From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Elver Subject: [PATCH v3 2/3] x86: Use static_cpu_has in uaccess region to avoid instrumentation Date: Fri, 31 May 2019 17:08:30 +0200 Message-ID: <20190531150828.157832-3-elver@google.com> References: <20190531150828.157832-1-elver@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190531150828.157832-1-elver@google.com> Sender: linux-kernel-owner@vger.kernel.org To: peterz@infradead.org, aryabinin@virtuozzo.com, dvyukov@google.com, glider@google.com, andreyknvl@google.com, mark.rutland@arm.com, hpa@zytor.com Cc: corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, arnd@arndb.de, jpoimboe@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kasan-dev@googlegroups.com, Marco Elver List-Id: linux-arch.vger.kernel.org This patch is a pre-requisite for enabling KASAN bitops instrumentation; using static_cpu_has instead of boot_cpu_has avoids instrumentation of test_bit inside the uaccess region. With instrumentation, the KASAN check would otherwise be flagged by objtool. For consistency, kernel/signal.c was changed to mirror this change, however, is never instrumented with KASAN (currently unsupported under x86 32bit). Signed-off-by: Marco Elver Suggested-by: H. Peter Anvin --- Changes in v3: * Use static_cpu_has instead of moving boot_cpu_has outside uaccess region. Changes in v2: * Replaces patch: 'tools/objtool: add kasan_check_* to uaccess whitelist' --- arch/x86/ia32/ia32_signal.c | 2 +- arch/x86/kernel/signal.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index 629d1ee05599..1cee10091b9f 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -358,7 +358,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(ptr_to_compat(&frame->uc), &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 364813cea647..52eb1d551aed 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -391,7 +391,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(&frame->uc, &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); -- 2.22.0.rc1.257.g3120a18244-goog From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vs1-f74.google.com ([209.85.217.74]:55266 "EHLO mail-vs1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726897AbfEaPLm (ORCPT ); Fri, 31 May 2019 11:11:42 -0400 Received: by mail-vs1-f74.google.com with SMTP id 184so1300780vsm.21 for ; Fri, 31 May 2019 08:11:42 -0700 (PDT) Date: Fri, 31 May 2019 17:08:30 +0200 In-Reply-To: <20190531150828.157832-1-elver@google.com> Message-ID: <20190531150828.157832-3-elver@google.com> Mime-Version: 1.0 References: <20190531150828.157832-1-elver@google.com> Subject: [PATCH v3 2/3] x86: Use static_cpu_has in uaccess region to avoid instrumentation From: Marco Elver Content-Type: text/plain; charset="UTF-8" Sender: linux-arch-owner@vger.kernel.org List-ID: To: peterz@infradead.org, aryabinin@virtuozzo.com, dvyukov@google.com, glider@google.com, andreyknvl@google.com, mark.rutland@arm.com, hpa@zytor.com Cc: corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, arnd@arndb.de, jpoimboe@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kasan-dev@googlegroups.com, Marco Elver Message-ID: <20190531150830.QYyMsy9h3m1YjDTIj5NE9l-f8b_uj08Hcb36yvP-1kY@z> This patch is a pre-requisite for enabling KASAN bitops instrumentation; using static_cpu_has instead of boot_cpu_has avoids instrumentation of test_bit inside the uaccess region. With instrumentation, the KASAN check would otherwise be flagged by objtool. For consistency, kernel/signal.c was changed to mirror this change, however, is never instrumented with KASAN (currently unsupported under x86 32bit). Signed-off-by: Marco Elver Suggested-by: H. Peter Anvin --- Changes in v3: * Use static_cpu_has instead of moving boot_cpu_has outside uaccess region. Changes in v2: * Replaces patch: 'tools/objtool: add kasan_check_* to uaccess whitelist' --- arch/x86/ia32/ia32_signal.c | 2 +- arch/x86/kernel/signal.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index 629d1ee05599..1cee10091b9f 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -358,7 +358,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(ptr_to_compat(&frame->uc), &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 364813cea647..52eb1d551aed 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -391,7 +391,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig, put_user_ex(&frame->uc, &frame->puc); /* Create the ucontext. */ - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (static_cpu_has(X86_FEATURE_XSAVE)) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); -- 2.22.0.rc1.257.g3120a18244-goog