In this patch, caller of libbpf is able to control the loaded programs by installing a preprocessor callback for a BPF program. With preprocessor, different instances can be created from one BPF program.
This patch will be used by perf to generate different prologue for different 'struct probe_trace_event' instances matched by one 'struct perf_probe_event'. bpf_program__set_prep() is added to support this feature. Caller should pass libbpf the number of instances should be created and a preprocessor function which will be called when doing real loading. The callback should return instructions arrays for each instances. fd field in bpf_programs is replaced by instance, which has an nr field and fds array. bpf_program__nth_fd() is introduced for read fd of instances. Old interface bpf_program__fd() is reimplemented by returning the first fd. Signed-off-by: Wang Nan <wangn...@huawei.com> Signed-off-by: He Kuang <heku...@huawei.com> Cc: Alexei Starovoitov <a...@plumgrid.com> Cc: Brendan Gregg <brendan.d.gr...@gmail.com> Cc: Daniel Borkmann <dan...@iogearbox.net> Cc: David Ahern <dsah...@gmail.com> Cc: He Kuang <heku...@huawei.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Kaixu Xia <xiaka...@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Paul Mackerras <pau...@samba.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Zefan Li <lize...@huawei.com> Cc: pi3or...@163.com Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Link: http://lkml.kernel.org/n/ebpf-6yw9eg0ej3l4jnqhinngk...@git.kernel.org --- tools/lib/bpf/libbpf.c | 143 +++++++++++++++++++++++++++++++++++++++++++++---- tools/lib/bpf/libbpf.h | 22 ++++++++ 2 files changed, 156 insertions(+), 9 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 4252fc2..6a07b26 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -98,7 +98,11 @@ struct bpf_program { } *reloc_desc; int nr_reloc; - int fd; + struct { + int nr; + int *fds; + } instance; + bpf_program_prep_t preprocessor; struct bpf_object *obj; void *priv; @@ -152,10 +156,24 @@ struct bpf_object { static void bpf_program__unload(struct bpf_program *prog) { + int i; + if (!prog) return; - zclose(prog->fd); + /* + * If the object is opened but the program is never loaded, + * it is possible that prog->instance.nr == -1. + */ + if (prog->instance.nr > 0) { + for (i = 0; i < prog->instance.nr; i++) + zclose(prog->instance.fds[i]); + } else if (prog->instance.nr != -1) + pr_warning("Internal error: instance.nr is %d\n", + prog->instance.nr); + + prog->instance.nr = -1; + zfree(&prog->instance.fds); } static void bpf_program__exit(struct bpf_program *prog) @@ -206,7 +224,8 @@ bpf_program__init(void *data, size_t size, char *name, int idx, memcpy(prog->insns, data, prog->insns_cnt * sizeof(struct bpf_insn)); prog->idx = idx; - prog->fd = -1; + prog->instance.fds = NULL; + prog->instance.nr = -1; return 0; errout: @@ -795,13 +814,71 @@ static int bpf_program__load(struct bpf_program *prog, char *license, u32 kern_version) { - int err, fd; + int err = 0, fd, i; + + if (prog->instance.nr < 0 || !prog->instance.fds) { + if (prog->preprocessor) { + pr_warning("Internal error: can't load program '%s'\n", + prog->section_name); + return -EINVAL; + } + + prog->instance.fds = malloc(sizeof(int)); + if (!prog->instance.fds) { + pr_warning("No enough memory for fds\n"); + return -ENOMEM; + } + prog->instance.nr = 1; + prog->instance.fds[0] = -1; + } + + if (!prog->preprocessor) { + if (prog->instance.nr != 1) + pr_warning("Program '%s' inconsistent: nr(%d) not 1\n", + prog->section_name, prog->instance.nr); - err = load_program(prog->insns, prog->insns_cnt, - license, kern_version, &fd); - if (!err) - prog->fd = fd; + err = load_program(prog->insns, prog->insns_cnt, + license, kern_version, &fd); + if (!err) + prog->instance.fds[0] = fd; + goto out; + } + + for (i = 0; i < prog->instance.nr; i++) { + struct bpf_prog_prep_result result; + bpf_program_prep_t preprocessor = prog->preprocessor; + + bzero(&result, sizeof(result)); + err = preprocessor(prog, i, prog->insns, + prog->insns_cnt, &result); + if (err) { + pr_warning("Preprocessing %dth instance of program '%s' failed\n", + i, prog->section_name); + goto out; + } + + if (!result.new_insn_ptr || !result.new_insn_cnt) { + pr_debug("Skip loading %dth instance of program '%s'\n", + i, prog->section_name); + prog->instance.fds[i] = -1; + continue; + } + + err = load_program(result.new_insn_ptr, + result.new_insn_cnt, + license, kern_version, &fd); + + if (err) { + pr_warning("Loading %dth instance of program '%s' failed\n", + i, prog->section_name); + goto out; + } + if (result.pfd) + *result.pfd = fd; + prog->instance.fds[i] = fd; + } +out: if (err) pr_warning("failed to load program '%s'\n", prog->section_name); @@ -1052,5 +1129,53 @@ const char *bpf_program__title(struct bpf_program *prog, bool dup) int bpf_program__fd(struct bpf_program *prog) { - return prog->fd; + return bpf_program__nth_fd(prog, 0); +} + +int bpf_program__set_prep(struct bpf_program *prog, int nr_instance, + bpf_program_prep_t prep) +{ + int *instance_fds; + + if (nr_instance <= 0 || !prep) + return -EINVAL; + + if (prog->instance.nr > 0 || prog->instance.fds) { + pr_warning("Can't set pre-processor after loading\n"); + return -EINVAL; + } + + instance_fds = malloc(sizeof(int) * nr_instance); + if (!instance_fds) { + pr_warning("alloc memory failed for instance of fds\n"); + return -ENOMEM; + } + + /* fill all fd with -1 */ + memset(instance_fds, 0xff, sizeof(int) * nr_instance); + + prog->instance.nr = nr_instance; + prog->instance.fds = instance_fds; + prog->preprocessor = prep; + return 0; +} + +int bpf_program__nth_fd(struct bpf_program *prog, int n) +{ + int fd; + + if (n >= prog->instance.nr || n < 0) { + pr_warning("Can't get the %dth fd from program %s: only %d instances\n", + n, prog->section_name, prog->instance.nr); + return -EINVAL; + } + + fd = prog->instance.fds[n]; + if (fd < 0) { + pr_warning("%dth instance of program '%s' is invalid\n", + n, prog->section_name); + return -ENOENT; + } + + return fd; } diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index f16170c..d82b89e 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -67,6 +67,28 @@ const char *bpf_program__title(struct bpf_program *prog, bool dup); int bpf_program__fd(struct bpf_program *prog); +struct bpf_insn; +struct bpf_prog_prep_result { + /* + * If not NULL, load new instruction array. + * If set to NULL, don't load this instance. + */ + struct bpf_insn *new_insn_ptr; + int new_insn_cnt; + + /* If not NULL, result fd is set to it */ + int *pfd; +}; + +typedef int (*bpf_program_prep_t)(struct bpf_program *, int n, + struct bpf_insn *, int insn_cnt, + struct bpf_prog_prep_result *res); + +int bpf_program__set_prep(struct bpf_program *prog, int nr_instance, + bpf_program_prep_t prep); + +int bpf_program__nth_fd(struct bpf_program *prog, int n); + /* * We don't need __attribute__((packed)) now since it is * unnecessary for 'bpf_map_def' because they are all aligned. -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
