From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B11EC433ED for ; Sat, 15 May 2021 01:11:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BF8561278 for ; Sat, 15 May 2021 01:11:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234733AbhEOBML (ORCPT ); Fri, 14 May 2021 21:12:11 -0400 Received: from terminus.zytor.com ([198.137.202.136]:57521 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234698AbhEOBMG (ORCPT ); Fri, 14 May 2021 21:12:06 -0400 Received: from tazenda.hos.anvin.org ([IPv6:2601:646:8602:8be0:7285:c2ff:fefb:fd4]) (authenticated bits=0) by mail.zytor.com (8.16.1/8.15.2) with ESMTPSA id 14F1ANfh3208415 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 14 May 2021 18:10:34 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 14F1ANfh3208415 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2021042801; t=1621041035; bh=aZN0ATCPGdNxz3c4p7s/Y7tkLQGd59xFZeraRg2D2s0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kuRUQM+VsYb9lrzW+0whFfIk5DSxPGv2gECG+NqLcOspnb6iOXevRThkUGiIyCYFV F41wH1p0Z4Lp32WteqUqyxi+nfG5H6uMyG1lFq/DSojh4SF+NDgKTN+DQg1cINrOmh ou91/mk4/dxUZP9zVskiqSeEez/79jnKn46ge9TOK4w1maAxqvKupOHEdW6W1628Qd uXoMbGqTXiAoqsXmddz8/4vJ9Z4jLFboE00gaZZwVfMFadJAAokJETH/Wg00ETZZz7 ZBorNKec/BzUeojpOAm6R/ez+xHe435P99itvUb92tode7uFxS1F3jrQX8z0U2TdZw Wjq42QR/xXyvg== From: "H. Peter Anvin" To: Ingo Molnar , Thomas Gleixner , Andy Lutomirski , Borislav Petkov , "H. Peter Anvin" Cc: Linux Kernel Mailing List Subject: [PATCH v3 4/4] x86/syscall: use int everywhere for system call numbers Date: Fri, 14 May 2021 18:10:15 -0700 Message-Id: <20210515011015.2707542-5-hpa@zytor.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210515011015.2707542-1-hpa@zytor.com> References: <20210515011015.2707542-1-hpa@zytor.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "H. Peter Anvin (Intel)" System call numbers are defined as int, so use int everywhere for system call numbers. This patch is strictly a cleanup; it should not change anything user visible; all ABI changes have been done in the preceeding patches. Signed-off-by: H. Peter Anvin (Intel) --- arch/x86/entry/common.c | 93 ++++++++++++++++++++++++---------- arch/x86/include/asm/syscall.h | 2 +- 2 files changed, 66 insertions(+), 29 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index f51bc17262db..714804f0970c 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -36,49 +36,87 @@ #include #ifdef CONFIG_X86_64 -__visible noinstr void do_syscall_64(struct pt_regs *regs, unsigned long nr) + +static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr) +{ + /* + * Convert negative numbers to very high and thus out of range + * numbers for comparisons. Use unsigned long to slightly + * improve the array_index_nospec() generated code. + */ + unsigned long unr = nr; + + if (likely(unr < NR_syscalls)) { + unr = array_index_nospec(unr, NR_syscalls); + regs->ax = sys_call_table[unr](regs); + return true; + } + return false; +} + +static __always_inline bool do_syscall_x32(struct pt_regs *regs, int nr) +{ + /* + * Adjust the starting offset of the table, and convert numbers + * < __X32_SYSCALL_BIT to very high and thus out of range + * numbers for comparisons. Use unsigned long to slightly + * improve the array_index_nospec() generated code. + */ + unsigned long xnr = nr - __X32_SYSCALL_BIT; + + if (IS_ENABLED(CONFIG_X86_X32_ABI) && + likely(xnr < X32_NR_syscalls)) { + xnr = array_index_nospec(xnr, X32_NR_syscalls); + regs->ax = x32_sys_call_table[xnr](regs); + return true; + } + return false; +} + +__visible noinstr void do_syscall_64(struct pt_regs *regs, int nr) { add_random_kstack_offset(); nr = syscall_enter_from_user_mode(regs, nr); instrumentation_begin(); - if (likely(nr < NR_syscalls)) { - nr = array_index_nospec(nr, NR_syscalls); - regs->ax = sys_call_table[nr](regs); -#ifdef CONFIG_X86_X32_ABI - } else if (likely((nr & __X32_SYSCALL_BIT) && - (nr & ~__X32_SYSCALL_BIT) < X32_NR_syscalls)) { - nr = array_index_nospec(nr & ~__X32_SYSCALL_BIT, - X32_NR_syscalls); - regs->ax = x32_sys_call_table[nr](regs); -#endif - } else if (unlikely((int)nr != -1)) { + + if (!do_syscall_x64(regs, nr) && + !do_syscall_x32(regs, nr) && + unlikely(nr != -1)) { + /* Invalid system call, but still a system call? */ regs->ax = __x64_sys_ni_syscall(regs); } + instrumentation_end(); syscall_exit_to_user_mode(regs); } #endif #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) -static __always_inline unsigned int syscall_32_enter(struct pt_regs *regs) +static __always_inline int syscall_32_enter(struct pt_regs *regs) { if (IS_ENABLED(CONFIG_IA32_EMULATION)) current_thread_info()->status |= TS_COMPAT; - return (unsigned int)regs->orig_ax; + return (int)regs->orig_ax; } /* * Invoke a 32-bit syscall. Called with IRQs on in CONTEXT_KERNEL. */ -static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, - unsigned int nr) +static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr) { - if (likely(nr < IA32_NR_syscalls)) { - nr = array_index_nospec(nr, IA32_NR_syscalls); - regs->ax = ia32_sys_call_table[nr](regs); - } else if (unlikely((int)nr != -1)) { + /* + * Convert negative numbers to very high and thus out of range + * numbers for comparisons. Use unsigned long to slightly + * improve the array_index_nospec() generated code. + */ + unsigned long unr = nr; + + if (likely(unr < IA32_NR_syscalls)) { + unr = array_index_nospec(unr, IA32_NR_syscalls); + regs->ax = ia32_sys_call_table[unr](regs); + } else if (unlikely(nr != -1)) { regs->ax = __ia32_sys_ni_syscall(regs); } } @@ -86,15 +124,15 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, /* Handles int $0x80 */ __visible noinstr void do_int80_syscall_32(struct pt_regs *regs) { - unsigned int nr = syscall_32_enter(regs); + int nr = syscall_32_enter(regs); add_random_kstack_offset(); /* - * Subtlety here: if ptrace pokes something larger than 2^32-1 into - * orig_ax, the unsigned int return value truncates it. This may - * or may not be necessary, but it matches the old asm behavior. + * Subtlety here: if ptrace pokes something larger than 2^31-1 into + * orig_ax, the int return value truncates it. This matches + * the semantics of syscall_get_nr(). */ - nr = (unsigned int)syscall_enter_from_user_mode(regs, nr); + nr = syscall_enter_from_user_mode(regs, nr); instrumentation_begin(); do_syscall_32_irqs_on(regs, nr); @@ -105,7 +143,7 @@ __visible noinstr void do_int80_syscall_32(struct pt_regs *regs) static noinstr bool __do_fast_syscall_32(struct pt_regs *regs) { - unsigned int nr = syscall_32_enter(regs); + int nr = syscall_32_enter(regs); int res; add_random_kstack_offset(); @@ -140,8 +178,7 @@ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs) return false; } - /* The case truncates any ptrace induced syscall nr > 2^32 -1 */ - nr = (unsigned int)syscall_enter_from_user_mode_work(regs, nr); + nr = syscall_enter_from_user_mode_work(regs, nr); /* Now this is just like a normal syscall. */ do_syscall_32_irqs_on(regs, nr); diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index f6593cafdbd9..f7e2d82d24fb 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -159,7 +159,7 @@ static inline int syscall_get_arch(struct task_struct *task) ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64; } -void do_syscall_64(struct pt_regs *regs, unsigned long nr); +void do_syscall_64(struct pt_regs *regs, int nr); void do_int80_syscall_32(struct pt_regs *regs); long do_fast_syscall_32(struct pt_regs *regs); -- 2.31.1