From nobody Sun Feb 8 12:36:44 2026 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 A2EA4238C25 for ; Fri, 25 Apr 2025 08:42:56 +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=1745570576; cv=none; b=UinnVVA2oCT3fw/2Q5jUjhtWTCxON8x3xsuRvizYrkAHRMGABy+Wl+NFGpQ1LJBl++aRLDx4nRnvLTuNyKFnWLtV1W+Gr4Vz5SAViGle2+HHTKmmSeI8E0BKhachPlY/lq+H5A63XPLJrkZdyuvYy17uAiUj2RFMFYj9KUn2W6Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745570576; c=relaxed/simple; bh=SX60kC/iqXz2oa2+SlcTIosGQupkYseFMYEmBsf6kzE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LYyjxxwMWyVkBu6Q9DYaobL+Tq7W+ORrwmHKoMmOcKFmnQgjEMToivqT2O59f7meiOkORDHQ+AzwtJwPOY3boaaDgcFxcIvYGQz3o00q/MpGnlVKhEk6hldV6iWdfreLqV3n8pxZqDTz4apskH6oc9MWI34QgtgjCT0hw1nBGj4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aZqQ6njr; 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="aZqQ6njr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 747C8C4CEEB; Fri, 25 Apr 2025 08:42:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745570576; bh=SX60kC/iqXz2oa2+SlcTIosGQupkYseFMYEmBsf6kzE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aZqQ6njrGYz3oREJOXH7zs4FgeqaYkLK4PxH3e4pBBIA8tpFoqB3/rTc3y3bRPG9F +Kc3R7HE1EjvIp+27nmo6+ayqjF9yNvaPl0RoClok8b4alY2lYCQmD6zMQyTB624PL iFs8RZh+Rqe4JLwk4yUXDDLxlok1wn3EZIBOL4rZbhEPSybZwzJJb2zMGSVcpKCtRz 8tVjcQ9mtdsTVZezu1cEVSwFY4c5N/fPMFgmIekeXimX2AKNlQYb5shmWfJy6lwjtP pyxVV0HOYTIcCkTfP1q3ViNhBRK8FhQyHJItjK3feeZHNoW1d1SJr/lfAeY7MpQjdW iPlsDIRkg47SQ== 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 Subject: [PATCH 08/15] x86/fpu: Remove MATH_EMULATION and related glue code Date: Fri, 25 Apr 2025 10:42:05 +0200 Message-ID: <20250425084216.3913608-9-mingo@kernel.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250425084216.3913608-1-mingo@kernel.org> References: <20250425084216.3913608-1-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: quoted-printable Content-Type: text/plain; charset="utf-8" Signed-off-by: Ingo Molnar --- 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 62a9db3efa93..cd9dd10b15d2 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1636,33 +1636,6 @@ 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 e12d5b7e39a2..cd551818f451 100644 --- a/arch/x86/Kconfig.cpufeatures +++ b/arch/x86/Kconfig.cpufeatures @@ -66,7 +66,6 @@ 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 594723005d95..15975f63952e 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -284,7 +284,6 @@ 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 f42de5f05e7e..def9f7261b0d 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(struct fpu *, fpu_fpregs_owner_ctx); =20 diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 91d6341f281f..59a4f430b46e 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -512,11 +512,6 @@ 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); =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 998a08f17e33..7f64d0677160 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)) - fpstate_init_soft(¤t->thread.fpu.fpstate->regs.soft); - else -#endif - asm volatile ("fninit"); + asm volatile ("fninit"); } =20 /* @@ -81,13 +76,11 @@ 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 8d5bbac04435..6467b7832fea 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1413,20 +1413,6 @@ 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. */ --=20 2.45.2