From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2255FBc47amMRUq1oEvan5mkQsa/iZuzBZZjizhKaup0B5+Gv2R7ISICQ+saYMMUz7Fn651p ARC-Seal: i=1; a=rsa-sha256; t=1519217989; cv=none; d=google.com; s=arc-20160816; b=Eu5p72QRCwaTcy9dcY7rM8RsYX1ksMUDULBzQO1JhpNy0or8oYAdJD/4hWxhoZy3hD Kx9EJ7K/39xeL12D62lhbYykOCD1D5MDUcHkoUhvvmgZbPMN2XDBcPdJgu7Sh2ZilkPa Qi0WYsPJcEB9OmB6JSEM8ENzKVjKApJzNme2gnylzOoo++2upM/W6VcLRoEZx/IoZ90G SEu7QezucNuL6T3i3tdRrDp5TDtu02IKp3dbXU1xFFDGcol7y0W0kBXEz2rNbeOCqIJJ Jl/jV6GtJ7gxR/PVTtwt4r/0iJSPGWLUhjEY3EqjeHB5ti08q53KbXtOqz2bc73jLSQM 6GJw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=D1npkwQD9eBXWujLLQOlStuGM048SS5muEkvkoq8Bhs=; b=jbsyTB/ca9EKhBDjMXGGmqrfXEXd7s9z/nwDqSfpaRMqy3PZy7+pUXCq5785VJcHBP sM3mONh8eKlr35X6IrzbN2rX9EehGEr4qV/hhGoE+uhsigziUrkHW60Gs1bvw0OiQZZc w9tlMPzHIILv4KS8PNX5OyNeKDRL+YXSTveuPB485AXj/QkTXnUPHwLGG+BpdMCJ7eGi pP9Hux6UDbCXKxgPA0tbwFwp2qTz1dIXa6KBqElwiU0bc7yAB9Skncw9/3pFjYnFhc0c iIa6QN9kZJUuGlS8fs8QBCCOvUDOsc6cIF97hoP0gmSk9Svi8hnf48TE1HUgGLGLfMP0 E97A== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Woodhouse , Andy Lutomirski , Arjan van de Ven , Borislav Petkov , Dan Williams , Dave Hansen , David Woodhouse , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , arjan.van.de.ven@intel.com, dave.hansen@intel.com, jmattson@google.com, karahmed@amazon.de, kvm@vger.kernel.org, pbonzini@redhat.com, rkrcmar@redhat.com, sironi@amazon.de, Ingo Molnar Subject: [PATCH 4.14 050/167] Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" Date: Wed, 21 Feb 2018 13:47:41 +0100 Message-Id: <20180221124527.275276976@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124524.639039577@linuxfoundation.org> References: <20180221124524.639039577@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593015522884375203?= X-GMAIL-MSGID: =?utf-8?q?1593015522884375203?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Woodhouse commit f208820a321f9b23d77d7eed89945d862d62a3ed upstream. This reverts commit 64e16720ea0879f8ab4547e3b9758936d483909b. We cannot call C functions like that, without marking all the call-clobbered registers as, well, clobbered. We might have got away with it for now because the __ibp_barrier() function was *fairly* unlikely to actually use any other registers. But no. Just no. Signed-off-by: David Woodhouse Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: Dave Hansen Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: arjan.van.de.ven@intel.com Cc: dave.hansen@intel.com Cc: jmattson@google.com Cc: karahmed@amazon.de Cc: kvm@vger.kernel.org Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Cc: sironi@amazon.de Link: http://lkml.kernel.org/r/1518305967-31356-3-git-send-email-dwmw@amazon.co.uk Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/nospec-branch.h | 13 +++++++++---- arch/x86/include/asm/processor.h | 3 --- arch/x86/kernel/cpu/bugs.c | 6 ------ 3 files changed, 9 insertions(+), 13 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -164,10 +164,15 @@ static inline void vmexit_fill_RSB(void) static inline void indirect_branch_prediction_barrier(void) { - alternative_input("", - "call __ibp_barrier", - X86_FEATURE_USE_IBPB, - ASM_NO_INPUT_CLOBBER("eax", "ecx", "edx", "memory")); + asm volatile(ALTERNATIVE("", + "movl %[msr], %%ecx\n\t" + "movl %[val], %%eax\n\t" + "movl $0, %%edx\n\t" + "wrmsr", + X86_FEATURE_USE_IBPB) + : : [msr] "i" (MSR_IA32_PRED_CMD), + [val] "i" (PRED_CMD_IBPB) + : "eax", "ecx", "edx", "memory"); } #endif /* __ASSEMBLY__ */ --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -968,7 +968,4 @@ bool xen_set_default_idle(void); void stop_this_cpu(void *dummy); void df_debug(struct pt_regs *regs, long error_code); - -void __ibp_barrier(void); - #endif /* _ASM_X86_PROCESSOR_H */ --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -337,9 +337,3 @@ ssize_t cpu_show_spectre_v2(struct devic spectre_v2_module_string()); } #endif - -void __ibp_barrier(void) -{ - __wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0); -} -EXPORT_SYMBOL_GPL(__ibp_barrier);