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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 886ADCEFD11 for ; Tue, 6 Jan 2026 21:19:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 126736B0096; Tue, 6 Jan 2026 16:19:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EFFC06B0098; Tue, 6 Jan 2026 16:19:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DC5196B009B; Tue, 6 Jan 2026 16:19:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id BFB556B0096 for ; Tue, 6 Jan 2026 16:19:47 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 6BD6D140BA3 for ; Tue, 6 Jan 2026 21:19:47 +0000 (UTC) X-FDA: 84302806014.12.1CBC949 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) by imf24.hostedemail.com (Postfix) with ESMTP id B54A9180009 for ; Tue, 6 Jan 2026 21:19:45 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=zytor.com header.s=2025122301 header.b=S4K0I4Ul; dmarc=pass (policy=none) header.from=zytor.com; spf=pass (imf24.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1767734385; a=rsa-sha256; cv=none; b=myzkZBOvTfzD4HgobJYZXNEwKapAtiekhOm5J5o59ChBU/0rK2GVuJyyDLud/H6hk42LsD HzRzDvHAmRJUcVQfwrMLpJOyGCh0I5UrC2MwB/D3oBWIS0wC2iyaugXReEZw0kjRO1uWXO LRgXxZu0XwZwC9A+a4n4mB0LyZFcZ1A= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=zytor.com header.s=2025122301 header.b=S4K0I4Ul; dmarc=pass (policy=none) header.from=zytor.com; spf=pass (imf24.hostedemail.com: domain of hpa@zytor.com designates 198.137.202.136 as permitted sender) smtp.mailfrom=hpa@zytor.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1767734385; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=XZJ8tAuCLXRb63lalw0MrBdPq41wQB+L/BAms3K0dhs=; b=uHyNcwyjTULNOt5UgdQhNQzhyHJ3y7quXGAbsMG0ccmWjkDxCUTHsKYWEXCt3HR6n0/XAZ Eli6966/uq9Ae/ZJreBz2EszOOaYNCo6z3AVm3BNY01AIk86527dmQC+++uezPYiN9DBQ+ s4RMuKdwb2+yI0MMtzlWRSsDPRS2URE= Received: from mail.zytor.com ([IPv6:2601:646:8081:9483:178c:dccb:2d71:85fe]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 606LIrDx029412 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Tue, 6 Jan 2026 13:19:10 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 606LIrDx029412 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025122301; t=1767734351; bh=XZJ8tAuCLXRb63lalw0MrBdPq41wQB+L/BAms3K0dhs=; h=From:To:Subject:Date:In-Reply-To:References:From; b=S4K0I4UlBuVG0GU6MjlFYvgF5uMBTa/+Rf90h2YlPF+GIZodYt62OWkKjFKpl8SlO +Q1QQCMjV2TmDq8PbsOTAt7Uk4t1sEYdtEWPiDTLg2r0lPSzVOfdNeLSi0mFqq1G/G Owbn8lRR0dWrHBDordOZdUKnK/Yad+HhAr1XiiAIbouuMc/G/wy+QMMzttU1I5rIVr Njft0b7ASZq1ffmzrUTLcgCXkwwD2G6ZicpLukyr/H5g2HxjyLXj27W/rzFdS23ytT inP0TKK9uFt44dcd5r0CjtpgYvrjsmIeXoGQ4p0vijzbg4ETcU6kr5YO3cXX98thFn Zs70dWAC7aKQQ== From: "H. Peter Anvin" To: "H. Peter Anvin" , "Jason A. Donenfeld" , "Peter Zijlstra (Intel)" , "Theodore Ts'o" , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Xin Li , Andrew Cooper , Andy Lutomirski , Ard Biesheuvel , Borislav Petkov , Brian Gerst , Dave Hansen , Ingo Molnar , James Morse , Jarkko Sakkinen , Josh Poimboeuf , Kees Cook , Nam Cao , Oleg Nesterov , Perry Yuan , Thomas Gleixner , Thomas Huth , Uros Bizjak , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-sgx@vger.kernel.org, x86@kernel.org Subject: [PATCH v4.1 09/10] x86/cpufeature: replace X86_FEATURE_SYSENTER32 with X86_FEATURE_SYSFAST32 Date: Tue, 6 Jan 2026 13:18:42 -0800 Message-ID: <20260106211856.560186-9-hpa@zytor.