From 4ddd32741da87657113d964588ce13ee64b34820 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 16 Nov 2015 11:36:29 -0300 Subject: tools: Adopt memdup() from tools/perf, moving it to tools/lib/string.c That will contain more string functions with counterparts, sometimes verbatim copies, in the kernel. Acked-by: Wang Nan Cc: Adrian Hunter Cc: Alexey Dobriyan Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Link: http://lkml.kernel.org/n/tip-rah6g97kn21vfgmlramorz6o@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/string.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 tools/lib/string.c (limited to 'tools/lib') diff --git a/tools/lib/string.c b/tools/lib/string.c new file mode 100644 index 0000000..ecfd43a --- /dev/null +++ b/tools/lib/string.c @@ -0,0 +1,19 @@ +#include +#include +#include + +/** + * memdup - duplicate region of memory + * + * @src: memory region to duplicate + * @len: memory region length + */ +void *memdup(const void *src, size_t len) +{ + void *p = malloc(len); + + if (p) + memcpy(p, src, len); + + return p; +} -- cgit v1.1 From 7d85c434214ea0b3416f7a62f76a0785b00d8797 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 16 Nov 2015 11:42:05 -0300 Subject: tools: Clone the kernel's strtobool function Copying it to tools/lib/string.c, the counterpart to the kernel's lib/string.c. This is preparation for enhancing BPF program configuration, which will allow config string like 'inlines=yes'. Signed-off-by: Wang Nan Cc: Alexei Starovoitov Cc: Jonathan Cameron Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1447675815-166222-6-git-send-email-wangnan0@huawei.com [ Copied it to tools/lib/string.c instead, to make it usable by other tools/ ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/string.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'tools/lib') diff --git a/tools/lib/string.c b/tools/lib/string.c index ecfd43a..065e54f 100644 --- a/tools/lib/string.c +++ b/tools/lib/string.c @@ -1,5 +1,20 @@ +/* + * linux/tools/lib/string.c + * + * Copied from linux/lib/string.c, where it is: + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * More specifically, the first copied function was strtobool, which + * was introduced by: + * + * d0f1fed29e6e ("Add a strtobool function matching semantics of existing in kernel equivalents") + * Author: Jonathan Cameron + */ + #include #include +#include #include /** @@ -17,3 +32,31 @@ void *memdup(const void *src, size_t len) return p; } + +/** + * strtobool - convert common user inputs into boolean values + * @s: input string + * @res: result + * + * This routine returns 0 iff the first character is one of 'Yy1Nn0'. + * Otherwise it will return -EINVAL. Value pointed to by res is + * updated upon finding a match. + */ +int strtobool(const char *s, bool *res) +{ + switch (s[0]) { + case 'y': + case 'Y': + case '1': + *res = true; + break; + case 'n': + case 'N': + case '0': + *res = false; + break; + default: + return -EINVAL; + } + return 0; +} -- cgit v1.1 From b580563e38487d9db8e94080149644da71c533c1 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 16 Nov 2015 12:10:09 +0000 Subject: bpf tools: Load a program with different instances using preprocessor This patch is a preparation for BPF prologue support which allows generating a series of BPF bytecode for fetching kernel data before calling program code. With the newly introduced multiple instances support, perf is able to create different prologues for different kprobe points. Before this patch, a bpf_program can be loaded into kernel only once, and get the only resulting fd. What this patch does is to allow creating and loading different variants of one bpf_program, then fetching their fds. Here we describe the basic idea in this patch. The detailed description of the newly introduced APIs can be found in comments in the patch body. The key of this patch is the new mechanism in bpf_program__load(). Instead of loading BPF program into kernel directly, it calls a 'pre-processor' to generate program instances which would be finally loaded into the kernel based on the original code. To enable the generation of multiple instances, libbpf passes an index to the pre-processor so it know which instance is being loaded. Pre-processor should be called from libbpf's user (perf) using bpf_program__set_prep(). The number of instances and the relationship between indices and the target instance should be clear when calling bpf_program__set_prep(). To retrieve a fd for a specific instance of a program, bpf_program__nth_fd() is introduced. It returns the resulting fd according to index. Signed-off-by: He Kuang Cc: Alexei Starovoitov Cc: He Kuang Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1447675815-166222-8-git-send-email-wangnan0@huawei.com Signed-off-by: Wang Nan [ Enclosed multi-line if/else blocks with {}, (*func_ptr)() -> func_ptr() ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/bpf/libbpf.