Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932170AbeAJBFi (ORCPT + 1 other); Tue, 9 Jan 2018 20:05:38 -0500 Received: from mga14.intel.com ([192.55.52.115]:41953 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755334AbeAJBDt (ORCPT ); Tue, 9 Jan 2018 20:03:49 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,337,1511856000"; d="scan'208";a="20335485" From: Andi Kleen To: tglx@linutronix.de Cc: x86@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, dwmw@amazon.co.uk, pjt@google.com, luto@kernel.org, peterz@infradead.org, thomas.lendacky@amd.com, tim.c.chen@linux.intel.com, gregkh@linux-foundation.org, dave.hansen@intel.com, jikos@kernel.org, Andi Kleen Subject: [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel Date: Tue, 9 Jan 2018 17:03:28 -0800 Message-Id: <20180110010328.22163-9-andi@firstfloor.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180110010328.22163-1-andi@firstfloor.org> References: <20180110010328.22163-1-andi@firstfloor.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Andi Kleen On a 32bit kernel clearing registers is much simpler than on 64bit. The arguments for syscalls are initially passed to a C function through the stack, so there's no need to figure out how many arguments to clear. So we always clear all registers (except frame pointer) for all entry points. Signed-off-by: Andi Kleen --- arch/x86/entry/entry_32.S | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index d2ef7f32905b..aee1085534ac 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -221,6 +221,18 @@ POP_GS_EX .endm +.macro CLEAR_ALL_REGS +#ifdef CONFIG_FRAME_POINTER + xorl %ebp, %ebp +#endif + xorl %eax, %eax + xorl %ebx, %ebx + xorl %ecx, %ecx + xorl %edx, %edx + xorl %edi, %edi + xorl %esi, %esi +.endm + /* * %eax: prev task * %edx: next task @@ -428,6 +440,7 @@ ENTRY(entry_SYSENTER_32) pushl $0 /* pt_regs->ip = 0 (placeholder) */ pushl %eax /* pt_regs->orig_ax */ SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ + CLEAR_ALL_REGS /* * SYSENTER doesn't filter flags, so we need to clear NT, AC @@ -539,6 +552,7 @@ ENTRY(entry_INT80_32) ASM_CLAC pushl %eax /* pt_regs->orig_ax */ SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest */ + CLEAR_ALL_REGS /* * User mode is traced as though IRQs are on, and the interrupt gate @@ -673,6 +687,7 @@ common_interrupt: ASM_CLAC addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */ SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER TRACE_IRQS_OFF movl %esp, %eax @@ -685,6 +700,7 @@ ENTRY(name) \ ASM_CLAC; \ pushl $~(nr); \ SAVE_ALL; \ + CLEAR_ALL_REGS; \ ENCODE_FRAME_POINTER; \ TRACE_IRQS_OFF \ movl %esp, %eax; \ @@ -812,6 +828,7 @@ END(spurious_interrupt_bug) ENTRY(xen_hypervisor_callback) pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER TRACE_IRQS_OFF @@ -867,6 +884,7 @@ ENTRY(xen_failsafe_callback) jmp iret_exc 5: pushl $-1 /* orig_ax = -1 => not a system call */ SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER jmp ret_from_exception @@ -921,6 +939,7 @@ common_exception: pushl %edx pushl %ecx pushl %ebx + CLEAR_ALL_REGS ENCODE_FRAME_POINTER cld movl $(__KERNEL_PERCPU), %ecx @@ -954,6 +973,7 @@ ENTRY(debug) ASM_CLAC pushl $-1 # mark this as an int SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER xorl %edx, %edx # error code 0 movl %esp, %eax # pt_regs pointer @@ -998,6 +1018,7 @@ ENTRY(nmi) pushl %eax # pt_regs->orig_ax SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER xorl %edx, %edx # zero error code movl %esp, %eax # pt_regs pointer @@ -1038,6 +1059,7 @@ ENTRY(nmi) .endr pushl %eax SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER FIXUP_ESPFIX_STACK # %eax == %esp xorl %edx, %edx # zero error code @@ -1052,6 +1074,7 @@ ENTRY(int3) ASM_CLAC pushl $-1 # mark this as an int SAVE_ALL + CLEAR_ALL_REGS ENCODE_FRAME_POINTER TRACE_IRQS_OFF xorl %edx, %edx # zero error code -- 2.14.3