From patchwork Sun Sep 29 13:27:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13815090 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D2BCAD24 for ; Sun, 29 Sep 2024 13:28:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616505; cv=none; b=LDpXJn8Ya7Ur2YFjf52uOkvqgp+MshBZhKAaRtKiGHesWJ3Vu0TlMquSGhU3apP4CaYojj0z4/uBYpOXJ/4PBAE3OH/sC4AQBCge4V4IUfCZL8FBm/uVDAEosl07Ieys0Pw+VZK58jbvcWjyyHLyvdEg1cqXkJk8abLy4axJr+k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616505; c=relaxed/simple; bh=yMAmXYf4BZsbnae4yK6RZZ1mIIAHY6/dxdBXhShYMQQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c7IAHWxa7k6AoK+I3bF70P8J/Od6Vb6f3Ph+VywdkBVmCaEzV2VR9VDdEckyM9FzhWc+fJZbf+rCXikJIe/qS+oVpM4X9UX9CwtQLJzPqu2OEkMo43H9p/JUXrctkzIdL2/WGHxzsLdp6Fd5wrFqAGs1LfOKhhiR3bSWshCTFxg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=GCobE5Fi; arc=none smtp.client-ip=95.215.58.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="GCobE5Fi" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1727616500; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rYm0TozD+NlcikAMF3XQ/i2UU+qh6ZhxO3+lSmttCKo=; b=GCobE5Fid7hnbw/UkF8Z9/yDALSGagP5MKynJMrgU1uKC7d2f3ny0WrazfVmNz9PMQTaSz Y/G4s+zJECWXqhmnVQH3u5jcAIInb91exwFMxKTiANHStI42wO8CIphDXYP2W+TQFnM0cn 98yAbKaHWoRQJSpwS4OdfRrjekY3zWw= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, yonghong.song@linux.dev, puranjay@kernel.org, xukuohai@huaweicloud.com, eddyz87@gmail.com, iii@linux.ibm.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v4 1/4] bpf: Prevent updating extended prog to prog_array map Date: Sun, 29 Sep 2024 21:27:54 +0800 Message-ID: <20240929132757.79826-2-leon.hwang@linux.dev> In-Reply-To: <20240929132757.79826-1-leon.hwang@linux.dev> References: <20240929132757.79826-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net This patch partially prevents a potential infinite loop issue caused by combination of tailcal and freplace. For example: tc_bpf2bpf.c: // SPDX-License-Identifier: GPL-2.0 \#include \#include __noinline int subprog_tc(struct __sk_buff *skb) { return skb->len * 2; } SEC("tc") int entry_tc(struct __sk_buff *skb) { return subprog_tc(skb); } char __license[] SEC("license") = "GPL"; tailcall_freplace.c: // SPDX-License-Identifier: GPL-2.0 \#include \#include struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); __uint(max_entries, 1); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } jmp_table SEC(".maps"); int count = 0; SEC("freplace") int entry_freplace(struct __sk_buff *skb) { count++; bpf_tail_call_static(skb, &jmp_table, 0); return count; } char __license[] SEC("license") = "GPL"; The attach target of entry_freplace is subprog_tc, and the tail callee in entry_freplace is entry_tc. Then, the infinite loop will be entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc, because tail_call_cnt in entry_freplace will count from zero for every time of entry_freplace execution. Kernel will panic, like: [ 15.310490] BUG: TASK stack guard page was hit at (____ptrval____) (stack is (____ptrval____)..(____ptrval____)) [ 15.310490] Oops: stack guard page: 0000 [#1] PREEMPT SMP NOPTI [ 15.310490] CPU: 1 PID: 89 Comm: test_progs Tainted: G OE 6.10.0-rc6-g026dcdae8d3e-dirty #72 [ 15.310490] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 15.310490] RIP: 0010:bpf_prog_3a140cef239a4b4f_subprog_tail+0x14/0x53 [ 15.310490] Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc f3 0f 1e fa 0f 1f 44 00 00 0f 1f 00 55 48 89 e5 f3 0f 1e fa <50> 50 53 41 55 48 89 fb 49 bd 00 2a 46 82 98 9c ff ff 48 89 df 4c [ 15.310490] RSP: 0018:ffffb500c0aa0000 EFLAGS: 00000202 [ 15.310490] RAX: ffffb500c0aa0028 RBX: ffff9c98808b7e00 RCX: 0000000000008cb5 [ 15.310490] RDX: 0000000000000000 RSI: ffff9c9882462a00 RDI: ffff9c98808b7e00 [ 15.310490] RBP: ffffb500c0aa0000 R08: 0000000000000000 R09: 0000000000000000 [ 15.310490] R10: 0000000000000001 R11: 0000000000000000 R12: ffffb500c01af000 [ 15.310490] R13: ffffb500c01cd000 R14: 0000000000000000 R15: 0000000000000000 [ 15.310490] FS: 00007f133b665140(0000) GS:ffff9c98bbd00000(0000) knlGS:0000000000000000 [ 15.310490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.310490] CR2: ffffb500c0a9fff8 CR3: 0000000102478000 CR4: 00000000000006f0 [ 15.310490] Call Trace: [ 15.310490] <#DF> [ 15.310490] ? die+0x36/0x90 [ 15.310490] ? handle_stack_overflow+0x4d/0x60 [ 15.310490] ? exc_double_fault+0x117/0x1a0 [ 15.310490] ? asm_exc_double_fault+0x23/0x30 [ 15.310490] ? bpf_prog_3a140cef239a4b4f_subprog_tail+0x14/0x53 [ 15.310490] [ 15.310490] [ 15.310490] bpf_prog_85781a698094722f_entry+0x4c/0x64 [ 15.310490] bpf_prog_1c515f389a9059b4_entry2+0x19/0x1b [ 15.310490] ... [ 15.310490] bpf_prog_85781a698094722f_entry+0x4c/0x64 [ 15.310490] bpf_prog_1c515f389a9059b4_entry2+0x19/0x1b [ 15.310490] bpf_test_run+0x210/0x370 [ 15.310490] ? bpf_test_run+0x128/0x370 [ 15.310490] bpf_prog_test_run_skb+0x388/0x7a0 [ 15.310490] __sys_bpf+0xdbf/0x2c40 [ 15.310490] ? clockevents_program_event+0x52/0xf0 [ 15.310490] ? lock_release+0xbf/0x290 [ 15.310490] __x64_sys_bpf+0x1e/0x30 [ 15.310490] do_syscall_64+0x68/0x140 [ 15.310490] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 15.310490] RIP: 0033:0x7f133b52725d [ 15.310490] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 8b bb 0d 00 f7 d8 64 89 01 48 [ 15.310490] RSP: 002b:00007ffddbc10258 EFLAGS: 00000206 ORIG_RAX: 0000000000000141 [ 15.310490] RAX: ffffffffffffffda RBX: 00007ffddbc10828 RCX: 00007f133b52725d [ 15.310490] RDX: 0000000000000050 RSI: 00007ffddbc102a0 RDI: 000000000000000a [ 15.310490] RBP: 00007ffddbc10270 R08: 0000000000000000 R09: 00007ffddbc102a0 [ 15.310490] R10: 0000000000000064 R11: 0000000000000206 R12: 0000000000000004 [ 15.310490] R13: 0000000000000000 R14: 0000558ec4c24890 R15: 00007f133b6ed000 [ 15.310490] [ 15.310490] Modules linked in: bpf_testmod(OE) [ 15.310490] ---[ end trace 0000000000000000 ]--- [ 15.310490] RIP: 0010:bpf_prog_3a140cef239a4b4f_subprog_tail+0x14/0x53 [ 15.310490] Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc f3 0f 1e fa 0f 1f 44 00 00 0f 1f 00 55 48 89 e5 f3 0f 1e fa <50> 50 53 41 55 48 89 fb 49 bd 00 2a 46 82 98 9c ff ff 48 89 df 4c [ 15.310490] RSP: 0018:ffffb500c0aa0000 EFLAGS: 00000202 [ 15.310490] RAX: ffffb500c0aa0028 RBX: ffff9c98808b7e00 RCX: 0000000000008cb5 [ 15.310490] RDX: 0000000000000000 RSI: ffff9c9882462a00 RDI: ffff9c98808b7e00 [ 15.310490] RBP: ffffb500c0aa0000 R08: 0000000000000000 R09: 0000000000000000 [ 15.310490] R10: 0000000000000001 R11: 0000000000000000 R12: ffffb500c01af000 [ 15.310490] R13: ffffb500c01cd000 R14: 0000000000000000 R15: 0000000000000000 [ 15.310490] FS: 00007f133b665140(0000) GS:ffff9c98bbd00000(0000) knlGS:0000000000000000 [ 15.310490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.310490] CR2: ffffb500c0a9fff8 CR3: 0000000102478000 CR4: 00000000000006f0 [ 15.310490] Kernel panic - not syncing: Fatal exception in interrupt [ 15.310490] Kernel Offset: 0x30000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) This patch partially prevents this panic by preventing updating extended prog to prog_array map. If a prog or its subprog has been extended by freplace prog, the prog can not be updated to prog_array map. Alongside next patch, the panic will be prevented completely. BTW, fix a minor style issue by replacing 8-spaces with a tab. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 2 ++ kernel/bpf/arraymap.c | 21 +++++++++++++++++---- kernel/bpf/core.c | 1 + kernel/bpf/syscall.c | 42 ++++++++++++++++++++++++++++++++++++------ 4 files changed, 56 insertions(+), 10 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 19d8ca8ac960f..aac6d2f42830c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1483,6 +1483,8 @@ struct bpf_prog_aux { bool xdp_has_frags; bool exception_cb; bool exception_boundary; + bool is_extended; /* true if extended by freplace program */ + struct mutex ext_mutex; /* mutex for is_extended */ struct bpf_arena *arena; /* BTF_KIND_FUNC_PROTO for valid attach_btf_id */ const struct btf_type *attach_func_proto; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 79660e3fca4c1..4a4de4f014be9 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -947,16 +947,29 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map, struct file *map_file, int fd) { struct bpf_prog *prog = bpf_prog_get(fd); + bool is_extended; if (IS_ERR(prog)) return prog; - if (!bpf_prog_map_compatible(map, prog)) { - bpf_prog_put(prog); - return ERR_PTR(-EINVAL); - } + if (!bpf_prog_map_compatible(map, prog)) + goto out_put_prog; + + mutex_lock(&prog->aux->ext_mutex); + is_extended = prog->aux->is_extended; + mutex_unlock(&prog->aux->ext_mutex); + if (is_extended) + /* Extended prog can not be tail callee. It's to prevent a + * potential infinite loop like: + * tail callee prog entry -> tail callee prog subprog -> + * freplace prog entry --tailcall-> tail callee prog entry. + */ + goto out_put_prog; return prog; +out_put_prog: + bpf_prog_put(prog); + return ERR_PTR(-EINVAL); } static void prog_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 4e07cc057d6f2..ea7f59374b378 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -131,6 +131,7 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag INIT_LIST_HEAD_RCU(&fp->aux->ksym_prefix.lnode); #endif mutex_init(&fp->aux->used_maps_mutex); + mutex_init(&fp->aux->ext_mutex); mutex_init(&fp->aux->dst_mutex); return fp; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index a8f1808a1ca54..db17c52fa35db 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3212,14 +3212,23 @@ static void bpf_tracing_link_release(struct bpf_link *link) { struct bpf_tracing_link *tr_link = container_of(link, struct bpf_tracing_link, link.link); - - WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->link, - tr_link->trampoline)); + struct bpf_prog *tgt_prog = tr_link->tgt_prog; + + if (link->prog->type == BPF_PROG_TYPE_EXT) { + mutex_lock(&tgt_prog->aux->ext_mutex); + WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->link, + tr_link->trampoline)); + tgt_prog->aux->is_extended = false; + mutex_unlock(&tgt_prog->aux->ext_mutex); + } else { + WARN_ON_ONCE(bpf_trampoline_unlink_prog(&tr_link->link, + tr_link->trampoline)); + } bpf_trampoline_put(tr_link->trampoline); /* tgt_prog is NULL if target is a kernel function */ - if (tr_link->tgt_prog) + if (tgt_prog) bpf_prog_put(tr_link->tgt_prog); } @@ -3270,6 +3279,24 @@ static const struct bpf_link_ops bpf_tracing_link_lops = { .fill_link_info = bpf_tracing_link_fill_link_info, }; +static int bpf_extend_prog(struct bpf_tracing_link *link, + struct bpf_trampoline *tr, + struct bpf_prog *tgt_prog) +{ + struct bpf_prog_aux *aux = tgt_prog->aux; + int err = 0; + + mutex_lock(&aux->ext_mutex); + err = bpf_trampoline_link_prog(&link->link, tr); + if (err) + goto out_unlock; + + aux->is_extended = true; +out_unlock: + mutex_unlock(&aux->ext_mutex); + return err; +} + static int bpf_tracing_prog_attach(struct bpf_prog *prog, int tgt_prog_fd, u32 btf_id, @@ -3354,7 +3381,7 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, * in prog->aux * * - if prog->aux->dst_trampoline is NULL, the program has already been - * attached to a target and its initial target was cleared (below) + * attached to a target and its initial target was cleared (below) * * - if tgt_prog != NULL, the caller specified tgt_prog_fd + * target_btf_id using the link_create API. @@ -3429,7 +3456,10 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, if (err) goto out_unlock; - err = bpf_trampoline_link_prog(&link->link, tr); + if (prog->type == BPF_PROG_TYPE_EXT) + err = bpf_extend_prog(link, tr, tgt_prog); + else + err = bpf_trampoline_link_prog(&link->link, tr); if (err) { bpf_link_cleanup(&link_primer); link = NULL; From patchwork Sun Sep 29 13:27:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13815091 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 38E7E156F33 for ; Sun, 29 Sep 2024 13:28:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616508; cv=none; b=NsWRWYkGAaebOD7zsus5GohPh5rWgyC1MnP86DWpksbNyvKpV2gzTf+1R07PByiNUFxUKOuk5kqe5BiEz+sziobvxvco55j8qqU9GATwqTDgNZfZ7/x7FLHZcU0/LR83XSicMHnOXx7mC7UWIFIn8F2ZO/DOJLxIRRMOZGwiUfc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616508; c=relaxed/simple; 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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1727616504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=S7wQGVt6KowL7GOQWyOQgnp6gS6bSqQriau6C3j7yhk=; b=cKVLfPWMSREAnBwGz+Cz/OFQafcQnwIG1o9hDuisqXkfRiQmeV1ofzotjFFjbHre9e6BGR SDLqBi0GPQbjqEDD0YB9BOjz19jQGUhLhvy5J5LAq5onxnU99yWNRNEL7zO+djoeQZDZac 690pXr7jfQ79/QdhOB5tz8KuyEOUKcI= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, yonghong.song@linux.dev, puranjay@kernel.org, xukuohai@huaweicloud.com, eddyz87@gmail.com, iii@linux.ibm.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v4 2/4] bpf: Prevent extending tail callee prog with freplace prog Date: Sun, 29 Sep 2024 21:27:55 +0800 Message-ID: <20240929132757.79826-3-leon.hwang@linux.dev> In-Reply-To: <20240929132757.79826-1-leon.hwang@linux.dev> References: <20240929132757.79826-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net Alongside previous patch, the infinite loop issue caused by combination of tailcal and freplace can be prevented completely. The previous patch can not prevent the use case that updates a prog to prog_array map and then extends subprog of the prog with freplace prog. This patch fixes the case by preventing extending a prog, which has been updated to prog_array map, with freplace prog. If a prog has been updated to prog_array map, it or its subprog can not be extended by freplace prog. Signed-off-by: Leon Hwang --- include/linux/bpf.h | 3 ++- kernel/bpf/arraymap.c | 9 ++++++++- kernel/bpf/syscall.c | 11 +++++++++++ 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index aac6d2f42830c..dc19ad99e2857 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1484,7 +1484,8 @@ struct bpf_prog_aux { bool exception_cb; bool exception_boundary; bool is_extended; /* true if extended by freplace program */ - struct mutex ext_mutex; /* mutex for is_extended */ + u32 prog_array_member_cnt; /* counts how many times as member of prog_array */ + struct mutex ext_mutex; /* mutex for is_extended and prog_array_member_cnt */ struct bpf_arena *arena; /* BTF_KIND_FUNC_PROTO for valid attach_btf_id */ const struct btf_type *attach_func_proto; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 4a4de4f014be9..91b5bdf4dc72d 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -957,6 +957,8 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map, mutex_lock(&prog->aux->ext_mutex); is_extended = prog->aux->is_extended; + if (!is_extended) + prog->aux->prog_array_member_cnt++; mutex_unlock(&prog->aux->ext_mutex); if (is_extended) /* Extended prog can not be tail callee. It's to prevent a @@ -974,8 +976,13 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map, static void prog_fd_array_put_ptr(struct bpf_map *map, void *ptr, bool need_defer) { + struct bpf_prog *prog = ptr; + + mutex_lock(&prog->aux->ext_mutex); + prog->aux->prog_array_member_cnt--; + mutex_unlock(&prog->aux->ext_mutex); /* bpf_prog is freed after one RCU or tasks trace grace period */ - bpf_prog_put(ptr); + bpf_prog_put(prog); } static u32 prog_fd_array_sys_lookup_elem(void *ptr) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index db17c52fa35db..4beec9729f742 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3287,6 +3287,17 @@ static int bpf_extend_prog(struct bpf_tracing_link *link, int err = 0; mutex_lock(&aux->ext_mutex); + if (aux->prog_array_member_cnt) { + /* Program extensions can not extend target prog when the target + * prog has been updated to any prog_array map as tail callee. + * It's to prevent a potential infinite loop like: + * tgt prog entry -> tgt prog subprog -> freplace prog entry + * --tailcall-> tgt prog entry. + */ + err = -EINVAL; + goto out_unlock; + } + err = bpf_trampoline_link_prog(&link->link, tr); if (err) goto out_unlock; From patchwork Sun Sep 29 13:27:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13815092 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A478D149DE4 for ; Sun, 29 Sep 2024 13:28:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.186 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616511; cv=none; b=sCX3HZl55x4ooHFRzN7GlQyVYfWFZazwaLiJeiWv/4xrjKH9ziHS9dojV2my5h/nPoFcKvI80eeMjjKjy7r6jGTlOiLIEX5arby1vvLQlS4Jc/FZ2u63wsVRs/+Q8+Lbkrv6Zgx6i9F4QuBHeWuMUI17kIs2KcxvqqBGGLPyJrM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616511; c=relaxed/simple; bh=oH68Zyi+ZvXqOyoe80TSA2W6sdYG6p/562blmsNweoo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZoDZsunia8aEhnAq9OYEy5ULzAQHYC93NiQ1AMtLB5zJzqjWwRkp9gRtleesBSzbhmf/WqLKBCmiTG3Zdw7CahJmYWLrmcuUTjgQZtKTJOfJbLzrWJ9cbiA3ndR3epDXDXOUp5Zva9Fzz0of1rmbGg1gKna9JAQAvvB9XOtkAQo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=J8tNJK6p; arc=none smtp.client-ip=95.215.58.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="J8tNJK6p" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1727616507; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+5jlWI/hvCd4YL4748QdUtZcIBNEyBMGmbw6HMTY2A0=; b=J8tNJK6pGF8hMXAj78yS8OvW2bSWTNsaEmswH3ahe0/qNRBkRpL+it1ArRLtG+wXMgJjDK SDXD9e1cgRHHw9kRk/JP8DCh/aBUXOTQYTZWngb32uQtzymHFq4shlCBet1Oew1rv8n/Zd jmRgWN7RTNLQcwaKFebTs5xnKWoJnmg= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, yonghong.song@linux.dev, puranjay@kernel.org, xukuohai@huaweicloud.com, eddyz87@gmail.com, iii@linux.ibm.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v4 3/4] selftests/bpf: Add a test case to confirm a tailcall infinite loop issue has been prevented Date: Sun, 29 Sep 2024 21:27:56 +0800 Message-ID: <20240929132757.79826-4-leon.hwang@linux.dev> In-Reply-To: <20240929132757.79826-1-leon.hwang@linux.dev> References: <20240929132757.79826-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net cd tools/testing/selftests/bpf; ./test_progs -t tailcalls 335/26 tailcalls/tailcall_bpf2bpf_freplace:OK 335 tailcalls:OK Summary: 1/26 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Leon Hwang --- .../selftests/bpf/prog_tests/tailcalls.c | 99 ++++++++++++++++++- .../testing/selftests/bpf/progs/tc_bpf2bpf.c | 24 ++++- 2 files changed, 119 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c index 21c5a37846ade..fa3f3bb11b098 100644 --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c @@ -1525,7 +1525,8 @@ static void test_tailcall_freplace(void) prog_fd = bpf_program__fd(tc_skel->progs.entry_tc); freplace_prog = freplace_skel->progs.entry_freplace; - err = bpf_program__set_attach_target(freplace_prog, prog_fd, "subprog"); + err = bpf_program__set_attach_target(freplace_prog, prog_fd, + "subprog_tailcall_tc"); if (!ASSERT_OK(err, "set_attach_target")) goto out; @@ -1534,7 +1535,7 @@ static void test_tailcall_freplace(void) goto out; freplace_link = bpf_program__attach_freplace(freplace_prog, prog_fd, - "subprog"); + "subprog_tailcall_tc"); if (!ASSERT_OK_PTR(freplace_link, "attach_freplace")) goto out; @@ -1556,6 +1557,98 @@ static void test_tailcall_freplace(void) tailcall_freplace__destroy(freplace_skel); } +/* test_tailcall_bpf2bpf_freplace checks the failure that fails to attach a tail + * callee prog with freplace prog or fails to update an