Hi Arnaldo, On Tue, Mar 14, 2023 at 5:23 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote: > > Em Mon, Mar 13, 2023 at 06:45:53PM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Mon, Mar 13, 2023 at 01:48:21PM -0700, Namhyung Kim escreveu: > > > Hello, > > > > > > This patchset improves the symbolization of locks for -l/--lock-addr mode. > > > As of now it only shows global lock symbols present in the kallsyms. But > > > we can add some more lock symbols by traversing pointers in the BPF program. > > > > > > For example, mmap_lock can be reached from the mm_struct of the current task > > > (task_struct->mm->mmap_lock) and we can compare the address of the give lock > > > with it. Similarly I've added 'siglock' for current->sighand->siglock. > > Hey, we can go a bit further by using something like pahole's > --expand_types and --expand_pointers and play iterating a type members > and looking for locks, like: > > ⬢[acme@toolbox pahole]$ pahole task_struct | grep spinlock_t > spinlock_t alloc_lock; /* 3280 4 */ > raw_spinlock_t pi_lock; /* 3284 4 */ > seqcount_spinlock_t mems_allowed_seq; /* 3616 4 */ > ⬢[acme@toolbox pahole]$ > > Expand points will find mmap_lock: > > ⬢[acme@toolbox pahole]$ pahole --expand_pointers -C task_struct | grep -B10 mmap_lock > } *pgd; > atomic_t membarrier_state; > atomic_t mm_users; > atomic_t mm_count; > > /* XXX 4 bytes hole, try to pack */ > > atomic_long_t pgtables_bytes; > int map_count; > spinlock_t page_table_lock; > struct rw_semaphore mmap_lock; > ^C > ⬢[acme@toolbox pahole]$ > > > ITs just too much expansion to see task_struct->mm, but it is there, of > course: > > ⬢[acme@toolbox pahole]$ pahole mm_struct | grep mmap_lock > struct rw_semaphore mmap_lock; /* 120 40 */ > ⬢[acme@toolbox pahole]$ > > Also: > > ⬢[acme@toolbox pahole]$ pahole --contains rw_semaphore > address_space > signal_struct > key > inode > super_block > quota_info > user_namespace > blocking_notifier_head > backing_dev_info > anon_vma > tty_struct > cpufreq_policy > tcf_block > ipc_ids > autogroup > kvm_arch > posix_clock > listener_list > uprobe > kernfs_root > configfs_fragment > ext4_inode_info > ext4_group_info > btrfs_fs_info > extent_buffer > btrfs_dev_replace > btrfs_space_info > btrfs_inode > btrfs_block_group > tpm_chip > ib_device > ib_xrcd > blk_crypto_profile > controller > led_classdev > cppc_pcc_data > dm_snapshot > ⬢[acme@toolbox pahole]$ > > And: > > ⬢[acme@toolbox pahole]$ pahole --find_pointers_to mm_struct > task_struct: mm > task_struct: active_mm > vm_area_struct: vm_mm > flush_tlb_info: mm > signal_struct: oom_mm > tlb_state: loaded_mm > linux_binprm: mm > mmu_gather: mm > trace_event_raw_xen_mmu_ptep_modify_prot: mm > trace_event_raw_xen_mmu_alloc_ptpage: mm > trace_event_raw_xen_mmu_pgd: mm > trace_event_raw_xen_mmu_flush_tlb_multi: mm > trace_event_raw_hyperv_mmu_flush_tlb_multi: mm > mmu_notifier: mm > mmu_notifier_range: mm > sgx_encl_mm: mm > rq: prev_mm > kvm: mm > cpuset_migrate_mm_work: mm > mmap_unlock_irq_work: mm > delayed_uprobe: mm > map_info: mm > trace_event_raw_mmap_lock: mm > trace_event_raw_mmap_lock_acquire_returned: mm > mm_walk: mm > make_exclusive_args: mm > mmu_interval_notifier: mm > mm_slot: mm > rmap_item: mm > trace_event_raw_mm_khugepaged_scan_pmd: mm > trace_event_raw_mm_collapse_huge_page: mm > trace_event_raw_mm_collapse_huge_page_swapin: mm > mm_slot: mm > move_charge_struct: mm > userfaultfd_ctx: mm > proc_maps_private: mm > remap_pfn: mm > intel_svm: mm > binder_alloc: vma_vm_mm > ⬢[acme@toolbox pahole]$ This looks really cool! especially. I'm especially interested in adding super_block and kernfs_root. Let me see how I can add them. Thanks, Namhyung
