From patchwork Wed Jul 15 23:36:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 1329854 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B6YnK50Wcz9sDX for ; Thu, 16 Jul 2020 09:41:41 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726929AbgGOXll (ORCPT ); Wed, 15 Jul 2020 19:41:41 -0400 Received: from mga06.intel.com ([134.134.136.31]:52501 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726786AbgGOXll (ORCPT ); Wed, 15 Jul 2020 19:41:41 -0400 IronPort-SDR: o6rDFv9xQw9pQV4dVLxMm38kkeO659jqIJNSRaOPTe9dOlhIiCrrDrwK/1ZIXrP684CK7EszC4 0t1JyJDi77AQ== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="210823662" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="210823662" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:41:40 -0700 IronPort-SDR: DZiKgIF1zsDDThR+ngJ9CKcOqgO1KH0RfW71YSewmRl9JafTA8FvTPL46SY6ecm9nIyjFjazMn W8j3BLezwrZA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="390935576" Received: from ranger.igk.intel.com ([10.102.21.164]) by fmsmga001.fm.intel.com with ESMTP; 15 Jul 2020 16:41:39 -0700 From: Maciej Fijalkowski To: ast@kernel.org, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, Maciej Fijalkowski Subject: [PATCH bpf-next 1/5] bpf, x64: use %rcx instead of %rax for tail call retpolines Date: Thu, 16 Jul 2020 01:36:30 +0200 Message-Id: <20200715233634.3868-2-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200715233634.3868-1-maciej.fijalkowski@intel.com> References: <20200715233634.3868-1-maciej.fijalkowski@intel.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Currently, %rax is used to store the jump target when BPF program is emitting the retpoline instructions that are handling the indirect tailcall. There is a plan to use %rax for different purpose, which is storing the tail call counter. In order to preserve this value across the tailcalls, use %rcx instead for jump target storage in retpoline instructions. Signed-off-by: Maciej Fijalkowski --- arch/x86/include/asm/nospec-branch.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index e7752b4038ff..e491c3d9f227 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -314,19 +314,19 @@ static inline void mds_idle_clear_cpu_buffers(void) * lfence * jmp spec_trap * do_rop: - * mov %rax,(%rsp) for x86_64 + * mov %rcx,(%rsp) for x86_64 * mov %edx,(%esp) for x86_32 * retq * * Without retpolines configured: * - * jmp *%rax for x86_64 + * jmp *%rcx for x86_64 * jmp *%edx for x86_32 */ #ifdef CONFIG_RETPOLINE # ifdef CONFIG_X86_64 -# define RETPOLINE_RAX_BPF_JIT_SIZE 17 -# define RETPOLINE_RAX_BPF_JIT() \ +# define RETPOLINE_RCX_BPF_JIT_SIZE 17 +# define RETPOLINE_RCX_BPF_JIT() \ do { \ EMIT1_off32(0xE8, 7); /* callq do_rop */ \ /* spec_trap: */ \ @@ -334,7 +334,7 @@ do { \ EMIT3(0x0F, 0xAE, 0xE8); /* lfence */ \ EMIT2(0xEB, 0xF9); /* jmp spec_trap */ \ /* do_rop: */ \ - EMIT4(0x48, 0x89, 0x04, 0x24); /* mov %rax,(%rsp) */ \ + EMIT4(0x48, 0x89, 0x0C, 0x24); /* mov %rcx,(%rsp) */ \ EMIT1(0xC3); /* retq */ \ } while (0) # else /* !CONFIG_X86_64 */ @@ -352,9 +352,9 @@ do { \ # endif #else /* !CONFIG_RETPOLINE */ # ifdef CONFIG_X86_64 -# define RETPOLINE_RAX_BPF_JIT_SIZE 2 -# define RETPOLINE_RAX_BPF_JIT() \ - EMIT2(0xFF, 0xE0); /* jmp *%rax */ +# define RETPOLINE_RCX_BPF_JIT_SIZE 2 +# define RETPOLINE_RCX_BPF_JIT() \ + EMIT2(0xFF, 0xE1); /* jmp *%rcx */ # else /* !CONFIG_X86_64 */ # define RETPOLINE_EDX_BPF_JIT() \ EMIT2(0xFF, 0xE2) /* jmp *%edx */ From patchwork Wed Jul 15 23:36:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 1329856 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B6YnM5F8Mz9sDX for ; Thu, 16 Jul 2020 09:41:43 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727047AbgGOXln (ORCPT ); Wed, 15 Jul 2020 19:41:43 -0400 Received: from mga06.intel.com ([134.134.136.31]:52501 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727042AbgGOXlm (ORCPT ); Wed, 15 Jul 2020 19:41:42 -0400 IronPort-SDR: XVhuE0l5QxPvET520x8oMt2hm4lfNN8ZI3JDLjl8vZBJuN7bK78SmV1bhpGKiybhlAwjFGlW6x F5g8i7yJFhlg== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="210823663" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="210823663" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:41:42 -0700 IronPort-SDR: 6UNKbwhd3zof/kOnMy0Q3kfn+PvHhCHrCijvgw39aBLQfLKFjcep/sc8ik/OT9YkjIFMjaYfN1 9dnt++gZVacw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="390935580" Received: from ranger.igk.intel.com ([10.102.21.164]) by fmsmga001.fm.intel.com with ESMTP; 15 Jul 2020 16:41:40 -0700 From: Maciej Fijalkowski To: ast@kernel.org, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, Maciej Fijalkowski Subject: [PATCH bpf-next 2/5] bpf: allow for tailcalls in BPF subprograms Date: Thu, 16 Jul 2020 01:36:31 +0200 Message-Id: <20200715233634.3868-3-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200715233634.3868-1-maciej.fijalkowski@intel.com> References: <20200715233634.3868-1-maciej.fijalkowski@intel.