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 DF3B3CEFD0C for ; Tue, 6 Jan 2026 21:20:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 513356B0005; Tue, 6 Jan 2026 16:20:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 49CCD6B0092; Tue, 6 Jan 2026 16:20:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3C00F6B0098; Tue, 6 Jan 2026 16:20:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 2F3286B0005 for ; Tue, 6 Jan 2026 16:20:01 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 0186D5D06F for ; Tue, 6 Jan 2026 21:20:00 +0000 (UTC) X-FDA: 84302806602.07.496E92D Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) by imf02.hostedemail.com (Postfix) with ESMTP id 36F8E80008 for ; Tue, 6 Jan 2026 21:19:59 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=zytor.com header.s=2025122301 header.b=GTkHjpbu; dmarc=pass (policy=none) header.from=zytor.com; spf=pass (imf02.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=1767734399; a=rsa-sha256; cv=none; b=FHEbQQoDtSXpNkQI0FrjMF3qqzq3kbjULO3zagwOEYpj1wBAiFG5iAQ5Xo81AsS6J1YQQi EUjhB60SKTYMVOAvY3oVZos2XGp5J/ZFPxJTgS9pFuysQcORgLfrnwLm+C4jq9RDmGBaX4 pyZpC1m2JqR72SR64Aim8JgOb36o7WI= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=zytor.com header.s=2025122301 header.b=GTkHjpbu; dmarc=pass (policy=none) header.from=zytor.com; spf=pass (imf02.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=1767734399; 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=KRPTBbWjYzkYkyARWAmnaxHY32CSHvovmdB11gernjU=; b=oNLi3GbSk4B1k8jPEPaVtCKJ05KTS8opbGpd84UXpiTHwKufsBMvOWOPmca7MDoVJBqZ2W J35ziq4ZazfUus+H6i2SxfNHIcR4Q4hc3lLoNZ81X/DmPA1C2TIKgq6cn71Sx/ru/enDz9 GbEk9L4faErvz37SbGWCXjotBo/0eCI= 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 606LIrDw029412 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Tue, 6 Jan 2026 13:19:08 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 606LIrDw029412 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025122301; t=1767734350; bh=KRPTBbWjYzkYkyARWAmnaxHY32CSHvovmdB11gernjU=; h=From:To:Subject:Date:In-Reply-To:References:From; b=GTkHjpbuISrDuiB7A8VJ67i0g1F95qKWdiZc8UDSUf+BnhZytBFHO29qAa9viu7Sr gWChQ85ZrwudTCiRb7XbEA/nhDQhm8xv/PO4kmwMzck6xCTQ4hUA6t2T81cxZq4pGt pti3AQrrQAvhT8xmXog/kDuyJhhFt1CqicUt5LXdObODEpHlxAe46jWPd8U7e9a87R WmsEYzTjOQrEPV34raGY8Y+Ynjd5zX8v75Fvovxq4rwGHL+UHYgC1S5/LHoN8gGd6N Q3uri6dX9DRLDXiIyzTKU1JpzT4hoFlKHt0f9Sin9hX5U3ul7s052moXbm2ntjqxG+ DPE2scfipXomw== 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 08/10] x86/vdso: abstract out vdso system call internals Date: Tue, 6 Jan 2026 13:18:41 -0800 Message-ID: <20260106211856.560186-8-hpa@zytor.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 36F8E80008 X-Stat-Signature: fcs8g1wjtakynr43imt8z6y3adbwzi4f X-HE-Tag: 1767734399-525776 X-HE-Meta: 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 qVowIZ0C hQ25pr8aAsKumfV39TF4a1DI8E+38IqdYXlK1xdM72xvNPJqJ+fuQMy+fhpvEg/IdAjXAvNYfotohaaAzI06CI3PPusRB/HcirCdeYzZ65xKg6/pU8vqsALJVoscKtSm53/bR6AG1hNERdWtYoHRwD/rTDR4Im99sbJp0V26MB9IE78TnEDUZREgxMLUKk4Ki4G3sE2/ifJXjF9BQAqHiVML/t4Dzsxyg2tya84bIX3l40lNif4lqz9bD7neszInfMmPvxN2O/guavPOZnqbqq8AfkX7mRbjd5GSt8+LSFaEkSR/oW90fG2zbd8iPU7MRecrrFgieCm2aBCRqYZIKuvfIa6AO1RAx7dB+ 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: Abstract out the calling of true system calls from the vdso into macros. It has been a very long time since gcc did not allow %ebx or %ebp in inline asm in 32-bit PIC mode; remove the corresponding hacks. Remove the use of memory output constraints in gettimeofday.h in favor of "memory" clobbers. The resulting code is identical for the current use cases, as the system call is usually