[v3,linux-trace,4/8] samples: bpf: simple tracing example in C

Message ID	1423539961-21792-5-git-send-email-ast@plumgrid.com
State	Not Applicable, archived
Delegated to:	David Miller
Headers	show Return-Path: <netdev-owner@vger.kernel.org> From: Alexei Starovoitov <ast@plumgrid.com> To: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@kernel.org>, Namhyung Kim <namhyung@kernel.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Jiri Olsa <jolsa@redhat.com>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, linux-api@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 linux-trace 4/8] samples: bpf: simple tracing example in C Date: Mon, 9 Feb 2015 19:45:57 -0800 Message-Id: <1423539961-21792-5-git-send-email-ast@plumgrid.com> In-Reply-To: <1423539961-21792-1-git-send-email-ast@plumgrid.com> References: <1423539961-21792-1-git-send-email-ast@plumgrid.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 789691374562..da28e1b6d3a6 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -7,6 +7,7 @@ hostprogs-y += sock_example hostprogs-y += sockex1 hostprogs-y += sockex2 hostprogs-y += dropmon +hostprogs-y += tracex1 dropmon-objs := dropmon.o libbpf.o test_verifier-objs := test_verifier.o libbpf.o @@ -14,17 +15,20 @@ test_maps-objs := test_maps.o libbpf.o sock_example-objs := sock_example.o libbpf.o sockex1-objs := bpf_load.o libbpf.o sockex1_user.o sockex2-objs := bpf_load.o libbpf.o sockex2_user.o +tracex1-objs := bpf_load.o libbpf.o tracex1_user.o # Tell kbuild to always build the programs always := $(hostprogs-y) always += sockex1_kern.o always += sockex2_kern.o +always += tracex1_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable HOSTLOADLIBES_sockex1 += -lelf HOSTLOADLIBES_sockex2 += -lelf +HOSTLOADLIBES_tracex1 += -lelf # point this to your LLVM backend with bpf support LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc diff --git a/samples/bpf/bpf_helpers.h b/samples/bpf/bpf_helpers.h index ca0333146006..406e9705d99e 100644 --- a/samples/bpf/bpf_helpers.h +++ b/samples/bpf/bpf_helpers.h @@ -15,6 +15,20 @@ static int (*bpf_map_update_elem)(void *map, void *key, void *value, (void *) BPF_FUNC_map_update_elem; static int (*bpf_map_delete_elem)(void *map, void *key) = (void *) BPF_FUNC_map_delete_elem; +static void *(*bpf_fetch_ptr)(void *unsafe_ptr) = + (void *) BPF_FUNC_fetch_ptr; +static unsigned long long (*bpf_fetch_u64)(void *unsafe_ptr) = + (void *) BPF_FUNC_fetch_u64; +static unsigned int (*bpf_fetch_u32)(void *unsafe_ptr) = + (void *) BPF_FUNC_fetch_u32; +static unsigned short (*bpf_fetch_u16)(void *unsafe_ptr) = + (void *) BPF_FUNC_fetch_u16; +static unsigned char (*bpf_fetch_u8)(void *unsafe_ptr) = + (void *) BPF_FUNC_fetch_u8; +static int (*bpf_probe_memcmp)(void *unsafe_ptr, void *safe_ptr, int size) = + (void *) BPF_FUNC_probe_memcmp; +static unsigned long long (*bpf_ktime_get_ns)(void) = + (void *) BPF_FUNC_ktime_get_ns; /* llvm builtin functions that eBPF C program may use to * emit BPF_LD_ABS and BPF_LD_IND instructions diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c index 1831d236382b..2aece65963e4 100644 --- a/samples/bpf/bpf_load.c +++ b/samples/bpf/bpf_load.c @@ -8,29 +8,47 @@ #include <unistd.h> #include <string.h> #include <stdbool.h> +#include <stdlib.h> #include <linux/bpf.h> #include <linux/filter.h> +#include <linux/perf_event.h> +#include <sys/syscall.h> +#include <sys/ioctl.h> +#include <sys/mman.h> +#include <poll.h> #include "libbpf.h" #include "bpf_helpers.h" #include "bpf_load.h" +#define DEBUGFS "/sys/kernel/debug/tracing/" + static char license[128]; static bool processed_sec[128]; int map_fd[MAX_MAPS]; int prog_fd[MAX_PROGS]; +int event_fd[MAX_PROGS]; int prog_cnt; static int load_and_attach(const char *event, struct bpf_insn *prog, int size) { - int fd; bool is_socket = strncmp(event, "socket", 6) == 0; + enum bpf_prog_type prog_type; + char path[256] = DEBUGFS; + char buf[32]; + int fd, efd, err, id; + struct perf_event_attr attr; - if (!is_socket) - /* tracing events tbd */ - return -1; + attr.type = PERF_TYPE_TRACEPOINT; + attr.sample_type = PERF_SAMPLE_RAW; + attr.sample_period = 1; + attr.wakeup_events = 1; + + if (is_socket) + prog_type = BPF_PROG_TYPE_SOCKET_FILTER; + else + prog_type = BPF_PROG_TYPE_TRACEPOINT; - fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, - prog, size, license); + fd = bpf_prog_load(prog_type, prog, size, license); if (fd < 0) { printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf); @@ -39,6 +57,39 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size) prog_fd[prog_cnt++] = fd; + if (is_socket) + return 0; + + strcat(path, event); + strcat(path, "/id"); + + efd = open(path, O_RDONLY, 0); + if (efd < 