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2020-12-15Merge branch 'exec-update-lock-for-v5.11' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull exec-update-lock update from Eric Biederman: "The key point of this is to transform exec_update_mutex into a rw_semaphore so readers can be separated from writers. This makes it easier to understand what the holders of the lock are doing, and makes it harder to contend or deadlock on the lock. The real deadlock fix wound up in perf_event_open" * 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: exec: Transform exec_update_mutex into a rw_semaphore
2020-12-14Merge tag 'perf-core-2020-12-14' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf updates from Thomas Gleixner: "Core: - Better handling of page table leaves on archictectures which have architectures have non-pagetable aligned huge/large pages. For such architectures a leaf can actually be part of a larger entry. - Prevent a deadlock vs exec_update_mutex Architectures: - The related updates for page size calculation of leaf entries - The usual churn to support new CPUs - Small fixes and improvements all over the place" * tag 'perf-core-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) perf/x86/intel: Add Tremont Topdown support uprobes/x86: Fix fall-through warnings for Clang perf/x86: Fix fall-through warnings for Clang kprobes/x86: Fix fall-through warnings for Clang perf/x86/intel/lbr: Fix the return type of get_lbr_cycles() perf/x86/intel: Fix rtm_abort_event encoding on Ice Lake x86/kprobes: Restore BTF if the single-stepping is cancelled perf: Break deadlock involving exec_update_mutex sparc64/mm: Implement pXX_leaf_size() support powerpc/8xx: Implement pXX_leaf_size() support arm64/mm: Implement pXX_leaf_size() support perf/core: Fix arch_perf_get_page_size() mm: Introduce pXX_leaf_size() mm/gup: Provide gup_get_pte() more generic perf/x86/intel: Add event constraint for CYCLE_ACTIVITY.STALLS_MEM_ANY perf/x86/intel/uncore: Add Rocket Lake support perf/x86/msr: Add Rocket Lake CPU support perf/x86/cstate: Add Rocket Lake CPU support perf/x86/intel: Add Rocket Lake CPU support perf,mm: Handle non-page-table-aligned hugetlbfs ...
2020-12-14Merge tag 'core-entry-2020-12-14' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core entry/exit updates from Thomas Gleixner: "A set of updates for entry/exit handling: - More generalization of entry/exit functionality - The consolidation work to reclaim TIF flags on x86 and also for non-x86 specific TIF flags which are solely relevant for syscall related work and have been moved into their own storage space. The x86 specific part had to be merged in to avoid a major conflict. - The TIF_NOTIFY_SIGNAL work which replaces the inefficient signal delivery mode of task work and results in an impressive performance improvement for io_uring. The non-x86 consolidation of this is going to come seperate via Jens. - The selective syscall redirection facility which provides a clean and efficient way to support the non-Linux syscalls of WINE by catching them at syscall entry and redirecting them to the user space emulation. This can be utilized for other purposes as well and has been designed carefully to avoid overhead for the regular fastpath. This includes the core changes and the x86 support code. - Simplification of the context tracking entry/exit handling for the users of the generic entry code which guarantee the proper ordering and protection. - Preparatory changes to make the generic entry code accomodate S390 specific requirements which are mostly related to their syscall restart mechanism" * tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) entry: Add syscall_exit_to_user_mode_work() entry: Add exit_to_user_mode() wrapper entry_Add_enter_from_user_mode_wrapper entry: Rename exit_to_user_mode() entry: Rename enter_from_user_mode() docs: Document Syscall User Dispatch selftests: Add benchmark for syscall user dispatch selftests: Add kselftest for syscall user dispatch entry: Support Syscall User Dispatch on common syscall entry kernel: Implement selective syscall userspace redirection signal: Expose SYS_USER_DISPATCH si_code type x86: vdso: Expose sigreturn address on vdso to the kernel MAINTAINERS: Add entry for common entry code entry: Fix boot for !CONFIG_GENERIC_ENTRY x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs sched: Detect call to schedule from critical entry code context_tracking: Don't implement exception_enter/exit() on CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK context_tracking: Introduce HAVE_CONTEXT_TRACKING_OFFSTACK x86: Reclaim unused x86 TI flags ...