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Relax verifier's restriction that was meant to forbid tailcall usage when subprog count was higher than 1. Also, do not max out the stack depth of program that utilizes tailcalls. Signed-off-by: Maciej Fijalkowski --- kernel/bpf/verifier.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c1efc9d08fd..6481342b31ba 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4172,10 +4172,6 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_FUNC_tail_call: if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) goto error; - if (env->subprog_cnt > 1) { - verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n"); - return -EINVAL; - } break; case BPF_FUNC_perf_event_read: case BPF_FUNC_perf_event_output: @@ -10252,7 +10248,6 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) * the program array. */ prog->cb_access = 1; - env->prog->aux->stack_depth = MAX_BPF_STACK; env->prog->aux->max_pkt_offset = MAX_PACKET_OFF; /* mark bpf_tail_call as different opcode to avoid From patchwork Wed Jul 15 23:36:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 1329858 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B6YnQ11SBz9sDX for ; Thu, 16 Jul 2020 09:41:46 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727075AbgGOXlp (ORCPT ); Wed, 15 Jul 2020 19:41:45 -0400 Received: from mga06.intel.com ([134.134.136.31]:52501 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727042AbgGOXlo (ORCPT ); Wed, 15 Jul 2020 19:41:44 -0400 IronPort-SDR: jmhNPQTZpE9UFZ/gnrUQtZTxonm0qMiA3FVBgycAYK9JXUzQSBtURaPgAaXicZ5fR67GpaLCEC KmgljHDtcVBw== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="210823664" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="210823664" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:41:44 -0700 IronPort-SDR: noQi8yOnnUPrvGa1AUOu207EPxmoFkDA8G+VT5M9J7IiRK15aNnYW9H4ce84r6TADgSXQ6cKgf PtZxrsFRASsg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="390935584" Received: from ranger.igk.intel.com ([10.102.21.164]) by fmsmga001.fm.intel.com with ESMTP; 15 Jul 2020 16:41:42 -0700 From: Maciej Fijalkowski To: ast@kernel.org, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, Maciej Fijalkowski Subject: [PATCH bpf-next 3/5] bpf: propagate poke descriptors to subprograms Date: Thu, 16 Jul 2020 01:36:32 +0200 Message-Id: <20200715233634.3868-4-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200715233634.3868-1-maciej.fijalkowski@intel.com> References: <20200715233634.3868-1-maciej.fijalkowski@intel.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Previously, there was no need for poke descriptors being present in subprogram's bpf_prog_aux struct since tailcalls were simply not allowed in them. Each subprog is JITed independently so in order to enable JITing such subprograms, simply copy poke descriptors from main program to subprogram's poke tab. Add also subprog's aux struct to the BPF map poke_progs list by calling on it map_poke_track(). Signed-off-by: Maciej Fijalkowski --- kernel/bpf/verifier.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6481342b31ba..3b406b2860ef 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9932,6 +9932,9 @@ static int jit_subprogs(struct bpf_verifier_env *env) goto out_undo_insn; for (i = 0; i < env->subprog_cnt; i++) { + struct bpf_map *map_ptr; + int j; + subprog_start = subprog_end; subprog_end = env->subprog_info[i + 1].start; @@ -9956,6 +9959,12 @@ static int jit_subprogs(struct bpf_verifier_env *env) func[i]->aux->btf = prog->aux->btf; func[i]->aux->func_info = prog->aux->func_info; + for (j = 0; j < prog->aux->size_poke_tab; j++) { + bpf_jit_add_poke_descriptor(func[i], &prog->aux->poke_tab[j]); + map_ptr = func[i]->aux->poke_tab[j].tail_call.map; + map_ptr->ops->map_poke_track(map_ptr, func[i]->aux); + } + /* Use bpf_prog_F_tag to indicate functions in stack traces. * Long term would need debug info to populate names */ From patchwork Wed Jul 15 23:36:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 1329862 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B6YqD2Tfrz9sQt for ; Thu, 16 Jul 2020 09:43:20 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727052AbgGOXnT (ORCPT ); Wed, 15 Jul 2020 19:43:19 -0400 Received: from mga06.intel.com ([134.134.136.31]:52501 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727042AbgGOXnT (ORCPT ); Wed, 15 Jul 2020 19:43:19 -0400 IronPort-SDR: hTqpvGqSuHbJefW803GjhV8A+Stbclh++GC0pniOCkrdco5S11mDYcU8e/CgiB7KsZeWgbkRMv