wireguard-linux/kernel/trace/trace_fprobe.c, branch jd/bump-compilers

tracing/probes: support '%pd' type for print struct dentry's name

2024-05-01T14:18:47Z

During fault locating, the file name needs to be printed based on the dentry address. The offset needs to be calculated each time, which is troublesome. Similar to printk, kprobe support print type '%pd' for print dentry's name. For example "name=$arg1:%pd" casts the `$arg1` as (struct dentry *), dereferences the "d_name.name" field and stores it to "name" argument as a kernel string. Here is an example: [tracing]# echo 'p:testprobe dput name=$arg1:%pd' > kprobe_events [tracing]# echo 1 > events/kprobes/testprobe/enable [tracing]# grep -q "1" events/kprobes/testprobe/enable [tracing]# echo 0 > events/kprobes/testprobe/enable [tracing]# cat trace | grep "enable" bash-14844 [002] ..... 16912.889543: testprobe: (dput+0x4/0x30) name="enable" grep-15389 [003] ..... 16922.834182: testprobe: (dput+0x4/0x30) name="enable" grep-15389 [003] ..... 16922.836103: testprobe: (dput+0x4/0x30) name="enable" bash-14844 [001] ..... 16931.820909: testprobe: (dput+0x4/0x30) name="enable" Note that this expects the given argument (e.g. $arg1) is an address of struct dentry. User must ensure it. Link: https://lore.kernel.org/all/20240322064308.284457-2-yebin10@huawei.com/ Signed-off-by: Ye Bin Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Support $argN in return probe (kprobe and fprobe)

2024-03-06T15:27:34Z

Support accessing $argN in the return probe events. This will help users to record entry data in function return (exit) event for simplfing the function entry/exit information in one event, and record the result values (e.g. allocated object/initialized object) at function exit. For example, if we have a function `int init_foo(struct foo *obj, int param)` sometimes we want to check how `obj` is initialized. In such case, we can define a new return event like below; # echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events Thus it records the function parameter `param` and its result `obj->field1` (the dereference will be done in the function exit timing) value at once. This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF is enabled, we can trace both function parameters and the return value by following command. # echo 'f target_function%return $arg* $retval' >> dynamic_events Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init

2024-03-06T15:27:15Z

Instead of incrementing the trace_probe::nr_args, init it at trace_probe_init(). Without this change, there is no way to get the number of trace_probe arguments while parsing it. This is a cleanup, so the behavior is not changed. Link: https://lore.kernel.org/all/170952363585.229804.13060759900346411951.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google)

tracing/fprobe-event: cleanup: Fix a wrong comment in fprobe event

2024-03-06T15:26:57Z

Despite the fprobe event, "Kretprobe" was commented. So fix it. Link: https://lore.kernel.org/all/170952361630.229804.10832200172327797860.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google)

tracing: fprobe-event: Fix to check tracepoint event and return

2023-11-10T11:06:12Z

Fix to check the tracepoint event is not valid with $retval. The commit 08c9306fc2e3 ("tracing/fprobe-event: Assume fprobe is a return event by $retval") introduced automatic return probe conversion with $retval. But since tracepoint event does not support return probe, $retval is not acceptable. Without this fix, ftracetest, tprobe_syntax_errors.tc fails; [22] Tracepoint probe event parser error log check [FAIL] ---- # tail 22-tprobe_syntax_errors.tc-log.mRKroL + ftrace_errlog_check trace_fprobe t kfree ^$retval dynamic_events + printf %s t kfree + wc -c + pos=8 + printf %s t kfree ^$retval + tr -d ^ + command=t kfree $retval + echo Test command: t kfree $retval Test command: t kfree $retval + echo ---- So 't kfree $retval' should fail (tracepoint doesn't support return probe) but passed it. Link: https://lore.kernel.org/all/169944555933.45057.12831706585287704173.stgit@devnote2/ Fixes: 08c9306fc2e3 ("tracing/fprobe-event: Assume fprobe is a return event by $retval") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google)

