linux/kernel/trace/ftrace.c, branch v5.19

ftrace: Keep address offset in ftrace_lookup_symbols

2022-06-17T02:42:21Z

We want to store the resolved address on the same index as the symbol string, because that's the user (bpf kprobe link) code assumption. Also making sure we don't store duplicates that might be present in kallsyms. Acked-by: Song Liu Acked-by: Steven Rostedt (Google) Fixes: bed0d9a50dac ("ftrace: Add ftrace_lookup_symbols function") Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20220615112118.497303-3-jolsa@kernel.org Signed-off-by: Alexei Starovoitov

Merge tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2022-05-29T17:31:36Z

Pull tracing updates from Steven Rostedt: "The majority of the changes are for fixes and clean ups. Notable changes: - Rework trace event triggers code to be easier to interact with. - Support for embedding bootconfig with the kernel (as suppose to having it embedded in initram). This is useful for embedded boards without initram disks. - Speed up boot by parallelizing the creation of tracefs files. - Allow absolute ring buffer timestamps handle timestamps that use more than 59 bits. - Added new tracing clock "TAI" (International Atomic Time) - Have weak functions show up in available_filter_function list as: __ftrace_invalid_address___ instead of using the name of the function before it" * tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (52 commits) ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function tracing: Fix comments for event_trigger_separate_filter() x86/traceponit: Fix comment about irq vector tracepoints x86,tracing: Remove unused headers ftrace: Clean up hash direct_functions on register failures tracing: Fix comments of create_filter() tracing: Disable kcov on trace_preemptirq.c tracing: Initialize integer variable to prevent garbage return value ftrace: Fix typo in comment ftrace: Remove return value of ftrace_arch_modify_*() tracing: Cleanup code by removing init "char *name" tracing: Change "char *" string form to "char []" tracing/timerlat: Do not wakeup the thread if the trace stops at the IRQ tracing/timerlat: Print stacktrace in the IRQ handler if needed tracing/timerlat: Notify IRQ new max latency only if stop tracing is set kprobes: Fix build errors with CONFIG_KRETPROBES=n tracing: Fix return value of trace_pid_write() tracing: Fix potential double free in create_var_ref() tracing: Use strim() to remove whitespace instead of doing it manually ftrace: Deal with error return code of the ftrace_process_locs() function ...

ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function

2022-05-28T13:31:19Z

If an unused weak function was traced, it's call to fentry will still exist, which gets added into the __mcount_loc table. Ftrace will use kallsyms to retrieve the name for each location in __mcount_loc to display it in the available_filter_functions and used to enable functions via the name matching in set_ftrace_filter/notrace. Enabling these functions do nothing but enable an unused call to ftrace_caller. If a traced weak function is overridden, the symbol of the function would be used for it, which will either created duplicate names, or if the previous function was not traced, it would be incorrectly be listed in available_filter_functions as a function that can be traced. This became an issue with BPF[1] as there are tooling that enables the direct callers via ftrace but then checks to see if the functions were actually enabled. The case of one function that was marked notrace, but was followed by an unused weak function that was traced. The unused function's call to fentry was added to the __mcount_loc section, and kallsyms retrieved the untraced function's symbol as the weak function was overridden. Since the untraced function would not get traced, the BPF check would detect this and fail. The real fix would be to fix kallsyms to not show addresses of weak functions as the function before it. But that would require adding code in the build to add function size to kallsyms so that it can know when the function ends instead of just using the start of the next known symbol. In the mean time, this is a work around. Add a FTRACE_MCOUNT_MAX_OFFSET macro that if defined, ftrace will ignore any function that has its call to fentry/mcount that has an offset from the symbol that is greater than FTRACE_MCOUNT_MAX_OFFSET. If CONFIG_HAVE_FENTRY is defined for x86, define FTRACE_MCOUNT_MAX_OFFSET to zero (unless IBT is enabled), which will have ftrace ignore all locations that are not at the start of the function (or one after the ENDBR instruction). A worker thread is added at boot up to scan all the ftrace record entries, and will mark any that fail the FTRACE_MCOUNT_MAX_OFFSET test as disabled. They will still appear in the available_filter_functions file as: __ftrace_invalid_address___ (showing the offset that caused it to be invalid). This is required for tools that use libtracefs (like trace-cmd does) that scan the available_filter_functions and enable set_ftrace_filter and set_ftrace_notrace using indexes of the function listed in the file (this is a speedup, as enabling thousands of files via names is an O(n^2) operation and can take minutes to complete, where the indexing takes less than a second). The invalid functions cannot be removed from available_filter_functions as the names there correspond to the ftrace records in the array that manages them (and the indexing depends on this). [1] https://lore.kernel.org/all/20220412094923.0abe90955e5db486b7bca279@kernel.org/ Link: https://lkml.kernel.org/r/20220526141912.794c2786@gandalf.local.home Signed-off-by: Steven Rostedt (Google)

ftrace: Clean up hash direct_functions on register failures

2022-05-27T01:13:01Z

We see the following GPF when register_ftrace_direct fails: [ ] general protection fault, probably for non-canonical address \ 0x200000000000010: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI [...] [ ] RIP: 0010:ftrace_find_rec_direct+0x53/0x70 [ ] Code: 48 c1 e0 03 48 03 42 08 48 8b 10 31 c0 48 85 d2 74 [...] [ ] RSP: 0018:ffffc9000138bc10 EFLAGS: 00010206 [ ] RAX: 0000000000000000 RBX: ffffffff813e0df0 RCX: 000000000000003b [ ] RDX: 0200000000000000 RSI: 000000000000000c RDI: ffffffff813e0df0 [ ] RBP: ffffffffa00a3000 R08: ffffffff81180ce0 R09: 0000000000000001 [ ] R10: ffffc9000138bc18 R11: 0000000000000001 R12: ffffffff813e0df0 [ ] R13: ffffffff813e0df0 R14: ffff888171b56400 R15: 0000000000000000 [ ] FS: 00007fa9420c7780(0000) GS:ffff888ff6a00000(0000) knlGS:000000000 [ ] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ ] CR2: 000000000770d000 CR3: 0000000107d50003 CR4: 0000000000370ee0 [ ] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ ] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ ] Call Trace: [ ] [ ] register_ftrace_direct+0x54/0x290 [ ] ? render_sigset_t+0xa0/0xa0 [ ] bpf_trampoline_update+0x3f5/0x4a0 [ ] ? 0xffffffffa00a3000 [ ] bpf_trampoline_link_prog+0xa9/0x140 [ ] bpf_tracing_prog_attach+0x1dc/0x450 [ ] bpf_raw_tracepoint_open+0x9a/0x1e0 [ ] ? find_held_lock+0x2d/0x90 [ ] ? lock_release+0x150/0x430 [ ] __sys_bpf+0xbd6/0x2700 [ ] ? lock_is_held_type+0xd8/0x130 [ ] __x64_sys_bpf+0x1c/0x20 [ ] do_syscall_64+0x3a/0x80 [ ] entry_SYSCALL_64_after_hwframe+0x44/0xae [ ] RIP: 0033:0x7fa9421defa9 [ ] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 9 f8 [...] [ ] RSP: 002b:00007ffed743bd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 [ ] RAX: ffffffffffffffda RBX: 00000000069d2480 RCX: 00007fa9421defa9 [ ] RDX: 0000000000000078 RSI: 00007ffed743bd80 RDI: 0000000000000011 [ ] RBP: 00007ffed743be00 R08: 0000000000bb7270 R09: 0000000000000000 [ ] R10: 00000000069da210 R11: 0000000000000246 R12: 0000000000000001 [ ] R13: 00007ffed743c4b0 R14: 00000000069d2480 R15: 0000000000000001 [ ] [ ] Modules linked in: klp_vm(OK) [ ] ---[ end trace 0000000000000000 ]--- One way to trigger this is: 1. load a livepatch that patches kernel function xxx; 2. run bpftrace -e 'kfunc:xxx {}', this will fail (expected for now); 3. repeat #2 => gpf. This is because the entry is added to direct_functions, but not removed. Fix this by remove the entry from direct_functions when register_ftrace_direct fails. Also remove the last trailing space from ftrace.c, so we don't have to worry about it anymore. Link: https://lkml.kernel.org/r/20220524170839.900849-1-song@kernel.org Cc: stable@vger.kernel.org Fixes: 763e34e74bb7 ("ftrace: Add register_ftrace_direct()") Signed-off-by: Song Liu Signed-off-by: Steven Rostedt (Google)

ftrace: Fix typo in comment

2022-05-27T01:13:00Z

Spelling mistake (triple letters) in comment. Detected with the help of Coccinelle. Link: https://lkml.kernel.org/r/20220521111145.81697-81-Julia.Lawall@inria.fr Signed-off-by: Julia Lawall Signed-off-by: Steven Rostedt (Google)

ftrace: Remove return value of ftrace_arch_modify_*()

