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 X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1EA8C388F9 for ; Thu, 12 Nov 2020 01:40:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CB8C207F7 for ; Thu, 12 Nov 2020 01:40:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="E2SDleIw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729466AbgKLBkW (ORCPT ); Wed, 11 Nov 2020 20:40:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728174AbgKLBA5 (ORCPT ); Wed, 11 Nov 2020 20:00:57 -0500 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D06DAC0613D4 for ; Wed, 11 Nov 2020 17:00:55 -0800 (PST) Received: by mail-pg1-x543.google.com with SMTP id m13so2697544pgl.7 for ; Wed, 11 Nov 2020 17:00:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=iWJMCBasD7Kt3omEYiLg083V4MvggRKPIB9CJhks3NU=; b=E2SDleIw33M0R8xWlLbP1dQQIqjSWTBo7g8TkOt+PBqigSw/fT8HHs9kqx7PPjcLGv o1PzOsS5nkJ6mpeXUfBONznwaCI9rG1jO4oLZ/EUdwAZXa7SOKAqoYSeNBGZq2MWNu7M vUP04AIrnYjexiysNCIln819wS3Xg81VV4ZwoiIGh1fXS92hgkKt4f1a465Evi57mdBx gFzv3ajsM/384IONJVUfJdnK8mnTvpxdDDFtez5K7dIBs+WDCdUt+0brrpEkYEVgY5IZ PpW4OP8C1nxhQZrsbGsS+dO7PWot0Qfrr3Keht1BiMkiDWAUHjMN1rlLPd40S4x8+UJa 3jwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=iWJMCBasD7Kt3omEYiLg083V4MvggRKPIB9CJhks3NU=; b=oe8/lmGzeBPiANyFffLkROBpUShFjEBDrWtW7fH2gUCUP3c8TYsV/Gr2I3joM1WsP4 czB3Y9/OOBo9dAN99i9hgAH3PFNN7RJton+oCpuVOiQx0VL0V3OJHkb+UmlnFf5qRbAJ G77czPquzX3Pac2GcjcklITPzteTosR/5/FRZgKiKgll7rdDR+JbZPMpoh+YX/FNobtM lILo0oqj0kRetl5Qe4aZJEIYMK1KxFdsOvmCHfgbd/2AlIRHKG+I9pxtqDXwCa8KigID cn+SqB+YbguvxDJGl2HSzkLK7otyMIvl11FlMbhcGyZK8UStS9X/j+e+KnmqFqJWTQiD LLKg== X-Gm-Message-State: AOAM533k1NaNxczMZqUweM+vXXGATvLdEvB3GjxkQkxiqzOCYGhTBXX5 gd3ELuV1Pj8yQXmmiaWGZCo0KBIhC2g40pxuUTF4/A== X-Google-Smtp-Source: ABdhPJxkqswZCwL0P/Yg/0r4uGE5OG25zH8IOLZ2KgScZYDTBgDvU23Qg5gcYVNB0Fuqxoq6QxZuVUKrDRLekie6l7g= X-Received: by 2002:a62:ed0d:0:b029:18b:78d:626 with SMTP id u13-20020a62ed0d0000b029018b078d0626mr213230pfh.15.1605142855176; Wed, 11 Nov 2020 17:00:55 -0800 (PST) MIME-Version: 1.0 References: <20201112001422.340449-1-willmcvicker@google.com> In-Reply-To: <20201112001422.340449-1-willmcvicker@google.com> From: Nick Desaulniers Date: Wed, 11 Nov 2020 17:00:43 -0800 Message-ID: Subject: Re: [PATCH] arm64: Fix off-by-one vdso trampoline return value To: Will McVicker Cc: Catalin Marinas , Will Deacon , Nathan Chancellor , Vincenzo Frascino , Andrei Vagin , Dmitry Safonov <0x7f454c46@gmail.com>, Thomas Gleixner , Linux ARM , LKML , clang-built-linux , kernel-team Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 11, 2020 at 4:14 PM Will McVicker wrote: > > Depending on your host nm version, the generated header > `include/generated/vdso32-offsets.h` may have the bottom bit set for the > thumb vdso offset addresses (as observed when using llvm-nm). This Sorry, the commit message seems to imply a bug in llvm-nm, but I don't think that's the case. If it is, please, send us a bugreport. $ aarch64-linux-gnu-nm arch/arm64/kernel/vdso32/vdso.so.raw | grep thumb 00000968 T __kernel_rt_sigreturn_thumb 00000960 T __kernel_sigreturn_thumb 00000968 t VDSO_compat_rt_sigreturn_thumb 00000960 t VDSO_compat_sigreturn_thumb $ llvm-nm arch/arm64/kernel/vdso32/vdso.so.raw | grep thumb 00000968 t VDSO_compat_rt_sigreturn_thumb 00000960 t VDSO_compat_sigreturn_thumb 00000968 T __kernel_rt_sigreturn_thumb 00000960 T __kernel_sigreturn_thumb $ /usr/bin/nm arch/arm64/kernel/vdso32/vdso.so.raw | grep thumb 00000969 T __kernel_rt_sigreturn_thumb 00000961 T __kernel_sigreturn_thumb 00000969 t VDSO_compat_rt_sigreturn_thumb 00000961 t VDSO_compat_sigreturn_thumb $ /usr/bin/nm --version GNU nm (GNU Binutils for Debian) 2.35.1 Would you mind amending the commit message to not imply that llvm-nm is broken? It might be of interest to find out why the host `nm` was invoked, rather than $(NM)/$(CROSS_COMPILE)nm. > results in an additional +1 for thumb vdso trampoline return values > since compat_setup_return() already includes `vdso_trampoline + thumb`. > As a result, I see a SIGBUS error when running the LTP test > syscalls.rt_sigaction01. To fix this, let's clear the bottom bit of the > vdso_offset in the VDSO_SYMBOL macro. > > Test: LTP test syscalls.rt_sigaction01 > Fixes: f01703b3d2e6 ("arm64: compat: Get sigreturn trampolines from vDSO") > Signed-off-by: Will McVicker > --- > arch/arm64/include/asm/vdso.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h > index f99dcb94b438..a7384379e8e1 100644 > --- a/arch/arm64/include/asm/vdso.h > +++ b/arch/arm64/include/asm/vdso.h > @@ -23,7 +23,7 @@ > > #define VDSO_SYMBOL(base, name) \ > ({ \ > - (void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \ > + (void *)((vdso_offset_##name & ~1UL) - VDSO_LBASE + (unsigned long)(base)); \ > }) > > #endif /* !__ASSEMBLY__ */ > -- > 2.29.2.299.gdc1121823c-goog > -- Thanks, ~Nick Desaulniers