pm24.git/kernel/trace, branch v6.6

tracing/kprobes: Fix symbol counting logic by looking at modules as well

2023-10-28T00:50:42Z

Recent changes to count number of matching symbols when creating a kprobe event failed to take into account kernel modules. As such, it breaks kprobes on kernel module symbols, by assuming there is no match. Fix this my calling module_kallsyms_on_each_symbol() in addition to kallsyms_on_each_match_symbol() to perform a proper counting. Link: https://lore.kernel.org/all/20231027233126.2073148-1-andrii@kernel.org/ Cc: Francis Laniel Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Steven Rostedt Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols") Signed-off-by: Andrii Nakryiko Acked-by: Song Liu Signed-off-by: Masami Hiramatsu (Google)

tracing/kprobes: Fix the description of variable length arguments

2023-10-27T13:20:28Z

Fix the following kernel-doc warnings: kernel/trace/trace_kprobe.c:1029: warning: Excess function parameter 'args' description in '__kprobe_event_gen_cmd_start' kernel/trace/trace_kprobe.c:1097: warning: Excess function parameter 'args' description in '__kprobe_event_add_fields' Refer to the usage of variable length arguments elsewhere in the kernel code, "@..." is the proper way to express it in the description. Link: https://lore.kernel.org/all/20231027041315.2613166-1-yujie.liu@intel.com/ Fixes: 2a588dd1d5d6 ("tracing: Add kprobe event command generation functions") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202310190437.paI6LYJF-lkp@intel.com/ Signed-off-by: Yujie Liu Reviewed-by: Mukesh Ojha Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google)

tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols

2023-10-20T13:10:41Z

When a kprobe is attached to a function that's name is not unique (is static and shares the name with other functions in the kernel), the kprobe is attached to the first function it finds. This is a bug as the function that it is attaching to is not necessarily the one that the user wants to attach to. Instead of blindly picking a function to attach to what is ambiguous, error with EADDRNOTAVAIL to let the user know that this function is not unique, and that the user must use another unique function with an address offset to get to the function they want to attach to. Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/ Cc: stable@vger.kernel.org Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer") Suggested-by: Masami Hiramatsu Signed-off-by: Francis Laniel Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/ 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)

tracing/user_events: Align set_bit() address for all archs

2023-09-30T20:25:41Z

All architectures should use a long aligned address passed to set_bit(). User processes can pass either a 32-bit or 64-bit sized value to be updated when tracing is enabled when on a 64-bit kernel. Both cases are ensured to be naturally aligned, however, that is not enough. The address must be long aligned without affecting checks on the value within the user process which require different adjustments for the bit for little and big endian CPUs. Add a compat flag to user_event_enabler that indicates when a 32-bit value is being used on a 64-bit kernel. Long align addresses and correct the bit to be used by set_bit() to account for this alignment. Ensure compat flags are copied during forks and used during deletion clears. Link: https://lore.kernel.org/linux-trace-kernel/20230925230829.341-2-beaub@linux.microsoft.com Link: https://lore.kernel.org/linux-trace-kernel/20230914131102.179100-1-cleger@rivosinc.com/ Cc: stable@vger.kernel.org Fixes: 7235759084a4 ("tracing/user_events: Use remote writes for event enablement") Reported-by: Clément Léger Suggested-by: Clément Léger Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google)

tracing: relax trace_event_eval_update() execution with cond_resched()

2023-09-30T20:24:55Z

When kernel is compiled without preemption, the eval_map_work_func() (which calls trace_event_eval_update()) will not be preempted up to its complete execution. This can actually cause a problem since if another CPU call stop_machine(), the call will have to wait for the eval_map_work_func() function to finish executing in the workqueue before being able to be scheduled. This problem was observe on a SMP system at boot time, when the CPU calling the initcalls executed clocksource_done_booting() which in the end calls stop_machine(). We observed a 1 second delay because one CPU was executing eval_map_work_func() and was not preempted by the stop_machine() task. Adding a call to cond_resched() in trace_event_eval_update() allows other tasks to be executed and thus continue working asynchronously like before without blocking any pending task at boot time. Link: https://lore.kernel.org/linux-trace-kernel/20230929191637.416931-1-cleger@rivosinc.com Cc: Masami Hiramatsu Signed-off-by: Clément Léger Tested-by: Atish Patra Reviewed-by: Atish Patra Signed-off-by: Steven Rostedt (Google)

ring-buffer: Update "shortest_full" in polling

2023-09-30T20:17:34Z

It was discovered that the ring buffer polling was incorrectly stating that read would not block, but that's because polling did not take into account that reads will block if the "buffer-percent" was set. Instead, the ring buffer polling would say reads would not block if there was any data in the ring buffer. This was incorrect behavior from a user space point of view. This was fixed by commit 42fb0a1e84ff by having the polling code check if the ring buffer had more data than what the user specified "buffer percent" had. The problem now is that the polling code did not register itself to the writer that it wanted to wait for a specific "full" value of the ring buffer. The result was that the writer would wake the polling waiter whenever there was a new event. The polling waiter would then wake up, see that there's not enough data in the ring buffer to notify user space and then go back to sleep. The next event would wake it up again. Before the polling fix was added, the code would wake up around 100 times for a hackbench 30 benchmark. After the "fix", due to the constant waking of the writer, it would wake up over 11,0000 times! It would never leave the kernel, so the user space behavior was still "correct", but this definitely is not the desired effect. To fix this, have the polling code add what it's waiting for to the "shortest_full" variable, to tell the writer not to wake it up if the buffer is not as full as it expects to be. Note, after this fix, it appears that the waiter is now woken up around 2x the times it was before (~200). This is a tremendous improvement from the 11,000 times, but I will need to spend some time to see why polling is more aggressive in its wakeups than the read blocking code. Link: https://lore.kernel.org/linux-trace-kernel/20230929180113.01c2cae3@rorschach.local.home Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Fixes: 42fb0a1e84ff ("tracing/ring-buffer: Have polling block on watermark") Reported-by: Julia Lawall Tested-by: Julia Lawall Signed-off-by: Steven Rostedt (Google)

Merge tag 'trace-v6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-09-24T20:55:34Z

Pull tracing fixes from Steven Rostedt: - Fix the "bytes" output of the per_cpu stat file The tracefs/per_cpu/cpu*/stats "bytes" was giving bogus values as the accounting was not accurate. It is suppose to show how many used bytes are still in the ring buffer, but even when the ring buffer was empty it would still show there were bytes used. - Fix a bug in eventfs where reading a dynamic event directory (open) and then creating a dynamic event that goes into that diretory screws up the accounting. On close, the newly created event dentry will get a "dput" without ever having a "dget" done for it. The fix is to allocate an array on dir open to save what dentries were actually "dget" on, and what ones to "dput" on close. * tag 'trace-v6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: eventfs: Remember what dentries were created on dir open ring-buffer: Fix bytes info in per_cpu buffer stats

ring-buffer: Fix bytes info in per_cpu buffer stats

2023-09-22T20:57:14Z

The 'bytes' info in file 'per_cpu/cpu/stats' means the number of bytes in cpu buffer that have not been consumed. However, currently after consuming data by reading file 'trace_pipe', the 'bytes' info was not changed as expected. # cat per_cpu/cpu0/stats entries: 0 overrun: 0 commit overrun: 0 bytes: 568 <--- 'bytes' is problematical !!! oldest event ts: 8651.371479 now ts: 8653.912224 dropped events: 0 read events: 8 The root cause is incorrect stat on cpu_buffer->read_bytes. To fix it: 1. When stat 'read_bytes', account consumed event in rb_advance_reader(); 2. When stat 'entries_bytes', exclude the discarded padding event which is smaller than minimum size because it is invisible to reader. Then use rb_page_commit() instead of BUF_PAGE_SIZE at where accounting for page-based read/remove/overrun. Also correct the comments of ring_buffer_bytes_cpu() in this patch. Link: https://lore.kernel.org/linux-trace-kernel/20230921125425.1708423-1-zhengyejian1@huawei.com Cc: stable@vger.kernel.org Fixes: c64e148a3be3 ("trace: Add ring buffer stats to measure rate of events") Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google)

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2023-09-16T10:16:00Z

Alexei Starovoitov says: ==================== The following pull-request contains BPF updates for your *net* tree. We've added 21 non-merge commits during the last 8 day(s) which contain a total of 21 files changed, 450 insertions(+), 36 deletions(-). The main changes are: 1) Adjust bpf_mem_alloc buckets to match ksize(), from Hou Tao. 2) Check whether override is allowed in kprobe mult, from Jiri Olsa. 3) Fix btf_id symbol generation with ld.lld, from Jiri and Nick. 4) Fix potential deadlock when using queue and stack maps from NMI, from Toke Høiland-Jørgensen. Please consider pulling these changes from: git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git Thanks a lot! Also thanks to reporters, reviewers and testers of commits in this pull-request: Alan Maguire, Biju Das, Björn Töpel, Dan Carpenter, Daniel Borkmann, Eduard Zingerman, Hsin-Wei Hung, Marcus Seyfarth, Nathan Chancellor, Satya Durga Srinivasu Prabhala, Song Liu, Stephen Rothwell ==================== Signed-off-by: David S. Miller