tracing/user_events: Remove eBPF interfaces
Remove eBPF interfaces within user_events to ensure they are fully reviewed. Link: https://lore.kernel.org/all/20220329165718.GA10381@kbox/ Link: https://lkml.kernel.org/r/20220329173051.10087-1-beaub@linux.microsoft.com Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Beau Belgrave
Steven Rostedt (Google)
parent
efe34e99fc
commit
768c1e7f1d
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@ -7,7 +7,7 @@ user_events: User-based Event Tracing
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Overview
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--------
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User based trace events allow user processes to create events and trace data
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that can be viewed via existing tools, such as ftrace, perf and eBPF.
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that can be viewed via existing tools, such as ftrace and perf.
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To enable this feature, build your kernel with CONFIG_USER_EVENTS=y.
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Programs can view status of the events via
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@ -67,8 +67,7 @@ The command string format is as follows::
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Supported Flags
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^^^^^^^^^^^^^^^
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**BPF_ITER** - EBPF programs attached to this event will get the raw iovec
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struct instead of any data copies for max performance.
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None yet
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Field Format
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^^^^^^^^^^^^
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@ -160,7 +159,7 @@ The following values are defined to aid in checking what has been attached:
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**EVENT_STATUS_FTRACE** - Bit set if ftrace has been attached (Bit 0).
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**EVENT_STATUS_PERF** - Bit set if perf/eBPF has been attached (Bit 1).
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**EVENT_STATUS_PERF** - Bit set if perf has been attached (Bit 1).
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Writing Data
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------------
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@ -204,13 +203,6 @@ It's advised for user programs to do the following::
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**NOTE:** *The write_index is not emitted out into the trace being recorded.*
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EBPF
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----
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EBPF programs that attach to a user-based event tracepoint are given a pointer
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to a struct user_bpf_context. The bpf context contains the data type (which can
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be a user or kernel buffer, or can be a pointer to the iovec) and the data
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length that was emitted (minus the write_index).
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Example Code
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------------
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See sample code in samples/user_events.
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@ -32,9 +32,6 @@
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/* Create dynamic location entry within a 32-bit value */
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#define DYN_LOC(offset, size) ((size) << 16 | (offset))
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/* Use raw iterator for attached BPF program(s), no affect on ftrace/perf */
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#define FLAG_BPF_ITER (1 << 0)
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/*
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* Describes an event registration and stores the results of the registration.
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* This structure is passed to the DIAG_IOCSREG ioctl, callers at a minimum
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@ -63,54 +60,4 @@ struct user_reg {
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/* Requests to delete a user_event */
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#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char*)
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/* Data type that was passed to the BPF program */
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enum {
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/* Data resides in kernel space */
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USER_BPF_DATA_KERNEL,
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/* Data resides in user space */
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USER_BPF_DATA_USER,
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/* Data is a pointer to a user_bpf_iter structure */
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USER_BPF_DATA_ITER,
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};
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/*
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* Describes an iovec iterator that BPF programs can use to access data for
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* a given user_event write() / writev() call.
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*/
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struct user_bpf_iter {
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/* Offset of the data within the first iovec */
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__u32 iov_offset;
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/* Number of iovec structures */
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__u32 nr_segs;
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/* Pointer to iovec structures */
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const struct iovec *iov;
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};
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/* Context that BPF programs receive when attached to a user_event */
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struct user_bpf_context {
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/* Data type being passed (see union below) */
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__u32 data_type;
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/* Length of the data */
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__u32 data_len;
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/* Pointer to data, varies by data type */
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union {
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/* Kernel data (data_type == USER_BPF_DATA_KERNEL) */
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void *kdata;
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/* User data (data_type == USER_BPF_DATA_USER) */
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void *udata;
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/* Direct iovec (data_type == USER_BPF_DATA_ITER) */
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struct user_bpf_iter *iter;
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};
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};
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#endif /* _UAPI_LINUX_USER_EVENTS_H */
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@ -42,9 +42,6 @@
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#define MAX_FIELD_ARRAY_SIZE 1024
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#define MAX_FIELD_ARG_NAME 256
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#define MAX_BPF_COPY_SIZE PAGE_SIZE
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#define MAX_STACK_BPF_DATA 512
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static char *register_page_data;
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static DEFINE_MUTEX(reg_mutex);
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@ -405,19 +402,6 @@ static int user_event_parse_field(char *field, struct user_event *user,
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type[0] != 'u', FILTER_OTHER);
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}
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static void user_event_parse_flags(struct user_event *user, char *flags)
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{
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char *flag;
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if (flags == NULL)
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return;
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while ((flag = strsep(&flags, ",")) != NULL) {
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if (strcmp(flag, "BPF_ITER") == 0)
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user->flags |= FLAG_BPF_ITER;
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}
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}
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static int user_event_parse_fields(struct user_event *user, char *args)
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{
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char *field;
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@ -713,64 +697,14 @@ static void user_event_ftrace(struct user_event *user, struct iov_iter *i,
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}
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#ifdef CONFIG_PERF_EVENTS
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static void user_event_bpf(struct user_event *user, struct iov_iter *i)
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{
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struct user_bpf_context context;
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struct user_bpf_iter bpf_i;
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char fast_data[MAX_STACK_BPF_DATA];
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void *temp = NULL;
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if ((user->flags & FLAG_BPF_ITER) && iter_is_iovec(i)) {
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/* Raw iterator */
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context.data_type = USER_BPF_DATA_ITER;
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context.data_len = i->count;
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context.iter = &bpf_i;
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bpf_i.iov_offset = i->iov_offset;
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bpf_i.iov = i->iov;
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bpf_i.nr_segs = i->nr_segs;
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} else if (i->nr_segs == 1 && iter_is_iovec(i)) {
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/* Single buffer from user */
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context.data_type = USER_BPF_DATA_USER;
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context.data_len = i->count;
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context.udata = i->iov->iov_base + i->iov_offset;
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} else {
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/* Multi buffer from user */
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struct iov_iter copy = *i;
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size_t copy_size = min_t(size_t, i->count, MAX_BPF_COPY_SIZE);
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context.data_type = USER_BPF_DATA_KERNEL;
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context.kdata = fast_data;
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if (unlikely(copy_size > sizeof(fast_data))) {
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temp = kmalloc(copy_size, GFP_NOWAIT);
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if (temp)
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context.kdata = temp;
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else
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copy_size = sizeof(fast_data);
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}
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context.data_len = copy_nofault(context.kdata,
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copy_size, ©);
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}
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trace_call_bpf(&user->call, &context);
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kfree(temp);
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}
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/*
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* Writes the user supplied payload out to perf ring buffer or eBPF program.
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* Writes the user supplied payload out to perf ring buffer.
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*/
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static void user_event_perf(struct user_event *user, struct iov_iter *i,
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void *tpdata, bool *faulted)
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{
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struct hlist_head *perf_head;
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if (bpf_prog_array_valid(&user->call))
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user_event_bpf(user, i);
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perf_head = this_cpu_ptr(user->call.perf_events);
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if (perf_head && !hlist_empty(perf_head)) {
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@ -1136,8 +1070,6 @@ static int user_event_parse(char *name, char *args, char *flags,
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user->tracepoint.name = name;
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user_event_parse_flags(user, flags);
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ret = user_event_parse_fields(user, args);
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if (ret)
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@ -1579,9 +1511,6 @@ static int user_seq_show(struct seq_file *m, void *p)
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busy++;
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}
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if (flags & FLAG_BPF_ITER)
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seq_puts(m, " FLAG:BPF_ITER");
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seq_puts(m, "\n");
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active++;
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}
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