extended prog to + * prog_array map. + */ +static void test_tailcall_bpf2bpf_freplace(void) +{ + struct tailcall_freplace *freplace_skel = NULL; + struct bpf_link *freplace_link = NULL; + struct tc_bpf2bpf *tc_skel = NULL; + char buff[128] = {}; + int prog_fd, map_fd; + int err, key; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .data_in = buff, + .data_size_in = sizeof(buff), + .repeat = 1, + ); + + tc_skel = tc_bpf2bpf__open_and_load(); + if (!ASSERT_OK_PTR(tc_skel, "tc_bpf2bpf__open_and_load")) + goto out; + + prog_fd = bpf_program__fd(tc_skel->progs.entry_tc); + freplace_skel = tailcall_freplace__open(); + if (!ASSERT_OK_PTR(freplace_skel, "tailcall_freplace__open")) + goto out; + + err = bpf_program__set_attach_target(freplace_skel->progs.entry_freplace, + prog_fd, "subprog_tc"); + if (!ASSERT_OK(err, "set_attach_target")) + goto out; + + err = tailcall_freplace__load(freplace_skel); + if (!ASSERT_OK(err, "tailcall_freplace__load")) + goto out; + + /* OK to attach then detach freplace prog. */ + + freplace_link = bpf_program__attach_freplace(freplace_skel->progs.entry_freplace, + prog_fd, "subprog_tc"); + if (!ASSERT_OK_PTR(freplace_link, "attach_freplace")) + goto out; + + err = bpf_link__destroy(freplace_link); + if (!ASSERT_OK(err, "destroy link")) + goto out; + + /* OK to update prog_array map then delete element from the map. */ + + key = 0; + map_fd = bpf_map__fd(freplace_skel->maps.jmp_table); + err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY); + if (!ASSERT_OK(err, "update jmp_table")) + goto out; + + err = bpf_map_delete_elem(map_fd, &key); + if (!ASSERT_OK(err, "delete_elem from jmp_table")) + goto out; + + /* Fail to attach a tail callee prog with freplace prog. */ + + err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY); + if (!ASSERT_OK(err, "update jmp_table")) + goto out; + + freplace_link = bpf_program__attach_freplace(freplace_skel->progs.entry_freplace, + prog_fd, "subprog_tc"); + if (!ASSERT_ERR_PTR(freplace_link, "attach_freplace failure")) + goto out; + + err = bpf_map_delete_elem(map_fd, &key); + if (!ASSERT_OK(err, "delete_elem from jmp_table")) + goto out; + + /* Fail to update an extended prog to prog_array map. */ + + freplace_link = bpf_program__attach_freplace(freplace_skel->progs.entry_freplace, + prog_fd, "subprog_tc"); + if (!ASSERT_OK_PTR(freplace_link, "attach_freplace")) + goto out; + + err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY); + if (!ASSERT_ERR(err, "update jmp_table failure")) + goto out; + +out: + bpf_link__destroy(freplace_link); + tailcall_freplace__destroy(freplace_skel); + tc_bpf2bpf__destroy(tc_skel); +} + void test_tailcalls(void) { if (test__start_subtest("tailcall_1")) @@ -1606,4 +1699,6 @@ void test_tailcalls(void) test_tailcall_bpf2bpf_hierarchy_3(); if (test__start_subtest("tailcall_freplace")) test_tailcall_freplace(); + if (test__start_subtest("tailcall_bpf2bpf_freplace")) + test_tailcall_bpf2bpf_freplace(); } diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c index 8a0632c37839a..34f3c780194e4 100644 --- a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c @@ -4,11 +4,30 @@ #include #include "bpf_misc.h" +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(max_entries, 1); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u32)); +} jmp_table SEC(".maps"); + +__noinline +int subprog_tailcall_tc(struct __sk_buff *skb) +{ + int ret = 1; + + bpf_tail_call_static(skb, &jmp_table, 0); + __sink(skb); + __sink(ret); + return ret; +} + __noinline -int subprog(struct __sk_buff *skb) +int subprog_tc(struct __sk_buff *skb) { int ret = 1; + __sink(skb); __sink(ret); return ret; } @@ -16,7 +35,8 @@ int subprog(struct __sk_buff *skb) SEC("tc") int entry_tc(struct __sk_buff *skb) { - return subprog(skb); + subprog_tc(skb); + return subprog_tailcall_tc(skb); } char __license[] SEC("license") = "GPL"; From patchwork Sun Sep 29 13:27:57 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13815093 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-180.mta1.migadu.com (out-180.mta1.migadu.com [95.215.58.