupt or exception. In the following example we can
see: 1) The backtrace of interrupt or exception handler is not expected,
it causes confusion. 2) Something is printed repeatedly. The line with
the kernel version "CPU: 0 PID: 70 Comm: test0 Not tainted 5.19.0+ #8",
the registers saved in "Exception stack" which 'regs' actually point to.

For example:
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 0-....: (499 ticks this GP) idle=379/1/0x40000002 softirq=91/91 fqs=249
(t=500 jiffies g=-911 q=13 ncpus=4)
CPU: 0 PID: 70 Comm: test0 Not tainted 5.19.0+ #8
Hardware name: ARM-Versatile Express
PC is at ktime_get+0x4c/0xe8
LR is at ktime_get+0x4c/0xe8
pc : 8019a474 lr : 8019a474 psr: 60000013
sp : cabd1f28 ip : 00000001 fp : 00000005
r10: 527bf1b8 r9 : 431bde82 r8 : d7b634db
r7 : 0000156e r6 : 61f234f8 r5 : 00000001 r4 : 80ca86c0
r3 : ffffffff r2 : fe5bce0b r1 : 00000000 r0 : 01a431f4
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 6121406a DAC: 00000051
CPU: 0 PID: 70 Comm: test0 Not tainted 5.19.0+ #8 <-----------start----------
Hardware name: ARM-Versatile Express |
unwind_backtrace from show_stack+0x10/0x14 |
show_stack from dump_stack_lvl+0x40/0x4c |
dump_stack_lvl from rcu_dump_cpu_stacks+0x10c/0x134 |
rcu_dump_cpu_stacks from rcu_sched_clock_irq+0x780/0xaf4 |
rcu_sched_clock_irq from update_process_times+0x54/0x74 |
update_process_times from tick_periodic+0x3c/0xd4 |
tick_periodic from tick_handle_periodic+0x20/0x80 worthless
tick_handle_periodic from twd_handler+0x30/0x40 or
twd_handler from handle_percpu_devid_irq+0x8c/0x1c8 duplicated
handle_percpu_devid_irq from generic_handle_domain_irq+0x24/0x34 |
generic_handle_domain_irq from gic_handle_irq+0x74/0x88 |
gic_handle_irq from generic_handle_arch_irq+0x34/0x44 |
generic_handle_arch_irq from call_with_stack+0x18/0x20 |
call_with_stack from __irq_svc+0x98/0xb0 |
Exception stack(0xcabd1ed8 to 0xcabd1f20) |
1ec0: 01a431f4 00000000 |
1ee0: fe5bce0b ffffffff 80ca86c0 00000001 61f234f8 0000156e d7b634db 431bde82 |
1f00: 527bf1b8 00000005 00000001 cabd1f28 8019a474 8019a474 60000013 ffffffff |
__irq_svc from ktime_get+0x4c/0xe8 <---------end--------------
ktime_get from test_task+0x44/0x110
test_task from kthread+0xd8/0xf4
kthread from ret_from_fork+0x14/0x2c
Exception stack(0xcabd1fb0 to 0xcabd1ff8)
1fa0: 00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000

After replacing dump_stack() with dump_backtrace():
rcu: INFO: rcu_sched self-detected stall on CPU
rcu: 0-....: (500 ticks this GP) idle=8f7/1/0x40000002 softirq=129/129 fqs=241
(t=500 jiffies g=-915 q=13 ncpus=4)
CPU: 0 PID: 69 Comm: test0 Not tainted 5.19.0+ #9
Hardware name: ARM-Versatile Express
PC is at ktime_get+0x4c/0xe8
LR is at ktime_get+0x4c/0xe8
pc : 8019a494 lr : 8019a494 psr: 60000013
sp : cabddf28 ip : 00000001 fp : 00000002
r10: 0779cb48 r9 : 431bde82 r8 : d7b634db
r7 : 00000a66 r6 : e835ab70 r5 : 00000001 r4 : 80ca86c0
r3 : ffffffff r2 : ff337d39 r1 : 00000000 r0 : 00cc82c6
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 611d006a DAC: 00000051
ktime_get from test_task+0x44/0x110
test_task from kthread+0xd8/0xf4
kthread from ret_from_fork+0x14/0x2c
Exception stack(0xcabddfb0 to 0xcabddff8)
dfa0: 00000000 00000000 00000000 00000000
dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
dfe0: 00000000 00000000 00000000 00000000 00000013 00000000

