Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965008Ab2B1Khn (ORCPT ); Tue, 28 Feb 2012 05:37:43 -0500 Received: from terminus.zytor.com ([198.137.202.10]:52150 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964817Ab2B1Khm (ORCPT ); Tue, 28 Feb 2012 05:37:42 -0500 Date: Tue, 28 Feb 2012 02:37:06 -0800 From: tip-bot for Jan Beulich Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, rostedt@goodmis.org, jbeulich@suse.com, JBeulich@suse.com, tglx@linutronix.de Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, JBeulich@suse.com, jbeulich@suse.com, tglx@linutronix.de In-Reply-To: <4F478B630200007800074A31@nat28.tlf.novell.com> References: <4F478B630200007800074A31@nat28.tlf.novell.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86-64: Fix CFI annotations for NMI nesting code Git-Commit-ID: 626109130267713cac020515504ec341e47c96f9 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-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Tue, 28 Feb 2012 02:37:32 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4678 Lines: 151 Commit-ID: 626109130267713cac020515504ec341e47c96f9 Gitweb: http://git.kernel.org/tip/626109130267713cac020515504ec341e47c96f9 Author: Jan Beulich AuthorDate: Fri, 24 Feb 2012 14:54:37 +0000 Committer: Steven Rostedt CommitDate: Fri, 24 Feb 2012 14:05:14 -0500 x86-64: Fix CFI annotations for NMI nesting code The saving and restoring of %rdx wasn't annotated at all, and the jumping over sections where state gets partly restored wasn't handled either. Further, by folding the pushing of the previous frame in repeat_nmi into that which so far was immediately preceding restart_nmi (after moving the restore of %rdx ahead of that, since it doesn't get used anymore when pushing prior frames), annotations of the replicated frame creations can be made consistent too. v2: Fully fold repeat_nmi into the normal code flow (adding a single redundant instruction to the "normal" code path), thus retaining the special protection of all instructions between repeat_nmi and end_repeat_nmi. Link: http://lkml.kernel.org/r/4F478B630200007800074A31@nat28.tlf.novell.com Signed-off-by: Jan Beulich Signed-off-by: Steven Rostedt --- arch/x86/kernel/entry_64.S | 52 +++++++++++++++++++++++-------------------- 1 files changed, 28 insertions(+), 24 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1333d98..e0eca00 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1530,6 +1530,7 @@ ENTRY(nmi) /* Use %rdx as out temp variable throughout */ pushq_cfi %rdx + CFI_REL_OFFSET rdx, 0 /* * If %cs was not the kernel segment, then the NMI triggered in user @@ -1554,6 +1555,7 @@ ENTRY(nmi) */ lea 6*8(%rsp), %rdx test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi + CFI_REMEMBER_STATE nested_nmi: /* @@ -1585,10 +1587,12 @@ nested_nmi: nested_nmi_out: popq_cfi %rdx + CFI_RESTORE rdx /* No need to check faults here */ INTERRUPT_RETURN + CFI_RESTORE_STATE first_nmi: /* * Because nested NMIs will use the pushed location that we @@ -1624,6 +1628,10 @@ first_nmi: * NMI may zero out. The original stack frame and the temp storage * is also used by nested NMIs and can not be trusted on exit. */ + /* Do not pop rdx, nested NMIs will corrupt it */ + movq (%rsp), %rdx + CFI_RESTORE rdx + /* Set the NMI executing variable on the stack. */ pushq_cfi $1 @@ -1631,14 +1639,31 @@ first_nmi: .rept 5 pushq_cfi 6*8(%rsp) .endr + CFI_DEF_CFA_OFFSET SS+8-RIP + + /* + * If there was a nested NMI, the first NMI's iret will return + * here. But NMIs are still enabled and we can take another + * nested NMI. The nested NMI checks the interrupted RIP to see + * if it is between repeat_nmi and end_repeat_nmi, and if so + * it will just return, as we are about to repeat an NMI anyway. + * This makes it safe to copy to the stack frame that a nested + * NMI will update. + */ +repeat_nmi: + /* + * Update the stack variable to say we are still in NMI (the update + * is benign for the non-repeat case, where 1 was pushed just above + * to this very stack slot). + */ + movq $1, 5*8(%rsp) /* Make another copy, this one may be modified by nested NMIs */ .rept 5 pushq_cfi 4*8(%rsp) .endr - - /* Do not pop rdx, nested NMIs will corrupt it */ - movq 11*8(%rsp), %rdx + CFI_DEF_CFA_OFFSET SS+8-RIP +end_repeat_nmi: /* * Everything below this point can be preempted by a nested @@ -1646,7 +1671,6 @@ first_nmi: * caused by an exception and nested NMI will start here, and * can still be preempted by another NMI. */ -restart_nmi: pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */ subq $ORIG_RAX-R15, %rsp CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15 @@ -1675,26 +1699,6 @@ nmi_restore: CFI_ENDPROC END(nmi) - /* - * If an NMI hit an iret because of an exception or breakpoint, - * it can lose its NMI context, and a nested NMI may come in. - * In that case, the nested NMI will change the preempted NMI's - * stack to jump to here when it does the final iret. - */ -repeat_nmi: - INTR_FRAME - /* Update the stack variable to say we are still in NMI */ - movq $1, 5*8(%rsp) - - /* copy the saved stack back to copy stack */ - .rept 5 - pushq_cfi 4*8(%rsp) - .endr - - jmp restart_nmi - CFI_ENDPROC -end_repeat_nmi: - ENTRY(ignore_sysret) CFI_STARTPROC mov $-ENOSYS,%eax -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/