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C25CA13C816 for ; Sun, 29 Sep 2024 13:28:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616514; cv=none; b=GU+gHgRb9NFZ3az18/6O5LBPRmLpYw1nCeIN1ogRr9qqFY4tauoHSwQysqipumnlZHN/30yhTHOMmG8xD6KbHraHn+MprgJPO6A0oFfr655ilzSrlBvODc+LRTqqjwYL3LqekAU91YnXcDjdnz+645mxKCzHjTwYsoltkrOXloY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727616514; c=relaxed/simple; bh=BrTdLoiyecOydf+gQn7r2d++I9wD0GS7HjY1tHl9mQU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kfN0V7wz9BfVvKMFcNAsxIAmPHw2TZJHeS8VzM7ZbyUVJ+eTF6N5CWozsYpkzD60e9xARSJVlPZz8/4w82t44DSAAteaw4bELnOHk3+mHfBbp6Xba507xE7ZPxlMuAJl2tinqi1dsOPooIPr6AXYabXcoTBWdeSYjw5Go4Nk4ME= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=sqW1iNRG; arc=none smtp.client-ip=95.215.58.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="sqW1iNRG" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1727616511; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LXH4TEyTyCpmffZ/AQBGWW5qkNpq1ttl9gYNsiMSSMw=; b=sqW1iNRGzO/JYiqkxpbyxveWs53FY7rOggwxxhPBogqzL6AXjYViI8pBM9MKMLoSMYJV2Q bOrkZCe3f/NQGppufsGRvLHN91snXPtb8xUw5tofKgXiO74o8YbSIZTGwQdV5ig5Th5Efl FEK58p8KMIu/r/wSSNHTLpA07QaLK5c= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, toke@redhat.com, martin.lau@kernel.org, yonghong.song@linux.dev, puranjay@kernel.org, xukuohai@huaweicloud.com, eddyz87@gmail.com, iii@linux.ibm.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v4 4/4] selftests/bpf: Add cases to test tailcall in freplace Date: Sun, 29 Sep 2024 21:27:57 +0800 Message-ID: <20240929132757.79826-5-leon.hwang@linux.dev> In-Reply-To: <20240929132757.79826-1-leon.hwang@linux.dev> References: <20240929132757.79826-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net cd tools/testing/selftests/bpf; ./test_progs -t tailcalls 335/27 tailcalls/tailcall_bpf2bpf_hierarchy_freplace_1:OK 335/28 tailcalls/tailcall_bpf2bpf_hierarchy_freplace_2:OK 335 tailcalls:OK Summary: 1/28 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Leon Hwang --- .../selftests/bpf/prog_tests/tailcalls.c | 97 +++++++++++++++++++ .../tailcall_bpf2bpf_hierarchy_freplace.c | 30 ++++++ .../testing/selftests/bpf/progs/tc_bpf2bpf.c | 13 +++ 3 files changed, 140 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy_freplace.c diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c index fa3f3bb11b098..0564ad6c9b288 100644 --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c @@ -5,6 +5,7 @@ #include "tailcall_poke.skel.h" #include "tailcall_bpf2bpf_hierarchy2.skel.h" #include "tailcall_bpf2bpf_hierarchy3.skel.h" +#include "tailcall_bpf2bpf_hierarchy_freplace.skel.h" #include "tailcall_freplace.skel.h" #include "tc_bpf2bpf.skel.h" @@ -1649,6 +1650,98 @@ static void test_tailcall_bpf2bpf_freplace(void) tc_bpf2bpf__destroy(tc_skel); } +static void test_tailcall_bpf2bpf_hierarchy_freplace(bool freplace_subprog, + bool target_entry2, + int count1, int count2) +{ + struct tailcall_bpf2bpf_hierarchy_freplace *freplace_skel = NULL; + struct bpf_link *freplace_link = NULL; + struct tc_bpf2bpf *tc_skel = NULL; + int prog_fd, map_fd; + char buff[128] = {}; + int err, key, val; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .data_in = buff, + .data_size_in = sizeof(buff), + .repeat = 1, + ); + + tc_skel = tc_bpf2bpf__open_and_load(); + if (!ASSERT_OK_PTR(tc_skel, "tc_bpf2bpf__open_and_load")) + goto out; + + prog_fd = bpf_program__fd(target_entry2 ? tc_skel->progs.entry_tc_2 : + tc_skel->progs.entry_tc); + freplace_skel = tailcall_bpf2bpf_hierarchy_freplace__open(); + if (!ASSERT_OK_PTR(freplace_skel, "tailcall_bpf2bpf_hierarchy_freplace__open")) + goto