tracing/fprobe-event: Assume fprobe is a return event by $retval

2023-08-23T00:41:32Z

Assume the fprobe event is a return event if there is $retval is used in the probe's argument without %return. e.g. echo 'f:myevent vfs_read $retval' >> dynamic_events then 'myevent' is a return probe event. Link: https://lore.kernel.org/all/169272160261.160970.13613040161560998787.stgit@devnote2/ Suggested-by: Steven Rostedt Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google)

tracing/probes: Support BTF argument on module functions

2023-08-23T00:39:15Z

Since the btf returned from bpf_get_btf_vmlinux() only covers functions in the vmlinux, BTF argument is not available on the functions in the modules. Use bpf_find_btf_id() instead of bpf_get_btf_vmlinux()+btf_find_name_kind() so that BTF argument can find the correct struct btf and btf_type in it. With this fix, fprobe events can use `$arg*` on module functions as below # grep nf_log_ip_packet /proc/kallsyms ffffffffa0005c00 t nf_log_ip_packet [nf_log_syslog] ffffffffa0005bf0 t __pfx_nf_log_ip_packet [nf_log_syslog] # echo 'f nf_log_ip_packet $arg*' > dynamic_events # cat dynamic_events f:fprobes/nf_log_ip_packet__entry nf_log_ip_packet net=net pf=pf hooknum=hooknum skb=skb in=in out=out loginfo=loginfo prefix=prefix To support the module's btf which is removable, the struct btf needs to be ref-counted. So this also records the btf in the traceprobe_parse_context and returns the refcount when the parse has done. Link: https://lore.kernel.org/all/169272154223.160970.3507930084247934031.stgit@devnote2/ Suggested-by: Alexei Starovoitov Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google)

tracing/probes: Add $arg* meta argument for all function args

2023-06-06T12:39:56Z

Add the '$arg*' meta fetch argument for function-entry probe events. This will be expanded to the all arguments of the function and the tracepoint using BTF function argument information. e.g. # echo 'p vfs_read $arg*' >> dynamic_events # echo 'f vfs_write $arg*' >> dynamic_events # echo 't sched_overutilized_tp $arg*' >> dynamic_events # cat dynamic_events p:kprobes/p_vfs_read_0 vfs_read file=file buf=buf count=count pos=pos f:fprobes/vfs_write__entry vfs_write file=file buf=buf count=count pos=pos t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized Also, single '$arg[0-9]*' will be converted to the BTF function argument. NOTE: This seems like a wildcard, but a fake one at this moment. This is just for telling user that this can be expanded to several arguments. And it is not like other $-vars, you can not use this $arg* as a part of fetch args, e.g. specifying name "foo=$arg*" and using it in dereferences "+0($arg*)" will lead a parse error. Link: https://lore.kernel.org/all/168507475126.913472.18329684401466211816.stgit@mhiramat.roam.corp.google.com/ Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Support function parameters if BTF is available

2023-06-06T12:39:56Z

Support function or tracepoint parameters by name if BTF support is enabled and the event is for function entry (this feature can be used with kprobe- events, fprobe-events and tracepoint probe events.) Note that the BTF variable syntax does not require a prefix. If it starts with an alphabetic character or an underscore ('_') without a prefix like '$' and '%', it is considered as a BTF variable. If you specify only the BTF variable name, the argument name will also be the same name instead of 'arg*'. # echo 'p vfs_read count pos' >> dynamic_events # echo 'f vfs_write count pos' >> dynamic_events # echo 't sched_overutilized_tp rd overutilized' >> dynamic_events # cat dynamic_events p:kprobes/p_vfs_read_0 vfs_read count=count pos=pos f:fprobes/vfs_write__entry vfs_write count=count pos=pos t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized Link: https://lore.kernel.org/all/168507474014.913472.16963996883278039183.stgit@mhiramat.roam.corp.google.com/ Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Alan Maguire Tested-by: Alan Maguire

tracing/probes: Move event parameter fetching code to common parser

2023-06-06T12:39:56Z

Move trace event parameter fetching code to common parser in trace_probe.c. This simplifies eprobe's trace-event variable fetching code by introducing a parse context data structure. Link: https://lore.kernel.org/all/168507472950.913472.2812253181558471278.stgit@mhiramat.roam.corp.google.com/ Signed-off-by: Masami Hiramatsu (Google)