2022-05-27T01:13:00Z

All instances of the function ftrace_arch_modify_prepare() and ftrace_arch_modify_post_process() return zero. There's no point in checking their return value. Just have them be void functions. Link: https://lkml.kernel.org/r/20220518023639.4065-1-kunyu@nfschina.com Signed-off-by: Li kunyu Signed-off-by: Steven Rostedt (Google)

ftrace: Deal with error return code of the ftrace_process_locs() function

2022-05-27T01:12:59Z

The ftrace_process_locs() function may return -ENOMEM error code, which should be handled by the callers. Link: https://lkml.kernel.org/r/20220120065949.1813231-1-ytcoode@gmail.com Signed-off-by: Yuntao Wang Signed-off-by: Steven Rostedt (Google)

tracing: Use trace_create_file() to simplify creation of tracefs entries

2022-05-27T01:12:52Z

Creating tracefs entries with tracefs_create_file() followed by pr_warn() is tedious and repetitive, we can use trace_create_file() to simplify this process and make the code more readable. Link: https://lkml.kernel.org/r/20220114131052.534382-1-ytcoode@gmail.com Acked-by: Masami Hiramatsu (Google) Signed-off-by: Yuntao Wang Signed-off-by: Steven Rostedt (Google)

Merge tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2022-05-26T23:57:20Z

Pull sysctl updates from Luis Chamberlain: "For two kernel releases now kernel/sysctl.c has been being cleaned up slowly, since the tables were grossly long, sprinkled with tons of #ifdefs and all this caused merge conflicts with one susbystem or another. This tree was put together to help try to avoid conflicts with these cleanups going on different trees at time. So nothing exciting on this pull request, just cleanups. Thanks a lot to the Uniontech and Huawei folks for doing some of this nasty work" * tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (28 commits) sched: Fix build warning without CONFIG_SYSCTL reboot: Fix build warning without CONFIG_SYSCTL kernel/kexec_core: move kexec_core sysctls into its own file sysctl: minor cleanup in new_dir() ftrace: fix building with SYSCTL=y but DYNAMIC_FTRACE=n fs/proc: Introduce list_for_each_table_entry for proc sysctl mm: fix unused variable kernel warning when SYSCTL=n latencytop: move sysctl to its own file ftrace: fix building with SYSCTL=n but DYNAMIC_FTRACE=y ftrace: Fix build warning ftrace: move sysctl_ftrace_enabled to ftrace.c kernel/do_mount_initrd: move real_root_dev sysctls to its own file kernel/delayacct: move delayacct sysctls to its own file kernel/acct: move acct sysctls to its own file kernel/panic: move panic sysctls to its own file kernel/lockdep: move lockdep sysctls to its own file mm: move page-writeback sysctls to their own file mm: move oom_kill sysctls to their own file kernel/reboot: move reboot sysctls to its own file sched: Move energy_aware sysctls to topology.c ...

Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2022-05-23T23:07:14Z

Daniel Borkmann says: ==================== pull-request: bpf-next 2022-05-23 We've added 113 non-merge commits during the last 26 day(s) which contain a total of 121 files changed, 7425 insertions(+), 1586 deletions(-). The main changes are: 1) Speed up symbol resolution for kprobes multi-link attachments, from Jiri Olsa. 2) Add BPF dynamic pointer infrastructure e.g. to allow for dynamically sized ringbuf reservations without extra memory copies, from Joanne Koong. 3) Big batch of libbpf improvements towards libbpf 1.0 release, from Andrii Nakryiko. 4) Add BPF link iterator to traverse links via seq_file ops, from Dmitrii Dolgov. 5) Add source IP address to BPF tunnel key infrastructure, from Kaixi Fan. 6) Refine unprivileged BPF to disable only object-creating commands, from Alan Maguire. 7) Fix JIT blinding of ld_imm64 when they point to subprogs, from Alexei Starovoitov. 8) Add BPF access to mptcp_sock structures and their meta data, from Geliang Tang. 9) Add new BPF helper for access to remote CPU's BPF map elements, from Feng Zhou. 10) Allow attaching 64-bit cookie to BPF link of fentry/fexit/fmod_ret, from Kui-Feng Lee. 11) Follow-ups to typed pointer support in BPF maps, from Kumar Kartikeya Dwivedi. 12) Add busy-poll test cases to the XSK selftest suite, from Magnus Karlsson. 13) Improvements in BPF selftest test_progs subtest output, from Mykola Lysenko. 14) Fill bpf_prog_pack allocator areas with illegal instructions, from Song Liu. 15) Add generic batch operations for BPF map-in-map cases, from Takshak Chahande. 16) Make bpf_jit_enable more user friendly when permanently on 1, from Tiezhu Yang. 17) Fix an array overflow in bpf_trampoline_get_progs(), from Yuntao Wang. ==================== Link: https://lore.kernel.org/r/20220523223805.27931-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski