From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C749BC433EF for ; Sun, 24 Apr 2022 05:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238221AbiDXFIx (ORCPT ); Sun, 24 Apr 2022 01:08:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231741AbiDXFIt (ORCPT ); Sun, 24 Apr 2022 01:08:49 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E33555F8B; Sat, 23 Apr 2022 22:05:48 -0700 (PDT) Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KmGHf6WYSzFr2x; Sun, 24 Apr 2022 13:03:10 +0800 (CST) Received: from [10.67.111.192] (10.67.111.192) by kwepemi500013.china.huawei.com (7.221.188.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sun, 24 Apr 2022 13:05:43 +0800 Message-ID: <13cd161b-43a2-ce66-6a27-6662fc36e063@huawei.com> Date: Sun, 24 Apr 2022 13:05:43 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH bpf-next v2 4/6] bpf, arm64: Impelment bpf_arch_text_poke() for arm64 Content-Language: en-US To: Jakub Sitnicki CC: , , , , , Catalin Marinas , Will Deacon , Steven Rostedt , Ingo Molnar , Daniel Borkmann , Alexei Starovoitov , Zi Shen Lim , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Borislav Petkov , Dave Hansen , , , Shuah Khan , Mark Rutland , Ard Biesheuvel , Pasha Tatashin , Peter Collingbourne , Daniel Kiss , Sudeep Holla , Steven Price , Marc Zyngier , Mark Brown , Kumar Kartikeya Dwivedi , Delyan Kratunov , References: <20220414162220.1985095-1-xukuohai@huawei.com> <20220414162220.1985095-5-xukuohai@huawei.com> <87levxfj32.fsf@cloudflare.com> From: Xu Kuohai In-Reply-To: <87levxfj32.fsf@cloudflare.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.192] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500013.china.huawei.com (7.221.188.120) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/2022 6:54 PM, Jakub Sitnicki wrote: > Hi Xu, > > Thanks for working on this. > > We are also looking forward to using fentry hooks on arm64. > In particular, attaching to entry/exit into/from XDP progs. > > On Thu, Apr 14, 2022 at 12:22 PM -04, Xu Kuohai wrote: >> Impelment bpf_arch_text_poke() for arm64, so bpf trampoline code can use >> it to replace nop with jump, or replace jump with nop. >> >> Signed-off-by: Xu Kuohai >> Acked-by: Song Liu >> --- >> arch/arm64/net/bpf_jit_comp.c | 52 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 52 insertions(+) >> >> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c >> index 8ab4035dea27..1a1c3ea75ee2 100644 >> --- a/arch/arm64/net/bpf_jit_comp.c >> +++ b/arch/arm64/net/bpf_jit_comp.c >> @@ -9,6 +9,7 @@ >> >> #include >> #include >> +#include >> #include >> #include >> #include >> @@ -18,6 +19,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> #include "bpf_jit.h" >> @@ -1529,3 +1531,53 @@ void bpf_jit_free_exec(void *addr) >> { >> return vfree(addr); >> } >> + >> +static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip, >> + void *addr, u32 *insn) >> +{ >> + if (!addr) >> + *insn = aarch64_insn_gen_nop(); >> + else >> + *insn = aarch64_insn_gen_branch_imm((unsigned long)ip, >> + (unsigned long)addr, >> + type); >> + >> + return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT; >> +} >> + >> +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, >> + void *old_addr, void *new_addr) >> +{ >> + int ret; >> + u32 old_insn; >> + u32 new_insn; >> + u32 replaced; >> + enum aarch64_insn_branch_type branch_type; >> + >> + if (poke_type == BPF_MOD_CALL) >> + branch_type = AARCH64_INSN_BRANCH_LINK; > > This path, bpf_arch_text_poke(, BPF_MOD_CALL, ...), is what we hit > when attaching a BPF program entry. It is exercised by selftest #232 > xdp_bpf2bpf. > > However, with this patchset alone it will not work because we don't > emit, yet, the ftrace patch (MOV X9, LR; NOP) as a part of BPF prog > prologue, like ftrace_init_nop() does. So patching attempt will fail. > > I think that is what you mentioned to in your reply to Hou [1] > > So my question is - is support for attaching to BPF progs in scope for > this patchset? > > If no, then perhaps it would be better for now to fail early with > something like -EOPNOTSUPP when poke_type is BPF_MOD_CALL, rather then > attempt to patch the code. > > If you plan to enable it as a part of this patchset, then I've given it > a quick try, and it seems that not a lot is needed get fentry to BPF > attachment to work. > > I'm including the diff for my quick and dirty attempt below. With that > patch on top, the xdp_bpf2bpf tests pass: > > #232 xdp_bpf2bpf:OK > > [1] https://lore.kernel.org/bpf/d8c4f1fb-a020-9457-44e2-dc63982a9213@huawei.com/ > Hi Jakub, Thanks for your testing and suggestion! I added bpf2bpf poking to this series and rebased it to [2] a few days ago, so there are some conflicts with the bpf-next branch. I'll rebase it to bpf-next and send v3. [2] https://lore.kernel.org/bpf/20220416042940.656344-1-kuifeng@fb.com/ >> + else >> + branch_type = AARCH64_INSN_BRANCH_NOLINK; >> + >> + if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0) >> + return -EFAULT; >> + >> + if (gen_branch_or_nop(branch_type, ip, new_addr, &new_insn) < 0) >> + return -EFAULT; >> + >> + mutex_lock(&text_mutex); >> + if (aarch64_insn_read(ip, &replaced)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + if (replaced != old_insn) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + ret = aarch64_insn_patch_text_nosync((void *)ip, new_insn); >> +out: >> + mutex_unlock(&text_mutex); > > The body of this critical section is identical as ftrace_modify_code(). > Perhaps we could export it and reuse? > ftrace_modify_code() is defined in the arch code, and the prototypes are not consistent across archs, so it doesn't seem appropriate to export ftrace_modify_code() as a public interface. >> + return ret; >> +} > > --- > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 5f6bd755050f..94d8251500ab 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -240,9 +240,9 @@ static bool is_lsi_offset(int offset, int scale) > /* Tail call offset to jump into */ > #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) || \ > IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) > -#define PROLOGUE_OFFSET 9 > +#define PROLOGUE_OFFSET 11 > #else > -#define PROLOGUE_OFFSET 8 > +#define PROLOGUE_OFFSET 10 > #endif > > static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) > @@ -281,6 +281,10 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) > * > */ > > + /* Set up ftrace patch (initially in disabled state) */ > + emit(A64_MOV(1, A64_R(9), A64_LR), ctx); > + emit(A64_NOP, ctx); > > /* Sign lr */ > if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) > emit(A64_PACIASP, ctx); > @@ -1888,10 +1892,16 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, > u32 replaced; > enum aarch64_insn_branch_type branch_type; > > - if (poke_type == BPF_MOD_CALL) > + if (poke_type == BPF_MOD_CALL) { > branch_type = AARCH64_INSN_BRANCH_LINK; > - else > + /* > + * Adjust addr to point at the BL in the callsite. > + * See ftrace_init_nop() for the callsite sequence. > + */ > + ip = (void *)((unsigned long)ip + AARCH64_INSN_SIZE); > + } else { > branch_type = AARCH64_INSN_BRANCH_NOLINK; > + } > > if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0) > return -EFAULT; > . From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E57E7C433F5 for ; Sun, 24 Apr 2022 05:07:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:CC:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=w4O9KEvJ0pNvzB4b1eDgMYW8jRCpAPw7IJ44HNSji3w=; b=dRWlcUOR7sbUzz CVYbfepi+xWsHSCPrnby14UfduJ3bnYq2VXE+u5l4pMGpCE7kh9d9QkBaP1sno1cNlqcHq4kHLUb5 Hg7H/6CKEEuNdgzUTicKkKJBJP8H6qOifQ6tl5+S/hDmP+6tkETUKfe2gXrT+zobMey00kVkuz6kY 0yf1t3yj/p4FLz9DXQyd/RCCkVGIZYp1/CQPTtiBYJLwidthS6Mgh6okzGw+TQ2mBIDQ4WsW0ax7W U8v5U4eHZRhfwgMfnHee8AMbZ6MMBEijBwJM5F6QLlWUAG2wGNoRLYfjYhvxAqSy5OsZYrLrlAIx6 a+tI1SampOuL1c/GVWxw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1niURf-005nfL-IF; Sun, 24 Apr 2022 05:06:03 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1niURY-005ndq-Pc for linux-arm-kernel@lists.infradead.org; Sun, 24 Apr 2022 05:06:00 +0000 Received: from kwepemi500013.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KmGHf6WYSzFr2x; Sun, 24 Apr 2022 13:03:10 +0800 (CST) Received: from [10.67.111.192] (10.67.111.192) by kwepemi500013.china.huawei.com (7.221.188.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sun, 24 Apr 2022 13:05:43 +0800 Message-ID: <13cd161b-43a2-ce66-6a27-6662fc36e063@huawei.com> Date: Sun, 24 Apr 2022 13:05:43 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH bpf-next v2 4/6] bpf, arm64: Impelment bpf_arch_text_poke() for arm64 Content-Language: en-US To: Jakub Sitnicki CC: , , , , , Catalin Marinas , Will Deacon , Steven Rostedt , Ingo Molnar , Daniel Borkmann , Alexei Starovoitov , Zi Shen Lim , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "David S . Miller" , Hideaki YOSHIFUJI , David Ahern , Thomas Gleixner , Borislav Petkov , Dave Hansen , , , Shuah Khan , Mark Rutland , Ard Biesheuvel , Pasha Tatashin , Peter Collingbourne , Daniel Kiss , Sudeep Holla , Steven Price , Marc Zyngier , Mark Brown , Kumar Kartikeya Dwivedi , Delyan Kratunov , References: <20220414162220.1985095-1-xukuohai@huawei.com> <20220414162220.1985095-5-xukuohai@huawei.com> <87levxfj32.fsf@cloudflare.com> From: Xu Kuohai In-Reply-To: <87levxfj32.fsf@cloudflare.com> X-Originating-IP: [10.67.111.192] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemi500013.china.huawei.com (7.221.188.120) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220423_220557_202401_7CEFEB2B X-CRM114-Status: GOOD ( 36.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 4/22/2022 6:54 PM, Jakub Sitnicki wrote: > Hi Xu, > > Thanks for working on this. > > We are also looking forward to using fentry hooks on arm64. > In particular, attaching to entry/exit into/from XDP progs. > > On Thu, Apr 14, 2022 at 12:22 PM -04, Xu Kuohai wrote: >> Impelment bpf_arch_text_poke() for arm64, so bpf trampoline code can use >> it to replace nop with jump, or replace jump with nop. >> >> Signed-off-by: Xu Kuohai >> Acked-by: Song Liu >> --- >> arch/arm64/net/bpf_jit_comp.c | 52 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 52 insertions(+) >> >> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c >> index 8ab4035dea27..1a1c3ea75ee2 100644 >> --- a/arch/arm64/net/bpf_jit_comp.c >> +++ b/arch/arm64/net/bpf_jit_comp.c >> @@ -9,6 +9,7 @@ >> >> #include >> #include >> +#include >> #include >> #include >> #include >> @@ -18,6 +19,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> #include "bpf_jit.h" >> @@ -1529,3 +1531,53 @@ void bpf_jit_free_exec(void *addr) >> { >> return vfree(addr); >> } >> + >> +static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip, >> + void *addr, u32 *insn) >> +{ >> + if (!addr) >> + *insn = aarch64_insn_gen_nop(); >> + else >> + *insn = aarch64_insn_gen_branch_imm((unsigned long)ip, >> + (unsigned long)addr, >> + type); >> + >> + return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT; >> +} >> + >> +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, >> + void *old_addr, void *new_addr) >> +{ >> + int ret; >> + u32 old_insn; >> + u32 new_insn; >> + u32 replaced; >> + enum aarch64_insn_branch_type branch_type; >> + >> + if (poke_type == BPF_MOD_CALL) >> + branch_type = AARCH64_INSN_BRANCH_LINK; > > This path, bpf_arch_text_poke(, BPF_MOD_CALL, ...), is