kernel/linux.git/arch/arm/include/asm/processor.h, branch v6.12.80

kernel: exit: cleanup release_thread()

2022-09-12T04:55:07+00:00

Only x86 has own release_thread(), introduce a new weak release_thread() function to clean empty definitions in other ARCHs. Link: https://lkml.kernel.org/r/20220819014406.32266-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Acked-by: Guo Ren [csky] Acked-by: Russell King (Oracle) Acked-by: Geert Uytterhoeven Acked-by: Brian Cain Acked-by: Michael Ellerman [powerpc] Acked-by: Stafford Horne [openrisc] Acked-by: Catalin Marinas [arm64] Acked-by: Huacai Chen [LoongArch] Cc: Alexander Gordeev Cc: Anton Ivanov Cc: Borislav Petkov Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Chris Zankel Cc: Dave Hansen Cc: "David S. Miller" Cc: Dinh Nguyen Cc: Guo Ren [csky] Cc: Heiko Carstens Cc: Helge Deller Cc: Ingo Molnar Cc: Ivan Kokshaysky Cc: James Bottomley Cc: Johannes Berg Cc: Jonas Bonn Cc: Matt Turner Cc: Max Filippov Cc: Michal Simek Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Richard Weinberger Cc: Rich Felker Cc: Stefan Kristiansson Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Will Deacon Cc: Xuerui Wang Cc: Yoshinori Sato Signed-off-by: Andrew Morton

ARM: 9180/1: Thumb2: align ALT_UP() sections in modules sufficiently

2022-01-19T11:10:54+00:00

When building for Thumb2, the .alt.smp.init sections that are emitted by the ALT_UP() patching code may not be 32-bit aligned, even though the fixup_smp_on_up() routine expects that. This results in alignment faults at module load time, which need to be fixed up by the fault handler. So let's align those sections explicitly, and prevent this from occurring. Cc: Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King (Oracle)

sched: Add wrapper for get_wchan() to keep task blocked

2021-10-15T09:25:14+00:00

Having a stable wchan means the process must be blocked and for it to stay that way while performing stack unwinding. Suggested-by: Peter Zijlstra Signed-off-by: Kees Cook Signed-off-by: Peter Zijlstra (Intel) Acked-by: Geert Uytterhoeven Acked-by: Russell King (Oracle) [arm] Tested-by: Mark Rutland [arm64] Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org

ARM: kernel: use relative references for UP/SMP alternatives

2020-10-28T16:05:39+00:00

Currently, the .alt.smp.init section contains the virtual addresses of the patch sites. Since patching may occur both before and after switching into virtual mode, this requires some manual handling of the address when applying the UP alternative. Let's simplify this by using relative offsets in the table entries: this allows us to simply add each entry's address to its contents, regardless of whether we are running in virtual mode or not. Reviewed-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel

arm: vdso: Enable arm to use common headers

2020-03-21T14:24:03+00:00

Enable arm to use only the common headers in the implementation of the vDSO library. Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Cc: Russell King Link: https://lkml.kernel.org/r/20200320145351.32292-25-vincenzo.frascino@arm.com

arm: use generic mmap top-down layout and brk randomization

2019-09-24T22:54:12+00:00

arm uses a top-down mmap layout by default that exactly fits the generic functions, so get rid of arch specific code and use the generic version by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, use the generic version of arch_randomize_brk since it also fits. Note that this commit also removes the possibility for arm to have elf randomization and no MMU: without MMU, the security added by randomization is worth nothing. Note that it is safe to remove STACK_RND_MASK since it matches the default value. Link: http://lkml.kernel.org/r/20190730055113.23635-9-alex@ghiti.fr Signed-off-by: Alexandre Ghiti Acked-by: Kees Cook Reviewed-by: Luis Chamberlain Cc: Albert Ou Cc: Alexander Viro Cc: Catalin Marinas Cc: Christoph Hellwig Cc: Christoph Hellwig Cc: James Hogan Cc: Palmer Dabbelt Cc: Paul Burton Cc: Ralf Baechle Cc: Russell King Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

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 published by the free software foundation 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 # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

