From 65223741ae1b759a14cab84ba88888bb025f816d Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Oct 2021 17:48:55 +0800 Subject: [PATCH 1/3] bpf: Support writable context for bare tracepoint Commit 9df1c28bb752 ("bpf: add writable context for raw tracepoints") supports writable context for tracepoint, but it misses the support for bare tracepoint which has no associated trace event. Bare tracepoint is defined by DECLARE_TRACE(), so adding a corresponding DECLARE_TRACE_WRITABLE() macro to generate a definition in __bpf_raw_tp_map section for bare tracepoint in a similar way to DEFINE_TRACE_WRITABLE(). Signed-off-by: Hou Tao Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211004094857.30868-2-hotforest@gmail.com --- include/trace/bpf_probe.h | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index a23be89119aa5..a8e97f84b6527 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -93,8 +93,7 @@ __section("__bpf_raw_tp_map") = { \ #define FIRST(x, ...) x -#undef DEFINE_EVENT_WRITABLE -#define DEFINE_EVENT_WRITABLE(template, call, proto, args, size) \ +#define __CHECK_WRITABLE_BUF_SIZE(call, proto, args, size) \ static inline void bpf_test_buffer_##call(void) \ { \ /* BUILD_BUG_ON() is ignored if the code is completely eliminated, but \ @@ -103,8 +102,12 @@ static inline void bpf_test_buffer_##call(void) \ */ \ FIRST(proto); \ (void)BUILD_BUG_ON_ZERO(size != sizeof(*FIRST(args))); \ -} \ -__DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), size) +} + +#undef DEFINE_EVENT_WRITABLE +#define DEFINE_EVENT_WRITABLE(template, call, proto, args, size) \ + __CHECK_WRITABLE_BUF_SIZE(call, PARAMS(proto), PARAMS(args), size) \ + __DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), size) #undef DEFINE_EVENT #define DEFINE_EVENT(template, call, proto, args) \ @@ -119,9 +122,17 @@ __DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), size) __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) \ __DEFINE_EVENT(call, call, PARAMS(proto), PARAMS(args), 0) +#undef DECLARE_TRACE_WRITABLE +#define DECLARE_TRACE_WRITABLE(call, proto, args, size) \ + __CHECK_WRITABLE_BUF_SIZE(call, PARAMS(proto), PARAMS(args), size) \ + __BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) \ + __DEFINE_EVENT(call, call, PARAMS(proto), PARAMS(args), size) + #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) +#undef DECLARE_TRACE_WRITABLE #undef DEFINE_EVENT_WRITABLE +#undef __CHECK_WRITABLE_BUF_SIZE #undef __DEFINE_EVENT #undef FIRST From ccaf12d6215a56836472db220520cda8024d6c4f Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Oct 2021 17:48:56 +0800 Subject: [PATCH 2/3] libbpf: Support detecting and attaching of writable tracepoint program Program on writable tracepoint is BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, but its attachment is the same as BPF_PROG_TYPE_RAW_TRACEPOINT. Signed-off-by: Hou Tao Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211004094857.30868-3-hotforest@gmail.com --- tools/lib/bpf/libbpf.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ed313fd491bd2..ae0889bebe329 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8077,6 +8077,8 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("tp/", TRACEPOINT, 0, SEC_NONE, attach_tp), SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), SEC_DEF("raw_tp/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tracepoint.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tp.