user/sven/linux.git/kernel/trace/fprobe.c, branch v6.7.3

Merge tag 'probes-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-11-02T02:15:42Z

Pull probes updates from Masami Hiramatsu: "Cleanups: - kprobes: Fixes typo in kprobes samples - tracing/eprobes: Remove 'break' after return kretprobe/fprobe performance improvements: - lib: Introduce new `objpool`, which is a high performance lockless object queue. This uses per-cpu ring array to allocate/release objects from the pre-allocated object pool. Since the index of ring array is a 32bit sequential counter, we can retry to push/pop the object pointer from the ring without lock (as seq-lock does) - lib: Add an objpool test module to test the functionality and evaluate the performance under some circumstances - kprobes/fprobe: Improve kretprobe and rethook scalability performance with objpool. This improves both legacy kretprobe and fprobe exit handler (which is based on rethook) to be scalable on SMP systems. Even with 8-threads parallel test, it shows a great scalability improvement - Remove unneeded freelist.h which is replaced by objpool - objpool: Add maintainers entry for the objpool - objpool: Fix to remove unused include header lines" * tag 'probes-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: kprobes: unused header files removed MAINTAINERS: objpool added kprobes: freelist.h removed kprobes: kretprobe scalability improvement lib: objpool test module added lib: objpool added: ring-array based lockless MPMC tracing/eprobe: drop unneeded breaks samples: kprobes: Fixes a typo

kprobes: kretprobe scalability improvement

2023-10-18T14:59:54Z

kretprobe is using freelist to manage return-instances, but freelist, as LIFO queue based on singly linked list, scales badly and reduces the overall throughput of kretprobed routines, especially for high contention scenarios. Here's a typical throughput test of sys_prctl (counts in 10 seconds, measured with perf stat -a -I 10000 -e syscalls:sys_enter_prctl): OS: Debian 10 X86_64, Linux 6.5rc7 with freelist HW: XEON 8336C x 2, 64 cores/128 threads, DDR4 3200MT/s 1T 2T 4T 8T 16T 24T 24150045 29317964 15446741 12494489 18287272 17708768 32T 48T 64T 72T 96T 128T 16200682 13737658 11645677 11269858 10470118 9931051 This patch introduces objpool to replace freelist. objpool is a high performance queue, which can bring near-linear scalability to kretprobed routines. Tests of kretprobe throughput show the biggest ratio as 159x of original freelist. Here's the result: 1T 2T 4T 8T 16T native: 41186213 82336866 164250978 328662645 658810299 freelist: 24150045 29317964 15446741 12494489 18287272 objpool: 23926730 48010314 96125218 191782984 385091769 32T 48T 64T 96T 128T native: 1330338351 1969957941 2512291791 2615754135 2671040914 freelist: 16200682 13737658 11645677 10470118 9931051 objpool: 764481096 1147149781 1456220214 1502109662 1579015050 Testings on 96-core ARM64 output similarly, but with the biggest ratio up to 448x: OS: Debian 10 AARCH64, Linux 6.5rc7 HW: Kunpeng-920 96 cores/2 sockets/4 NUMA nodes, DDR4 2933 MT/s 1T 2T 4T 8T 16T native: . 30066096 63569843 126194076 257447289 505800181 freelist: 16152090 11064397 11124068 7215768 5663013 objpool: 13997541 28032100 55726624 110099926 221498787 24T 32T 48T 64T 96T native: 763305277 1015925192 1521075123 2033009392 3021013752 freelist: 5015810 4602893 3766792 3382478 2945292 objpool: 328192025 439439564 668534502 887401381 1319972072 Link: https://lore.kernel.org/all/20231017135654.82270-4-wuqiang.matt@bytedance.com/ Signed-off-by: wuqiang.matt Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google)

fprobe: Fix to ensure the number of active retprobes is not zero

2023-10-17T01:22:42Z

The number of active retprobes can be zero but it is not acceptable, so return EINVAL error if detected. Link: https://lore.kernel.org/all/169750018550.186853.11198884812017796410.stgit@devnote2/ Reported-by: wuqiang.matt Closes: https://lore.kernel.org/all/20231016222103.cb9f426edc60220eabd8aa6a@kernel.org/ Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support") Signed-off-by: Masami Hiramatsu (Google)