ARM: 8853/1: drop WASM to work around LLVM issue

2019-04-23T16:20:53+00:00

Currently LLVM's integrated assembler does not recognize .w form of the pld instructions (LLVM Bug 40972 [0]): ./arch/arm/include/asm/processor.h:133:5: error: invalid instruction "pldw.wt%a0 n" ^ :2:1: note: instantiated into assembly here pldw.w [r0] ^ 1 error generated. The W macro for generating wide instructions when targeting Thumb-2 is not strictly required for the preload data instructions (pld, pldw) since they are only available as wide instructions. The GNU assembler works with or without the .w appended when compiling an Thumb-2 kernel. Drop the macro to work around LLVM Bug 40972 issue. [0] https://bugs.llvm.org/show_bug.cgi?id=40972 Signed-off-by: Stefan Agner Reviewed-by: Nick Desaulniers Signed-off-by: Russell King

ARM: avoid Cortex-A9 livelock on tight dmb loops

2019-02-01T22:05:50+00:00

machine_crash_nonpanic_core() does this: while (1) cpu_relax(); because the kernel has crashed, and we have no known safe way to deal with the CPU. So, we place the CPU into an infinite loop which we expect it to never exit - at least not until the system as a whole is reset by some method. In the absence of erratum 754327, this code assembles to: b . In other words, an infinite loop. When erratum 754327 is enabled, this becomes: 1: dmb b 1b It has been observed that on some systems (eg, OMAP4) where, if a crash is triggered, the system tries to kexec into the panic kernel, but fails after taking the secondary CPU down - placing it into one of these loops. This causes the system to livelock, and the most noticable effect is the system stops after issuing: Loading crashdump kernel... to the system console. The tested as working solution I came up with was to add wfe() to these infinite loops thusly: while (1) { cpu_relax(); wfe(); } which, without 754327 builds to: 1: wfe b 1b or with 754327 is enabled: 1: dmb wfe b 1b Adding "wfe" does two things depending on the environment we're running under: - where we're running on bare metal, and the processor implements "wfe", it stops us spinning endlessly in a loop where we're never going to do any useful work. - if we're running in a VM, it allows the CPU to be given back to the hypervisor and rescheduled for other purposes (maybe a different VM) rather than wasting CPU cycles inside a crashed VM. However, in light of erratum 794072, Will Deacon wanted to see 10 nops as well - which is reasonable to cover the case where we have erratum 754327 enabled _and_ we have a processor that doesn't implement the wfe hint. So, we now end up with: 1: wfe b 1b when erratum 754327 is disabled, or: 1: dmb nop nop nop nop nop nop nop nop nop nop wfe b 1b when erratum 754327 is enabled. We also get the dmb + 10 nop sequence elsewhere in the kernel, in terminating loops. This is reasonable - it means we get the workaround for erratum 794072 when erratum 754327 is enabled, but still relinquish the dead processor - either by placing it in a lower power mode when wfe is implemented as such or by returning it to the hypervisior, or in the case where wfe is a no-op, we use the workaround specified in erratum 794072 to avoid the problem. These as two entirely orthogonal problems - the 10 nops addresses erratum 794072, and the wfe is an optimisation that makes the system more efficient when crashed either in terms of power consumption or by allowing the host/other VMs to make use of the CPU. I don't see any reason not to use kexec() inside a VM - it has the potential to provide automated recovery from a failure of the VMs kernel with the opportunity for saving a crashdump of the failure. A panic() with a reboot timeout won't do that, and reading the libvirt documentation, setting on_reboot to "preserve" won't either (the documentation states "The preserve action for an on_reboot event is treated as a destroy".) Surely it has to be a good thing to avoiding having CPUs spinning inside a VM that is doing no useful work. Acked-by: Will Deacon Signed-off-by: Russell King

treewide: remove current_text_addr

2018-10-31T15:54:12+00:00

Prefer _THIS_IP_ defined in linux/kernel.h. Most definitions of current_text_addr were the same as _THIS_IP_, but a few archs had inline assembly instead. This patch removes the final call site of current_text_addr, making all of the definitions dead code. [akpm@linux-foundation.org: fix arch/csky/include/asm/processor.h] Link: http://lkml.kernel.org/r/20180911182413.180715-1-ndesaulniers@google.com Signed-off-by: Nick Desaulniers Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds