From nobody Fri Dec 19 04:01:55 2025 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 EA337C54EBE for ; Tue, 10 Jan 2023 07:29:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237802AbjAJH3O (ORCPT ); Tue, 10 Jan 2023 02:29:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237664AbjAJH2o (ORCPT ); Tue, 10 Jan 2023 02:28:44 -0500 Received: from 1wt.eu (wtarreau.pck.nerim.net [62.212.114.60]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8DC9B4FCC2 for ; Mon, 9 Jan 2023 23:26:35 -0800 (PST) Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 30A7OcXA003936; Tue, 10 Jan 2023 08:24:38 +0100 From: Willy Tarreau To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, Willy Tarreau Subject: [PATCH v2 09/22] tools/nolibc: export environ as a weak symbol on arm Date: Tue, 10 Jan 2023 08:24:21 +0100 Message-Id: <20230110072434.3863-10-w@1wt.eu> X-Mailer: git-send-email 2.17.5 In-Reply-To: <20230110072434.3863-1-w@1wt.eu> References: <20230110072434.3863-1-w@1wt.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The environ is retrieved from the _start code and is easy to store at this moment. Let's declare the variable weak and store the value into it. By not being static it will be visible to all units. By being weak, if some programs already declared it, they will continue to be able to use it. This was tested in arm and thumb1 and thumb2 modes, and for each mode, both with environ inherited from _start and extracted from envp. Signed-off-by: Willy Tarreau --- tools/include/nolibc/arch-arm.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-ar= m.h index 48bd95492c87..79666b590e87 100644 --- a/tools/include/nolibc/arch-arm.h +++ b/tools/include/nolibc/arch-arm.h @@ -196,6 +196,8 @@ struct sys_stat_struct { _arg1; \ }) =20 +char **environ __attribute__((weak)); + /* startup code */ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(= void) { @@ -206,6 +208,8 @@ void __attribute__((weak,noreturn,optimize("omit-frame-= pointer"))) _start(void) "add %r2, %r0, $1\n" // envp =3D (argc + 1) ... "lsl %r2, %r2, $2\n" // * 4 ... "add %r2, %r2, %r1\n" // + argv + "ldr %r3, 1f\n" // r3 =3D &environ (see below) + "str %r2, [r3]\n" // store envp into environ =20 "mov %r3, $8\n" // AAPCS : sp must be 8-byte aligned in the "neg %r3, %r3\n" // callee, and bl doesn't push (lr= =3Dpc) @@ -215,7 +219,10 @@ void __attribute__((weak,noreturn,optimize("omit-frame= -pointer"))) _start(void) "bl main\n" // main() returns the status code, we'll e= xit with it. "movs r7, $1\n" // NR_exit =3D=3D 1 "svc $0x00\n" - ); + ".align 2\n" // below are the pointers to a few variabl= es + "1:\n" + ".word environ\n" + ); __builtin_unreachable(); } =20 --=20 2.17.5