2020-12-10exec: Transform exec_update_mutex into a rw_semaphoreEric W. Biederman
Recently syzbot reported[0] that there is a deadlock amongst the users of exec_update_mutex. The problematic lock ordering found by lockdep was: perf_event_open (exec_update_mutex -> ovl_i_mutex) chown (ovl_i_mutex -> sb_writes) sendfile (sb_writes -> p->lock) by reading from a proc file and writing to overlayfs proc_pid_syscall (p->lock -> exec_update_mutex) While looking at possible solutions it occured to me that all of the users and possible users involved only wanted to state of the given process to remain the same. They are all readers. The only writer is exec. There is no reason for readers to block on each other. So fix this deadlock by transforming exec_update_mutex into a rw_semaphore named exec_update_lock that only exec takes for writing. Cc: Jann Horn <jannh@google.com> Cc: Vasiliy Kulikov <segoon@openwall.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Bernd Edlinger <bernd.edlinger@hotmail.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Christopher Yeoh <cyeoh@au1.ibm.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Fixes: eea9673250db ("exec: Add exec_update_mutex to replace cred_guard_mutex") [0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2020-12-09perf: Break deadlock involving exec_update_mutexpeterz@infradead.org
Syzbot reported a lock inversion involving perf. The sore point being perf holding exec_update_mutex() for a very long time, specifically across a whole bunch of filesystem ops in pmu::event_init() (uprobes) and anon_inode_getfile(). This then inverts against procfs code trying to take exec_update_mutex. Move the permission checks later, such that we need to hold the mutex over less code. Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-12-03perf/core: Fix arch_perf_get_page_size()Peter Zijlstra
The (new) page-table walker in arch_perf_get_page_size() is broken in various ways. Specifically while it is used in a lockless manner, it doesn't depend on CONFIG_HAVE_FAST_GUP nor uses the proper _lockless offset methods, nor is careful to only read each entry only once. Also the hugetlb support is broken due to calling pte_page() without first checking pte_special(). Rewrite the whole thing to be a proper lockless page-table walker and employ the new pXX_leaf_size() pgtable functions to determine the pagetable size without looking at the page-frames. Fixes: 51b646b2d9f8 ("perf,mm: Handle non-page-table-aligned hugetlbfs") Fixes: 8d97e71811aa ("perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lkml.kernel.org/r/20201126124207.GM3040@hirez.programming.kicks-ass.net
2020-11-26Merge remote-tracking branch 'origin/master' into perf/corePeter Zijlstra
Further perf/core patches will depend on: d3f7b1bb2040 ("mm/gup: fix gup_fast with dynamic page table folding") which is already in Linus' tree.
2020-11-09perf: Tweak perf_event_attr::exclusive semanticsPeter Zijlstra
Currently perf_event_attr::exclusive can be used to ensure an event(group) is the sole group scheduled on the PMU. One consequence is that when you have a pinned event (say the watchdog) you can no longer have regular exclusive event(group)s. Inspired by the fact that !pinned events are considered less strict, allow !pinned,exclusive events to share the PMU with pinned,!exclusive events. Pinned,exclusive is still fully exclusive. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201029162902.105962225@infradead.org
2020-11-09perf: Fix event multiplexing for exclusive groupsPeter Zijlstra
Commit 9e6302056f80 ("perf: Use hrtimers for event multiplexing") placed the hrtimer (re)start call in the wrong place. Instead of capturing all scheduling failures, it only considered the PMU failure. The result is that groups using perf_event_attr::exclusive are no longer rotated. Fixes: 9e6302056f80 ("perf: Use hrtimers for event multiplexing") Reported-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201029162902.038667689@infradead.org
2020-11-09perf: Simplify group_sched_in()Peter Zijlstra
Collate the error paths. Code duplication only leads to divergence and extra bugs. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201029162901.972161394@infradead.org
2020-11-09perf: Simplify group_sched_out()Peter Zijlstra
Since event_sched_out() clears cpuctx->exclusive upon removal of an exclusive event (and only group leaders can be exclusive), there is no point in group_sched_out() trying to do it too. It is impossible for cpuctx->exclusive to still be set here. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201029162901.904060564@infradead.org
2020-11-09perf/arch: Remove perf_sample_data::regs_user_copyPeter Zijlstra
struct perf_sample_data lives on-stack, we should be careful about it's size. Furthermore, the pt_regs copy in there is only because x86_64 is a trainwreck, solve it differently. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/20201030151955.258178461@infradead.org
2020-11-09perf: Optimize get_recursion_context()Peter Zijlstra
"Look ma, no branches!" Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Link: https://lkml.kernel.org/r/20201030151955.187580298@infradead.org
2020-11-09perf: Fix get_recursion_context()Peter Zijlstra
One should use in_serving_softirq() to detect SoftIRQ context. Fixes: 96f6d4444302 ("perf_counter: avoid recursion") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201030151955.120572175@infradead.org
2020-11-09perf: Reduce stack usage of perf_output_begin()Peter Zijlstra
__perf_output_begin() has an on-stack struct perf_sample_data in the unlikely case it needs to generate a LOST record. However, every call to perf_output_begin() must already have a perf_sample_data on-stack. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201030151954.985416146@infradead.org
2020-11-07perf/core: Fix a memory leak in perf_event_parse_addr_filter()kiyin(尹亮)
As shown through runtime testing, the "filename" allocation is not always freed in perf_event_parse_addr_filter(). There are three possible ways that this could happen: - It could be allocated twice on subsequent iterations through the loop, - or leaked on the success path, - or on the failure path. Clean up the code flow to make it obvious that 'filename' is always freed in the reallocation path and in the two return paths as well. We rely on the fact that kfree(NULL) is NOP and filename is initialized with NULL. This fixes the leak. No other side effects expected. [ Dan Carpenter: cleaned up the code flow & added a changelog. ] [ Ingo Molnar: updated the changelog some more. ] Fixes: 375637bc5249 ("perf/core: Introduce address range filtering") Signed-off-by: "kiyin(尹亮)" <kiyin@tencent.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: "Srivatsa S. Bhat" <srivatsa@csail.mit.edu> Cc: Anthony Liguori <aliguori@amazon.com> -- kernel/events/core.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)
2020-11-04Merge branch 'core/urgent' into core/entryThomas Gleixner
Pick up the entry fix before further modifications.
