From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sandipan Das Subject: [PATCH bpf 6/6] bpf: fix JITed dump for multi-function programs via syscall Date: Thu, 17 May 2018 12:05:48 +0530 Message-ID: <20180517063548.6373-7-sandipan@linux.vnet.ibm.com> References: <20180517063548.6373-1-sandipan@linux.vnet.ibm.com> Cc: netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, naveen.n.rao@linux.vnet.ibm.com To: ast@kernel.org, daniel@iogearbox.net Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:43758 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751916AbeEQGgO (ORCPT ); Thu, 17 May 2018 02:36:14 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w4H6Zrmh049342 for ; Thu, 17 May 2018 02:36:14 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0b-001b2d01.pphosted.com with ESMTP id 2j140u1fq6-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 17 May 2018 02:36:13 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 17 May 2018 07:36:05 +0100 In-Reply-To: <20180517063548.6373-1-sandipan@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: Currently, for multi-function programs, we cannot get the JITed instructions using the bpf system call's BPF_OBJ_GET_INFO_BY_FD command. Because of this, userspace tools such as bpftool fail to identify a multi-function program as being JITed or not. With the JIT enabled and the test program running, this can be verified as follows: # cat /proc/sys/net/core/bpf_jit_enable 1 Before applying this patch: # bpftool prog list 1: kprobe name foo tag b811aab41a39ad3d gpl loaded_at 2018-05-16T11:43:38+0530 uid 0 xlated 216B not jited memlock 65536B ... # bpftool prog dump jited id 1 no instructions returned After applying this patch: # bpftool prog list 1: kprobe name foo tag b811aab41a39ad3d gpl loaded_at 2018-05-16T12:13:01+0530 uid 0 xlated 216B jited 308B memlock 65536B ... # bpftool prog dump jited id 1 0: nop 4: nop 8: mflr r0 c: std r0,16(r1) 10: stdu r1,-112(r1) 14: std r31,104(r1) 18: addi r31,r1,48 1c: li r3,10 ... Signed-off-by: Sandipan Das --- kernel/bpf/syscall.c | 38 ++++++++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 03c8437a2990..b2f70718aca7 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1896,7 +1896,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, struct bpf_prog_info info = {}; u32 info_len = attr->info.info_len; char __user *uinsns; - u32 ulen; + u32 ulen, i; int err; err = check_uarg_tail_zero(uinfo, sizeof(info), info_len); @@ -1922,7 +1922,6 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, ulen = min_t(u32, info.nr_map_ids, ulen); if (ulen) { u32 __user *user_map_ids = u64_to_user_ptr(info.map_ids); - u32 i; for (i = 0; i < ulen; i++) if (put_user(prog->aux->used_maps[i]->id, @@ -1970,13 +1969,41 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, * for offload. */ ulen = info.jited_prog_len; - info.jited_prog_len = prog->jited_len; + if (prog->aux->func_cnt) { + info.jited_prog_len = 0; + for (i = 0; i < prog->aux->func_cnt; i++) + info.jited_prog_len += prog->aux->func[i]->jited_len; + } else { + info.jited_prog_len = prog->jited_len; + } + if (info.jited_prog_len && ulen) { if (bpf_dump_raw_ok()) { uinsns = u64_to_user_ptr(info.jited_prog_insns); ulen = min_t(u32, info.jited_prog_len, ulen); - if (copy_to_user(uinsns, prog->bpf_func, ulen)) - return -EFAULT; + + /* for multi-function programs, copy the JITed + * instructions for all the functions + */ + if (prog->aux->func_cnt) { + u32 len, free; + u8 *img; + + free = ulen; + for (i = 0; i < prog->aux->func_cnt; i++) { + len = prog->aux->func[i]->jited_len; + img = (u8 *) prog->aux->func[i]->bpf_func; + if (len > free) + break; + if (copy_to_user(uinsns, img, len)) + return -EFAULT; + uinsns += len; + free -= len; + } + } else { + if (copy_to_user(uinsns, prog->bpf_func, ulen)) + return -EFAULT; + } } else { info.jited_prog_insns = 0; } @@ -1987,7 +2014,6 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, if (info.nr_jited_ksyms && ulen) { u64 __user *user_jited_ksyms = u64_to_user_ptr(info.jited_ksyms); ulong ksym_addr; - u32 i; /* copy the address of the kernel symbol corresponding to * each function -- 2.14.3