From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELuWJzLwDtUq79ch+1zhC6hgxafcFMmD9bsfwlbrcwi2iuCNf+PP1opusxA0qIVdfCM81eZ+ ARC-Seal: i=1; a=rsa-sha256; t=1521228602; cv=none; d=google.com; s=arc-20160816; b=ZYbMxdC3gI9Ad8aSzkJ7InxkE8sbSDEzFOnk+PB0iSnMRe0Ice/FrxhmvnlQPTVKZf GlIRWseY7y9+bWAXWZLsMeiIBlAtFdPFuGCLhQBM791qgYojF+PPvX2Ctof1hy4zQZRc theFYADMIG/U5R68lBYOM0wYF81r6bkQLODNwxddCeOfPXm1CVn5VDapvs9GDvAcODT+ 2jBQZWV7GKaUSWtbCMY+ChwY9/EBk6AnwIe3Nly5HFbHfGOAPfI1b60RzWVUFIRvtlZI qkDIpWoUQrQf95uTSLz0PuTS9oeq4irO7zw21VehK1YthXxpUOtfVnd6xO9+APsMQxP6 cVmg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=lFVEWZD8iyFBLPwCnkcx5rWQZtK2TQ+3za/aoOilQ44=; b=EjozxuxkaFbZU4zDZixBYl/wAkrI5Hp37ItpZnkHkDTgyz232kBC2o19RcDPHoIWLo Wims9c1aW1VSCo+Lla7JiJYTIz9MiJY2Nvr2Ljzd5YSmZZqEIHOePQzUHxC/R5AgXz/c QX8RGfE0bJFPjq1+tu0OFM3dJgaapgMFxOEZ/c+YD3mCSxCWrjAIqIu67f7/BtcrrNyi otRh3r+JyvgP3Qq68iKbdENBoyEFmKmRZsHm31u7koh6CsU2CyiRu2uHs/Z8NOb00uNv avt/CIZDvfE88j/5EYkityb2/LEDf3jPg/1QuCJHujQjRZXKSH1vlWQlsCE4ExW2KEM2 kd5g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=cNHKdLAn; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=cNHKdLAn; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 04/35] x86/entry/32: Put ESPFIX code into a macro Date: Fri, 16 Mar 2018 20:29:22 +0100 Message-Id: <1521228593-3820-5-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521228593-3820-1-git-send-email-joro@8bytes.org> References: <1521228593-3820-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1595123802672199055?= X-GMAIL-MSGID: =?utf-8?q?1595123802672199055?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Joerg Roedel This makes it easier to split up the shared iret code path. Signed-off-by: Joerg Roedel --- arch/x86/entry/entry_32.S | 97 ++++++++++++++++++++++++----------------------- 1 file changed, 49 insertions(+), 48 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index e659776..0289bde 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -221,6 +221,54 @@ POP_GS_EX .endm +.macro CHECK_AND_APPLY_ESPFIX +#ifdef CONFIG_X86_ESPFIX32 +#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8) + + ALTERNATIVE "jmp .Lend_\@", "", X86_BUG_ESPFIX + + movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS + /* + * Warning: PT_OLDSS(%esp) contains the wrong/random values if we + * are returning to the kernel. + * See comments in process.c:copy_thread() for details. + */ + movb PT_OLDSS(%esp), %ah + movb PT_CS(%esp), %al + andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax + cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax + jne .Lend_\@ # returning to user-space with LDT SS + + /* + * Setup and switch to ESPFIX stack + * + * We're returning to userspace with a 16 bit stack. The CPU will not + * restore the high word of ESP for us on executing iret... This is an + * "official" bug of all the x86-compatible CPUs, which we can work + * around to make dosemu and wine happy. We do this by preloading the + * high word of ESP with the high word of the userspace ESP while + * compensating for the offset by changing to the ESPFIX segment with + * a base address that matches for the difference. + */ + mov %esp, %edx /* load kernel esp */ + mov PT_OLDESP(%esp), %eax /* load userspace esp */ + mov %dx, %ax /* eax: new kernel esp */ + sub %eax, %edx /* offset (low word is 0) */ + shr $16, %edx + mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */ + mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */ + pushl $__ESPFIX_SS + pushl %eax /* new kernel esp */ + /* + * Disable interrupts, but do not irqtrace this section: we + * will soon execute iret and the tracer was already set to + * the irqstate after the IRET: + */ + DISABLE_INTERRUPTS(CLBR_ANY) + lss (%esp), %esp /* switch to espfix segment */ +.Lend_\@: +#endif /* CONFIG_X86_ESPFIX32 */ +.endm /* * %eax: prev task * %edx: next task @@ -548,21 +596,7 @@ ENTRY(entry_INT80_32) restore_all: TRACE_IRQS_IRET .Lrestore_all_notrace: -#ifdef CONFIG_X86_ESPFIX32 - ALTERNATIVE "jmp .Lrestore_nocheck", "", X86_BUG_ESPFIX - - movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS - /* - * Warning: PT_OLDSS(%esp) contains the wrong/random values if we - * are returning to the kernel. - * See comments in process.c:copy_thread() for details. - */ - movb PT_OLDSS(%esp), %ah - movb PT_CS(%esp), %al - andl $(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax - cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax - je .Lldt_ss # returning to user-space with LDT SS -#endif + CHECK_AND_APPLY_ESPFIX .Lrestore_nocheck: RESTORE_REGS 4 # skip orig_eax/error_code .Lirq_return: @@ -575,39 +609,6 @@ ENTRY(iret_exc ) jmp common_exception .previous _ASM_EXTABLE(.Lirq_return, iret_exc) - -#ifdef CONFIG_X86_ESPFIX32 -.Lldt_ss: -/* - * Setup and switch to ESPFIX stack - * - * We're returning to userspace with a 16 bit stack. The CPU will not - * restore the high word of ESP for us on executing iret... This is an - * "official" bug of all the x86-compatible CPUs, which we can work - * around to make dosemu and wine happy. We do this by preloading the - * high word of ESP with the high word of the userspace ESP while - * compensating for the offset by changing to the ESPFIX segment with - * a base address that matches for the difference. - */ -#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8) - mov %esp, %edx /* load kernel esp */ - mov PT_OLDESP(%esp), %eax /* load userspace esp */ - mov %dx, %ax /* eax: new kernel esp */ - sub %eax, %edx /* offset (low word is 0) */ - shr $16, %edx - mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */ - mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */ - pushl $__ESPFIX_SS - pushl %eax /* new kernel esp */ - /* - * Disable interrupts, but do not irqtrace this section: we - * will soon execute iret and the tracer was already set to - * the irqstate after the IRET: - */ - DISABLE_INTERRUPTS(CLBR_ANY) - lss (%esp), %esp /* switch to espfix segment */ - jmp .Lrestore_nocheck -#endif ENDPROC(entry_INT80_32) .macro FIXUP_ESPFIX_STACK -- 2.7.4