From patchwork Wed Mar 14 17:23:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 885957 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.b="oH4mOALl"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 401dqP65H2z9sTC for ; Thu, 15 Mar 2018 04:23:45 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932147AbeCNRXn (ORCPT ); Wed, 14 Mar 2018 13:23:43 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:48882 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752038AbeCNRXl (ORCPT ); Wed, 14 Mar 2018 13:23:41 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.22/8.16.0.22) with SMTP id w2EHHJ4H008414 for ; Wed, 14 Mar 2018 10:23:40 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=iMLodEiVloRaIIc59cjLtfgU1E/cFqf47YC+89pvBQQ=; b=oH4mOALl0tMsjgsAAJzkGy8+prhFkFQeIGeLgbPiI7Kvnn+XRnmVPbInEC2kjPf2j2Ld GrH7f4GTSowd4Z9z5s1/CjyGJJh6Xblvpt0nW7LERB61rCZOuXUqaeVdEqlr29WliNcM kM177uPxwhlt7VVUo5lLVwzwa6fCsOfZyHE= Received: from mail.thefacebook.com ([199.201.64.23]) by m0001303.ppops.net with ESMTP id 2gq7n7r331-2 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 14 Mar 2018 10:23:40 -0700 Received: from mx-out.facebook.com (192.168.52.123) by PRN-CHUB03.TheFacebook.com (192.168.16.13) with Microsoft SMTP Server id 14.3.361.1; Wed, 14 Mar 2018 10:23:31 -0700 Received: by devbig102.frc2.facebook.com (Postfix, from userid 4523) id 94D3042826D3; Wed, 14 Mar 2018 10:23:31 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig102.frc2.facebook.com To: , , , CC: , , , Song Liu Smtp-Origin-Cluster: frc2c02 Subject: [PATCH bpf-next v6 1/2] bpf: extend stackmap to save binary_build_id+offset instead of address Date: Wed, 14 Mar 2018 10:23:21 -0700 Message-ID: <20180314172323.3957483-2-songliubraving@fb.com> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20180314172323.3957483-1-songliubraving@fb.com> References: <20180314172323.3957483-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2018-03-14_09:, , signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, bpf stackmap store address for each entry in the call trace. To map these addresses to user space files, it is necessary to maintain the mapping from these virtual address to symbols in the binary. Usually, the user space profiler (such as perf) has to scan /proc/pid/maps at the beginning of profiling, and monitor mmap2() calls afterwards. Given the cost of maintaining the address map, this solution is not practical for system wide profiling that is always on. This patch tries to solve this problem with a variation of stackmap. This variation is enabled by flag BPF_F_STACK_BUILD_ID. Instead of storing addresses, the variation stores ELF file build_id + offset. Build_id is only meaningful for user stack. If a kernel stack is added to a stackmap with BPF_F_STACK_BUILD_ID, it will automatically fallback to only store ip (status == BPF_STACK_BUILD_ID_IP). Build ID is a 20-byte unique identifier for ELF files. The following command shows the Build ID of /bin/bash: [user@]$ readelf -n /bin/bash ... Build ID: XXXXXXXXXX ... With BPF_F_STACK_BUILD_ID, bpf_get_stackid() tries to parse Build ID for each entry in the call trace, and translate it into the following struct: struct bpf_stack_build_id_offset { __s32 status; unsigned char build_id[BPF_BUILD_ID_SIZE]; union { __u64 offset; __u64 ip; }; }; The search of build_id is limited to the first page of the file, and this page should be in page cache. Otherwise, we fallback to store ip for this entry (ip field in struct bpf_stack_build_id_offset). This requires the build_id to be stored in the first page. A quick survey of binary and dynamic library files in a few different systems shows that almost all binary and dynamic library files have build_id in the first page. Build_id is only meaningful for user stack. If a kernel stack is added to a stackmap with BPF_F_STACK_BUILD_ID, it will automatically fallback to only store ip (status == BPF_STACK_BUILD_ID_IP). Similarly, if build_id lookup failed for some reason, it will also fallback to store ip. User space can access struct bpf_stack_build_id_offset with bpf syscall BPF_MAP_LOOKUP_ELEM. It is necessary for user space to maintain mapping from build id to binary files. This mostly static mapping is much easier to maintain than per process address maps. Note: Stackmap with build_id only works in non-nmi context at