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

tracing/probes: Add string type check with BTF

2023-08-23T00:41:13Z

Add a string type checking with BTF information if possible. This will check whether the given BTF argument (and field) is signed char array or pointer to signed char. If not, it reject the 'string' type. If it is pointer to signed char, it adds a dereference opration so that it can correctly fetch the string data from memory. # echo 'f getname_flags%return retval->name:string' >> dynamic_events # echo 't sched_switch next->comm:string' >> dynamic_events The above cases, 'struct filename::name' is 'char *' and 'struct task_struct::comm' is 'char []'. But in both case, user can specify ':string' to fetch the string data. Link: https://lore.kernel.org/all/169272159250.160970.1881112937198526188.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google)

tracing/probes: Support BTF field access from $retval

2023-08-23T00:40:51Z

Support BTF argument on '$retval' for function return events including kretprobe and fprobe for accessing the return value. This also allows user to access its fields if the return value is a pointer of a data structure. E.g. # echo 'f getname_flags%return +0($retval->name):string' \ > dynamic_events # echo 1 > events/fprobes/getname_flags__exit/enable # ls > /dev/null # head -n 40 trace | tail ls-87 [000] ...1. 8067.616101: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./function_profile_enabled" ls-87 [000] ...1. 8067.616108: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./trace_stat" ls-87 [000] ...1. 8067.616115: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_graph_notrace" ls-87 [000] ...1. 8067.616122: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_graph_function" ls-87 [000] ...1. 8067.616129: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_notrace" ls-87 [000] ...1. 8067.616135: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_filter" ls-87 [000] ...1. 8067.616143: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./touched_functions" ls-87 [000] ...1. 8067.616237: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./enabled_functions" ls-87 [000] ...1. 8067.616245: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./available_filter_functions" ls-87 [000] ...1. 8067.616253: getname_flags__exit: (vfs_fstatat+0x3c/0x70 <- getname_flags) arg1="./set_ftrace_notrace_pid" Link: https://lore.kernel.org/all/169272158234.160970.2446691104240645205.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) Acked-by: Steven Rostedt (Google)

tracing/probes: Support BTF based data structure field access

2023-08-23T00:40:28Z

Using BTF to access the fields of a data structure. You can use this for accessing the field with '->' or '.' operation with BTF argument. # echo 't sched_switch next=next->pid vruntime=next->se.vruntime' \ > dynamic_events # echo 1 > events/tracepoints/sched_switch/enable # head -n 40 trace | tail -0 [000] d..3. 272.565382: sched_switch: (__probestub_sched_switch+0x4/0x10) next=26 vruntime=956533179 kcompactd0-26 [000] d..3. 272.565406: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0 -0 [000] d..3. 273.069441: sched_switch: (__probestub_sched_switch+0x4/0x10) next=9 vruntime=956533179 kworker/0:1-9 [000] d..3. 273.069464: sched_switch: (__probestub_sched_switch+0x4/0x10) next=26 vruntime=956579181 kcompactd0-26 [000] d..3. 273.069480: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0 -0 [000] d..3. 273.141434: sched_switch: (__probestub_sched_switch+0x4/0x10) next=22 vruntime=956533179 kworker/u2:1-22 [000] d..3. 273.141461: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0 -0 [000] d..3. 273.480872: sched_switch: (__probestub_sched_switch+0x4/0x10) next=22 vruntime=956585857 kworker/u2:1-22 [000] d..3. 273.480905: sched_switch: (__probestub_sched_switch+0x4/0x10) next=70 vruntime=959533179 sh-70 [000] d..3. 273.481102: sched_switch: (__probestub_sched_switch+0x4/0x10) next=0 vruntime=0 Link: https://lore.kernel.org/all/169272157251.160970.9318175874130965571.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Alan Maguire Acked-by: Steven Rostedt (Google)

tracing/probes: Move finding func-proto API and getting func-param API to trace_btf

2023-08-23T00:39:45Z

Move generic function-proto find API and getting function parameter API to BTF library code from trace_probe.c. This will avoid redundant efforts on different feature. Link: https://lore.kernel.org/all/169272155255.160970.719426926348706349.stgit@devnote2/ 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: Fix to add NULL check for BTF APIs

