kernel.git/arch/arm/kernel, branch linux-5.12.y

sched/core: Initialize the idle task with preemption disabled

2021-07-14T14:59:16Z

[ Upstream commit f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 ] As pointed out by commit de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread") init_idle() can and will be invoked more than once on the same idle task. At boot time, it is invoked for the boot CPU thread by sched_init(). Then smp_init() creates the threads for all the secondary CPUs and invokes init_idle() on them. As the hotplug machinery brings the secondaries to life, it will issue calls to idle_thread_get(), which itself invokes init_idle() yet again. In this case it's invoked twice more per secondary: at _cpu_up(), and at bringup_cpu(). Given smp_init() already initializes the idle tasks for all *possible* CPUs, no further initialization should be required. Now, removing init_idle() from idle_thread_get() exposes some interesting expectations with regards to the idle task's preempt_count: the secondary startup always issues a preempt_disable(), requiring some reset of the preempt count to 0 between hot-unplug and hotplug, which is currently served by idle_thread_get() -> idle_init(). Given the idle task is supposed to have preemption disabled once and never see it re-enabled, it seems that what we actually want is to initialize its preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove init_idle() from idle_thread_get(). Secondary startups were patched via coccinelle: @begone@ @@ -preempt_disable(); ... cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); Signed-off-by: Valentin Schneider Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com Signed-off-by: Sasha Levin

arm_pmu: Fix write counter incorrect in ARMv7 big-endian mode

2021-07-14T14:59:04Z

commit fdbef8c4e68ad423416aa6cc93d1616d6f8ac5b3 upstream. Commit 3a95200d3f89 ("arm_pmu: Change API to support 64bit counter values") changes the input "value" type from 32-bit to 64-bit, which introduces the following problem: ARMv7 PMU counters is 32-bit width, in big-endian mode, write counter uses high 32-bit, which writes an incorrect value. Before: Performance counter stats for 'ls': 2.22 msec task-clock # 0.675 CPUs utilized 0 context-switches # 0.000 K/sec 0 cpu-migrations # 0.000 K/sec 49 page-faults # 0.022 M/sec 2150476593 cycles # 966.663 GHz 2148588788 instructions # 1.00 insn per cycle 2147745484 branches # 965435.074 M/sec 2147508540 branch-misses # 99.99% of all branches None of the above hw event counters are correct. Solution: "value" forcibly converted to 32-bit type before being written to PMU register. After: Performance counter stats for 'ls': 2.09 msec task-clock # 0.681 CPUs utilized 0 context-switches # 0.000 K/sec 0 cpu-migrations # 0.000 K/sec 46 page-faults # 0.022 M/sec 2807301 cycles # 1.344 GHz 1060159 instructions # 0.38 insn per cycle 250496 branches # 119.914 M/sec 23192 branch-misses # 9.26% of all branches Fixes: 3a95200d3f89 ("arm_pmu: Change API to support 64bit counter values") Cc: Signed-off-by: Yang Jihong Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20210430012659.232110-1-yangjihong1@huawei.com Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

ARM: 9081/1: fix gcc-10 thumb2-kernel regression

2021-06-30T12:46:54Z

commit dad7b9896a5dbac5da8275d5a6147c65c81fb5f2 upstream. When building the kernel wtih gcc-10 or higher using the CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE=y flag, the compiler picks a slightly different set of registers for the inline assembly in cpu_init() that subsequently results in a corrupt kernel stack as well as remaining in FIQ mode. If a banked register is used for the last argument, the wrong version of that register gets loaded into CPSR_c. When building in Arm mode, the arguments are passed as immediate values and the bug cannot happen. This got introduced when Daniel reworked the FIQ handling and was technically always broken, but happened to work with both clang and gcc before gcc-10 as long as they picked one of the lower registers. This is probably an indication that still very few people build the kernel in Thumb2 mode. Marek pointed out the problem on IRC, Arnd narrowed it down to this inline assembly and Russell pinpointed the exact bug. Change the constraints to force the final mode switch to use a non-banked register for the argument to ensure that the correct constant gets loaded. Another alternative would be to always use registers for the constant arguments to avoid the #ifdef that has now become more complex. Cc: # v3.18+ Cc: Daniel Thompson Reported-by: Marek Vasut Acked-by: Ard Biesheuvel Fixes: c0e7f7ee717e ("ARM: 8150/3: fiq: Replace default FIQ handler") Signed-off-by: Arnd Bergmann Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: 9075/1: kernel: Fix interrupted SMC calls

