From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 0D4CE340A43; Fri, 8 May 2026 05:40:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778218859; cv=none; b=tukqFs8gVwyvcnrmJ4kwh3PhVtw/g5c9rSgKfn16NCXwKwx5sbp6sldqai2GspaBRJFlrFRDdmqaGbXD4i5be6qM5lfaFX/2DXLBisfFtgNjn9YNTjv+dEuCXZo49sF0qA+5sslyrrZ0XVS3MeOOlEk4KdzKyqtuScNHx1xdg6k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778218859; c=relaxed/simple; bh=HzacTt6t1UU8jd1Zcyszvezsp0yCBvuNDqLVEA6DwLI=; h=Date:From:To:Subject:Cc:MIME-Version:Message-ID:Content-Type; b=PsX4B8WSXrP4Kt1Sonr7fxcKGo5tC0mSeNVDz8bqQTYZfBDN5qE4jZkfe/0RVM7He8m03iPoFm/oMJf6Cx4fu+2F34zy60Fw9BVwfe55C8fnVxLdm8luGSo/2L4DVqEdIpK9iE6xc8eGi7eGBgjk7j6R2D4VFFnpu9oDi9sWgaM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=c0v4dMuq; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=7Q//fPzL; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="c0v4dMuq"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="7Q//fPzL" Date: Fri, 08 May 2026 05:40:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1778218842; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=O+6d2Z/XSrTuyiRKC/pSun27RX7Rr6HC92ayIRm1mRg=; b=c0v4dMuqwXe2usShKM9GzMtPSI+WIIUrUJhkuR+ab4vBB3GIKmUlVn4uQTPNz7Vw9SV2cX S7Ruu4V4dxX3zMw26p1V10IuSxQUylj2JI4NN6dYjOwoGVWYYqXhdyy9k4kKIaVJ3eIiE2 LYqAJU20RuCuf16WVfptg1jjqFbH0AqihJxmEG7SniyK46rNlONYf3byeqF2B+re26K0+3 oD5LJrVSJk+fgrf3yAaGuZxE2vOxQ2N1dVy87NowUNGZid/msvJ9SXbxsUZxG2yi32ltXA 8TRGcDpO96ESGxf0wKAF2eq/dG9t+9L1b2B5CfH39K82nH/zsEPDeTuFjQU6fg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1778218842; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=O+6d2Z/XSrTuyiRKC/pSun27RX7Rr6HC92ayIRm1mRg=; b=7Q//fPzLD6gSYVlxn8yxrEBs1vjKwxiEA/D/UdOperEsAW0YeoSwphKF4V3Rx252ptOXmI t0/+u/8WRJ32NoCg== From: "tip-bot2 for Ingo Molnar" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/cpu] x86/fpu: Remove MATH_EMULATION and related glue code Cc: Ingo Molnar , Arnd Bergmann , Dave Hansen , Linus Torvalds , x86@kernel.org, linux-kernel@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <177821884071.864.13221211001264896976.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/cpu branch of tip: Commit-ID: ab05214025ee2af262591cd48df17883648bdb1a Gitweb: https://git.kernel.org/tip/ab05214025ee2af262591cd48df17883648= bdb1a Author: Ingo Molnar AuthorDate: Thu, 15 May 2025 10:28:27 +02:00 Committer: Ingo Molnar CommitterDate: Fri, 08 May 2026 07:33:03 +02:00 x86/fpu: Remove MATH_EMULATION and related glue code Now that support for 486 CPUs is gone upstream, remove the x86 mathemu code integration. Signed-off-by: Ingo Molnar Reviewed-by: Arnd Bergmann Acked-by: Dave Hansen Cc: Linus Torvalds 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 6865471..f67af15 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1633,33 +1633,6 @@ config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK Set whether the default state of memory_corruption_check is on or off. =20 -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 532cbc2..89cbf8f 100644 --- a/arch/x86/Kconfig.cpufeatures +++ b/arch/x86/Kconfig.cpufeatures @@ -70,7 +70,6 @@ config X86_REQUIRED_FEATURE_UP =20 config X86_REQUIRED_FEATURE_FPU def_bool y - depends on !MATH_EMULATION =20 config X86_REQUIRED_FEATURE_PAE def_bool y diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 46fec0b..96bfa13 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -276,7 +276,6 @@ archprepare: $(cpufeaturemasks.hdr) libs-y +=3D arch/x86/lib/ =20 # drivers-y are linked after core-y -drivers-$(CONFIG_MATH_EMULATION) +=3D arch/x86/math-emu/ drivers-$(CONFIG_PCI) +=3D arch/x86/pci/ =20 # suspend and hibernation support diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index cd6f194..90c63fe 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); =20 -#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 6089838..584fb99 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -558,11 +558,6 @@ static inline void fpstate_init_fstate(struct fpstate *f= pstate) */ 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); =20 if (cpu_feature_enabled(X86_FEATURE_FXSR)) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index ff988b9..0d33c21 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); =20 /* 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"); } =20 /* @@ -86,13 +81,11 @@ static void __init fpu__init_system_early_generic(void) setup_clear_cpu_cap(X86_FEATURE_FPU); } =20 -#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 } =20 /* diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 52177bc..30aa836 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1543,20 +1543,6 @@ DEFINE_IDTENTRY(exc_device_not_available) if (handle_xfd_event(regs)) return; =20 -#ifdef CONFIG_MATH_EMULATION - if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) { - struct math_emu_info info =3D { }; - - cond_local_irq_enable(regs); - - info.regs =3D 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. */