2023-07-26T03:53:38Z

Since find_btf_func_param() abd btf_type_by_id() can return NULL, the caller must check the return value correctly. Link: https://lore.kernel.org/all/169024903951.395371.11361556840733470934.stgit@devnote2/ Fixes: b576e09701c7 ("tracing/probes: Support function parameters if BTF is available") Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (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

Revert "tracing: Add "(fault)" name injection to kernel probes"

2023-07-13T15:37:43Z

This reverts commit 2e9906f84fc7c99388bb7123ade167250d50f1c0. It was turned out that commit 2e9906f84fc7 ("tracing: Add "(fault)" name injection to kernel probes") did not work correctly and probe events still show just '(fault)' (instead of '"(fault)"'). Also, current '(fault)' is more explicit that it faulted. This also moves FAULT_STRING macro to trace.h so that synthetic event can keep using it, and uses it in trace_probe.c too. Link: https://lore.kernel.org/all/168908495772.123124.1250788051922100079.stgit@devnote2/ Link: https://lore.kernel.org/all/20230706230642.3793a593@rorschach.local.home/ Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Tom Zanussi Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google)

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

2023-06-30T17:44:53Z

Pull probes updates from Masami Hiramatsu: - fprobe: Pass return address to the fprobe entry/exit callbacks so that the callbacks don't need to analyze pt_regs/stack to find the function return address. - kprobe events: cleanup usage of TPARG_FL_FENTRY and TPARG_FL_RETURN flags so that those are not set at once. - fprobe events: - Add a new fprobe events for tracing arbitrary function entry and exit as a trace event. - Add a new tracepoint events for tracing raw tracepoint as a trace event. This allows user to trace non user-exposed tracepoints. - Move eprobe's event parser code into probe event common file. - Introduce BTF (BPF type format) support to kernel probe (kprobe, fprobe and tracepoint probe) events so that user can specify traced function arguments by name. This also applies the type of argument when fetching the argument. - Introduce '$arg*' wildcard support if BTF is available. This expands the '$arg*' meta argument to all function argument automatically. - Check the return value types by BTF. If the function returns 'void', '$retval' is rejected. - Add some selftest script for fprobe events, tracepoint events and BTF support. - Update documentation about the fprobe events. - Some fixes for above features, document and selftests. - selftests for ftrace (in addition to the new fprobe events): - Add a test case for multiple consecutive probes in a function which checks if ftrace based kprobe, optimized kprobe and normal kprobe can be defined in the same target function. - Add a test case for optimized probe, which checks whether kprobe can be optimized or not. * tag 'probes-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/probes: Fix tracepoint event with $arg* to fetch correct argument Documentation: Fix typo of reference file name tracing/probes: Fix to return NULL and keep using current argc selftests/ftrace: Add new test case which checks for optimized probes selftests/ftrace: Add new test case which adds multiple consecutive probes in a function Documentation: tracing/probes: Add fprobe event tracing document selftests/ftrace: Add BTF arguments test cases selftests/ftrace: Add tracepoint probe test case tracing/probes: Add BTF retval type support tracing/probes: Add $arg* meta argument for all function args tracing/probes: Support function parameters if BTF is available tracing/probes: Move event parameter fetching code to common parser tracing/probes: Add tracepoint support on fprobe_events selftests/ftrace: Add fprobe related testcases tracing/probes: Add fprobe events for tracing function entry and exit. tracing/probes: Avoid setting TPARG_FL_FENTRY and TPARG_FL_RETURN fprobe: Pass return address to the handlers

tracing/probes: Fix tracepoint event with $arg* to fetch correct argument

2023-06-23T08:35:49Z

To hide the first dummy 'data' argument on the tracepoint probe events, the BTF argument array was modified (skip the first argument for tracepoint), but the '$arg*' meta argument parser missed that. Fix to increment the argument index if it is tracepoint probe. And decrement the index when searching the type of the argument. Link: https://lore.kernel.org/all/168657113778.3038017.12245893750241701312.stgit@mhiramat.roam.corp.google.com/ Reviewed-by: Steven Rostedt (Google) Signed-off-by: Masami Hiramatsu (Google)