a terminal fallback anyway, and it merely complicates the macroization. This patch adds only a handful of more lines of code than it removes, and in fact could be made substantially smaller by removing the macros for the argument counts that aren't currently used, however, it seems better to be general from the start. [ v3: remove stray comment from prototyping; remove VDSO_SYSCALL6() since it would require special handling on 32 bits and is currently unused. (Uros Bizjak). Indent nested preprocessor directives. ] Signed-off-by: H. Peter Anvin (Intel) --- arch/x86/include/asm/vdso/gettimeofday.h | 108 ++--------------------- arch/x86/include/asm/vdso/sys_call.h | 103 +++++++++++++++++++++ 2 files changed, 111 insertions(+), 100 deletions(-) create mode 100644 arch/x86/include/asm/vdso/sys_call.h diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h index 73b2e7ee8f0f..3cf214cc4a75 100644 --- a/arch/x86/include/asm/vdso/gettimeofday.h +++ b/arch/x86/include/asm/vdso/gettimeofday.h @@ -18,6 +18,7 @@ #include #include #include +#include #define VDSO_HAS_TIME 1 @@ -53,130 +54,37 @@ extern struct ms_hyperv_tsc_page hvclock_page __attribute__((visibility("hidden"))); #endif -#ifndef BUILD_VDSO32 - static __always_inline long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) { - long ret; - - asm ("syscall" : "=a" (ret), "=m" (*_ts) : - "0" (__NR_clock_gettime), "D" (_clkid), "S" (_ts) : - "rcx", "r11"); - - return ret; + return VDSO_SYSCALL2(clock_gettime,64,_clkid,_ts); } static __always_inline long gettimeofday_fallback(struct __kernel_old_timeval *_tv, struct timezone *_tz) { - long ret; - - asm("syscall" : "=a" (ret) : - "0" (__NR_gettimeofday), "D" (_tv), "S" (_tz) : "memory"); - - return ret; + return VDSO_SYSCALL2(gettimeofday,,_tv,_tz); } static __always_inline long clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) { - long ret; - - asm ("syscall" : "=a" (ret), "=m" (*_ts) : - "0" (__NR_clock_getres), "D" (_clkid), "S" (_ts) : - "rcx", "r11"); - - return ret; + return VDSO_SYSCALL2(clock_getres,_time64,_clkid,_ts); } -#else - -static __always_inline -long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) -{ - long ret; - - asm ( - "mov %%ebx, %%edx \n" - "mov %[clock], %%ebx \n" - "call __kernel_vsyscall \n" - "mov %%edx, %%ebx \n" - : "=a" (ret), "=m" (*_ts) - : "0" (__NR_clock_gettime64), [clock] "g" (_clkid), "c" (_ts) - : "edx"); - - return ret; -} +#ifndef CONFIG_X86_64 static __always_inline long clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) { - long ret; - - asm ( - "mov %%ebx, %%edx \n" - "mov %[clock], %%ebx \n" - "call __kernel_vsyscall \n" - "mov %%edx, %%ebx \n" - : "=a" (ret), "=m" (*_ts) - : "0" (__NR_clock_gettime), [clock] "g" (_clkid), "c" (_ts) - : "edx"); - - return ret; -} - -static __always_inline -long gettimeofday_fallback(struct __kernel_old_timeval *_tv, - struct timezone *_tz) -{ - long ret; - - asm( - "mov %%ebx, %%edx \n" - "mov %2, %%ebx \n" - "call __kernel_vsyscall \n" - "mov %%edx, %%ebx \n" - : "=a" (ret) - : "0" (__NR_gettimeofday), "g" (_tv), "c" (_tz) - : "memory", "edx"); - - return ret; + return VDSO_SYSCALL2(clock_gettime,,_clkid,_ts); } static __always_inline long -clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) -{ - long ret; - - asm ( - "mov %%ebx, %%edx \n" - "mov %[clock], %%ebx \n" - "call __kernel_vsyscall \n" - "mov %%edx, %%ebx \n" - : "=a" (ret), "=m" (*_ts) - : "0" (__NR_clock_getres_time64), [clock] "g" (_clkid), "c" (_ts) - : "edx"); - - return ret; -} - -static __always_inline -long clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) +clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) { - long ret; - - asm ( - "mov %%ebx, %%edx \n" - "mov %[clock], %%ebx \n" - "call __kernel_vsyscall \n" - "mov %%edx, %%ebx \n" - : "=a" (ret), "=m" (*_ts) - : "0" (__NR_clock_getres), [clock] "g" (_clkid), "c" (_ts) - : "edx"); - - return ret; + return VDSO_SYSCALL2(clock_getres,,_clkid,_ts); } #endif diff --git a/arch/x86/include/asm/vdso/sys_call.h b/arch/x86/include/asm/vdso/sys_call.h new file mode 100644 index 000000000000..dcfd17c6dd57 --- /dev/null +++ b/arch/x86/include/asm/vdso/sys_call.h @@ -0,0 +1,103 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Macros for issuing an inline system call from the vDSO. + */ + +#ifndef X86_ASM_VDSO_SYS_CALL_H +#define X86_ASM_VDSO_SYS_CALL_H + +#include +#include +#include + +#ifdef CONFIG_X86_64 +# define __sys_instr "syscall" +# define __sys_clobber "rcx", "r11", "memory" +# define __sys_nr(x,y) __NR_ ## x +# define __sys_reg1 "rdi" +# define __sys_reg2 "rsi" +# define __sys_reg3 "rdx" +# define __sys_reg4 "r10" +# define __sys_reg5 "r8" +#else +# define __sys_instr "call __kernel_vsyscall" +# define __sys_clobber "memory" +# define __sys_nr(x,y) __NR_ ## x ## y +# define __sys_reg1 "ebx" +# define __sys_reg2 "ecx" +# define __sys_reg3 "edx" +# define __sys_reg4 "esi" +# define __sys_reg5 "edi" +#endif + +/* + * Example usage: + * + * result = VDSO_SYSCALL3(foo,64,x,y,z); + * + * ... calls foo(x,y,z) on 64 bits, and foo64(x,y,z) on 32 bits. + * + * VDSO_SYSCALL6() is currently missing, because it would require + * special handling for %ebp on 32 bits when the vdso is compiled with + * frame pointers enabled (the default on 32 bits.) Add it as a special + * case when and if it becomes necessary. + */ +#define _VDSO_SYSCALL(name,suf32,...) \ + ({ \ + long _sys_num_ret = __sys_nr(name,suf32); \ + asm_inline volatile( \ + __sys_instr \ + : "+a" (_sys_num_ret) \ + : __VA_ARGS__ \ + : __sys_clobber); \ + _sys_num_ret; \ + }) + +#define VDSO_SYSCALL0(name,suf32) \ + _VDSO_SYSCALL(name,suf32) +#define VDSO_SYSCALL1(name,suf32,a1) \ + ({ \ + register long _sys_arg1 asm(__sys_reg1) = (long)(a1); \ + _VDSO_SYSCALL(name,suf32, \ + "r" (_sys_arg1)); \ + }) +#define VDSO_SYSCALL2(name,suf32,a1,a2) \ + ({ \ + register long _sys_arg1 asm(__sys_reg1) = (long)(a1); \ + register long _sys_arg2 asm(__sys_reg2) = (long)(a2); \ + _VDSO_SYSCALL(name,suf32, \ + "r" (_sys_arg1), "r" (_sys_arg2)); \ + }) +#define VDSO_SYSCALL3(name,suf32,a1,a2,a3) \ + ({ \ + register long _sys_arg1 asm(__sys_reg1) = (long)(a1); \ + register long _sys_arg2 asm(__sys_reg2) = (long)(a2); \ + register long _sys_arg3 asm(__sys_reg3) = (long)(a3); \ + _VDSO_SYSCALL(name,suf32, \ + "r" (_sys_arg1), "r" (_sys_arg2), \ + "r" (_sys_arg3)); \ + }) +#define VDSO_SYSCALL4(name,suf32,a1,a2,a3,a4) \ + ({ \ + register long _sys_arg1 asm(__sys_reg1) = (long)(a1); \ + register long _sys_arg2 asm(__sys_reg2) = (long)(a2); \ + register long _sys_arg3 asm(__sys_reg3) = (long)(a3); \ + register long _sys_arg4 asm(__sys_reg4) = (long)(a4); \ + _VDSO_SYSCALL(name,suf32, \ + "r" (_sys_arg1), "r" (_sys_arg2), \ + "r" (_sys_arg3), "r" (_sys_arg4)); \ + }) +#define VDSO_SYSCALL5(name,suf32,a1,a2,a3,a4,a5) \ + ({ \ + register long _sys_arg1 asm(__sys_reg1) = (long)(a1); \ + register long _sys_arg2 asm(__sys_reg2) = (long)(a2); \ + register long _sys_arg3 asm(__sys_reg3) = (long)(a3); \ + register long _sys_arg4 asm(__sys_reg4) = (long)(a4); \ + register long _sys_arg5 asm(__sys_reg5) = (long)(a5); \ + _VDSO_SYSCALL(name,suf32, \ + "r" (_sys_arg1), "r" (_sys_arg2), \ + "r" (_sys_arg3), "r" (_sys_arg4), \ + "r" (_sys_arg5)); \ + }) + +#endif /* X86_VDSO_SYS_CALL_H */ -- 2.52.0