this time. This is because we need to take mm->mmap_sem for find_vma(). If this changes, we would like to allow build_id lookup in nmi context. Signed-off-by: Song Liu --- include/uapi/linux/bpf.h | 22 ++++ kernel/bpf/stackmap.c | 257 +++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 257 insertions(+), 22 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 2a66769..1e15d17 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -231,6 +231,28 @@ enum bpf_attach_type { #define BPF_F_RDONLY (1U << 3) #define BPF_F_WRONLY (1U << 4) +/* Flag for stack_map, store build_id+offset instead of pointer */ +#define BPF_F_STACK_BUILD_ID (1U << 5) + +enum bpf_stack_build_id_status { + /* user space need an empty entry to identify end of a trace */ + BPF_STACK_BUILD_ID_EMPTY = 0, + /* with valid build_id and offset */ + BPF_STACK_BUILD_ID_VALID = 1, + /* couldn't get build_id, fallback to ip */ + BPF_STACK_BUILD_ID_IP = 2, +}; + +#define BPF_BUILD_ID_SIZE 20 +struct bpf_stack_build_id { + __s32 status; + unsigned char build_id[BPF_BUILD_ID_SIZE]; + union { + __u64 offset; + __u64 ip; + }; +}; + union bpf_attr { struct { /* anonymous struct used by BPF_MAP_CREATE command */ __u32 map_type; /* one of enum bpf_map_type */ diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index b0ecf43..57eeb12 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -9,16 +9,19 @@ #include #include #include +#include +#include #include "percpu_freelist.h" -#define STACK_CREATE_FLAG_MASK \ - (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY) +#define STACK_CREATE_FLAG_MASK \ + (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ + BPF_F_STACK_BUILD_ID) struct stack_map_bucket { struct pcpu_freelist_node fnode; u32 hash; u32 nr; - u64 ip[]; + u64 data[]; }; struct bpf_stack_map { @@ -29,6 +32,17 @@ struct bpf_stack_map { struct stack_map_bucket *buckets[]; }; +static inline bool stack_map_use_build_id(struct bpf_map *map) +{ + return (map->map_flags & BPF_F_STACK_BUILD_ID); +} + +static inline int stack_map_data_size(struct bpf_map *map) +{ + return stack_map_use_build_id(map) ? + sizeof(struct bpf_stack_build_id) : sizeof(u64); +} + static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) { u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; @@ -68,8 +82,16 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || - value_size < 8 || value_size % 8 || - value_size / 8 > sysctl_perf_event_max_stack) + value_size < 8 || value_size % 8) + return ERR_PTR(-EINVAL); + + BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); + if (attr->map_flags & BPF_F_STACK_BUILD_ID) { + if (value_size % sizeof(struct bpf_stack_build_id) || + value_size / sizeof(struct bpf_stack_build_id) + > sysctl_perf_event_max_stack) + return ERR_PTR(-EINVAL); + } else if (value_size / 8 > sysctl_perf_event_max_stack) return ERR_PTR(-EINVAL); /* hash table size must be power of 2 */ @@ -114,13 +136,184 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) return ERR_PTR(err); } +#define BPF_BUILD_ID 3 +/* + * Parse build id from the note segment. This logic can be shared between + * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are + * identical. + */ +static inline int stack_map_parse_build_id(void *page_addr, + unsigned char *build_id, + void *note_start, + Elf32_Word note_size) +{ + Elf32_Word note_offs = 0, new_offs; + + /* check for overflow */ + if (note_start < page_addr || note_start + note_size < note_start) + return -EINVAL; + + /* only supports note that fits in the first page */ + if (note_start + note_size > page_addr + PAGE_SIZE) + return -EINVAL; + + while (note_offs + sizeof(Elf32_Nhdr) < note_size) { + Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); + + if (nhdr->n_type == BPF_BUILD_ID && + nhdr->n_namesz == sizeof("GNU") && + nhdr->n_descsz == BPF_BUILD_ID_SIZE) { + memcpy(build_id, + note_start + note_offs + + ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), + BPF_BUILD_ID_SIZE); + return 0; + } + new_offs = note_offs + sizeof(Elf32_Nhdr) + + ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); + if (new_offs <= note_offs) /* overflow */ + break; + note_offs = new_offs; + } + return -EINVAL; +} + +/* Parse build ID from 32-bit ELF */ +static int stack_map_get_build_id_32(void *page_addr, + unsigned char *build_id) +{ + Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; + Elf32_Phdr *phdr; + int i; + + /* only supports phdr that fits in one page */ + if (ehdr->e_phnum > + (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) + return -EINVAL; + + phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); + + for (i = 0; i < ehdr->e_phnum; ++i) + if (phdr[i].p_type == PT_NOTE) + return stack_map_parse_build_id(page_addr, build_id, + page_addr + phdr[i].p_offset, + phdr[i].p_filesz); + return -EINVAL; +} + +/* Parse build ID from 64-bit ELF */ +static int stack_map_get_build_id_64(void *page_addr, + unsigned char *build_id) +{ + Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; + Elf64_Phdr *phdr; + int i; + + /* only supports phdr that fits in one page */ + if (ehdr->e_phnum > + (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) + return -EINVAL; + + phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); + + for (i = 0; i < ehdr->e_phnum; ++i) + if (phdr[i].p_type == PT_NOTE) + return stack_map_parse_build_id(page_addr, build_id, + page_addr + phdr[i].p_offset, + phdr[i].p_filesz); + return -EINVAL; +} + +/* Parse build ID of ELF file mapped to vma */ +static int stack_map_get_build_id(struct vm_area_struct *vma, + unsigned char *build_id) +{ + Elf32_Ehdr *ehdr; + struct page *page; + void *page_addr; + int ret; + + /* only works for page backed storage */ + if (!vma->vm_file) + return -EINVAL; + + page = find_get_page(vma->vm_file->f_mapping, 0); + if (!page) + return -EFAULT; /* page not mapped */ + + ret = -EINVAL; + page_addr = page_address(page); + ehdr = (Elf32_Ehdr *)page_addr; + + /* compare magic x7f "ELF" */ + if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) + goto out; + + /* only support executable file and shared object file */ + if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) + goto out; + + if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) + ret = stack_map_get_build_id_32(page_addr, build_id); + else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) + ret = stack_map_get_build_id_64(page_addr, build_id); +out: + put_page(page); + return ret; +} + +static void stack_map_get_build_id_offset(struct bpf_map *map, + struct stack_map_bucket *bucket, + u64 *ips, u32 trace_nr, bool user) +{ + int i; + struct vm_area_struct *vma; + struct bpf_stack_build_id *id_offs; + + bucket->nr = trace_nr; + id_offs = (struct bpf_stack_build_id *)bucket->data; + + /* + * We cannot do up_read() in nmi context, so build_id lookup is + * only supported for non-nmi events. If at some point, it is + * possible to run find_vma() without taking the semaphore, we + * would like to allow build_id lookup in nmi context. + * + * Same fallback is used for kernel stack (!user) on a stackmap + * with build_id. + */ + if (!user || !current || !current->mm || in_nmi() || + down_read_trylock(¤t->mm->mmap_sem) == 0) { + /* cannot access current->mm, fall back to ips */ + for (i = 0; i < trace_nr; i++) { + id_offs[i].status = BPF_STACK_BUILD_ID_IP; + id_offs[i].ip = ips[i]; + } + return; + } + + for (i = 0; i < trace_nr; i++) { + vma = find_vma(current->mm, ips[i]); + if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) { + /* per entry fall back to ips */ + id_offs[i].status = BPF_STACK_BUILD_ID_IP; + id_offs[i].ip = ips[i]; + continue; + } + id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] + - vma->vm_start; + id_offs[i].status = BPF_STACK_BUILD_ID_VALID; + } + up_read(¤t->mm->mmap_sem); +} + BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, u64, flags) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct perf_callchain_entry *trace; struct stack_map_bucket *bucket, *new_bucket, *old_bucket; - u32 max_depth = map->value_size / 8; + u32 max_depth = map->value_size / stack_map_data_size(map); /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ u32 init_nr = sysctl_perf_event_max_stack - max_depth; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; @@ -128,6 +321,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, bool user = flags & BPF_F_USER_STACK; bool kernel = !user; u64 *ips; + bool hash_matches; if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) @@ -156,24 +350,43 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, id = hash & (smap->n_buckets - 1); bucket = READ_ONCE(smap->buckets[id]); - if (bucket && bucket->hash == hash) { - if (flags & BPF_F_FAST_STACK_CMP) + hash_matches = bucket && bucket->hash == hash; + /* fast cmp */ + if (hash_matches && flags & BPF_F_FAST_STACK_CMP) + return id; + + if (stack_map_use_build_id(map)) { + /* for build_id+offset, pop a bucket before slow cmp */ + new_bucket = (struct stack_map_bucket *) + pcpu_freelist_pop(&smap->freelist); + if (unlikely(!new_bucket)) + return -ENOMEM; + stack_map_get_build_id_offset(map, new_bucket, ips, + trace_nr, user); + trace_len = trace_nr * sizeof(struct bpf_stack_build_id); + if (hash_matches && bucket->nr == trace_nr && + memcmp(bucket->data, new_bucket->data, trace_len) == 0) { + pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return id; - if (bucket->nr == trace_nr && - memcmp(bucket->ip, ips, trace_len) == 0) + } + if (bucket && !(flags & BPF_F_REUSE_STACKID)) { + pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); + return -EEXIST; + } + } else { + if (hash_matches && bucket->nr == trace_nr && + memcmp(bucket->data, ips, trace_len) == 0) return id; + if (bucket && !(flags & BPF_F_REUSE_STACKID)) + return -EEXIST; + + new_bucket = (struct stack_map_bucket *) + pcpu_freelist_pop(&smap->freelist); + if (unlikely(!new_bucket)) + return -ENOMEM; + memcpy(new_bucket->data, ips, trace_len); } - /* this call stack is not in the map, try to add it */ - if (bucket && !(flags & BPF_F_REUSE_STACKID)) - return -EEXIST; - - new_bucket = (struct stack_map_bucket *) - pcpu_freelist_pop(&smap->freelist); - if (unlikely(!new_bucket)) - return -ENOMEM; - - memcpy(new_bucket->ip, ips, trace_len); new_bucket->hash = hash; new_bucket->nr = trace_nr; @@ -212,8 +425,8 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) if (!bucket) return -ENOENT; - trace_len = bucket->nr * sizeof(u64); - memcpy(value, bucket->ip, trace_len); + trace_len = bucket->nr * stack_map_data_size(map); + memcpy(value, bucket->data, trace_len); memset(value + trace_len, 0, map->value_size - trace_len); old_bucket = xchg(&smap->buckets[id], bucket); From patchwork Wed Mar 14 17:23:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 885956 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; 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Wed, 14 Mar 2018 10:23:31 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig102.frc2.facebook.com To: , , , CC: , , , Song Liu Smtp-Origin-Cluster: frc2c02 Subject: [PATCH bpf-next v6 2/2] bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID Date: Wed, 14 Mar 2018 10:23:22 -0700 Message-ID: <20180314172323.3957483-3-songliubraving@fb.com> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20180314172323.3957483-1-songliubraving@fb.com> References: <20180314172323.3957483-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2018-03-14_09:, , signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org test_stacktrace_build_id() is added. It accesses tracepoint urandom_read with "dd" and "urandom_read" and gathers stack traces. Then it reads the stack traces from the stackmap. urandom_read is a statically link binary that reads from /dev/urandom. test_stacktrace_build_id() calls readelf to read build ID of urandom_read and compares it with build ID from the stackmap. Signed-off-by: Song Liu --- tools/include/uapi/linux/bpf.h | 22 +++ tools/testing/selftests/bpf/Makefile | 12 +- tools/testing/selftests/bpf/test_progs.c | 164 ++++++++++++++++++++- .../selftests/bpf/test_stacktrace_build_id.c | 60 ++++++++ tools/testing/selftests/bpf/urandom_read.c | 22 +++ 5 files changed, 278 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/test_stacktrace_build_id.c create mode 100644 tools/testing/selftests/bpf/urandom_read.c diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index db6bdc3..1944d0a 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -231,6 +231,28 @@ enum bpf_attach_type { #define BPF_F_RDONLY (1U << 3) #define BPF_F_WRONLY (1U << 4) +/* Flag for stack_map, store build_id+offset instead of pointer */ +#define BPF_F_STACK_BUILD_ID (1U << 5) + +enum bpf_stack_build_id_status { + /* user space need an empty entry to identify end of a trace */ + BPF_STACK_BUILD_ID_EMPTY = 0, + /* with valid build_id and offset */ + BPF_STACK_BUILD_ID_VALID = 1, + /* couldn't get build_id, fallback to ip */ + BPF_STACK_BUILD_ID_IP = 2, +}; + +#define BPF_BUILD_ID_SIZE 20 +struct bpf_stack_build_id { + __s32 status; + unsigned char build_id[BPF_BUILD_ID_SIZE]; + union { + __u64 offset; + __u64 ip; + }; +}; + union bpf_attr { struct { /* anonymous struct used by BPF_MAP_CREATE command */ __u32 map_type; /* one of enum bpf_map_type */ diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 8567a858..b0d29fd 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -13,6 +13,14 @@ endif CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include LDLIBS += -lcap -lelf -lrt -lpthread +TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read +all: $(TEST_CUSTOM_PROGS) + +$(TEST_CUSTOM_PROGS): urandom_read + +urandom_read: urandom_read.c + $(CC) -o $(TEST_CUSTOM_PROGS) -static $< + # Order correspond to 'make run_tests' order TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \ test_align test_verifier_log test_dev_cgroup test_tcpbpf_user @@ -21,7 +29,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \ sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \ test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \ - sample_map_ret0.o test_tcpbpf_kern.o + sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o # Order correspond to 'make run_tests' order TEST_PROGS := test_kmod.sh \ @@ -74,3 +82,5 @@ $(OUTPUT)/%.o: %.c $(CLANG) $(CLANG_FLAGS) \ -O2 -target bpf -emit-llvm -c $< -o - | \ $(LLC) -march=bpf -mcpu=$(CPU) -filetype=obj -o $@ + +EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index 27ad540..e9df48b 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -841,7 +841,8 @@ static void test_tp_attach_query(void) static int compare_map_keys(int map1_fd, int map2_fd) { __u32 key, next_key; - char val_buf[PERF_MAX_STACK_DEPTH * sizeof(__u64)]; + char val_buf[PERF_MAX_STACK_DEPTH * + sizeof(struct bpf_stack_build_id)]; int err; err = bpf_map_get_next_key(map1_fd, NULL, &key); @@ -964,6 +965,166 @@ static void test_stacktrace_map() return; } +static int extract_build_id(char *build_id, size_t size) +{ + FILE *fp; + char *line = NULL; + size_t len = 0; + + fp = popen("readelf -n ./urandom_read | grep 'Build ID'", "r"); + if (fp == NULL) + return -1; + + if (getline(&line, &len, fp) == -1) + goto err; + fclose(fp); + + if (len > size) + len = size; + memcpy(build_id, line, len); + build_id[len] = '\0'; + return 0; +err: + fclose(fp); + return -1; +} + +static void test_stacktrace_build_id(void) +{ + int control_map_fd, stackid_hmap_fd, stackmap_fd; + const char *file = "./test_stacktrace_build_id.o"; + int bytes, efd, err, pmu_fd, prog_fd; + struct perf_event_attr attr = {}; + __u32 key, previous_key, val, duration = 0; + struct bpf_object *obj; + char buf[256]; + int i, j; + struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH]; + int build_id_matches = 0; + + err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd); + if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno)) + goto out; + + /* Get the ID for the sched/sched_switch tracepoint */ + snprintf(buf, sizeof(buf), + "/sys/kernel/debug/tracing/events/random/urandom_read/id"); + efd = open(buf, O_RDONLY, 0); + if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno)) + goto close_prog; + + bytes = read(efd, buf, sizeof(buf)); + close(efd); + if (CHECK(bytes <= 0 || bytes >= sizeof(buf), + "read", "bytes %d errno %d\n", bytes, errno)) + goto close_prog; + + /* Open the perf event and attach bpf progrram */ + attr.config = strtol(buf, NULL, 0); + attr.type = PERF_TYPE_TRACEPOINT; + attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN; + attr.sample_period = 1; + attr.wakeup_events = 1; + pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, + 0 /* cpu 0 */, -1 /* group id */, + 0 /* flags */); + if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", + pmu_fd, errno)) + goto close_prog; + + err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0); + if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n", + err, errno)) + goto close_pmu; + + err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); + if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n", + err, errno)) + goto disable_pmu; + + /* find map fds */ + control_map_fd = bpf_find_map(__func__, obj, "control_map"); + if (CHECK(control_map_fd < 0, "bpf_find_map control_map", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap"); + if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + stackmap_fd = bpf_find_map(__func__, obj, "stackmap"); + if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n", + err, errno)) + goto