Merge tag 'probes-fixes-v6.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-07-16T19:13:51Z

Pull probe fixes from Masami Hiramatsu: - fprobe: Add a comment why fprobe will be skipped if another kprobe is running in fprobe_kprobe_handler(). - probe-events: Fix some issues related to fetch-arguments: - Fix double counting of the string length for user-string and symstr. This will require longer buffer in the array case. - Fix not to count error code (minus value) for the total used length in array argument. This makes the total used length shorter. - Fix to update dynamic used data size counter only if fetcharg uses the dynamic size data. This may mis-count the used dynamic data size and corrupt data. - Revert "tracing: Add "(fault)" name injection to kernel probes" because that did not work correctly with a bug, and we agreed the current '(fault)' output (instead of '"(fault)"' like a string) explains what happened more clearly. - Fix to record 0-length (means fault access) data_loc data in fetch function itself, instead of store_trace_args(). If we record an array of string, this will fix to save fault access data on each entry of the array correctly. * tag 'probes-fixes-v6.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails Revert "tracing: Add "(fault)" name injection to kernel probes" tracing/probes: Fix to update dynamic data counter if fetcharg uses it tracing/probes: Fix not to count error code to total length tracing/probes: Fix to avoid double count of the string length on the array fprobes: Add a comment why fprobe_kprobe_handler exits if kprobe is running

fprobes: Add a comment why fprobe_kprobe_handler exits if kprobe is running

2023-07-13T15:24:00Z

Add a comment the reason why fprobe_kprobe_handler() exits if any other kprobe is running. Link: https://lore.kernel.org/all/168874788299.159442.2485957441413653858.stgit@devnote2/ Suggested-by: Steven Rostedt Link: https://lore.kernel.org/all/20230706120916.3c6abf15@gandalf.local.home/ Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google)

Merge tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-07-12T19:01:16Z

Pull probes fixes from Masami Hiramatsu: - Fix fprobe's rethook release issues: - Release rethook after ftrace_ops is unregistered so that the rethook is not accessed after free. - Stop rethook before ftrace_ops is unregistered so that the rethook is NOT used after exiting unregister_fprobe() - Fix eprobe cleanup logic. If it attaches to multiple events and failes to enable one of them, rollback all enabled events correctly. - Fix fprobe to unlock ftrace recursion lock correctly when it missed by another running kprobe. - Cleanup kprobe to remove unnecessary NULL. - Cleanup kprobe to remove unnecessary 0 initializations. * tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free() kernel: kprobes: Remove unnecessary ‘0’ values kprobes: Remove unnecessary ‘NULL’ values from correct_ret_addr fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock kernel/trace: Fix cleanup logic of enable_trace_eprobe fprobe: Release rethook after the ftrace_ops is unregistered

fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free()

2023-07-11T00:17:01Z

Ensure running fprobe_exit_handler() has finished before calling rethook_free() in the unregister_fprobe() so that caller can free the fprobe right after unregister_fprobe(). unregister_fprobe() ensured that all running fprobe_entry/exit_handler() have finished by calling unregister_ftrace_function() which synchronizes RCU. But commit 5f81018753df ("fprobe: Release rethook after the ftrace_ops is unregistered") changed to call rethook_free() after unregister_ftrace_function(). So call rethook_stop() to make rethook disabled before unregister_ftrace_function() and ensure it again. Here is the possible code flow that can call the exit handler after unregister_fprobe(). ------ CPU1 CPU2 call unregister_fprobe(fp) ... __fprobe_handler() rethook_hook() on probed function unregister_ftrace_function() return from probed function rethook hooks find rh->handler == fprobe_exit_handler call fprobe_exit_handler() rethook_free(): set rh->handler = NULL; return from unreigster_fprobe; call fp->exit_handler() <- (*) ------ (*) At this point, the exit handler is called after returning from unregister_fprobe(). This fixes it as following; ------ CPU1 CPU2 call unregister_fprobe() ... rethook_stop(): set rh->handler = NULL; __fprobe_handler() rethook_hook() on probed function unregister_ftrace_function() return from probed function rethook hooks find rh->handler == NULL return from rethook rethook_free() return from unreigster_fprobe; ------ Link: https://lore.kernel.org/all/168873859949.156157.13039240432299335849.stgit@devnote2/ Fixes: 5f81018753df ("fprobe: Release rethook after the ftrace_ops is unregistered") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google)

fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock

2023-07-10T15:48:33Z

Unlock ftrace recursion lock when fprobe_kprobe_handler() is failed because of some running kprobe. Link: https://lore.kernel.org/all/20230703092336.268371-1-zegao@tencent.com/ Fixes: 3cc4e2c5fbae ("fprobe: make fprobe_kprobe_handler recursion free") Reported-by: Yafang Closes: https://lore.kernel.org/linux-trace-kernel/CALOAHbC6UpfFOOibdDiC7xFc5YFUgZnk3MZ=3Ny6we=AcrNbew@mail.gmail.com/ Signed-off-by: Ze Gao Acked-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Reviewed-by: Steven Rostedt (Google) Signed-off-by: Masami Hiramatsu (Google)

fprobe: Release rethook after the ftrace_ops is unregistered

2023-06-27T14:38:31Z

While running bpf selftests it's possible to get following fault: general protection fault, probably for non-canonical address \ 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI ... Call Trace: fprobe_handler+0xc1/0x270 ? __pfx_bpf_testmod_init+0x10/0x10 ? __pfx_bpf_testmod_init+0x10/0x10 ? bpf_fentry_test1+0x5/0x10 ? bpf_fentry_test1+0x5/0x10 ? bpf_testmod_init+0x22/0x80 ? do_one_initcall+0x63/0x2e0 ? rcu_is_watching+0xd/0x40 ? kmalloc_trace+0xaf/0xc0 ? do_init_module+0x60/0x250 ? __do_sys_finit_module+0xac/0x120 ? do_syscall_64+0x37/0x90 ? entry_SYSCALL_64_after_hwframe+0x72/0xdc In unregister_fprobe function we can't release fp->rethook while it's possible there are some of its users still running on another cpu. Moving rethook_free call after fp->ops is unregistered with unregister_ftrace_function call. Link: https://lore.kernel.org/all/20230615115236.3476617-1-jolsa@kernel.org/ Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support") Cc: stable@vger.kernel.org Reviewed-by: Steven Rostedt (Google) Signed-off-by: Jiri Olsa Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Add fprobe events for tracing function entry and exit.

2023-06-06T12:39:55Z

Add fprobe events for tracing function entry and exit instead of kprobe events. With this change, we can continue to trace function entry/exit even if the CONFIG_KPROBES_ON_FTRACE is not available. Since CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS, it is not available if the architecture only supports CONFIG_DYNAMIC_FTRACE_WITH_ARGS. And that means kprobe events can not probe function entry/exit effectively on such architecture. But this can be solved if the dynamic events supports fprobe events. The fprobe event is a new dynamic events which is only for the function (symbol) entry and exit. This event accepts non register fetch arguments so that user can trace the function arguments and return values. The fprobe events syntax is here; f[:[GRP/][EVENT]] FUNCTION [FETCHARGS] f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS] E.g. # echo 'f vfs_read $arg1' >> dynamic_events # echo 'f vfs_read%return $retval' >> dynamic_events # cat dynamic_events f:fprobes/vfs_read__entry vfs_read arg1=$arg1 f:fprobes/vfs_read__exit vfs_read%return arg1=$retval # echo 1 > events/fprobes/enable # head -n 20 trace | tail # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | sh-142 [005] ...1. 448.386420: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540 sh-142 [005] ..... 448.386436: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1 sh-142 [005] ...1. 448.386451: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540 sh-142 [005] ..... 448.386458: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1 sh-142 [005] ...1. 448.386469: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540 sh-142 [005] ..... 448.386476: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1 sh-142 [005] ...1. 448.602073: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540 sh-142 [005] ..... 448.602089: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1 Link: https://lore.kernel.org/all/168507469754.913472.6112857614708350210.stgit@mhiramat.roam.corp.google.com/ Reported-by: kernel test robot Link: https://lore.kernel.org/all/202302011530.7vm4O8Ro-lkp@intel.com/ Signed-off-by: Masami Hiramatsu (Google)