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), SEC_DEF("tp_btf/", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fentry/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fmod_ret/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace), @@ -9846,12 +9848,26 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie) { - const char *tp_name; + static const char *const prefixes[] = { + "raw_tp/", + "raw_tracepoint/", + "raw_tp.w/", + "raw_tracepoint.w/", + }; + size_t i; + const char *tp_name = NULL; - if (str_has_pfx(prog->sec_name, "raw_tp/")) - tp_name = prog->sec_name + sizeof("raw_tp/") - 1; - else - tp_name = prog->sec_name + sizeof("raw_tracepoint/") - 1; + for (i = 0; i < ARRAY_SIZE(prefixes); i++) { + if (str_has_pfx(prog->sec_name, prefixes[i])) { + tp_name = prog->sec_name + strlen(prefixes[i]); + break; + } + } + if (!tp_name) { + pr_warn("prog '%s': invalid section name '%s'\n", + prog->name, prog->sec_name); + return libbpf_err_ptr(-EINVAL); + } return bpf_program__attach_raw_tracepoint(prog, tp_name); } From fa7f17d066bd0996b930b664aa0ed1f213fc1828 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Oct 2021 17:48:57 +0800 Subject: [PATCH 3/3] bpf/selftests: Add test for writable bare tracepoint Add a writable bare tracepoint in bpf_testmod module, and trigger its calling when reading /sys/kernel/bpf_testmod with a specific buffer length. The reading will return the value in writable context if the early return flag is enabled in writable context. Signed-off-by: Hou Tao Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211004094857.30868-4-hotforest@gmail.com --- .../bpf/bpf_testmod/bpf_testmod-events.h | 15 ++++++++ .../selftests/bpf/bpf_testmod/bpf_testmod.c | 10 ++++++ .../selftests/bpf/bpf_testmod/bpf_testmod.h | 5 +++ .../selftests/bpf/prog_tests/module_attach.c | 35 +++++++++++++++++++ .../selftests/bpf/progs/test_module_attach.c | 14 ++++++++ tools/testing/selftests/bpf/test_progs.c | 4 +-- tools/testing/selftests/bpf/test_progs.h | 2 ++ 7 files changed, 83 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h index 89c6d58e5dd68..11ee801e75e7e 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h @@ -34,6 +34,21 @@ DECLARE_TRACE(bpf_testmod_test_write_bare, TP_ARGS(task, ctx) ); +#undef BPF_TESTMOD_DECLARE_TRACE +#ifdef DECLARE_TRACE_WRITABLE +#define BPF_TESTMOD_DECLARE_TRACE(call, proto, args, size) \ + DECLARE_TRACE_WRITABLE(call, PARAMS(proto), PARAMS(args), size) +#else +#define BPF_TESTMOD_DECLARE_TRACE(call, proto, args, size) \ + DECLARE_TRACE(call, PARAMS(proto), PARAMS(args)) +#endif + +BPF_TESTMOD_DECLARE_TRACE(bpf_testmod_test_writable_bare, + TP_PROTO(struct bpf_testmod_test_writable_ctx *ctx), + TP_ARGS(ctx), + sizeof(struct bpf_testmod_test_writable_ctx) +); + #endif /* _BPF_TESTMOD_EVENTS_H */ #undef TRACE_INCLUDE_PATH diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index b892948dc134c..5d52ea2768df4 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -50,6 +50,16 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj, if (bpf_testmod_loop_test(101) > 100) trace_bpf_testmod_test_read(current, &ctx); + /* Magic number to enable writable tp */ + if (len == 64) { + struct bpf_testmod_test_writable_ctx writable = { + .val = 1024, + }; + trace_bpf_testmod_test_writable_bare(&writable); + if (writable.early_ret) + return snprintf(buf, len, "%d\n", writable.val); + } + return -EIO; /* always fail */ } EXPORT_SYMBOL(bpf_testmod_test_read); diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h index b3892dc401113..0d71e2607832e 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h @@ -17,4 +17,9 @@ struct bpf_testmod_test_write_ctx { size_t len; }; +struct bpf_testmod_test_writable_ctx { + bool early_ret; + int val; +}; + #endif /* _BPF_TESTMOD_H */ diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c index 1797a6e4d6d84..6d0e50dcf47cc 100644 --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c @@ -2,10 +2,36 @@ /* Copyright (c) 2020 Facebook */ #include +#include #include "test_module_attach.skel.h" static int duration; +static int trigger_module_test_writable(int *val) +{ + int fd, err; + char buf[65]; + ssize_t rd; + + fd = open(BPF_TESTMOD_TEST_FILE, O_RDONLY); + err = -errno; + if (!ASSERT_GE(fd, 0, "testmode_file_open")) + return err; + + rd = read(fd, buf, sizeof(buf) - 1); + err = -errno; + if (!ASSERT_GT(rd, 0, "testmod_file_rd_val")) { + close(fd); + return err; + } + + buf[rd] = '\0'; + *val = strtol(buf, NULL, 0); + close(fd); + + return 0; +} + static int delete_module(const char *name, int flags) { return syscall(__NR_delete_module, name, flags); @@ -19,6 +45,7 @@ void test_module_attach(void) struct test_module_attach__bss *bss; struct bpf_link *link; int err; + int writable_val = 0; skel = test_module_attach__open(); if (CHECK(!skel, "skel_open", "failed to open skeleton\n")) @@ -51,6 +78,14 @@ void test_module_attach(void) ASSERT_EQ(bss->fexit_ret, -EIO, "fexit_tet"); ASSERT_EQ(bss->fmod_ret_read_sz, READ_SZ, "fmod_ret"); + bss->raw_tp_writable_bare_early_ret = true; + bss->raw_tp_writable_bare_out_val = 0xf1f2f3f4; + ASSERT_OK(trigger_module_test_writable(&writable_val), + "trigger_writable"); + ASSERT_EQ(bss->raw_tp_writable_bare_in_val, 1024, "writable_test_in"); + ASSERT_EQ(bss->raw_tp_writable_bare_out_val, writable_val, + "writable_test_out"); + test_module_attach__detach(skel); /* attach fentry/fexit and make sure it get's module reference */ diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c index bd37ceec55877..b36857093f71f 100644 --- a/tools/testing/selftests/bpf/progs/test_module_attach.c +++ b/tools/testing/selftests/bpf/progs/test_module_attach.c @@ -27,6 +27,20 @@ int BPF_PROG(handle_raw_tp_bare, return 0; } +int raw_tp_writable_bare_in_val = 0; +int raw_tp_writable_bare_early_ret = 0; +int raw_tp_writable_bare_out_val = 0; + +SEC("raw_tp.w/bpf_testmod_test_writable_bare") +int BPF_PROG(handle_raw_tp_writable_bare, + struct bpf_testmod_test_writable_ctx *writable) +{ + raw_tp_writable_bare_in_val = writable->val; + writable->early_ret = raw_tp_writable_bare_early_ret; + writable->val = raw_tp_writable_bare_out_val; + return 0; +} + __u32 tp_btf_read_sz = 0; SEC("tp_btf/bpf_testmod_test_read") diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index 2ed01f615d20f..007b4ff85fea7 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -747,7 +747,7 @@ int trigger_module_test_read(int read_sz) { int fd, err; - fd = open("/sys/kernel/bpf_testmod", O_RDONLY); + fd = open(BPF_TESTMOD_TEST_FILE, O_RDONLY); err = -errno; if (!ASSERT_GE(fd, 0, "testmod_file_open")) return err; @@ -769,7 +769,7 @@ int trigger_module_test_write(int write_sz) memset(buf, 'a', write_sz); buf[write_sz-1] = '\0'; - fd = open("/sys/kernel/bpf_testmod", O_WRONLY); + fd = open(BPF_TESTMOD_TEST_FILE, O_WRONLY); err = -errno; if (!ASSERT_GE(fd, 0, "testmod_file_open")) { free(buf); diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h index 94bef0aa74cf5..9b8a1810b700a 100644 --- a/tools/testing/selftests/bpf/test_progs.h +++ b/tools/testing/selftests/bpf/test_progs.h @@ -301,3 +301,5 @@ int trigger_module_test_write(int write_sz); #else #define SYS_NANOSLEEP_KPROBE_NAME "sys_nanosleep" #endif + +#define BPF_TESTMOD_TEST_FILE "/sys/kernel/bpf_testmod"