aEePobqLPoaw== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="210823668" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="210823668" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:41:46 -0700 IronPort-SDR: D8DlGLKhpznfQvgbTccqisMWcCTEZ+i1xNUQNytziB5AiWttIxx6F58sGGKFEzEcVikvkfqxwn 7w0lqiM5ObVQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="390935592" Received: from ranger.igk.intel.com ([10.102.21.164]) by fmsmga001.fm.intel.com with ESMTP; 15 Jul 2020 16:41:44 -0700 From: Maciej Fijalkowski To: ast@kernel.org, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, Maciej Fijalkowski Subject: [PATCH bpf-next 4/5] bpf, x64: rework pro/epilogue and tailcall handling in JIT Date: Thu, 16 Jul 2020 01:36:33 +0200 Message-Id: <20200715233634.3868-5-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200715233634.3868-1-maciej.fijalkowski@intel.com> References: <20200715233634.3868-1-maciej.fijalkowski@intel.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This commit serves two things: 1) it optimizes BPF prologue/epilogue generation 2) it makes possible to have tailcalls within BPF subprogram Both points are related to each other since without 1), 2) could not be achieved. In [1], Alexei says: "The prologue will look like: nop5 xor eax,eax  // two new bytes if bpf_tail_call() is used in this // function push rbp mov rbp, rsp sub rsp, rounded_stack_depth push rax // zero init tail_call counter variable number of push rbx,r13,r14,r15 Then bpf_tail_call will pop variable number rbx,.. and final 'pop rax' Then 'add rsp, size_of_current_stack_frame' jmp to next function and skip over 'nop5; xor eax,eax; push rpb; mov rbp, rsp' This way new function will set its own stack size and will init tail call counter with whatever value the parent had. If next function doesn't use bpf_tail_call it won't have 'xor eax,eax'. Instead it would need to have 'nop2' in there." Implement that suggestion. Since the layout of stack is changed, tail call counter handling can not rely anymore on popping it to rbx just like it have been handled for constant prologue case and later overwrite of rbx with actual value of rbx pushed to stack. Therefore, let's use one of the register (%rcx) that is considered to be volatile/caller-saved and pop the value of tail call counter in there in the epilogue. Drop the BUILD_BUG_ON in emit_prologue and in emit_bpf_tail_call_indirect where instruction layout is not constant anymore. Introduce new poke target, 'tailcall_bypass' to poke descriptor that is dedicated for skipping the register pops and stack unwind that are generated right before the actual jump to target program. Reflect also the actual purpose of poke->ip and rename it to poke->tailcall_target so that it will not the be confused with the poke target that is being introduced here. For case when the target program is not present, BPF program will skip the pop instructions and nop5 dedicated for jmpq $target. An example of such state when only R6 of callee saved registers is used by program: ffffffffc0513aa1: e9 0e 00 00 00 jmpq 0xffffffffc0513ab4 ffffffffc0513aa6: 5b pop %rbx ffffffffc0513aa7: 58 pop %rax ffffffffc0513aa8: 48 81 c4 00 00 00 00 add $0x0,%rsp ffffffffc0513aaf: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) ffffffffc0513ab4: 48 89 df mov %rbx,%rdi When target program is inserted, the jump that was there to skip pops/nop5 will become the nop5, so CPU will go over pops and do the actual tailcall. One might ask why there simply can not be pushes after the nop5? In the following example snippet: ffffffffc037030c: 48 89 fb mov %rdi,%rbx (...) ffffffffc0370332: 5b pop %rbx ffffffffc0370333: 58 pop %rax ffffffffc0370334: 48 81 c4 00 00 00 00 add $0x0,%rsp ffffffffc037033b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) ffffffffc0370340: 48 81 ec 00 00 00 00 sub $0x0,%rsp ffffffffc0370347: 50 push %rax ffffffffc0370348: 53 push %rbx ffffffffc0370349: 48 89 df mov %rbx,%rdi ffffffffc037034c: e8 f7 21 00 00 callq 0xffffffffc0372548 There is the bpf2bpf call (at ffffffffc037034c) right after the tailcall and jump target is not present. ctx is in %rbx register and BPF subprogram that we will call into on ffffffffc037034c is relying on it, e.g. it will pick ctx from there. Such code layout is therefore broken as we would overwrite the content of %rbx with the value that was pushed on the prologue. That is the reason for the 'bypass' approach. Special care needs to be taken during the install/update/remove of tailcall target. In case when target program is not present, the CPU must not execute the pop instructions that precede the tailcall. To address that, the following states can be defined: A nop, unwind, nop B nop, unwind, tail C