what we hit > when attaching a BPF program entry. It is exercised by selftest #232 > xdp_bpf2bpf. > > However, with this patchset alone it will not work because we don't > emit, yet, the ftrace patch (MOV X9, LR; NOP) as a part of BPF prog > prologue, like ftrace_init_nop() does. So patching attempt will fail. > > I think that is what you mentioned to in your reply to Hou [1] > > So my question is - is support for attaching to BPF progs in scope for > this patchset? > > If no, then perhaps it would be better for now to fail early with > something like -EOPNOTSUPP when poke_type is BPF_MOD_CALL, rather then > attempt to patch the code. > > If you plan to enable it as a part of this patchset, then I've given it > a quick try, and it seems that not a lot is needed get fentry to BPF > attachment to work. > > I'm including the diff for my quick and dirty attempt below. With that > patch on top, the xdp_bpf2bpf tests pass: > > #232 xdp_bpf2bpf:OK > > [1] https://lore.kernel.org/bpf/d8c4f1fb-a020-9457-44e2-dc63982a9213@huawei.com/ > Hi Jakub, Thanks for your testing and suggestion! I added bpf2bpf poking to this series and rebased it to [2] a few days ago, so there are some conflicts with the bpf-next branch. I'll rebase it to bpf-next and send v3. [2] https://lore.kernel.org/bpf/20220416042940.656344-1-kuifeng@fb.com/ >> + else >> + branch_type = AARCH64_INSN_BRANCH_NOLINK; >> + >> + if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0) >> + return -EFAULT; >> + >> + if (gen_branch_or_nop(branch_type, ip, new_addr, &new_insn) < 0) >> + return -EFAULT; >> + >> + mutex_lock(&text_mutex); >> + if (aarch64_insn_read(ip, &replaced)) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + if (replaced != old_insn) { >> + ret = -EFAULT; >> + goto out; >> + } >> + >> + ret = aarch64_insn_patch_text_nosync((void *)ip, new_insn); >> +out: >> + mutex_unlock(&text_mutex); > > The body of this critical section is identical as ftrace_modify_code(). > Perhaps we could export it and reuse? > ftrace_modify_code() is defined in the arch code, and the prototypes are not consistent across archs, so it doesn't seem appropriate to export ftrace_modify_code() as a public interface. >> + return ret; >> +} > > --- > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 5f6bd755050f..94d8251500ab 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -240,9 +240,9 @@ static bool is_lsi_offset(int offset, int scale) > /* Tail call offset to jump into */ > #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) || \ > IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL) > -#define PROLOGUE_OFFSET 9 > +#define PROLOGUE_OFFSET 11 > #else > -#define PROLOGUE_OFFSET 8 > +#define PROLOGUE_OFFSET 10 > #endif > > static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) > @@ -281,6 +281,10 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) > * > */ > > + /* Set up ftrace patch (initially in disabled state) */ > + emit(A64_MOV(1, A64_R(9), A64_LR), ctx); > + emit(A64_NOP, ctx); > > /* Sign lr */ > if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) > emit(A64_PACIASP, ctx); > @@ -1888,10 +1892,16 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, > u32 replaced; > enum aarch64_insn_branch_type branch_type; > > - if (poke_type == BPF_MOD_CALL) > + if (poke_type == BPF_MOD_CALL) { > branch_type = AARCH64_INSN_BRANCH_LINK; > - else > + /* > + * Adjust addr to point at the BL in the callsite. > + * See ftrace_init_nop() for the callsite sequence. > + */ > + ip = (void *)((unsigned long)ip + AARCH64_INSN_SIZE); > + } else { > branch_type = AARCH64_INSN_BRANCH_NOLINK; > + } > > if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0) > return -EFAULT; > . _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel