linux/kernel/events/core.c, branch v5.10

perf: Tweak perf_event_attr::exclusive semantics

2020-11-09T17:12:36Z

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) Link: https://lkml.kernel.org/r/20201029162902.105962225@infradead.org

perf: Fix event multiplexing for exclusive groups

2020-11-09T17:12:36Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201029162902.038667689@infradead.org

perf: Simplify group_sched_in()

2020-11-09T17:12:35Z

Collate the error paths. Code duplication only leads to divergence and extra bugs. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201029162901.972161394@infradead.org

perf: Simplify group_sched_out()

2020-11-09T17:12:35Z

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) Link: https://lkml.kernel.org/r/20201029162901.904060564@infradead.org

perf/arch: Remove perf_sample_data::regs_user_copy

2020-11-09T17:12:34Z

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 Signed-off-by: Peter Zijlstra (Intel) Tested-by: Steven Rostedt Link: https://lkml.kernel.org/r/20201030151955.258178461@infradead.org

perf: Reduce stack usage of perf_output_begin()

2020-11-09T17:12:33Z

__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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201030151954.985416146@infradead.org

perf/core: Fix a memory leak in perf_event_parse_addr_filter()

2020-11-07T12:07:26Z

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)" Signed-off-by: Dan Carpenter Signed-off-by: Ingo Molnar Cc: "Srivatsa S. Bhat" Cc: Anthony Liguori -- kernel/events/core.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)

Merge tag 'perf-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-10-12T21:14:35Z

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 ...

perf/core: Fix race in the perf_mmap_close() function

2020-10-12T11:24:26Z

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; 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 Signed-off-by: Jiri Olsa Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Namhyung Kim Acked-by: Wade Mealing Fixes: 9bb5d40cd93c ("perf: Fix mmap() accounting hole"); Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava

perf: Fix task_function_call() error handling

2020-10-09T06:18:33Z

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 Signed-off-by: Kajol Jain Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Barret Rhoden Tested-by: Srikar Dronamraju Link: https://lkml.kernel.org/r/20200827064732.20860-1-kjain@linux.ibm.com