BMC/Intel-BMC/linux.git/arch/nds32/kernel, branch dev-5.15-intel

perf: Protect perf_guest_cbs with RCU

2022-01-20T08:13:14+00:00

commit ff083a2d972f56bebfd82409ca62e5dfce950961 upstream. Protect perf_guest_cbs with RCU to fix multiple possible errors. Luckily, all paths that read perf_guest_cbs already require RCU protection, e.g. to protect the callback chains, so only the direct perf_guest_cbs touchpoints need to be modified. Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure perf_guest_cbs isn't reloaded between a !NULL check and a dereference. Fixed via the READ_ONCE() in rcu_dereference(). Bug #2 is that on weakly-ordered architectures, updates to the callbacks themselves are not guaranteed to be visible before the pointer is made visible to readers. Fixed by the smp_store_release() in rcu_assign_pointer() when the new pointer is non-NULL. Bug #3 is that, because the callbacks are global, it's possible for readers to run in parallel with an unregisters, and thus a module implementing the callbacks can be unloaded while readers are in flight, resulting in a use-after-free. Fixed by a synchronize_rcu() call when unregistering callbacks. Bug #1 escaped notice because it's extremely unlikely a compiler will reload perf_guest_cbs in this sequence. perf_guest_cbs does get reloaded for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest() guard all but guarantees the consumer will win the race, e.g. to nullify perf_guest_cbs, KVM has to completely exit the guest and teardown down all VMs before KVM start its module unload / unregister sequence. This also makes it all but impossible to encounter bug #3. Bug #2 has not been a problem because all architectures that register callbacks are strongly ordered and/or have a static set of callbacks. But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming kvm_intel module load/unload leads to: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:perf_misc_flags+0x1c/0x70 Call Trace: perf_prepare_sample+0x53/0x6b0 perf_event_output_forward+0x67/0x160 __perf_event_overflow+0x52/0xf0 handle_pmi_common+0x207/0x300 intel_pmu_handle_irq+0xcf/0x410 perf_event_nmi_handler+0x28/0x50 nmi_handle+0xc7/0x260 default_do_nmi+0x6b/0x170 exc_nmi+0x103/0x130 asm_exc_nmi+0x76/0xbf Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host") Signed-off-by: Sean Christopherson Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paolo Bonzini Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com Signed-off-by: Greg Kroah-Hartman

ftrace/nds32: Update the proto for ftrace_trace_function to match ftrace_stub

2021-10-27T17:00:17+00:00

The ftrace callback prototype was changed to pass a special ftrace_regs instead of pt_regs as the last parameter, but the static ftrace for nds32 missed updating ftrace_trace_function and this caused a warning when compared to ftrace_stub: ../arch/nds32/kernel/ftrace.c: In function '_mcount': ../arch/nds32/kernel/ftrace.c:24:35: error: comparison of distinct pointer types lacks a cast [-Werror] 24 | if (ftrace_trace_function != ftrace_stub) | ^~ Link: https://lore.kernel.org/all/20211027055554.19372-1-rdunlap@infradead.org/ Link: https://lkml.kernel.org/r/20211027125101.33449969@gandalf.local.home Cc: Ingo Molnar Cc: Andrew Morton Cc: Nick Hu Cc: Greentime Hu Cc: Vincent Chen Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: d19ad0775dcd6 ("ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs") Reported-by: Randy Dunlap Signed-off-by: Steven Rostedt (VMware)

nds32/setup: remove unused memblock_region variable in setup_memory()

2021-09-09T01:45:53+00:00

kernel test robot reports unused variable warning: arch/nds32/kernel/setup.c:247:26: warning: Unused variable: region [unusedVariable] struct memblock_region *region; ^ Remove the unused variable. Link: https://lkml.kernel.org/r/20210712125218.28951-1-rppt@kernel.org Signed-off-by: Mike Rapoport Reported-by: kernel test robot Reviewed-by: Guenter Roeck Tested-by: Guenter Roeck Cc: Greentime Hu Cc: Nick Hu Cc: Vincent Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

trap: cleanup trap_init()

2021-09-08T18:50:27+00:00

There are some empty trap_init() definitions in different ARCHs, Introduce a new weak trap_init() function to clean them up. Link: https://lkml.kernel.org/r/20210812123602.76356-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Acked-by: Russell King (Oracle) [arm32] Acked-by: Vineet Gupta [arc] Acked-by: Michael Ellerman [powerpc] Cc: Yoshinori Sato Cc: Ley Foon Tan Cc: Jonas Bonn Cc: Stefan Kristiansson Cc: Stafford Horne Cc: James E.J. Bottomley Cc: Helge Deller Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Paul Walmsley Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

nds32: convert to setup_initial_init_mm()

2021-07-08T18:48:21+00:00

Use setup_initial_init_mm() helper to simplify code. Link: https://lkml.kernel.org/r/20210608083418.137226-9-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Cc: Nick Hu Cc: Greentime Hu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched: Introduce task_is_running()

2021-06-18T09:43:07+00:00

Replace a bunch of 'p->state == TASK_RUNNING' with a new helper: task_is_running(p). Signed-off-by: Peter Zijlstra (Intel) Acked-by: Davidlohr Bueso Acked-by: Geert Uytterhoeven Acked-by: Will Deacon Link: https://lore.kernel.org/r/20210611082838.222401495@infradead.org

tracing: Fix various typos in comments

2021-03-23T18:08:18+00:00

Fix ~59 single-word typos in the tracing code comments, and fix the grammar in a handful of places. Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com Reviewed-by: Randy Dunlap Signed-off-by: Ingo Molnar Signed-off-by: Steven Rostedt (VMware)

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

2021-02-27T16:29:02+00:00

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 ...

nds32: Fix bogus reference to

2021-02-25T06:31:49+00:00

Andestech(nds32) never had . Signed-off-by: Geert Uytterhoeven Acked-by: Greentime Hu Signed-off-by: Greentime Hu

nds32: use get_kernel_nofault in dump_mem

2021-02-25T06:31:49+00:00

Use the proper get_kernel_nofault helper to access an unsafe kernel pointer without faulting instead of playing with set_fs and get_user. Signed-off-by: Christoph Hellwig Acked-by: Nick Hu Acked-by: Greentime Hu Signed-off-by: Greentime Hu