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++--- tools/lib/bpf/libbpf.h | 64 ++++++++++++++++++++++ 2 files changed, 201 insertions(+), 9 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index e176bad..e3f4c33 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -152,7 +152,11 @@ struct bpf_program { } *reloc_desc; int nr_reloc; - int fd; + struct { + int nr; + int *fds; + } instances; + bpf_program_prep_t preprocessor; struct bpf_object *obj; void *priv; @@ -206,10 +210,25 @@ 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 was never loaded, + * it is possible that prog->instances.nr == -1. + */ + if (prog->instances.nr > 0) { + for (i = 0; i < prog->instances.nr; i++) + zclose(prog->instances.fds[i]); + } else if (prog->instances.nr != -1) { + pr_warning("Internal error: instances.nr is %d\n", + prog->instances.nr); + } + + prog->instances.nr = -1; + zfree(&prog->instances.fds); } static void bpf_program__exit(struct bpf_program *prog) @@ -260,7 +279,8 @@ 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->instances.fds = NULL; + prog->instances.nr = -1; return 0; errout: @@ -860,13 +880,73 @@ static int bpf_program__load(struct bpf_program *prog, char *license, u32 kern_version) { - int err, fd; + int err = 0, fd, i; - err = load_program(prog->insns, prog->insns_cnt, - license, kern_version, &fd); - if (!err) - prog->fd = fd; + if (prog->instances.nr < 0 || !prog->instances.fds) { + if (prog->preprocessor) { + pr_warning("Internal error: can't load program '%s'\n", + prog->section_name); + return -LIBBPF_ERRNO__INTERNAL; + } + prog->instances.fds = malloc(sizeof(int)); + if (!prog->instances.fds) { + pr_warning("Not enough memory for BPF fds\n"); + return -ENOMEM; + } + prog->instances.nr = 1; + prog->instances.fds[0] = -1; + } + + if (!prog->preprocessor) { + if (prog->instances.nr != 1) { + pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n", + prog->section_name, prog->instances.nr); + } + err = load_program(prog->insns, prog->insns_cnt, + license, kern_version, &fd); + if (!err) + prog->instances.fds[0] = fd; + goto out; + } + + for (i = 0; i < prog->instances.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 the %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 the %dth instance of program '%s'\n", + i, prog->section_name); + prog->instances.fds[i] = -1; + if (result.pfd) + *result.pfd = -1; + continue; + } + + err = load_program(result.new_insn_ptr, + result.new_insn_cnt, + license, kern_version, &fd); + + if (err) { + pr_warning("Loading the %dth instance of program '%s' failed\n", + i, prog->section_name); + goto out; + } + + if (result.pfd) + *result.pfd = fd; + prog->instances.fds[i] = fd; + } +out: if (err) pr_warning("failed to load program '%s'\n", prog->section_name); @@ -1121,5 +1201,53 @@ const char *bpf_program__title(struct bpf_program *prog, bool needs_copy) 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_instances, + bpf_program_prep_t prep) +{ + int *instances_fds; + + if (nr_instances <= 0 || !prep) + return -EINVAL; + + if (prog->instances.nr > 0 || prog->instances.fds) { + pr_warning("Can't set pre-processor after loading\n"); + return -EINVAL; + } + + instances_fds = malloc(sizeof(int) * nr_instances); + if (!instances_fds) { + pr_warning("alloc memory failed for fds\n"); + return -ENOMEM; + } + + /* fill all fd with -1 */ + memset(instances_fds, -1, sizeof(int) * nr_instances); + + prog->instances.nr = nr_instances; + prog->instances.fds = instances_fds; + prog->preprocessor = prep; + return 0; +} + +int bpf_program__nth_fd(struct bpf_program *prog, int n) +{ + int fd; + + if (n >= prog->instances.nr || n < 0) { + pr_warning("Can't get the %dth fd from program %s: only %d instances\n", + n, prog->section_name, prog->instances.nr); + return -EINVAL; + } + + fd = prog->instances.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 c9a9aef..949df4b 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -88,6 +88,70 @@ const char *bpf_program__title(struct bpf_program *prog, bool needs_copy); int bpf_program__fd(struct bpf_program *prog); +struct bpf_insn; + +/* + * Libbpf allows callers to adjust BPF programs before being loaded + * into kernel. One program in an object file can be transform into + * multiple variants to be attached to different code. + * + * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd + * are APIs for this propose. + * + * - bpf_program_prep_t: + * It defines 'preprocessor', which is a caller defined function + * passed to libbpf through bpf_program__set_prep(), and will be + * called before program is loaded. The processor should adjust + * the program one time for each instances according to the number + * passed to it. + * + * - bpf_program__set_prep: + * Attachs a preprocessor to a BPF program. The number of instances + * whould be created is also passed through this function. + * + * - bpf_program__nth_fd: + * After the program is loaded, get resuling fds from bpf program for + * each instances. + * + * If bpf_program__set_prep() is not used, the program whould be loaded + * without adjustment during bpf_object__load(). The program has only + * one instance. In this case bpf_program__fd(prog) is equal to + * bpf_program__nth_fd(prog, 0). + */ + +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; +}; + +/* + * Parameters of bpf_program_prep_t: + * - prog: The bpf_program being loaded. + * - n: Index of instance being generated. + * - insns: BPF instructions array. + * - insns_cnt:Number of instructions in insns. + * - res: Output parameter, result of transformation. + * + * Return value: + * - Zero: pre-processing success. + * - Non-zero: pre-processing, stop loading. + */ +typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n, + struct bpf_insn *insns, int insns_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. -- cgit v1.1