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: B54A9180009 X-Stat-Signature: j7uxib57i5eetuk3fdw73b9a1jmqq1bs X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1767734385-22304 X-HE-Meta: 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 8RvtQ3yk 0jY1CBXWVzWnWFSj6pep3VjpByxWLklQuxr90D80bFYF5xHbkrZ5fAq2paHuy5rZ1Q6xRly7KCI9BEWhURfjivY9cBIg5z225pNYv6iu2iRLL2mVWsP/fP9n2mV8tN6btTyucL7NV1EWcQTClvGgJBMevBVegv0pao3Kc0irAGMmEgRyyAJUrQLm2LwfZALYl5RG/za3kwtDVnzMZ5YIASRid2AHxP2BV8LpsxF8JwHWIQ0mUWunqY1uNHe6n+Xv3xVvJhMFv7IcPPLoMOkITYCEabaZCgxUvsxvUdYlqNV7bdhImHX0x0IqhyoKypzcArwAAkwtvzQZzPRAwhFakDhoAas1/6wA3RlEfQylb8uPFnrI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: In most cases, the use of "fast 32-bit system call" depends either on X86_FEATURE_SEP or X86_FEATURE_SYSENTER32 || X86_FEATURE_SYSCALL32. However, nearly all the logic for both is identical. Define X86_FEATURE_SYSFAST32 which indicates that *either* SYSENTER32 or SYSCALL32 should be used, for either 32- or 64-bit kernels. This defaults to SYSENTER; use SYSCALL if the SYSCALL32 bit is also set. As this removes ALL existing uses of X86_FEATURE_SYSENTER32, which is a kernel-only synthetic feature bit, simply remove it and replace it with X86_FEATURE_SYSFAST32. This leaves an unused alternative for a true 32-bit kernel, but that should really not matter in any way. The clearing of X86_FEATURE_SYSCALL32 can be removed once the patches for automatically clearing disabled features has been merged. Signed-off-by: H. Peter Anvin (Intel) --- arch/x86/Kconfig.cpufeatures | 8 +++++++ arch/x86/entry/vdso/vdso32/system_call.S | 8 ++----- arch/x86/include/asm/cpufeatures.h | 2 +- arch/x86/kernel/cpu/centaur.c | 3 --- arch/x86/kernel/cpu/common.c | 8 +++++++ arch/x86/kernel/cpu/intel.c | 4 +--- arch/x86/kernel/cpu/zhaoxin.c | 4 +--- arch/x86/kernel/fred.c | 2 +- arch/x86/xen/setup.c | 28 +++++++++++++++--------- arch/x86/xen/smp_pv.c | 5 ++--- arch/x86/xen/xen-ops.h | 1 - 11 files changed, 42 insertions(+), 31 deletions(-) diff --git a/arch/x86/Kconfig.cpufeatures b/arch/x86/Kconfig.cpufeatures index 733d5aff2456..423ac795baa7 100644 --- a/arch/x86/Kconfig.cpufeatures +++ b/arch/x86/Kconfig.cpufeatures @@ -56,6 +56,10 @@ config X86_REQUIRED_FEATURE_MOVBE def_bool y depends on MATOM +config X86_REQUIRED_FEATURE_SYSFAST32 + def_bool y + depends on X86_64 && !X86_FRED + config X86_REQUIRED_FEATURE_CPUID def_bool y depends on X86_64 @@ -120,6 +124,10 @@ config X86_DISABLED_FEATURE_CENTAUR_MCR def_bool y depends on X86_64 +config X86_DISABLED_FEATURE_SYSCALL32 + def_bool y + depends on !X86_64 + config X86_DISABLED_FEATURE_PCID def_bool y depends on !X86_64 diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S index 2a15634bbe75..7b1c0f16e511 100644 --- a/arch/x86/entry/vdso/vdso32/system_call.S +++ b/arch/x86/entry/vdso/vdso32/system_call.S @@ -52,13 +52,9 @@ __kernel_vsyscall: #define SYSENTER_SEQUENCE "movl %esp, %ebp; sysenter" #define SYSCALL_SEQUENCE "movl %ecx, %ebp; syscall" -#ifdef BUILD_VDSO32_64 /* If SYSENTER (Intel) or SYSCALL32 (AMD) is available, use it. */ - ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSENTER32, \ - SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32 -#else - ALTERNATIVE "", SYSENTER_SEQUENCE, X86_FEATURE_SEP -#endif + ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSFAST32, \ + SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32 /* Enter using int $0x80 */ int $0x80 diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index c3b53beb1300..63b0f9aa9b3e 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -84,7 +84,7 @@ #define X86_FEATURE_PEBS ( 3*32+12) /* "pebs" Precise-Event Based Sampling */ #define X86_FEATURE_BTS ( 3*32+13) /* "bts" Branch Trace Store */ #define X86_FEATURE_SYSCALL32 ( 3*32+14) /* syscall in IA32 userspace */ -#define X86_FEATURE_SYSENTER32 ( 3*32+15) /* sysenter in IA32 userspace */ +#define X86_FEATURE_SYSFAST32 ( 3*32+15) /* sysenter/syscall in IA32 userspace */ #define X86_FEATURE_REP_GOOD ( 3*32+16) /* "rep_good" REP microcode works well */ #define X86_FEATURE_AMD_LBR_V2 ( 3*32+17) /* "amd_lbr_v2" AMD Last Branch Record Extension Version 2 */ #define X86_FEATURE_CLEAR_CPU_BUF ( 3*32+18) /* Clear CPU buffers using VERW */ diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c index a3b55db35c96..9833f837141c 100644 --- a/arch/x86/kernel/cpu/centaur.c +++ b/arch/x86/kernel/cpu/centaur.c @@ -102,9 +102,6 @@ static void early_init_centaur(struct cpuinfo_x86 *c) (c->x86 >= 7)) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#endif if (c->x86_power & (1 << 8)) { set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e7ab22fce3b5..1c3261cae40c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1068,6 +1068,9 @@ void get_cpu_cap(struct cpuinfo_x86 *c) init_scattered_cpuid_features(c); init_speculation_control(c); + if (IS_ENABLED(CONFIG_X86_64) || cpu_has(c, X86_FEATURE_SEP)) + set_cpu_cap(c, X86_FEATURE_SYSFAST32); + /* * Clear/Set all flags overridden by options, after probe. * This needs to happen each time we re-probe, which may happen @@ -1813,6 +1816,11 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) * that it can't be enabled in 32-bit mode. */ setup_clear_cpu_cap(X86_FEATURE_PCID); + + /* + * Never use SYSCALL on a 32-bit kernel + */ + setup_clear_cpu_cap(X86_FEATURE_SYSCALL32); #endif /* diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 98ae4c37c93e..646ff33c4651 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -236,9 +236,7 @@ static void early_init_intel(struct cpuinfo_x86 *c) clear_cpu_cap(c, X86_FEATURE_PSE); } -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#else +#ifndef CONFIG_X86_64 /* Netburst reports 64 bytes clflush size, but does IO in 128 bytes */ if (c->x86 == 15 && c->x86_cache_alignment == 64) c->x86_cache_alignment = 128; diff --git a/arch/x86/kernel/cpu/zhaoxin.c b/arch/x86/kernel/cpu/zhaoxin.c index 89b1c8a70fe8..031379b7d4fa 100644 --- a/arch/x86/kernel/cpu/zhaoxin.c +++ b/arch/x86/kernel/cpu/zhaoxin.c @@ -59,9 +59,7 @@ static void early_init_zhaoxin(struct cpuinfo_x86 *c) { if (c->x86 >= 0x6) set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); -#ifdef CONFIG_X86_64 - set_cpu_cap(c, X86_FEATURE_SYSENTER32); -#endif + if (c->x86_power & (1 << 8)) { set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC); set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC); diff --git a/arch/x86/kernel/fred.c b/arch/x86/kernel/fred.c index 816187da3a47..e736b19e18de 100644 --- a/arch/x86/kernel/fred.c +++ b/arch/x86/kernel/fred.c @@ -68,7 +68,7 @@ void cpu_init_fred_exceptions(void) idt_invalidate(); /* Use int $0x80 for 32-bit system calls in FRED mode */ - setup_clear_cpu_cap(X86_FEATURE_SYSENTER32); + setup_clear_cpu_cap(X86_FEATURE_SYSFAST32); setup_clear_cpu_cap(X86_FEATURE_SYSCALL32); } diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 3823e52aef52..ac8021c3a997 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -990,13 +990,6 @@ static int register_callback(unsigned type, const void *func) return HYPERVISOR_callback_op(CALLBACKOP_register, &callback); } -void xen_enable_sysenter(void) -{ - if (cpu_feature_enabled(X86_FEATURE_SYSENTER32) && - register_callback(CALLBACKTYPE_sysenter, xen_entry_SYSENTER_compat)) - setup_clear_cpu_cap(X86_FEATURE_SYSENTER32); -} - void xen_enable_syscall(void) { int ret; @@ -1008,11 +1001,27 @@ void xen_enable_syscall(void) mechanism for syscalls. */ } - if (cpu_feature_enabled(X86_FEATURE_SYSCALL32) && - register_callback(CALLBACKTYPE_syscall32, xen_entry_SYSCALL_compat)) + if (!cpu_feature_enabled(X86_FEATURE_SYSFAST32)) + return; + + if (cpu_feature_enabled(X86_FEATURE_SYSCALL32)) { + /* Use SYSCALL32 */ + ret = register_callback(CALLBACKTYPE_syscall32, + xen_entry_SYSCALL_compat); + + } else { + /* Use SYSENTER32 */ + ret = register_callback(CALLBACKTYPE_sysenter, + xen_entry_SYSENTER_compat); + } + + if (ret) { setup_clear_cpu_cap(X86_FEATURE_SYSCALL32); + setup_clear_cpu_cap(X86_FEATURE_SYSFAST32); + } } + static void __init xen_pvmmu_arch_setup(void) { HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_writable_pagetables); @@ -1022,7 +1031,6 @@ static void __init xen_pvmmu_arch_setup(void) register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback)) BUG(); - xen_enable_sysenter(); xen_enable_syscall(); } diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 9bb8ff8bff30..c40f326f0c3a 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -65,10 +65,9 @@ static void cpu_bringup(void) touch_softlockup_watchdog(); /* PVH runs in ring 0 and allows us to do native syscalls. Yay! */ - if (!xen_feature(XENFEAT_supervisor_mode_kernel)) { - xen_enable_sysenter(); + if (!xen_feature(XENFEAT_supervisor_mode_kernel)) xen_enable_syscall(); - } + cpu = smp_processor_id(); identify_secondary_cpu(cpu); set_cpu_sibling_map(cpu); diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 090349baec09..f6c331b20fad 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -60,7 +60,6 @@ phys_addr_t __init xen_find_free_area(phys_addr_t size); char * __init xen_memory_setup(void); void __init xen_arch_setup(void); void xen_banner(void); -void xen_enable_sysenter(void); void xen_enable_syscall(void); void xen_vcpu_restore(void); -- 2.52.0