skip, unwind, nop D skip, unwind, tail A is forbidden (lead to incorrectness). The state transitions between tailcall install/update/remove will work as follows: First install tail call f: C->D->B(f) * poke the tailcall, after that get rid of the skip Update tail call f to f': B(f)->B(f') * poke the tailcall (poke->tailcall_target) and do NOT touch the poke->tailcall_bypass Remove tail call: B(f')->C(f') * poke->tailcall_bypass is poked back to jump, then we wait the RCU grace period so that other programs will finish its execution and after that we are safe to remove the poke->tailcall_target Install new tail call (f''): C(f')->D(f'')->B(f''). * same as first step This way CPU can never be exposed to "unwind, tail" state. For regression checks, 'tailcalls' kselftest was executed: $ sudo ./test_progs -t tailcalls #64/1 tailcall_1:OK #64/2 tailcall_2:OK #64/3 tailcall_3:OK #64/4 tailcall_4:OK #64/5 tailcall_5:OK #64 tailcalls:OK Summary: 1/5 PASSED, 0 SKIPPED, 0 FAILED Tail call related cases from test_verifier kselftest are also working fine. Sample BPF programs that utilize tail calls (sockex3, tracex5) work properly as well. [1]: https://lore.kernel.org/bpf/20200517043227.2gpq22ifoq37ogst@ast-mbp.dhcp.thefacebook.com/ Suggested-by: Alexei Starovoitov Signed-off-by: Maciej Fijalkowski --- arch/x86/net/bpf_jit_comp.c | 241 +++++++++++++++++++++++++++--------- include/linux/bpf.h | 8 +- kernel/bpf/arraymap.c | 61 +++++++-- kernel/bpf/core.c | 3 +- 4 files changed, 239 insertions(+), 74 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 42b6709e6dc7..4e83b13fb19f 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -219,16 +219,47 @@ struct jit_context { #define BPF_MAX_INSN_SIZE 128 #define BPF_INSN_SAFETY 64 -/* Number of bytes emit_patch() needs to generate instructions */ -#define X86_PATCH_SIZE 5 +/* Number of bytes that will be skipped on tailcall */ +#define X86_TAIL_CALL_OFFSET 11 -#define PROLOGUE_SIZE 25 +static void push_callee_regs(u8 **pprog, bool *callee_regs_used) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (callee_regs_used[0]) + EMIT1(0x53); /* push rbx */ + if (callee_regs_used[1]) + EMIT2(0x41, 0x55); /* push r13 */ + if (callee_regs_used[2]) + EMIT2(0x41, 0x56); /* push r14 */ + if (callee_regs_used[3]) + EMIT2(0x41, 0x57); /* push r15 */ + *pprog = prog; +} + +static void pop_callee_regs(u8 **pprog, bool *callee_regs_used) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (callee_regs_used[3]) + EMIT2(0x41, 0x5F); /* pop r15 */ + if (callee_regs_used[2]) + EMIT2(0x41, 0x5E); /* pop r14 */ + if (callee_regs_used[1]) + EMIT2(0x41, 0x5D); /* pop r13 */ + if (callee_regs_used[0]) + EMIT1(0x5B); /* pop rbx */ + *pprog = prog; +} /* - * Emit x86-64 prologue code for BPF program and check its size. + * Emit x86-64 prologue code for BPF program. * bpf_tail_call helper will skip it while jumping into another program */ -static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf) +static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, + bool tail_call) { u8 *prog = *pprog; int cnt = X86_PATCH_SIZE; @@ -238,19 +269,16 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf) */ memcpy(prog, ideal_nops[NOP_ATOMIC5], cnt); prog += cnt; + if (!ebpf_from_cbpf && tail_call) + EMIT2(0x31, 0xC0); /* xor eax, eax */ + else + EMIT2(0x66, 0x90); /* nop2 */ EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ /* sub rsp, rounded_stack_depth */ EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8)); - EMIT1(0x53); /* push rbx */ - EMIT2(0x41, 0x55); /* push r13 */ - EMIT2(0x41, 0x56); /* push r14 */ - EMIT2(0x41, 0x57); /* push r15 */ - if (!ebpf_from_cbpf) { - /* zero init tail_call_cnt */ - EMIT2(0x6a, 0x00); - BUILD_BUG_ON(cnt != PROLOGUE_SIZE); - } + if (!ebpf_from_cbpf && tail_call) + EMIT1(0x50); /* push rax */ *pprog = prog; } @@ -337,6 +365,22 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, return __bpf_arch_text_poke(ip, t, old_addr, new_addr, true); } +static int get_pop_bytes(bool *callee_regs_used) +{ + int bytes = 0; + + if (callee_regs_used[3]) + bytes += 2; + if (callee_regs_used[2]) + bytes += 2; + if (callee_regs_used[1]) + bytes += 2; + if (callee_regs_used[0]) + bytes += 1; + + return bytes; +} + /* * Generate the following code: * @@ -351,12 +395,25 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, * goto *(prog->bpf_func + prologue_size); * out: */ -static void emit_bpf_tail_call_indirect(u8 **pprog) +static void emit_bpf_tail_call_indirect(u8 **pprog, bool *callee_regs_used, + u32 stack_depth) { u8 *prog = *pprog; - int label1, label2, label3; + int pop_bytes = 0; + int off1 = 49; + int off2 = 38; + int off3 = 16; int cnt = 0; + /* count the additional bytes used for