out; + + err = bpf_program__set_attach_target(freplace_skel->progs.entry_freplace, + prog_fd, freplace_subprog ? + "subprog_tailcall_tc" : "entry_tc"); + if (!ASSERT_OK(err, "set_attach_target")) + goto out; + + err = tailcall_bpf2bpf_hierarchy_freplace__load(freplace_skel); + if (!ASSERT_OK(err, "tailcall_bpf2bpf_hierarchy_freplace__load")) + goto out; + + val = bpf_program__fd(freplace_skel->progs.entry_freplace); + map_fd = bpf_map__fd(freplace_skel->maps.jmp_table); + key = 0; + err = bpf_map_update_elem(map_fd, &key, &val, BPF_ANY); + if (!ASSERT_OK(err, "update jmp_table")) + goto out; + + freplace_link = bpf_program__attach_freplace(freplace_skel->progs.entry_freplace, + prog_fd, freplace_subprog ? + "subprog_tailcall_tc" : "entry_tc"); + if (!ASSERT_OK_PTR(freplace_link, "attach_freplace")) + goto out; + + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "test_run_opts"); + ASSERT_EQ(topts.retval, count1, "test_run_opts retval"); + + err = bpf_map_delete_elem(map_fd, &key); + if (!ASSERT_OK(err, "delete_elem from jmp_table")) + goto out; + + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "test_run_opts again"); + ASSERT_EQ(topts.retval, count2, "test_run_opts retval again"); + +out: + bpf_link__destroy(freplace_link); + tailcall_bpf2bpf_hierarchy_freplace__destroy(freplace_skel); + tc_bpf2bpf__destroy(tc_skel); +} + +/* test_tailcall_bpf2bpf_hierarchy_freplace_1 checks the count value of tail + * call limit enforcement matches with expectation for the case: + * + * subprog_tail --tailcall-> entry_freplace + * entry_tc --jump-> entry_freplace < + * subprog_tail --tailcall-> entry_freplace + */ +static void test_tailcall_bpf2bpf_hierarchy_freplace_1(void) +{ + test_tailcall_bpf2bpf_hierarchy_freplace(false, false, 34, 35); +} + +/* test_tailcall_bpf2bpf_hierarchy_freplace_2 checks the count value of tail + * call limit enforcement matches with expectation for the case: + * + * subprog_tail --tailcall-> entry_freplace + * entry_tc_2 --> subprog_tailcall_tc (call 10 times) --jump-> entry_freplace < + * subprog_tail --tailcall-> entry_freplace + */ +static void test_tailcall_bpf2bpf_hierarchy_freplace_2(void) +{ + test_tailcall_bpf2bpf_hierarchy_freplace(true, true, 340, 350); +} + void test_tailcalls(void) { if (test__start_subtest("tailcall_1")) @@ -1701,4 +1794,8 @@ void test_tailcalls(void) test_tailcall_freplace(); if (test__start_subtest("tailcall_bpf2bpf_freplace")) test_tailcall_bpf2bpf_freplace(); + if (test__start_subtest("tailcall_bpf2bpf_hierarchy_freplace_1")) + test_tailcall_bpf2bpf_hierarchy_freplace_1(); + if (test__start_subtest("tailcall_bpf2bpf_hierarchy_freplace_2")) + test_tailcall_bpf2bpf_hierarchy_freplace_2(); } diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy_freplace.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy_freplace.c new file mode 100644 index 0000000000000..6f7c1fac9ddb7 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy_freplace.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(max_entries, 1); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u32)); +} jmp_table SEC(".maps"); + +int count = 0; + +static __noinline +int subprog_tail(struct __sk_buff *skb) +{ + bpf_tail_call_static(skb, &jmp_table, 0); + return 0; +} + +SEC("freplace") +int entry_freplace(struct __sk_buff *skb) +{ + count++; + subprog_tail(skb); + subprog_tail(skb); + return count; +} + +char __license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c index 34f3c780194e4..beacf60a52677 100644 --- a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c @@ -39,4 +39,17 @@ int entry_tc(struct __sk_buff *skb) return subprog_tailcall_tc(skb); } +SEC("tc") +int entry_tc_2(struct __sk_buff *skb) +{ + int ret, i; + + for (i = 0; i < 10; i++) { + ret = subprog_tailcall_tc(skb); + __sink(ret); + } + + return ret; +} + char __license[] SEC("license") = "GPL";