From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755346AbdKBH7h (ORCPT ); Thu, 2 Nov 2017 03:59:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:38090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751567AbdKBH7e (ORCPT ); Thu, 2 Nov 2017 03:59:34 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F35D2218D2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org From: Andy Lutomirski To: X86 ML Cc: Borislav Petkov , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds , Andy Lutomirski Subject: [PATCH v2 02/20] x86/asm/64: Split the iret-to-user and iret-to-kernel paths Date: Thu, 2 Nov 2017 00:58:59 -0700 Message-Id: X-Mailer: git-send-email 2.13.6 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org These code paths will diverge soon. Signed-off-by: Andy Lutomirski --- arch/x86/entry/entry_64.S | 34 +++++++++++++++++++++++++--------- arch/x86/entry/entry_64_compat.S | 2 +- arch/x86/kernel/head_64.S | 2 +- 3 files changed, 27 insertions(+), 11 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index afe1f403fa0e..07fe816f0d28 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -321,7 +321,7 @@ syscall_return_via_sysret: opportunistic_sysret_failed: SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode END(entry_SYSCALL_64) ENTRY(stub_ptregs_64) @@ -423,7 +423,7 @@ ENTRY(ret_from_fork) call syscall_return_slowpath /* returns with IRQs disabled */ TRACE_IRQS_ON /* user mode is traced as IRQS on */ SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode 1: /* kernel thread */ @@ -612,7 +612,20 @@ GLOBAL(retint_user) call prepare_exit_to_usermode TRACE_IRQS_IRETQ SWAPGS - jmp restore_regs_and_iret + +GLOBAL(restore_regs_and_return_to_usermode) +#ifdef CONFIG_DEBUG_ENTRY + /* Assert that pt_regs indicates user mode. */ + testl $3, CS(%rsp) + jnz 1f + ud2 +1: +#endif + RESTORE_EXTRA_REGS + RESTORE_C_REGS + REMOVE_PT_GPREGS_FROM_STACK 8 + INTERRUPT_RETURN + /* Returning to kernel space */ retint_kernel: @@ -632,11 +645,14 @@ retint_kernel: */ TRACE_IRQS_IRETQ -/* - * At this label, code paths which return to kernel and to user, - * which come from interrupts/exception and from syscalls, merge. - */ -GLOBAL(restore_regs_and_iret) +GLOBAL(restore_regs_and_return_to_kernel) +#ifdef CONFIG_DEBUG_ENTRY + /* Assert that pt_regs indicates kernel mode. */ + testl $3, CS(%rsp) + jz 1f + ud2 +1: +#endif RESTORE_EXTRA_REGS RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 @@ -1327,7 +1343,7 @@ ENTRY(nmi) * work, because we don't want to enable interrupts. */ SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode .Lnmi_from_kernel: /* diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index e26c25ca7756..9ca014a99968 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -337,7 +337,7 @@ ENTRY(entry_INT80_compat) /* Go back to user mode. */ TRACE_IRQS_ON SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode END(entry_INT80_compat) ENTRY(stub32_clone) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 513cbb012ecc..0b01a105251b 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -326,7 +326,7 @@ early_idt_handler_common: 20: decl early_recursion_flag(%rip) - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_kernel ENDPROC(early_idt_handler_common) __INITDATA -- 2.13.6