From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CC082283FD9 for ; Sun, 14 Dec 2025 08:47:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765702072; cv=none; b=aNfhHuJbz792gGDE+tuAZvqa+9kbviSwyNzBudqwVCKid5KEmpuWwuh95AXpJjfNk8t+4AmhvyPCO/It4DwN2FQW30UF/9rRzEDu+Ln6FhRmPxJFr69EuHWH2S1LtrTsOl508nHxPO4CQNMVyKfOlTgWqAx3FBDKjb+uP0LyTf0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765702072; c=relaxed/simple; bh=1YU25Kmljq0Jxmajdrxeu3dQFed5HPqj6lEvGKCgWuY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QxrvhXY1MePveClSr6AWOll+w2lpjySMY2miTwcLCSqnQc0/I6woNYYDdfZm92vXS8MqKTwMooM2qnvs9UZkGmLHJsZP7An/UnZRyvu8ISWOtpvSuhTlMyZW9C0hf00wXDzmYORdsPqyS/BDiRdxArD+gFM8IZNGfM9TSRnC79s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LOQe495Z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LOQe495Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5485FC16AAE; Sun, 14 Dec 2025 08:47:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765702072; bh=1YU25Kmljq0Jxmajdrxeu3dQFed5HPqj6lEvGKCgWuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LOQe495ZRGFYhbwnDF8CcYew/43Ic+0Wd/VDp+hTdEnpa28rNtB2e41A6D5WbtS2v kVt1nds9j+JSZP+BYFmhKiqzx/b5wmSE4viRfmV21OlBhcqwiTXb2dV+npl0gD5aMd qgKtlWpmeJaEsrcqXzmHwSBxTseIAcUn1e9d8Gn6zPsyANUd760ekRQdd9ZkmvfFJv T8GuVZBHrK3x3/1IyQiF0ofwyp4wEqt6mGaVe6rDf3Ujg1iZTeAVIq74A3rvrLgfId PJEtoTnk0wfOJcAD79QswiNk1OA96oKs1YzDvdaNi6oVYlSKzvoJS61NSRbijhteRy bEMzExZVTpHPw== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , "Ahmed S . Darwish" , Andrew Cooper , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , John Ogness , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Arnd Bergmann Subject: [PATCH 08/15] x86/fpu: Remove MATH_EMULATION and related glue code Date: Sun, 14 Dec 2025 09:46:56 +0100 Message-ID: <20251214084710.3606385-9-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251214084710.3606385-1-mingo@kernel.org> References: <20251214084710.3606385-1-mingo@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Signed-off-by: Ingo Molnar Reviewed-by: Arnd Bergmann Acked-by: Dave Hansen Cc: Ahmed S . Darwish Cc: Andrew Cooper Cc: Ard Biesheuvel Cc: H . Peter Anvin Cc: John Ogness Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250425084216.3913608-9-mingo@kernel.org --- arch/x86/Kconfig | 27 --------------------------- arch/x86/Kconfig.cpufeatures | 1 - arch/x86/Makefile | 1 - arch/x86/include/asm/fpu/api.h | 6 ------ arch/x86/kernel/fpu/core.c | 5 ----- arch/x86/kernel/fpu/init.c | 9 +-------- arch/x86/kernel/traps.c | 14 -------------- 7 files changed, 1 insertion(+), 62 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ecd4c77827e9..60a03b61214a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1622,33 +1622,6 @@ config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK Set whether the default state of memory_corruption_check is on or off. -config MATH_EMULATION - bool - depends on MODIFY_LDT_SYSCALL - prompt "Math emulation" if X86_32 && (M486SX || MELAN) - help - Linux can emulate a math coprocessor (used for floating point - operations) if you don't have one. 486DX and Pentium processors have - a math coprocessor built in, 486SX and 386 do not, unless you added - a 487DX or 387, respectively. (The messages during boot time can - give you some hints here ["man dmesg"].) Everyone needs either a - coprocessor or this emulation. - - If you don't have a math coprocessor, you need to say Y here; if you - say Y here even though you have a coprocessor, the coprocessor will - be used nevertheless. (This behavior can be changed with the kernel - command line option "no387", which comes handy if your coprocessor - is broken. Try "man bootparam" or see the documentation of your boot - loader (lilo or loadlin) about how to pass options to the kernel at - boot time.) This means that it is a good idea to say Y here if you - intend to use this kernel on different machines. - - More information about the internals of the Linux math coprocessor - emulation can be found in . - - If you are not sure, say Y; apart from resulting in a 66 KB bigger - kernel, it won't hurt. - config MTRR def_bool y prompt "MTRR (Memory Type Range Register) support" if EXPERT diff --git a/arch/x86/Kconfig.cpufeatures b/arch/x86/Kconfig.cpufeatures index 733d5aff2456..888487e109bf 100644 --- a/arch/x86/Kconfig.cpufeatures +++ b/arch/x86/Kconfig.cpufeatures @@ -66,7 +66,6 @@ config X86_REQUIRED_FEATURE_UP config X86_REQUIRED_FEATURE_FPU def_bool y - depends on !MATH_EMULATION config X86_REQUIRED_FEATURE_PAE def_bool y diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 1d403a3612ea..be7d282bebc6 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -280,7 +280,6 @@ archprepare: $(cpufeaturemasks.hdr) libs-y += arch/x86/lib/ # drivers-y are linked after core-y -drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/ drivers-$(CONFIG_PCI) += arch/x86/pci/ # suspend and hibernation support diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index cd6f194a912b..90c63fe19c0f 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -119,12 +119,6 @@ extern void fpu__init_system(void); extern void fpu__init_check_bugs(void); extern void fpu__resume_cpu(void); -#ifdef CONFIG_MATH_EMULATION -extern void fpstate_init_soft(struct swregs_state *soft); -#else -static inline void fpstate_init_soft(struct swregs_state *soft) {} -#endif - /* State tracking */ DECLARE_PER_CPU(bool, kernel_fpu_allowed); DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx); diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index da233f20ae6f..2996c1c8c71a 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -532,11 +532,6 @@ static inline void fpstate_init_fstate(struct fpstate *fpstate) */ void fpstate_init_user(struct fpstate *fpstate) { - if (!cpu_feature_enabled(X86_FEATURE_FPU)) { - fpstate_init_soft(&fpstate->regs.soft); - return; - } - xstate_init_xcomp_bv(&fpstate->regs.xsave, fpstate->xfeatures); if (cpu_feature_enabled(X86_FEATURE_FXSR)) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index ff988b9ea39f..0d33c217b71c 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -36,12 +36,7 @@ static void fpu__init_cpu_generic(void) write_cr0(cr0); /* Flush out any pending x87 state: */ -#ifdef CONFIG_MATH_EMULATION - if (!boot_cpu_has(X86_FEATURE_FPU)) - ; - else -#endif - asm volatile ("fninit"); + asm volatile ("fninit"); } /* @@ -86,13 +81,11 @@ static void __init fpu__init_system_early_generic(void) setup_clear_cpu_cap(X86_FEATURE_FPU); } -#ifndef CONFIG_MATH_EMULATION if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_FPU)) { pr_emerg("x86/fpu: Giving up, no FPU found and no math emulation present\n"); for (;;) asm volatile("hlt"); } -#endif } /* diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 5434cba078fb..d974b22e8b2a 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1541,20 +1541,6 @@ DEFINE_IDTENTRY(exc_device_not_available) if (handle_xfd_event(regs)) return; -#ifdef CONFIG_MATH_EMULATION - if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) { - struct math_emu_info info = { }; - - cond_local_irq_enable(regs); - - info.regs = regs; - math_emulate(&info); - - cond_local_irq_disable(regs); - return; - } -#endif - /* This should not happen. */ if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) { /* Try to fix it up and carry on. */ -- 2.51.0