2020-10-29perf,mm: Handle non-page-table-aligned hugetlbfsPeter Zijlstra
A limited nunmber of architectures support hugetlbfs sizes that do not align with the page-tables (ARM64, Power, Sparc64). Add support for this to the generic perf_get_page_size() implementation, and also allow an architecture to override this implementation. This latter is only needed when it uses non-page-table aligned huge pages in its kernel map. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-10-29perf/core: Add support for PERF_SAMPLE_CODE_PAGE_SIZEStephane Eranian
When studying code layout, it is useful to capture the page size of the sampled code address. Add a new sample type for code page size. The new sample type requires collecting the ip. The code page size can be calculated from the NMI-safe perf_get_page_size(). For large PEBS, it's very unlikely that the mapping is gone for the earlier PEBS records. Enable the feature for the large PEBS. The worst case is that page-size '0' is returned. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201001135749.2804-5-kan.liang@linux.intel.com
2020-10-29perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZEKan Liang
Current perf can report both virtual addresses and physical addresses, but not the MMU page size. Without the MMU page size information of the utilized page, users cannot decide whether to promote/demote large pages to optimize memory usage. Add a new sample type for the data MMU page size. Current perf already has a facility to collect data virtual addresses. A page walker is required to walk the pages tables and calculate the MMU page size from a given virtual address. On some platforms, e.g., X86, the page walker is invoked in an NMI handler. So the page walker must be NMI-safe and low overhead. Besides, the page walker should work for both user and kernel virtual address. The existing generic page walker, e.g., walk_page_range_novma(), is a little bit complex and doesn't guarantee the NMI-safe. The follow_page() is only for user-virtual address. Add a new function perf_get_page_size() to walk the page tables and calculate the MMU page size. In the function: - Interrupts have to be disabled to prevent any teardown of the page tables. - For user space threads, the current->mm is used for the page walker. For kernel threads and the like, the current->mm is NULL. The init_mm is used for the page walker. The active_mm is not used here, because it can be NULL. Quote from Peter Zijlstra, "context_switch() can set prev->active_mm to NULL when it transfers it to @next. It does this before @current is updated. So an NMI that comes in between this active_mm swizzling and updating @current will see !active_mm." - The MMU page size is calculated from the page table level. The method should work for all architectures, but it has only been verified on X86. Should there be some architectures, which support perf, where the method doesn't work, it can be fixed later separately. Reporting the wrong page size would not be fatal for the architecture. Some under discussion features may impact the method in the future. Quote from Dave Hansen, "There are lots of weird things folks are trying to do with the page tables, like Address Space Isolation. For instance, if you get a perf NMI when running userspace, current->mm->pgd is *different* than the PGD that was in use when userspace was running. It's close enough today, but it might not stay that way." If the case happens later, lots of consecutive page walk errors will happen. The worst case is that lots of page-size '0' are returned, which would not be fatal. In the perf tool, a check is implemented to detect this case. Once it happens, a kernel patch could be implemented accordingly then. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201001135749.2804-2-kan.liang@linux.intel.com
2020-10-29signal: Add task_sigpending() helperJens Axboe
This is in preparation for maintaining signal_pending() as the decider of whether or not a schedule() loop should be broken, or continue sleeping. This is different than the core signal use cases, which really need to know whether an actual signal is pending or not. task_sigpending() returns non-zero if TIF_SIGPENDING is set. Only core kernel use cases should care about the distinction between the two, make sure those use the task_sigpending() helper. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20201026203230.386348-2-axboe@kernel.dk
2020-10-17task_work: cleanup notification modesJens Axboe
A previous commit changed the notification mode from true/false to an int, allowing notify-no, notify-yes, or signal-notify. This was backwards compatible in the sense that any existing true/false user would translate to either 0 (on notification sent) or 1, the latter which mapped to TWA_RESUME. TWA_SIGNAL was assigned a value of 2. Clean this up properly, and define a proper enum for the notification mode. Now we have: - TWA_NONE. This is 0, same as before the original change, meaning no notification requested. - TWA_RESUME. This is 1, same as before the original change, meaning that we use TIF_NOTIFY_RESUME. - TWA_SIGNAL. This uses TIF_SIGPENDING/JOBCTL_TASK_WORK for the notification. Clean up all the callers, switching their 0/1/false/true to using the appropriate TWA_* mode for notifications. Fixes: e91b48162332 ("task_work: teach task_work_add() to do signal_wake_up()") Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-12Merge tag 'perf-core-2020-10-12' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull performance events updates from Ingo Molnar: "x86 Intel updates: - Add Jasper Lake support - Add support for TopDown metrics on Ice Lake - Fix Ice Lake & Tiger Lake uncore support, add Snow Ridge support - Add a PCI sub driver to support uncore PMUs where the PCI resources have been claimed already - extending the range of supported systems. x86 AMD updates: - Restore 'perf stat -a' behaviour to program the uncore PMU to count all CPU threads. - Fix setting the proper count when sampling Large Increment per Cycle events / 'paired' events. - Fix IBS Fetch sampling on F17h and some other IBS fine tuning, greatly reducing the number of interrupts when large sample periods are specified. - Extends Family 17h RAPL support to also work on compatible F19h machines. Core code updates: - Fix race in perf_mmap_close() - Add PERF_EV_CAP_SIBLING, to denote that sibling events should be closed if the leader is removed. - Smaller fixes and updates" * tag 'perf-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits) perf/core: Fix race in the perf_mmap_close() function perf/x86: Fix n_metric for cancelled txn perf/x86: Fix n_pair for cancelled txn x86/events/amd/iommu: Fix sizeof mismatch perf/x86/intel: Check perf metrics feature for each CPU perf/x86/intel: Fix Ice Lake event constraint table perf/x86/intel/uncore: Fix the scale of the IMC free-running events perf/x86/intel/uncore: Fix for iio mapping on Skylake Server perf/x86/msr: Add Jasper Lake support perf/x86/intel: Add Jasper Lake support perf/x86/intel/uncore: Reduce the number of CBOX counters perf/x86/intel/uncore: Update Ice Lake uncore units perf/x86/intel/uncore: Split the Ice Lake and Tiger Lake MSR uncore support perf/x86/intel/uncore: Support PCIe3 unit on Snow Ridge perf/x86/intel/uncore: Generic support for the PCI sub driver perf/x86/intel/uncore: Factor out uncore_pci_pmu_unregister() perf/x86/intel/uncore: Factor out uncore_pci_pmu_register() perf/x86/intel/uncore: Factor out uncore_pci_find_dev_pmu() perf/x86/intel/uncore: Factor out uncore_pci_get_dev_die_info() perf/amd/uncore: Inform the user how many counters each uncore PMU has ...
2020-10-12perf/core: Fix race in the perf_mmap_close() functionJiri Olsa
There's a possible race in perf_mmap_close() when checking ring buffer's mmap_count refcount value. The problem is that the mmap_count check is not atomic because we call atomic_dec() and atomic_read() separately. perf_mmap_close: ... atomic_dec(&rb->mmap_count); ... if (atomic_read(&rb->mmap_count)) goto out_put; <ring buffer detach> free_uid out_put: ring_buffer_put(rb); /* could be last */ The race can happen when we have two (or more) events sharing same ring buffer and they go through atomic_dec() and then they both see 0 as refcount value later in atomic_read(). Then both will go on and execute code which is meant to be run just once. The code that detaches ring buffer is probably fine to be executed more than once, but the problem is in calling free_uid(), which will later on demonstrate in related crashes and refcount warnings, like: refcount_t: addition on 0; use-after-free. ... RIP: 0010:refcount_warn_saturate+0x6d/0xf ... Call Trace: prepare_creds+0x190/0x1e0 copy_creds+0x35/0x172 copy_process+0x471/0x1a80 _do_fork+0x83/0x3a0 __do_sys_wait4+0x83/0x90 __do_sys_clone+0x85/0xa0 do_syscall_64+0x5b/0x1e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Using atomic decrease and check instead of separated calls. Tested-by: Michael Petlan <mpetlan@redhat.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Wade Mealing <wmealing@redhat.com> Fixes: 9bb5d40cd93c ("perf: Fix mmap() accounting hole"); Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava
2020-10-09perf: Fix task_function_call() error handlingKajol Jain
The error handling introduced by commit: 2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()") looses any return value from smp_call_function_single() that is not {0, -EINVAL}. This is a problem because it will return -EXNIO when the target CPU is offline. Worse, in that case it'll turn into an infinite loop. Fixes: 2ed6edd33a21 ("perf: Add cond_resched() to task_function_call()") Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Kajol Jain <kjain@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Barret Rhoden <brho@google.com> Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: https://lkml.kernel.org/r/20200827064732.20860-1-kjain@linux.ibm.com
2020-09-10perf/core: Pull pmu::sched_task() into perf_event_context_sched_out()Kan Liang
