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Pull ARM updates from Russell King:
"Updates for IRQ stacks and virtually mapped stack support, and ftrace:
- Support for IRQ and vmap'ed stacks
This covers all the work related to implementing IRQ stacks and
vmap'ed stacks for all 32-bit ARM systems that are currently
supported by the Linux kernel, including RiscPC and Footbridge. It
has been submitted for review in four different waves:
- IRQ stacks support for v7 SMP systems [0]
- vmap'ed stacks support for v7 SMP systems[1]
- extending support for both IRQ stacks and vmap'ed stacks for all
remaining configurations, including v6/v7 SMP multiplatform
kernels and uniprocessor configurations including v7-M [2]
- fixes and updates in [3]
- ftrace fixes and cleanups
Make all flavors of ftrace available on all builds, regardless of
ISA choice, unwinder choice or compiler [4]:
- use ADD not POP where possible
- fix a couple of Thumb2 related issues
- enable HAVE_FUNCTION_GRAPH_FP_TEST for robustness
- enable the graph tracer with the EABI unwinder
- avoid clobbering frame pointer registers to make Clang happy
- Fixes for the above"
[0] https://lore.kernel.org/linux-arm-kernel/20211115084732.3704393-1-ardb@kernel.org/
[1] https://lore.kernel.org/linux-arm-kernel/20211122092816.2865873-1-ardb@kernel.org/
[2] https://lore.kernel.org/linux-arm-kernel/20211206164659.1495084-1-ardb@kernel.org/
[3] https://lore.kernel.org/linux-arm-kernel/20220124174744.1054712-1-ardb@kernel.org/
[4] https://lore.kernel.org/linux-arm-kernel/20220203082204.1176734-1-ardb@kernel.org/
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (62 commits)
ARM: fix building NOMMU ARMv4/v5 kernels
ARM: unwind: only permit stack switch when unwinding call_with_stack()
ARM: Revert "unwind: dump exception stack from calling frame"
ARM: entry: fix unwinder problems caused by IRQ stacks
ARM: unwind: set frame.pc correctly for current-thread unwinding
ARM: 9184/1: return_address: disable again for CONFIG_ARM_UNWIND=y
ARM: 9183/1: unwind: avoid spurious warnings on bogus code addresses
Revert "ARM: 9144/1: forbid ftrace with clang and thumb2_kernel"
ARM: mach-bcm: disable ftrace in SMC invocation routines
ARM: cacheflush: avoid clobbering the frame pointer
ARM: kprobes: treat R7 as the frame pointer register in Thumb2 builds
ARM: ftrace: enable the graph tracer with the EABI unwinder
ARM: unwind: track location of LR value in stack frame
ARM: ftrace: enable HAVE_FUNCTION_GRAPH_FP_TEST
ARM: ftrace: avoid unnecessary literal loads
ARM: ftrace: avoid redundant loads or clobbering IP
ARM: ftrace: use trampolines to keep .init.text in branching range
ARM: ftrace: use ADD not POP to counter PUSH at entry
ARM: ftrace: ensure that ADR takes the Thumb bit into account
ARM: make get_current() and __my_cpu_offset() __always_inline
...
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Use the SMP_ON_UP patching framework to elide HWCAP_TLS tests from the
context switch and return to userspace code paths, as SMP systems are
guaranteed to have this h/w capability.
At the same time, omit the update of __entry_task if the system is
detected to be UP at runtime, as in that case, the value is never used.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Since commit bcf9033e5449 ("sched: move CPU field back into thread_info
if THREAD_INFO_IN_TASK=y"), the CPU field in thread_info went back to
being managed by the core code, so we no longer have to keep it in sync
in arch code.
While at it, mark THREAD_INFO_IN_TASK as done for ARM in the
documentation.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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On UP systems, only a single task can be 'current' at the same time,
which means we can use a global variable to track it. This means we can
also enable THREAD_INFO_IN_TASK for those systems, as in that case,
thread_info is accessed via current rather than the other way around,
removing the need to store thread_info at the base of the task stack.
This, in turn, permits us to enable IRQ stacks and vmap'ed stacks on UP
systems as well.
To partially mitigate the performance overhead of this arrangement, use
a ADD/ADD/LDR sequence with the appropriate PC-relative group
relocations to load the value of current when needed. This means that
accessing current will still only require a single load as before,
avoiding the need for a literal to carry the address of the global
variable in each function. However, accessing thread_info will now
require this load as well.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
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Now that we no longer rely on thread_info living at the base of the task
stack to be able to access the 'current' pointer, we can wire up the
generic support for moving thread_info into the task struct itself.
Note that this requires us to update the cpu field in thread_info
explicitly, now that the core code no longer does so. Ideally, we would
switch the percpu code to access the cpu field in task_struct instead,
but this unleashes #include circular dependency hell.
Co-developed-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
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Now that the user space TLS register is assigned on every return to user
space, we can use it to keep the 'current' pointer while running in the
kernel. This removes the need to access it via thread_info, which is
located at the base of the stack, but will be moved out of there in a
subsequent patch.
Use the __builtin_thread_pointer() helper when available - this will
help GCC understand that reloading the value within the same function is
not necessary, even when using the per-task stack protector (which also
generates accesses via the TLS register). For example, the generated
code below loads TPIDRURO only once, and uses it to access both the
stack canary and the preempt_count fields.
<do_one_initcall>:
e92d 41f0 stmdb sp!, {r4, r5, r6, r7, r8, lr}
ee1d 4f70 mrc 15, 0, r4, cr13, cr0, {3}
4606 mov r6, r0
b094 sub sp, #80 ; 0x50
f8d4 34e8 ldr.w r3, [r4, #1256] ; 0x4e8 <- stack canary
9313 str r3, [sp, #76] ; 0x4c
f8d4 8004 ldr.w r8, [r4, #4] <- preempt count
Co-developed-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Keith Packard <keithpac@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
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CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.
Switch the entry code, cache over to use CONFIG_PREEMPTION and add output
in show_stack() for PREEMPT_RT.
[bigeasy: +traps.c]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20191015191821.11479-2-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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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>
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Fold finish_arch_switch() into switch_to().
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: 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
Cc: linux@arm.linux.org.uk
[ Fixed up the SOB chain. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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When unlocking a spinlock, we use the sev instruction to signal other
CPUs waiting on the lock. Since sev is not a memory access instruction,
we require a dsb in order to ensure that the sev is not issued ahead
of the store placing the lock in an unlocked state.
However, as sev is only concerned with other processors in a
multiprocessor system, we can restrict the scope of the preceding dsb
to the inner-shareable domain. Furthermore, we can restrict the scope to
consider only stores, since there are no independent loads on the unlock
path.
A side-effect of this change is that a spin_unlock operation no longer
forces completion of pending TLB invalidation, something which we rely
on when unlocking runqueues to ensure that CPU migration during TLB
maintenance routines doesn't cause us to continue before the operation
has completed.
This patch adds the -ishst suffix to the ARMv7 definition of dsb_sev()
and adds an inner-shareable dsb to the context-switch path when running
a preemptible, SMP, v7 kernel.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Disintegrate asm/system.h for ARM.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org
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