From patchwork Mon Feb 5 18:39:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viktor Malik X-Patchwork-Id: 13546050 X-Patchwork-Delegate: bpf@iogearbox.net Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 D4A6D2E3FD for ; Mon, 5 Feb 2024 18:39:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707158386; cv=none; b=ssBBP9QPYSiPXd3QjsYZlyaaciqG9fZaKsqQ+GQ9Dk+NGyKXYLovfbFvTaG6UxGzCqoMJrXEFPDw47qRR9te5KnBjE5gdIDaR4zJWerJYGBQT5qh04a4854GLM1ILsUY11aBIgfYQEiGJ68o6D/IlSxWWxi+ElG2PDD4CQc6KKk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707158386; c=relaxed/simple; bh=OHzPMP6U9NLmEzs5Kvq/TJRoQQRxdGYSlX+zoaNGwA4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KdI9bt7C0hBw09qa5O8kci/hhHox1SFM/LY3QegGEyeexo9WeMtjYAdM+deg8oQ5JhZpf9N7TtAPFcc2mFcrBY55djHOeGruk7T0vARZfDkvLqBHyoPaHt2n1vKQ6XjBLNxPn4PmC5TYARB6hHw6Jy0DzbXqIcEVn1LhzgjRugM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=GaEqN+BI; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GaEqN+BI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707158383; 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=Mh4iGaE2NikyDZuV/sDewbg3UtNj7deDZh6O3B7MnWA=; b=GaEqN+BIoGmNDhHB6qxXOTvIkci66ntyCVgAzvzXsB0cQHKfqsVoYmmTisqNZ3B1qSl+8s ENY6ZhxpnCbtvMjciJqeFH9EAqItE74kLUny8qP3k37aqSxjq2dQvrFrFHQH78IrupS7cR kF61gzyF4VSxiVpQtKwqUAD1bhSVCVI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-508-4cOoKKcrM7O8t0bQcW8ARg-1; Mon, 05 Feb 2024 13:39:38 -0500 X-MC-Unique: 4cOoKKcrM7O8t0bQcW8ARg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 91127937701; Mon, 5 Feb 2024 18:39:37 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.45.224.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 49A182026D66; Mon, 5 Feb 2024 18:39:34 +0000 (UTC) From: Viktor Malik To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Viktor Malik , Alexey Dobriyan , Andrew Morton , Kumar Kartikeya Dwivedi , Daniel Xu , Manu Bretelle Subject: [PATCH bpf-next v3 2/2] tools/resolve_btfids: fix cross-compilation to non-host endianness Date: Mon, 5 Feb 2024 19:39:23 +0100 Message-ID: <6dd0762c68d6bff65c7ffb1534d96776aff4ade7.1707157553.git.vmalik@redhat.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 X-Patchwork-Delegate: bpf@iogearbox.net The .BTF_ids section is pre-filled with zeroed BTF ID entries during the build and afterwards patched by resolve_btfids with correct values. Since resolve_btfids always writes in host-native endianness, it relies on libelf to do the translation when the target ELF is cross-compiled to a different endianness (this was introduced in commit 61e8aeda9398 ("bpf: Fix libelf endian handling in resolv_btfids")). Unfortunately, the translation will corrupt the flags fields of SET8 entries because these were written during vmlinux compilation and are in the correct endianness already. This will lead to numerous selftests failures such as: $ sudo ./test_verifier 502 502 #502/p sleepable fentry accept FAIL Failed to load prog 'Invalid argument'! bpf_fentry_test1 is not sleepable verification time 34 usec stack depth 0 processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 Summary: 0 PASSED, 0 SKIPPED, 1 FAILED Since it's not possible to instruct libelf to translate just certain values, let's manually bswap the flags (both global and entry flags) in resolve_btfids when needed, so that libelf then translates everything correctly. Fixes: ef2c6f370a63 ("tools/resolve_btfids: Add support for 8-byte BTF sets") Signed-off-by: Viktor Malik --- tools/bpf/resolve_btfids/main.c | 35 +++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index 9ffe8163081a..b34de276e531 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -90,6 +90,14 @@ #define ADDR_CNT 100 +#if __BYTE_ORDER == __LITTLE_ENDIAN +# define ELFDATANATIVE ELFDATA2LSB +#elif __BYTE_ORDER == __BIG_ENDIAN +# define ELFDATANATIVE ELFDATA2MSB +#else +# error "Unknown machine endianness!" +#endif + struct btf_id { struct rb_node rb_node; char *name; @@ -117,6 +125,7 @@ struct object { int idlist_shndx; size_t strtabidx; unsigned long idlist_addr; + int encoding; } efile; struct rb_root sets; @@ -320,6 +329,7 @@ static int elf_collect(struct object *obj) { Elf_Scn *scn = NULL; size_t shdrstrndx; + GElf_Ehdr ehdr; int idx = 0; Elf *elf; int fd; @@ -351,6 +361,13 @@ static int elf_collect(struct object *obj) return -1; } + if (gelf_getehdr(obj->efile.elf, &ehdr) == NULL) { + pr_err("FAILED cannot get ELF header: %s\n", + elf_errmsg(-1)); + return -1; + } + obj->efile.encoding = ehdr.e_ident[EI_DATA]; + /* * Scan all the elf sections and look for save data * from .BTF_ids section and symbols. @@ -683,6 +700,24 @@ static int sets_patch(struct object *obj) */ BUILD_BUG_ON(set8->pairs != &set8->pairs[0].id); qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id); + + /* + * When ELF endianness does not match endianness of the + * host, libelf will do the translation when updating + * the ELF. This, however, corrupts SET8 flags which are + * already in the target endianness. So, let's bswap + * them to the host endianness and libelf will then + * correctly translate everything. + */ + if (obj->efile.encoding != ELFDATANATIVE) { + int i; + + set8->flags = bswap_32(set8->flags); + for (i = 0; i < set8->cnt; i++) { + set8->pairs[i].flags = + bswap_32(set8->pairs[i].flags); + } + } } pr_debug("sorting addr %5lu: cnt %6d [%s]\n",