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Revert "ARM: rethook: Add rethook arm implementation"

This reverts commit 515a49173b80a4aabcbad9a4fa2a247042378ea1.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

ARM: rethook: Add rethook arm implementation

Add rethook arm implementation. Most of the code has been copied from
kretprobes on arm.
Since the arm's ftrace implementation is a bit special, this needs a
special care using from fprobe.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/164735289643.1084943.15184590256680485720.stgit@devnote2

ARM: Revert "unwind: dump exception stack from calling frame"

After simplifying the stack switch code in the IRQ exception handler by
deferring the actual stack switch to call_with_stack(), we no longer
need to special case the way we dump the exception stack, since it will
always be at the top of whichever stack was active when the exception
was taken.

So revert this special handling for the ARM unwinder.

This reverts commit 4ab6827081c63b83011a18d8e27f621ed34b1194.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

ARM: unwind: track location of LR value in stack frame

The ftrace graph tracer needs to override the return address of an
instrumented function, in order to install a hook that gets invoked when
the function returns again.

Currently, we only support this when building for ARM using GCC with
frame pointers, as in this case, it is guaranteed that the function will
reload LR from [FP, #-4] in all cases, and we can simply pass that
address to the ftrace code.

In order to support this for configurations that rely on the EABI
unwinder, such as Thumb2 builds, make the unwinder keep track of the
address from which LR was unwound, permitting ftrace to make use of this
in a subsequent patch.

Drop the call to is_kernel_text_address(), which is problematic in terms
of ftrace recursion, given that it may be instrumented itself. The call
is redundant anyway, as no unwind directives will be found unless the PC
points to memory that is known to contain executable code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

ARM: unwind: dump exception stack from calling frame

The existing code that dumps the contents of the pt_regs structure
passed to __entry routines does so while unwinding the callee frame, and
dereferences the stack pointer as a struct pt_regs*. This will no longer
work when we enable support for IRQ or overflow stacks, because the
struct pt_regs may live on the task stack, while we are executing from
another stack.

The unwinder has access to this information, but only while unwinding
the calling frame. So let's combine the exception stack dumping code
with the handling of the calling frame as well. By printing it before
dumping the caller/callee addresses, the output order is preserved.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Keith Packard <keithpac@amazon.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M

ARM: export dump_mem() to other objects

The unwind info based stack unwinder will make its own call to
dump_mem() to dump the exception stack, so give it external linkage.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Keith Packard <keithpac@amazon.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M

ARM: Recover kretprobe modified return address in stacktrace

Since the kretprobe replaces the function return address with
the kretprobe_trampoline on the stack, arm unwinder shows it
instead of the correct return address.

This finds the correct return address from the per-task
kretprobe_instances list and verify it is in between the
caller fp and callee fp.

Note that this supports both GCC and clang if CONFIG_FRAME_POINTER=y
and CONFIG_ARM_UNWIND=n. For the ARM unwinder, this is still
not working correctly.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARM: 8070/1: Introduce arm_get_current_stack_frame()

Currently there are numerous places where "struct pt_regs" are used to
populate "struct stackframe", however all of those location do not
consider the situation where the kernel might be compiled in THUMB2
mode, in which case the framepointer member of pt_regs become ARM_r7
instead of ARM_fp (r11). Document this idiosyncracy in the
definition of "struct stackframe"

The easiest solution is to introduce a new function (in the spirit of
https://groups.google.com/forum/#!topic/linux.kernel/dA2YuUcSpZ4)
which would hide the complexity of initializing the stackframe struct
from pt_regs.

Also implement a macro frame_pointer(regs) that would return the correct
register so that we can use it in cases where we just require the frame
pointer and not a whole struct stackframe

Signed-off-by: Nikolay Borisov <Nikolay.Borisov@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Robert Richter <rric@kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

[ARM] 5382/1: unwind: Reorganise the stacktrace support

This patch changes the walk_stacktrace and its callers for easier
integration of stack unwinding. The arch/arm/kernel/stacktrace.h file is
also moved to arch/arm/include/asm/stacktrace.h.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>