2021-05-22T09:43:48Z

[ Upstream commit 57ac51667d8cd62731223d687e5fe7b41c502f89 ] On Qualcomm ARM32 platforms, the SMC call can return before it has completed. If this occurs, the call can be restarted, but it requires using the returned session ID value from the interrupted SMC call. The ARM32 SMCC code already has the provision to add platform specific quirks for things like this. So let's make use of it and add the Qualcomm specific quirk (ARM_SMCCC_QUIRK_QCOM_A6) used by the QCOM_SCM driver. This change is similar to the below one added for ARM64 a while ago: commit 82bcd087029f ("firmware: qcom: scm: Fix interrupted SCM calls") Without this change, the Qualcomm ARM32 platforms like SDX55 will return -EINVAL for SMC calls used for modem firmware loading and validation. Signed-off-by: Manivannan Sadhasivam Reviewed-by: Bjorn Andersson Signed-off-by: Russell King Signed-off-by: Sasha Levin

ARM: 9066/1: ftrace: pause/unpause function graph tracer in cpu_suspend()

2021-05-22T09:43:46Z

[ Upstream commit 8252ca87c7a2111502ee13994956f8c309faad7f ] Enabling function_graph tracer on ARM causes kernel panic, because the function graph tracer updates the "return address" of a function in order to insert a trace callback on function exit, it saves the function's original return address in a return trace stack, but cpu_suspend() may not return through the normal return path. cpu_suspend() will resume directly via the cpu_resume path, but the return trace stack has been set-up by the subfunctions of cpu_suspend(), which makes the "return address" inconsistent with cpu_suspend(). This patch refers to Commit de818bd4522c40ea02a81b387d2fa86f989c9623 ("arm64: kernel: pause/unpause function graph tracer in cpu_suspend()"), fixes the issue by pausing/resuming the function graph tracer on the thread executing cpu_suspend(), so that the function graph tracer state is kept consistent across functions that enter power down states and never return by effectively disabling graph tracer while they are executing. Signed-off-by: louis.wang Signed-off-by: Russell King Signed-off-by: Sasha Levin

ARM: 9064/1: hw_breakpoint: Do not directly check the event's overflow_handler hook

2021-05-19T08:56:22Z

[ Upstream commit a506bd5756290821a4314f502b4bafc2afcf5260 ] The commit 1879445dfa7b ("perf/core: Set event's default ::overflow_handler()") set a default event->overflow_handler in perf_event_alloc(), and replace the check event->overflow_handler with is_default_overflow_handler(), but one is missing. Currently, the bp->overflow_handler can not be NULL. As a result, enable_single_step() is always not invoked. Comments from Zhen Lei: https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210207105934.2001-1-thunder.leizhen@huawei.com/ Fixes: 1879445dfa7b ("perf/core: Set event's default ::overflow_handler()") Signed-off-by: Zhen Lei Cc: Wang Nan Acked-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Sasha Levin

Merge tag 'io_uring-worker.v3-2021-02-25' of git://git.kernel.dk/linux-block

2021-02-27T16:29:02Z

Pull io_uring thread rewrite from Jens Axboe: "This converts the io-wq workers to be forked off the tasks in question instead of being kernel threads that assume various bits of the original task identity. This kills > 400 lines of code from io_uring/io-wq, and it's the worst part of the code. We've had several bugs in this area, and the worry is always that we could be missing some pieces for file types doing unusual things (recent /dev/tty example comes to mind, userfaultfd reads installing file descriptors is another fun one... - both of which need special handling, and I bet it's not the last weird oddity we'll find). With these identical workers, we can have full confidence that we're never missing anything. That, in itself, is a huge win. Outside of that, it's also more efficient since we're not wasting space and code on tracking state, or switching between different states. I'm sure we're going to find little things to patch up after this series, but testing has been pretty thorough, from the usual regression suite to production. Any issue that may crop up should be manageable. There's also a nice series of further reductions we can do on top of this, but I wanted to get the meat of it out sooner rather than later. The general worry here isn't that it's fundamentally broken. Most of the little issues we've found over the last week have been related to just changes in how thread startup/exit is done, since that's the main difference between using kthreads and these kinds of threads. In fact, if all goes according to plan, I want to get this into the 5.10 and 5.11 stable branches as well. That said, the changes outside of io_uring/io-wq are: - arch setup, simple one-liner to each arch copy_thread() implementation. - Removal of net and proc restrictions for io_uring, they are no longer needed or useful" * tag 'io_uring-worker.v3-2021-02-25' of git://git.kernel.dk/linux-block: (30 commits) io-wq: remove now unused IO_WQ_BIT_ERROR io_uring: fix SQPOLL thread handling over exec io-wq: improve manager/worker handling over exec io_uring: ensure SQPOLL startup is triggered before error shutdown io-wq: make buffered file write hashed work map per-ctx io-wq: fix race around io_worker grabbing io-wq: fix races around manager/worker creation and task exit io_uring: ensure io-wq context is always destroyed for tasks arch: ensure parisc/powerpc handle PF_IO_WORKER in copy_thread() io_uring: cleanup ->user usage io-wq: remove nr_process accounting io_uring: flag new native workers with IORING_FEAT_NATIVE_WORKERS net: remove cmsg restriction from io_uring based send/recvmsg calls Revert "proc: don't allow async path resolution of /proc/self components" Revert "proc: don't allow async path resolution of /proc/thread-self components" io_uring: move SQPOLL thread io-wq forked worker io-wq: make io_wq_fork_thread() available to other users io-wq: only remove worker from free_list, if it was there io_uring: remove io_identity io_uring: remove any grabbing of context ...

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2021-02-22T22:27:07Z

Pull ARM updates from Russell King: - Generalise byte swapping assembly - Update debug addresses for STI - Validate start of physical memory with DTB - Do not clear SCTLR.nTLSMD in decompressor - amba/locomo/sa1111 devices remove method return type is void - address markers for KASAN in page table dump * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 9065/1: OABI compat: fix build when EPOLL is not enabled ARM: 9055/1: mailbox: arm_mhuv2: make remove callback return void amba: Make use of bus_type functions amba: Make the remove callback return void vfio: platform: simplify device removal amba: reorder functions amba: Fix resource leak for drivers without .remove ARM: 9054/1: arch/arm/mm/mmu.c: Remove duplicate header ARM: 9053/1: arm/mm/ptdump:Add address markers for KASAN regions ARM: 9051/1: vdso: remove unneded extra-y addition ARM: 9050/1: Kconfig: Select ARCH_HAVE_NMI_SAFE_CMPXCHG where possible ARM: 9049/1: locomo: make locomo bus's remove callback return void ARM: 9048/1: sa1111: make sa1111 bus's remove callback return void ARM: 9047/1: smp: remove unused variable ARM: 9046/1: decompressor: Do not clear SCTLR.nTLSMD for ARMv7+ cores ARM: 9045/1: uncompress: Validate start of physical memory against passed DTB ARM: 9042/1: debug: no uncompress debugging while semihosting ARM: 9041/1: sti LL_UART: add STiH418 SBC UART0 support ARM: 9040/1: use DEBUG_UART_PHYS and DEBUG_UART_VIRT for sti LL_UART ARM: 9039/1: assembler: generalize byte swapping macro into rev_l

ARM: 9065/1: OABI compat: fix build when EPOLL is not enabled

2021-02-22T13:07:13Z

When CONFIG_EPOLL is not set/enabled, sys_oabi-compat.c has build errors. Fix these by surrounding them with ifdef CONFIG_EPOLL/endif and providing stubs for the "EPOLL is not set" case. ../arch/arm/kernel/sys_oabi-compat.c: In function 'sys_oabi_epoll_ctl': ../arch/arm/kernel/sys_oabi-compat.c:257:6: error: implicit declaration of function 'ep_op_has_event' [-Werror=implicit-function-declaration] 257 | if (ep_op_has_event(op) && | ^~~~~~~~~~~~~~~ ../arch/arm/kernel/sys_oabi-compat.c:264:9: error: implicit declaration of function 'do_epoll_ctl'; did you mean 'sys_epoll_ctl'? [-Werror=implicit-function-declaration] 264 | return do_epoll_ctl(epfd, op, fd, &kernel, false); | ^~~~~~~~~~~~ Fixes: c281634c8652 ("ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()") Signed-off-by: Randy Dunlap Reported-by: kernel test robot # from an lkp .config file Cc: linux-arm-kernel@lists.infradead.org Cc: Nicolas Pitre Cc: Alexander Viro Cc: patches@armlinux.org.uk Acked-by: Nicolas Pitre Signed-off-by: Russell King

arch: setup PF_IO_WORKER threads like PF_KTHREAD

2021-02-22T00:25:22Z

PF_IO_WORKER are kernel threads too, but they aren't PF_KTHREAD in the sense that we don't assign ->set_child_tid with our own structure. Just ensure that every arch sets up the PF_IO_WORKER threads like kthreads in the arch implementation of copy_thread(). Signed-off-by: Jens Axboe