disable_pmu; + + assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null") + == 0); + assert(system("./urandom_read if=/dev/urandom of=/dev/zero count=4 2> /dev/null") == 0); + /* disable stack trace collection */ + key = 0; + val = 1; + bpf_map_update_elem(control_map_fd, &key, &val, 0); + + /* for every element in stackid_hmap, we can find a corresponding one + * in stackmap, and vise versa. + */ + err = compare_map_keys(stackid_hmap_fd, stackmap_fd); + if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + err = compare_map_keys(stackmap_fd, stackid_hmap_fd); + if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + err = extract_build_id(buf, 256); + + if (CHECK(err, "get build_id with readelf", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + err = bpf_map_get_next_key(stackmap_fd, NULL, &key); + if (CHECK(err, "get_next_key from stackmap", + "err %d, errno %d\n", err, errno)) + goto disable_pmu; + + do { + char build_id[64]; + + err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs); + if (CHECK(err, "lookup_elem from stackmap", + "err %d, errno %d\n", err, errno)) + goto disable_pmu; + for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i) + if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID && + id_offs[i].offset != 0) { + for (j = 0; j < 20; ++j) + sprintf(build_id + 2 * j, "%02x", + id_offs[i].build_id[j] & 0xff); + if (strstr(buf, build_id) != NULL) + build_id_matches = 1; + } + previous_key = key; + } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0); + + CHECK(build_id_matches < 1, "build id match", + "Didn't find expected build ID from the map"); + +disable_pmu: + ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE); + +close_pmu: + close(pmu_fd); + +close_prog: + bpf_object__close(obj); + +out: + return; +} + int main(void) { test_pkt_access(); @@ -976,6 +1137,7 @@ int main(void) test_obj_name(); test_tp_attach_query(); test_stacktrace_map(); + test_stacktrace_build_id(); printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt); return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS; diff --git a/tools/testing/selftests/bpf/test_stacktrace_build_id.c b/tools/testing/selftests/bpf/test_stacktrace_build_id.c new file mode 100644 index 0000000..b755bd7 --- /dev/null +++ b/tools/testing/selftests/bpf/test_stacktrace_build_id.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2018 Facebook + +#include +#include "bpf_helpers.h" + +#ifndef PERF_MAX_STACK_DEPTH +#define PERF_MAX_STACK_DEPTH 127 +#endif + +struct bpf_map_def SEC("maps") control_map = { + .type = BPF_MAP_TYPE_ARRAY, + .key_size = sizeof(__u32), + .value_size = sizeof(__u32), + .max_entries = 1, +}; + +struct bpf_map_def SEC("maps") stackid_hmap = { + .type = BPF_MAP_TYPE_HASH, + .key_size = sizeof(__u32), + .value_size = sizeof(__u32), + .max_entries = 10000, +}; + +struct bpf_map_def SEC("maps") stackmap = { + .type = BPF_MAP_TYPE_STACK_TRACE, + .key_size = sizeof(__u32), + .value_size = sizeof(struct bpf_stack_build_id) + * PERF_MAX_STACK_DEPTH, + .max_entries = 128, + .map_flags = BPF_F_STACK_BUILD_ID, +}; + +/* taken from /sys/kernel/debug/tracing/events/random/urandom_read/format */ +struct random_urandom_args { + unsigned long long pad; + int got_bits; + int pool_left; + int input_left; +}; + +SEC("tracepoint/random/urandom_read") +int oncpu(struct random_urandom_args *args) +{ + __u32 key = 0, val = 0, *value_p; + + value_p = bpf_map_lookup_elem(&control_map, &key); + if (value_p && *value_p) + return 0; /* skip if non-zero *value_p */ + + /* The size of stackmap and stackid_hmap should be the same */ + key = bpf_get_stackid(args, &stackmap, BPF_F_USER_STACK); + if ((int)key >= 0) + bpf_map_update_elem(&stackid_hmap, &key, &val, 0); + + return 0; +} + +char _license[] SEC("license") = "GPL"; +__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */ diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c new file mode 100644 index 0000000..4acfdeb --- /dev/null +++ b/tools/testing/selftests/bpf/urandom_read.c @@ -0,0 +1,22 @@ +#include +#include +#include +#include +#include +#include + +#define BUF_SIZE 256 +int main(void) +{ + int fd = open("/dev/urandom", O_RDONLY); + int i; + char buf[BUF_SIZE]; + + if (fd < 0) + return 1; + for (i = 0; i < 4; ++i) + read(fd, buf, BUF_SIZE); + + close(fd); + return 0; +}