0) { + printf("failed to open event %s\n", event); + return -1; + } + + err = read(efd, buf, sizeof(buf)); + if (err < 0 || err >= sizeof(buf)) { + printf("read from '%s' failed '%s'\n", event, strerror(errno)); + return -1; + } + + close(efd); + + buf[err] = 0; + id = atoi(buf); + attr.config = id; + + efd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0); + if (efd < 0) { + printf("event %d fd %d err %s\n", id, efd, strerror(errno)); + return -1; + } + event_fd[prog_cnt - 1] = efd; + ioctl(efd, PERF_EVENT_IOC_ENABLE, 0); + ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd); + return 0; } @@ -201,3 +252,69 @@ int load_bpf_file(char *path) close(fd); return 0; } + +int page_size; +int page_cnt = 8; +volatile struct perf_event_mmap_page *header; + +int perf_event_mmap(int fd) +{ + void *base; + int mmap_size; + + page_size = getpagesize(); + mmap_size = page_size * (page_cnt + 1); + + base = mmap(NULL, mmap_size, PROT_READ, MAP_SHARED, fd, 0); + if (base == MAP_FAILED) { + printf("mmap err\n"); + return -1; + } + + header = base; + return 0; +} + +int perf_event_poll(int fd) +{ + struct pollfd pfd = {.fd = fd, .events = POLLIN}; + return poll(&pfd, 1, -1); +} + +struct perf_event_sample { + struct perf_event_header header; + __u32 size; + char data[]; +}; + +void perf_event_read(print_fn fn) +{ + static __u64 old_data_head = 0; + __u64 data_head = header->data_head; + __u64 buffer_size = page_cnt * page_size; + void *base, *begin, *end; + + if (data_head == old_data_head) + return; + + base = ((char *)header) + page_size; + + begin = base + old_data_head % buffer_size; + end = base + data_head % buffer_size; + + while (begin < end) { + struct perf_event_sample *e; + + e = begin; + + if (e->header.type != PERF_RECORD_SAMPLE) { + printf("event is not a sample type %d\n", e->header.type); + } + + begin += sizeof(*e) + e->size; + fn(e->data, e->size); + } + /* else when end > begin - the events had wrapped. ignored for now */ + + old_data_head = data_head; +} diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h index 27789a34f5e6..cf55663405da 100644 --- a/samples/bpf/bpf_load.h +++ b/samples/bpf/bpf_load.h @@ -6,6 +6,7 @@ extern int map_fd[MAX_MAPS]; extern int prog_fd[MAX_PROGS]; +extern int event_fd[MAX_PROGS]; /* parses elf file compiled by llvm .c->.o * . parses 'maps' section and creates maps via BPF syscall @@ -21,4 +22,15 @@ extern int prog_fd[MAX_PROGS]; */ int load_bpf_file(char *path); +int perf_event_mmap(int fd); +int perf_event_poll(int fd); +typedef void (*print_fn)(void *data, int size); +void perf_event_read(print_fn fn); +struct trace_entry { + unsigned short type; + unsigned char flags; + unsigned char preempt_count; + int pid; +}; + #endif diff --git a/samples/bpf/tracex1_kern.c b/samples/bpf/tracex1_kern.c new file mode 100644 index 000000000000..449db961c642 --- /dev/null +++ b/samples/bpf/tracex1_kern.c @@ -0,0 +1,28 @@ +#include <linux/skbuff.h> +#include <linux/netdevice.h> +#include <uapi/linux/bpf.h> +#include <trace/bpf_trace.h> +#include "bpf_helpers.h" + +SEC("events/net/netif_receive_skb") +int bpf_prog1(struct bpf_context *ctx) +{ + /* + * attaches to net:netif_receive_skb + * and filters events for loobpack device only + */ + char devname[] = "lo"; + struct net_device *dev; + struct sk_buff *skb = 0; + + skb = (struct sk_buff *) ctx->arg1; + dev = bpf_fetch_ptr(&skb->dev); + if (bpf_probe_memcmp(dev->name, devname, 2) == 0) + /* pass event to userspace via perf ring_buffer */ + return 1; + + /* drop event */ + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/samples/bpf/tracex1_user.c b/samples/bpf/tracex1_user.c new file mode 100644 index 000000000000..a49de23eb30b --- /dev/null +++ b/samples/bpf/tracex1_user.c @@ -0,0 +1,50 @@ +#include <stdio.h> +#include <linux/bpf.h> +#include <unistd.h> +#include "libbpf.h" +#include "bpf_load.h" + +static char *get_str(void *entry, __u32 arrloc) +{ + int off = arrloc & 0xffff; + return entry + off; +} + +static void print_netif_receive_skb(void *data, int size) +{ + struct ftrace_raw_netif_receive_skb { + struct trace_entry t; + void *skb; + __u32 len; + __u32 name; + } *e = data; + + printf("pid %d skb %p len %d dev %s\n", + e->t.pid, e->skb, e->len, get_str(e, e->name)); +} + +int main(int ac, char **argv) +{ + FILE *f; + char filename[256]; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + + if (perf_event_mmap(event_fd[0]) < 0) + return 1; + + f = popen("taskset 1 ping -c5 localhost", "r"); + (void) f; + + for (;;) { + perf_event_poll(event_fd[0]); + perf_event_read(print_netif_receive_skb); + } + + return 0; +}

[v3,linux-trace,4/8] samples: bpf: simple tracing example in C

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