popping callee regs from stack + * that need to be taken into account for each of the offsets that + * are used for bailing out of the tail call + */ + pop_bytes = get_pop_bytes(callee_regs_used); + off1 += pop_bytes; + off2 += pop_bytes; + off3 += pop_bytes; + /* * rdi - pointer to ctx * rsi - pointer to bpf_array @@ -370,72 +427,108 @@ static void emit_bpf_tail_call_indirect(u8 **pprog) EMIT2(0x89, 0xD2); /* mov edx, edx */ EMIT3(0x39, 0x56, /* cmp dword ptr [rsi + 16], edx */ offsetof(struct bpf_array, map.max_entries)); -#define OFFSET1 (41 + RETPOLINE_RAX_BPF_JIT_SIZE) /* Number of bytes to jump */ +#define OFFSET1 (off1 + RETPOLINE_RCX_BPF_JIT_SIZE) /* Number of bytes to jump */ EMIT2(X86_JBE, OFFSET1); /* jbe out */ - label1 = cnt; /* * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ - EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ + EMIT2_off32(0x8B, 0x85 /* mov eax, dword ptr [rbp - (4 + sd)] */, + -4 - round_up(stack_depth, 8)); EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ -#define OFFSET2 (30 + RETPOLINE_RAX_BPF_JIT_SIZE) +#define OFFSET2 (off2 + RETPOLINE_RCX_BPF_JIT_SIZE) EMIT2(X86_JA, OFFSET2); /* ja out */ - label2 = cnt; EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ - EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ + EMIT2_off32(0x89, 0x85, /* mov dword ptr [rbp - (4 + sd)], eax */ + -4 - round_up(stack_depth, 8)); /* prog = array->ptrs[index]; */ - EMIT4_off32(0x48, 0x8B, 0x84, 0xD6, /* mov rax, [rsi + rdx * 8 + offsetof(...)] */ + EMIT4_off32(0x48, 0x8B, 0x8C, 0xD6, /* mov rcx, [rsi + rdx * 8 + offsetof(...)] */ offsetof(struct bpf_array, ptrs)); /* * if (prog == NULL) * goto out; */ - EMIT3(0x48, 0x85, 0xC0); /* test rax,rax */ -#define OFFSET3 (8 + RETPOLINE_RAX_BPF_JIT_SIZE) - EMIT2(X86_JE, OFFSET3); /* je out */ - label3 = cnt; + EMIT3(0x48, 0x85, 0xC9); /* test rcx,rcx */ +#define OFFSET3 (off3 + RETPOLINE_RCX_BPF_JIT_SIZE) + EMIT2(X86_JE, OFFSET3); /* je out */ - /* goto *(prog->bpf_func + prologue_size); */ - EMIT4(0x48, 0x8B, 0x40, /* mov rax, qword ptr [rax + 32] */ - offsetof(struct bpf_prog, bpf_func)); - EMIT4(0x48, 0x83, 0xC0, PROLOGUE_SIZE); /* add rax, prologue_size */ + *pprog = prog; + pop_callee_regs(pprog, callee_regs_used); + prog = *pprog; + + EMIT1(0x58); /* pop rax */ + EMIT3_off32(0x48, 0x81, 0xC4, /* add rsp, sd */ + round_up(stack_depth, 8)); + /* goto *(prog->bpf_func + X86_TAIL_CALL_OFFSET); */ + EMIT4(0x48, 0x8B, 0x49, /* mov rcx, qword ptr [rcx + 32] */ + offsetof(struct bpf_prog, bpf_func)); + EMIT4(0x48, 0x83, 0xC1, /* add rcx, X86_TAIL_CALL_OFFSET */ + X86_TAIL_CALL_OFFSET); /* - * Wow we're ready to jump into next BPF program + * Now we're ready to jump into next BPF program * rdi == ctx (1st arg) - * rax == prog->bpf_func + prologue_size + * rcx == prog->bpf_func + X86_TAIL_CALL_OFFSET */ - RETPOLINE_RAX_BPF_JIT(); + RETPOLINE_RCX_BPF_JIT(); /* out: */ - BUILD_BUG_ON(cnt - label1 != OFFSET1); - BUILD_BUG_ON(cnt - label2 != OFFSET2); - BUILD_BUG_ON(cnt - label3 != OFFSET3); *pprog = prog; } static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke, - u8 **pprog, int addr, u8 *image) + u8 **pprog, int addr, u8 *image, + bool *callee_regs_used, u32 stack_depth) { u8 *prog = *pprog; + int pop_bytes = 0; + int off1 = 27; + int poke_off; int cnt = 0; + /* count the additional bytes used for popping callee regs to stack + * that need to be taken into account for jump offset that is used for + * bailing out from the tail call when limit is reached + */ + pop_bytes = get_pop_bytes(callee_regs_used); + off1 += pop_bytes; + + /* + * total bytes for: + * - nop5/ jmpq $off + * - pop callee regs + * - sub rsp, $val + * - pop rax + */ + poke_off = X86_PATCH_SIZE + pop_bytes + 7 + 1; + /* * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ - EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ + EMIT2_off32(0x8B, 0x85, + -4 - round_up(stack_depth, 8)); /* mov eax, dword ptr [rbp - (4 + sd)] */ EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ - EMIT2(X86_JA, 14); /* ja out */ + EMIT2(X86_JA, off1); /* ja out */ EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ - EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ + EMIT2_off32(0x89, 0x85, + -4 - round_up(stack_depth, 8)); /* mov dword ptr [rbp - (4 + sd)], eax */ + + poke->tailcall_bypass = image + (addr - poke_off - X86_PATCH_SIZE); + poke->adj_off = X86_TAIL_CALL_OFFSET; + poke->tailcall_target = image + (addr - X86_PATCH_SIZE); + + emit_jump(&prog, (u8 *)poke->tailcall_target + X86_PATCH_SIZE, + poke->tailcall_bypass); - poke->ip = image + (addr - X86_PATCH_SIZE); - poke->adj_off = PROLOGUE_SIZE; + *pprog = prog; + pop_callee_regs(pprog, callee_regs_used); + prog = *pprog; + EMIT1(0x58); /* pop rax */ + EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8)); memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE); prog += X86_PATCH_SIZE; @@ -453,7 +546,7 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) for (i = 0; i < prog->aux->size_poke_tab; i++) { poke = &prog->aux->poke_tab[i]; - WARN_ON_ONCE(READ_ONCE(poke->ip_stable)); + WARN_ON_ONCE(READ_ONCE(poke->tailcall_target_stable)); if (poke->reason != BPF_POKE_REASON_TAIL_CALL) continue; @@ -462,20 +555,26 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) mutex_lock(&array->aux->poke_mutex); target = array->ptrs[poke->tail_call.key]; if (target) { - /* Plain memcpy is used when image is not live yet - * and still not locked as read-only. Once poke - * location is active (poke->ip_stable), any parallel + /* Plain memcpy is used when image is not live yet and + * still not locked as read-only. Once poke location is + * active (poke->tailcall_target_stable), any parallel * bpf_arch_text_poke() might occur still on the * read-write image until we finally locked it as * read-only. Both modifications on the given image * are under text_mutex to avoid interference. */ - ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL, + ret = __bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, NULL, (u8 *)target->bpf_func + poke->adj_off, false); BUG_ON(ret < 0); + ret = __bpf_arch_text_poke(poke->tailcall_bypass, + BPF_MOD_JUMP, + (u8 *)poke->tailcall_target + + X86_PATCH_SIZE, NULL, false); + BUG_ON(ret < 0); } - WRITE_ONCE(poke->ip_stable, true); + WRITE_ONCE(poke->tailcall_target_stable, true); mutex_unlock(&array->aux->poke_mutex); } } @@ -652,19 +751,44 @@ static bool ex_handler_bpf(const struct exception_table_entry *x, return true; } +static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt, + bool *regs_used, bool *tail_call_seen) +{ + int i; + + for (i = 1; i <= insn_cnt; i++, insn++) { + if (insn->code == (BPF_JMP | BPF_TAIL_CALL)) + *tail_call_seen = true; + if (insn->dst_reg == BPF_REG_6 || insn->src_reg == BPF_REG_6) + regs_used[0] = true; + if (insn->dst_reg == BPF_REG_7 || insn->src_reg == BPF_REG_7) + regs_used[1] = true; + if (insn->dst_reg == BPF_REG_8 || insn->src_reg == BPF_REG_8) + regs_used[2] = true; + if (insn->dst_reg == BPF_REG_9 || insn->src_reg == BPF_REG_9) + regs_used[3] = true; + } +} + static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, int oldproglen, struct jit_context *ctx) { struct bpf_insn *insn = bpf_prog->insnsi; + bool callee_regs_used[4] = {}; int insn_cnt = bpf_prog->len; + bool tail_call_seen = false; bool seen_exit = false; u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; int i, cnt = 0, excnt = 0; int proglen = 0; u8 *prog = temp; + detect_reg_usage(insn, insn_cnt, callee_regs_used, + &tail_call_seen); + emit_prologue(&prog, bpf_prog->aux->stack_depth, - bpf_prog_was_classic(bpf_prog)); + bpf_prog_was_classic(bpf_prog), tail_call_seen); + push_callee_regs(&prog, callee_regs_used); addrs[0] = prog - temp; for (i = 1; i <= insn_cnt; i++, insn++) { @@ -1109,9 +1233,13 @@ xadd: if (is_imm8(insn->off)) case BPF_JMP | BPF_TAIL_CALL: if (imm32) emit_bpf_tail_call_direct(&bpf_prog->aux->poke_tab[imm32 - 1], - &prog, addrs[i], image); + &prog, addrs[i], image, + callee_regs_used, + bpf_prog->aux->stack_depth); else - emit_bpf_tail_call_indirect(&prog); + emit_bpf_tail_call_indirect(&prog, + callee_regs_used, + bpf_prog->aux->stack_depth); break; /* cond jump */ @@ -1294,12 +1422,9 @@ xadd: if (is_imm8(insn->off)) seen_exit = true; /* Update cleanup_addr */ ctx->cleanup_addr = proglen; - if (!bpf_prog_was_classic(bpf_prog)) - EMIT1(0x5B); /* get rid of tail_call_cnt */ - EMIT2(0x41, 0x5F); /* pop r15 */ - EMIT2(0x41, 0x5E); /* pop r14 */ - EMIT2(0x41, 0x5D); /* pop r13 */ - EMIT1(0x5B); /* pop rbx */ + pop_callee_regs(&prog, callee_regs_used); + if (!bpf_prog_was_classic(bpf_prog) && tail_call_seen) + EMIT1(0x59); /* pop rcx, get rid of tail_call_cnt */ EMIT1(0xC9); /* leave */ EMIT1(0xC3); /* ret */ break; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c67c88ad35f8..38897b9c7d61 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -651,14 +651,15 @@ enum bpf_jit_poke_reason { /* Descriptor of pokes pointing /into/ the JITed image. */ struct bpf_jit_poke_descriptor { - void *ip; + void *tailcall_target; + void *tailcall_bypass; union { struct { struct bpf_map *map; u32 key; } tail_call; }; - bool ip_stable; + bool tailcall_target_stable; u8 adj_off; u16 reason; }; @@ -1775,6 +1776,9 @@ enum bpf_text_poke_type { BPF_MOD_JUMP, }; +/* Number of bytes emit_patch() needs to generate instructions */ +#define X86_PATCH_SIZE 5 + int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *addr1, void *addr2); diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index c66e8273fccd..d15729a3f46c 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -750,6 +750,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, struct bpf_prog *old, struct bpf_prog *new) { + u8 *bypass_addr, *old_addr, *new_addr; struct prog_poke_elem *elem; struct bpf_array_aux *aux; @@ -770,12 +771,13 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * there could be danger of use after free otherwise. * 2) Initially when we start tracking aux, the program * is not JITed yet and also does not have a kallsyms - * entry. We skip these as poke->ip_stable is not - * active yet. The JIT will do the final fixup before - * setting it stable. The various poke->ip_stable are - * successively activated, so tail call updates can - * arrive from here while JIT is still finishing its - * final fixup for non-activated poke entries. + * entry. We skip these as poke->tailcall_target_stable + * is not active yet. The JIT will do the final fixup + * before setting it stable. The various + * poke->tailcall_target_stable are successively activated, + * so tail call updates can arrive from here while JIT + * is still finishing its final fixup for non-activated + * poke entries. * 3) On program teardown, the program's kallsym entry gets * removed out of RCU callback, but we can only untrack * from sleepable context, therefore bpf_arch_text_poke() @@ -792,20 +794,53 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * 5) Any other error happening below from bpf_arch_text_poke() * is a unexpected bug. */ - if (!READ_ONCE(poke->ip_stable)) + if (!READ_ONCE(poke->tailcall_target_stable)) continue; if (poke->reason != BPF_POKE_REASON_TAIL_CALL) continue; if (poke->tail_call.map != map || poke->tail_call.key != key) continue; + /* protect against un-updated poke descriptors since + * we could fill them from subprog and the same desc + * is present on main's program poke tab + */ + if (!poke->tailcall_bypass || !poke->tailcall_target) + continue; + + if (!old && !new) + continue; - ret = bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, - old ? (u8 *)old->bpf_func + - poke->adj_off : NULL, - new ? (u8 *)new->bpf_func + - poke->adj_off : NULL); - BUG_ON(ret < 0 && ret != -EINVAL); + bypass_addr = (u8 *)poke->tailcall_target + X86_PATCH_SIZE; + old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL; + new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL; + + if (new) { + ret = bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, + old_addr, new_addr); + BUG_ON(ret < 0 && ret != -EINVAL); + if (!old) { + ret = bpf_arch_text_poke(poke->tailcall_bypass, + BPF_MOD_JUMP, + bypass_addr, NULL); + BUG_ON(ret < 0 && ret != -EINVAL); + } + } else { + ret = bpf_arch_text_poke(poke->tailcall_bypass, + BPF_MOD_JUMP, + NULL, bypass_addr); + BUG_ON(ret < 0 && ret != -EINVAL); + /* let other CPUs finish the execution of program + * so that it will not possible to expose them + * to invalid nop, stack unwind, nop state + */ + synchronize_rcu(); + ret = bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, + old_addr, NULL); + BUG_ON(ret < 0 && ret != -EINVAL); + } } } } diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 9df4cc9a2907..cebf12a2cbbf 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -773,7 +773,8 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, if (size > poke_tab_max) return -ENOSPC; - if (poke->ip || poke->ip_stable || poke->adj_off) + if (poke->tailcall_target || poke->tailcall_target_stable || + poke->tailcall_bypass || poke->adj_off) return -EINVAL; switch (poke->reason) { From patchwork Wed Jul 15 23:36:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maciej Fijalkowski X-Patchwork-Id: 1329860 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=intel.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B6YnT1Rzhz9sDX for ; Thu, 16 Jul 2020 09:41:49 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727121AbgGOXls (ORCPT ); Wed, 15 Jul 2020 19:41:48 -0400 Received: from mga06.intel.com ([134.134.136.31]:52537 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727114AbgGOXls (ORCPT ); Wed, 15 Jul 2020 19:41:48 -0400 IronPort-SDR: qdOKp5mOq79kyIvAOqNtZgeSe85lBMABwHnZ0+rX9NX4AR6/3fvAxSzQFrVKqYc/PUv0Q/8wUD 2VYs8ILBnOpQ== X-IronPort-AV: E=McAfee;i="6000,8403,9683"; a="210823671" X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="210823671" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jul 2020 16:41:48 -0700 IronPort-SDR: lxDrqOEyVXCgEjk6kzEUufp93S3XQdgvTnLdxEGgGmZTQc0BPlK11RTaoTjydXgGNn0dnUHSK3 aFiRGwE3+fvA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,357,1589266800"; d="scan'208";a="390935600" Received: from ranger.igk.intel.com ([10.102.21.164]) by fmsmga001.fm.intel.com with ESMTP; 15 Jul 2020 16:41:46 -0700 From: Maciej Fijalkowski To: ast@kernel.org, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, Maciej Fijalkowski Subject: [PATCH bpf-next 5/5] selftests: bpf: add dummy prog for bpf2bpf with tailcall Date: Thu, 16 Jul 2020 01:36:34 +0200 Message-Id: <20200715233634.3868-6-maciej.fijalkowski@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200715233634.3868-1-maciej.fijalkowski@intel.com> References: <20200715233634.3868-1-maciej.fijalkowski@intel.