From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227NsnTG7AN8p2XWbgR+B3QAYAqcxwjaTw3fs62G7Q3fNbmIQ7cJyAMeF1cdP1sRq/XqB/12 ARC-Seal: i=1; a=rsa-sha256; t=1518513274; cv=none; d=google.com; s=arc-20160816; b=YIRBncofKPpfwbgKyAJOpCHiaroSocRH2qS2C2ogxbeRIY5R25eMzcL29X+0o20kJL kyqrnb/ipeMXDeZ1KQQhAFR74iAuhoDrQQsz7otPIwr7ZY3HKGXOgLYymE+Jx/ttKGj7 mGnWBgDcUri459PqnMNWsSUY+X5MIRGTEqxxWzzbZbczpqZFY/29iV0J83dZ9aTv63Jy F0LxC6fyEGsXm/d1OWjGpRbF0comYV1bthM8LJ36xJaQK1hYvS/r3DWI+v9uUF+1ixiN hjZcwLUvipDtQiyHy8o46KmsJM4lqx6/u5P+ME0qRC5NKHeb4sX1jRZHC/WGGrjkSds2 iieg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=precedence:content-disposition:content-transfer-encoding :mime-version:robot-unsubscribe:robot-id:git-commit-id:subject:to :references:in-reply-to:reply-to:cc:message-id:from:sender:date :arc-authentication-results; bh=PPRp5aiwEPTmr7+9TfZMoIrTYGLKLtTOutqqYnXLRoI=; b=AZ27F2u0XC14eNUEQJwLooqN33CPWTIW/E+xTdoisYdxK108WnX0PwFhqExQNcgoj/ vaB2gKeOWmijJ4jJ2Tix26XBUEbZm/ym+auzaFOt89LAit/eLayoLgOyW2jonHgEGTn2 j6m+3vvORHKWPnkf2oI87zg/KXpZ8qLMQ7Gn+OsdXKUd4HHCwJkgBp4YaWzReyknySmO 9PLPgqzSSKJxpwtiZaLYGNbFV8vDwG4flioAhtDbBYZG2MpO3f1IeEFbaLHFd3j9CZlu vQadpmXskPPinX42gPNuhb5pEuRXP9qkPDNoXM4BLVBHXx40NDdeGKpRUUjpf2PJ6o9j ESxA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of tipbot@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=tipbot@zytor.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of tipbot@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=tipbot@zytor.com Date: Tue, 13 Feb 2018 00:58:21 -0800 Sender: tip tree robot From: tip-bot for David Woodhouse Message-ID: Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, dwmw2@infradead.org, dan.j.williams@intel.com, gregkh@linuxfoundation.org, luto@kernel.org, dwmw@amazon.co.uk, jpoimboe@redhat.com, torvalds@linux-foundation.org, dave.hansen@linux.intel.com, bp@alien8.de, peterz@infradead.org, tglx@linutronix.de, arjan@linux.intel.com Reply-To: torvalds@linux-foundation.org, dave.hansen@linux.intel.com, bp@alien8.de, tglx@linutronix.de, peterz@infradead.org, arjan@linux.intel.com, mingo@kernel.org, linux-kernel@vger.kernel.org, dwmw2@infradead.org, hpa@zytor.com, gregkh@linuxfoundation.org, dan.j.williams@intel.com, dwmw@amazon.co.uk, luto@kernel.org, jpoimboe@redhat.com In-Reply-To: <1518305967-31356-3-git-send-email-dwmw@amazon.co.uk> References: <1518305967-31356-3-git-send-email-dwmw@amazon.co.uk> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/pti] Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" Git-Commit-ID: f208820a321f9b23d77d7eed89945d862d62a3ed X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1592160265203742206?= X-GMAIL-MSGID: =?utf-8?q?1592276574714010482?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Commit-ID: f208820a321f9b23d77d7eed89945d862d62a3ed Gitweb: https://git.kernel.org/tip/f208820a321f9b23d77d7eed89945d862d62a3ed Author: David Woodhouse AuthorDate: Sat, 10 Feb 2018 23:39:23 +0000 Committer: Ingo Molnar CommitDate: Tue, 13 Feb 2018 08:59:00 +0100 Revert "x86/speculation: Simplify indirect_branch_prediction_barrier()" 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 --- 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(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 4d57894..300cc15 100644 --- 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__ */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 513f960..99799fb 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -969,7 +969,4 @@ 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 */ diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 71949bf..61152aa 100644 --- 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 device *dev, spectre_v2_module_string()); } #endif - -void __ibp_barrier(void) -{ - __wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0); -} -EXPORT_SYMBOL_GPL(__ibp_barrier);