The pmu::sched_task() is a context switch callback. It passes the cpuctx->task_ctx as a parameter to the lower code. To find the cpuctx->task_ctx, the current code iterates a cpuctx list. The same context will iterated in perf_event_context_sched_out() soon. Share the cpuctx->task_ctx can avoid the unnecessary iteration of the cpuctx list. The pmu::sched_task() is also required for the optimization case for equivalent contexts. The task_ctx_sched_out() will eventually disable and reenable the PMU when schedule out events. Add perf_pmu_disable() and perf_pmu_enable() around task_ctx_sched_out() don't break anything. Drop the cpuctx->ctx.lock for the pmu::sched_task(). The lock is for per-CPU context, which is not necessary for the per-task context schedule. No one uses sched_cb_entry, perf_sched_cb_usages, sched_cb_list, and perf_pmu_sched_task() any more. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200821195754.20159-2-kan.liang@linux.intel.com
2020-09-10perf/core: Pull pmu::sched_task() into perf_event_context_sched_in()Kan Liang
The pmu::sched_task() is a context switch callback. It passes the cpuctx->task_ctx as a parameter to the lower code. To find the cpuctx->task_ctx, the current code iterates a cpuctx list. The same context was just iterated in perf_event_context_sched_in(), which is invoked right before the pmu::sched_task(). Reuse the cpuctx->task_ctx from perf_event_context_sched_in() can avoid the unnecessary iteration of the cpuctx list. Both pmu::sched_task and perf_event_context_sched_in() have to disable PMU. Pull the pmu::sched_task into perf_event_context_sched_in() can also save the overhead from the PMU disable and reenable. The new and old tasks may have equivalent contexts. The current code optimize this case by swapping the context, which avoids the scheduling. For this case, pmu::sched_task() is still required, e.g., restore the LBR content. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200821195754.20159-1-kan.liang@linux.intel.com
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-21uprobes: __replace_page() avoid BUG in munlock_vma_page()Hugh Dickins
syzbot crashed on the VM_BUG_ON_PAGE(PageTail) in munlock_vma_page(), when called from uprobes __replace_page(). Which of many ways to fix it? Settled on not calling when PageCompound (since Head and Tail are equals in this context, PageCompound the usual check in uprobes.c, and the prior use of FOLL_SPLIT_PMD will have cleared PageMlocked already). Fixes: 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [5.4+] Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008161338360.20413@eggly.anvils Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-18perf/core: Add a new PERF_EV_CAP_SIBLING event capabilityKan Liang
Current perf assumes that events in a group are independent. Close an event doesn't impact the value of the other events in the same group. If the closed event is a member, after the event closure, other events are still running like a group. If the closed event is a leader, other events are running as singleton events. Add PERF_EV_CAP_SIBLING to allow events to indicate they require being part of a group, and when the leader dies they cannot exist independently. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200723171117.9918-8-kan.liang@linux.intel.com
2020-08-15Merge tag 'perf-urgent-2020-08-15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "Misc fixes, an expansion of perf syscall access to CAP_PERFMON privileged tools, plus a RAPL HW-enablement for Intel SPR platforms" * tag 'perf-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/x86/rapl: Add support for Intel SPR platform perf/x86/rapl: Support multiple RAPL unit quirks perf/x86/rapl: Fix missing psys sysfs attributes hw_breakpoint: Remove unused __register_perf_hw_breakpoint() declaration kprobes: Remove show_registers() function prototype perf/core: Take over CAP_SYS_PTRACE creds to CAP_PERFMON capability
2020-08-12mm/gup: remove task_struct pointer for all gup codePeter Xu
After the cleanup of page fault accounting, gup does not need to pass task_struct around any more. Remove that parameter in the whole gup stack. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12uaccess: add force_uaccess_{begin,end} helpersChristoph Hellwig
Add helpers to wrap the get_fs/set_fs magic for undoing any damange done by set_fs(KERNEL_DS). There is no real functional benefit, but this documents the intent of these calls better, and will allow stubbing the functions out easily for kernels builds that do not allow address space overrides in the future. [hch@lst.de: drop two incorrect hunks, fix a commit log typo] Link: http://lkml.kernel.org/r/20200714105505.935079-6-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Greentime Hu <green.hu@gmail.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Nick Hu <nickhu@andestech.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Link: http://lkml.kernel.org/r/20200710135706.537715-6-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12mm/vmscan: protect the workingset on anonymous LRUJoonsoo Kim
In current implementation, newly created or swap-in anonymous page is started on active list. Growing active list results in rebalancing active/inactive list so old pages on active list are demoted to inactive list. Hence, the page on active list isn't protected at all. Following is an example of this situation. Assume that 50 hot pages on active list. Numbers denote the number of pages on active/inactive list (active | inactive). 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(uo) | 50(h) 3. workload: another 50 newly created (used-once) pages 50(uo) | 50(uo), swap-out 50(h) This patch tries to fix this issue. Like as file LRU, newly created or swap-in anonymous pages will be inserted to the inactive list. They are promoted to active list if enough reference happens. This simple modification changes the above example as following. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(h) | 50(uo) 3. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(uo) As you can see, hot pages on active list would be protected. Note that, this implementation has a drawback that the page cannot be promoted and will be swapped-out if re-access interval is greater than the size of inactive list but less than the size of total(active+inactive). To solve this potential issue, following patch will apply workingset detection similar to the one that's already applied to file LRU. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-06perf/core: Take over CAP_SYS_PTRACE creds to CAP_PERFMON capabilityAlexey Budankov
Open access to per-process monitoring for CAP_PERFMON only privileged processes [1]. Extend ptrace_may_access() check in perf_events subsystem with perfmon_capable() to simplify user experience and make monitoring more secure by reducing attack surface. [1] https://lore.kernel.org/lkml/7776fa40-6c65-2aa6-1322-eb3a01201000@linux.intel.com/ Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/6e8392ff-4732-0012-2949-e1587709f0f6@linux.intel.com
2020-08-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextLinus Torvalds
Pull networking updates from David Miller: 1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan. 2) Support UDP segmentation in code TSO code, from Eric Dumazet. 3) Allow flashing different flash images in cxgb4 driver, from Vishal Kulkarni. 4) Add drop frames counter and flow status to tc flower offloading, from Po Liu. 5) Support n-tuple filters in cxgb4, from Vishal Kulkarni. 6) Various new indirect call avoidance, from Eric Dumazet and Brian Vazquez. 7) Fix BPF verifier failures on 32-bit pointer arithmetic, from Yonghong Song. 8) Support querying and setting hardware address of a port function via devlink, use this in mlx5, from Parav Pandit. 9) Support hw ipsec offload on bonding slaves, from Jarod Wilson. 10) Switch qca8k driver over to phylink, from Jonathan McDowell. 11) In bpftool, show list of processes holding BPF FD references to maps, programs, links, and btf objects. From Andrii Nakryiko. 12) Several conversions over to generic power management, from Vaibhav Gupta. 13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry Yakunin. 14) Various https url conversions, from Alexander A. Klimov. 15) Timestamping and PHC support for mscc PHY driver, from Antoine Tenart. 16) Support bpf iterating over tcp and udp sockets, from Yonghong Song. 17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov. 18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan. 19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several drivers. From Luc Van Oostenryck. 20) XDP support for xen-netfront, from Denis Kirjanov. 21) Support receive buffer autotuning in MPTCP, from Florian Westphal. 22) Support EF100 chip in sfc driver, from Edward Cree. 23) Add XDP support to mvpp2 driver, from Matteo Croce. 24) Support MPTCP in sock_diag, from Paolo Abeni. 25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic infrastructure, from Jakub Kicinski. 26) Several pci_ --> dma_ API conversions, from Christophe JAILLET. 27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel. 28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki. 29) Refactor a lot of networking socket option handling code in order to avoid set_fs() calls, from Christoph Hellwig. 30) Add rfc4884 support to icmp code, from Willem de Bruijn. 31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei. 32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin. 33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin. 34) Support TCP syncookies in MPTCP, from Flowian Westphal. 35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano Brivio. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits) net: thunderx: initialize VF's mailbox mutex before first usage usb: hso: remove bogus check for EINPROGRESS usb: hso: no complaint about kmalloc failure hso: fix bailout in error case of probe ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM selftests/net: relax cpu affinity requirement in msg_zerocopy test mptcp: be careful on subflow creation selftests: rtnetlink: make kci_test_encap() return sub-test result selftests: rtnetlink: correct the final return value for the test net: dsa: sja1105: use detected device id instead of DT one on mismatch tipc: set ub->ifindex for local ipv6 address ipv6: add ipv6_dev_find() net: openvswitch: silence suspicious RCU usage warning Revert "vxlan: fix tos value before xmit" ptp: only allow phase values lower than 1 period farsync: switch from 'pci_' to 'dma_' API wan: wanxl: switch from 'pci_' to 'dma_' API hv_netvsc: do not use VF device if link is down dpaa2-eth: Fix passing zero to 'PTR_ERR' warning net: macb: Properly handle phylink on at91sam9x ...
2020-08-04Merge tag 'uninit-macro-v5.9-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull uninitialized_var() macro removal from Kees Cook: "This is long overdue, and has hidden too many bugs over the years. The series has several "by hand" fixes, and then a trivial treewide replacement. - Clean up non-trivial uses of uninitialized_var() - Update documentation and checkpatch for uninitialized_var() removal - Treewide removal of uninitialized_var()" * tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: compiler: Remove uninitialized_var() macro treewide: Remove uninitialized_var() usage checkpatch: Remove awareness of uninitialized_var() macro mm/debug_vm_pgtable: Remove uninitialized_var() usage f2fs: Eliminate usage of uninitialized_var() macro media: sur40: Remove uninitialized_var() usage KVM: PPC: Book3S PR: Remove uninitialized_var() usage clk: spear: Remove uninitialized_var() usage clk: st: Remove uninitialized_var() usage spi: davinci: Remove uninitialized_var() usage ide: Remove uninitialized_var() usage rtlwifi: rtl8192cu: Remove uninitialized_var() usage b43: Remove uninitialized_var() usage drbd: Remove uninitialized_var() usage x86/mm/numa: Remove uninitialized_var() usage docs: deprecated.rst: Add uninitialized_var()
2020-07-28Merge tag 'v5.8-rc7' into perf/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-07-25bpf: Fail PERF_EVENT_IOC_SET_BPF when bpf_get_[stack|stackid] cannot workSong Liu
bpf_get_[stack|stackid] on perf_events with precise_ip uses callchain attached to perf_sample_data. If this callchain is not presented, do not allow attaching BPF program that calls bpf_get_[stack|stackid] to this event. In the error case, -EPROTO is returned so that libbpf can identify this error and print proper hint message. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200723180648.1429892-3-songliubraving@fb.com
2020-07-25Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netDavid S. Miller
The UDP reuseport conflict was a little bit tricky. The net-next code, via bpf-next, extracted the reuseport handling into a helper so that the BPF sk lookup code could invoke it. At the same time, the logic for reuseport handling of unconnected sockets changed via commit efc6b6f6c3113e8b203b9debfb72d81e0f3dcace which changed the logic to carry on the reuseport result into the rest of the lookup loop if we do not return immediately. This requires moving the reuseport_has_conns() logic into the callers. While we are here, get rid of inline directives as they do not belong in foo.c files. The other changes were cases of more straightforward overlapping modifications. Signed-off-by: David S. Miller <davem@davemloft.net>
2020-07-24uprobes: Change handle_swbp() to send SIGTRAP with si_code=SI_KERNEL, to fix ↵Oleg Nesterov
GDB regression If a tracee is uprobed and it hits int3 inserted by debugger, handle_swbp() does send_sig(SIGTRAP, current, 0) which means si_code == SI_USER. This used to work when this code was written, but then GDB started to validate si_code and now it simply can't use breakpoints if the tracee has an active uprobe: # cat test.c void unused_func(void) { } int main(void) { return 0; } # gcc -g test.c -o test # perf probe -x ./test -a unused_func # perf record -e probe_test:unused_func gdb ./test -ex run GNU gdb (GDB) 10.0.50.20200714-git ... Program received signal SIGTRAP, Trace/breakpoint trap. 0x00007ffff7ddf909 in dl_main () from /lib64/ld-linux-x86-64.so.2 (gdb) The tracee hits the internal breakpoint inserted by GDB to monitor shared library events but GDB misinterprets this SIGTRAP and reports a signal. Change handle_swbp() to use force_sig(SIGTRAP), this matches do_int3_user() and fixes the problem. This is the minimal fix for -stable, arch/x86/kernel/uprobes.c is equally wrong; it should use send_sigtrap(TRAP_TRACE) instead of send_sig(SIGTRAP), but this doesn't confuse GDB and needs another x86-specific patch. Reported-by: Aaron Merey <amerey@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200723154420.GA32043@redhat.com
2020-07-16treewide: Remove uninitialized_var() usageKees Cook
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
2020-07-08perf/x86: Remove task_ctx_sizeKan Liang
A new kmem_cache method has replaced the kzalloc() to allocate the PMU specific data. The task_ctx_size is not required anymore. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1593780569-62993-19-git-send-email-kan.liang@linux.intel.com
2020-07-08perf/core: Use kmem_cache to allocate the PMU specific dataKan Liang
Currently, the PMU specific data task_ctx_data is allocated by the function kzalloc() in the perf generic code. When there is no specific alignment requirement for the task_ctx_data, the method works well for now. However, there will be a problem once a specific alignment requirement is introduced in future features, e.g., the Architecture LBR XSAVE feature requires 64-byte alignment. If the specific alignment requirement is not fulfilled, the XSAVE family of instructions will fail to save/restore the xstate to/from the task_ctx_data. The function kzalloc() itself only guarantees a natural alignment. A new method to allocate the task_ctx_data has to be introduced, which has to meet the requirements as below: - must be a generic method can be used by different architectures, because the allocation of the task_ctx_data is implemented in the perf generic code; - must be an alignment-guarantee method (The alignment requirement is not changed after the boot); - must be able to allocate/free a buffer (smaller than a page size) dynamically; - should not cause extra CPU overhead or space overhead. Several options were considered as below: - One option is to allocate a larger buffer for task_ctx_data. E.g., ptr = kmalloc(size + alignment, GFP_KERNEL); ptr &= ~(alignment - 1); This option causes space overhead. - Another option is to allocate the task_ctx_data in the PMU specific code. To do so, several function pointers have to be added. As a result, both the generic structure and the PMU specific structure will become bigger. Besides, extra function calls are added when allocating/freeing the buffer. This option will increase both the space overhead and CPU overhead. - The third option is to use a kmem_cache to allocate a buffer for the task_ctx_data. The kmem_cache can be created with a specific alignment requirement by the PMU at boot time. A new pointer for kmem_cache has to be added in the generic struct pmu, which would be used to dynamically allocate a buffer for the task_ctx_data at run time. Although the new pointer is added to the struct pmu, the existing variable task_ctx_size is not required anymore. The size of the generic structure is kept the same. The third option which meets all the aforementioned requirements is used to replace kzalloc() for the PMU specific data allocation. A later patch will remove the kzalloc() method and the related variables. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1593780569-62993-17-git-send-email-kan.liang@linux.intel.com
2020-07-08perf/core: Factor out functions to allocate/free the task_ctx_dataKan Liang
The method to allocate/free the task_ctx_data is going to be changed in the following patch. Currently, the task_ctx_data is allocated/freed in several different places. To avoid repeatedly modifying the same codes in several different places, alloc_task_ctx_data() and free_task_ctx_data() are factored out to allocate/free the task_ctx_data. The modification only needs to be applied once. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1593780569-62993-16-git-send-email-kan.liang@linux.intel.com
2020-07-01perf: Expose get/put_callchain_entry()Song Liu
Sanitize and expose get/put_callchain_entry(). This would be used by bpf stack map. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200630062846.664389-2-songliubraving@fb.com
2020-06-15perf: Add perf text poke eventAdrian Hunter
Record (single instruction) changes to the kernel text (i.e. self-modifying code) in order to support tracers like Intel PT and ARM CoreSight. A copy of the running kernel code is needed as a reference point (e.g. from /proc/kcore). The text poke event records the old bytes and the new bytes so that the event can be processed forwards or backwards. The basic problem is recording the modified instruction in an unambiguous manner given SMP instruction cache (in)coherence. That is, when modifying an instruction concurrently any solution with one or multiple timestamps is not sufficient: CPU0 CPU1 0 1 write insn A 2 execute insn A 3 sync-I$ 4 Due to I$, CPU1 might execute either the old or new A. No matter where we record tracepoints on CPU0, one simply cannot tell what CPU1 will have observed, except that at 0 it must be the old one and at 4 it must be the new one. To solve this, take inspiration from x86 text poking, which has to solve this exact problem due to variable length instruction encoding and I-fetch windows. 1) overwrite the instruction with a breakpoint and sync I$ This guarantees that that code flow will never hit the target instruction anymore, on any CPU (or rather, it will cause an exception). 2) issue the TEXT_POKE event 3) overwrite the breakpoint with the new instruction and sync I$ Now we know that any execution after the TEXT_POKE event will either observe the breakpoint (and hit the exception) or the new instruction. So by guarding the TEXT_POKE event with an exception on either side; we can now tell, without doubt, which instruction another CPU will have observed. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200512121922.8997-2-adrian.hunter@intel.com
2020-06-09Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge even more updates from Andrew Morton: - a kernel-wide sweep of show_stack() - pagetable cleanups - abstract out accesses to mmap_sem - prep for mmap_sem scalability work - hch's user acess work Subsystems affected by this patch series: debug, mm/pagemap, mm/maccess, mm/documentation. * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (93 commits) include/linux/cache.h: expand documentation over __read_mostly maccess: return -ERANGE when probe_kernel_read() fails x86: use non-set_fs based maccess routines maccess: allow architectures to provide kernel probing directly maccess: move user access routines together maccess: always use strict semantics for probe_kernel_read maccess: remove strncpy_from_unsafe tracing/kprobes: handle mixed kernel/userspace probes better bpf: rework the compat kernel probe handling bpf:bpf_seq_printf(): handle potentially unsafe format string better bpf: handle the compat string in bpf_trace_copy_string better bpf: factor out a bpf_trace_copy_string helper maccess: unify the probe kernel arch hooks maccess: remove probe_read_common and probe_write_common maccess: rename strnlen_unsafe_user to strnlen_user_nofault maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault maccess: update the top of file comment maccess: clarify kerneldoc comments maccess: remove duplicate kerneldoc comments ...
2020-06-09uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly alignedOleg Nesterov
uprobe_write_opcode() must not cross page boundary; prepare_uprobe() relies on arch_uprobe_analyze_insn() which should validate "vaddr" but some architectures (csky, s390, and sparc) don't do this. We can remove the BUG_ON() check in prepare_uprobe() and validate the offset early in __uprobe_register(). The new IS_ALIGNED() check matches the alignment check in arch_prepare_kprobe() on supported architectures, so I think that all insns must be aligned to UPROBE_SWBP_INSN_SIZE. Another problem is __update_ref_ctr() which was wrong from the very beginning, it can read/write outside of kmap'ed page unless "vaddr" is aligned to sizeof(short), __uprobe_register() should check this too. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Tested-by: Sven Schnelle <svens@linux.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09mmap locking API: convert mmap_sem commentsMichel Lespinasse
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>