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Introduce 6th test to taicalls kselftest that checks if tailcall can be correctly executed from the BPF subprogram. Signed-off-by: Maciej Fijalkowski --- .../selftests/bpf/prog_tests/tailcalls.c | 85 +++++++++++++++++++ tools/testing/selftests/bpf/progs/tailcall6.c | 38 +++++++++ 2 files changed, 123 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/tailcall6.c diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c index bb8fe646dd9f..192c94896809 100644 --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include /* test_tailcall_1 checks basic functionality by patching multiple locations * in a single program for a single tail call slot with nop->jmp, jmp->nop @@ -472,6 +473,88 @@ static void test_tailcall_5(void) bpf_object__close(obj); } +/* test_tailcall_6 purpose is to make sure that tailcalls are working + * correctly in correlation with BPF subprograms + */ +static void test_tailcall_6(void) +{ + int err, map_fd, prog_fd, main_fd, i; + struct bpf_map *prog_array; + struct bpf_program *prog; + struct bpf_object *obj; + __u32 retval, duration; + char prog_name[32]; + + err = bpf_prog_load("tailcall6.o", BPF_PROG_TYPE_SCHED_CLS, &obj, + &prog_fd); + if (CHECK_FAIL(err)) + return; + + prog = bpf_object__find_program_by_title(obj, "classifier"); + if (CHECK_FAIL(!prog)) + goto out; + + main_fd = bpf_program__fd(prog); + if (CHECK_FAIL(main_fd < 0)) + goto out; + + prog_array = bpf_object__find_map_by_name(obj, "jmp_table"); + if (CHECK_FAIL(!prog_array)) + goto out; + + map_fd = bpf_map__fd(prog_array); + if (CHECK_FAIL(map_fd < 0)) + goto out; + + /* nop -> jmp */ + for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) { + snprintf(prog_name, sizeof(prog_name), "classifier/%i", i); + + prog = bpf_object__find_program_by_title(obj, prog_name); + if (CHECK_FAIL(!prog)) + goto out; + + prog_fd = bpf_program__fd(prog); + if (CHECK_FAIL(prog_fd < 0)) + goto out; + + err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY); + if (CHECK_FAIL(err)) + goto out; + } + + err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0, + 0, &retval, &duration); + CHECK(err || retval != 1, "tailcall", + "err %d errno %d retval %d\n", err, errno, retval); + + /* jmp -> nop, call subprog that will do tailcall */ + i = 1; + err = bpf_map_delete_elem(map_fd, &i); + if (CHECK_FAIL(err)) + goto out; + + err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0, + 0, &retval, &duration); + CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n", + err, errno, retval); + + /* make sure that subprog can access ctx and entry prog that + * called this subprog can properly return + */ + i = 0; + err = bpf_map_delete_elem(map_fd, &i); + if (CHECK_FAIL(err)) + goto out; + + err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0, + 0, &retval, &duration); + CHECK(err || retval != 108, "tailcall", "err %d errno %d retval %d\n", + err, errno, retval); +out: + bpf_object__close(obj); +} + void test_tailcalls(void) { if (test__start_subtest("tailcall_1")) @@ -484,4 +567,6 @@ void test_tailcalls(void) test_tailcall_4(); if (test__start_subtest("tailcall_5")) test_tailcall_5(); + if (test__start_subtest("tailcall_6")) + test_tailcall_6(); } diff --git a/tools/testing/selftests/bpf/progs/tailcall6.c b/tools/testing/selftests/bpf/progs/tailcall6.c new file mode 100644 index 000000000000..e72ca5869b58 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/tailcall6.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(max_entries, 2); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u32)); +} jmp_table SEC(".maps"); + +#define TAIL_FUNC(x) \ + SEC("classifier/" #x) \ + int bpf_func_##x(struct __sk_buff *skb) \ + { \ + return x; \ + } +TAIL_FUNC(0) +TAIL_FUNC(1) + +static __attribute__ ((noinline)) +int subprog_tail(struct __sk_buff *skb) +{ + bpf_tail_call(skb, &jmp_table, 0); + + return skb->len * 2; +} + +SEC("classifier") +int entry(struct __sk_buff *skb) +{ + bpf_tail_call(skb, &jmp_table, 1); + + return subprog_tail(skb); +} + +char __license[] SEC("license") = "GPL"; +int _version SEC("version") = 1;