github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-28 01:55:51 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

x86/fpu: Remove MATH_EMULATION and related glue code

Browse Source 
Now that support for 486 CPUs is gone upstream, remove
the x86 mathemu code integration.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250425084216.3913608-9-mingo@kernel.org
This commit is contained in:
Ingo Molnar 2025-05-15 10:28:27 +02:00
parent 7b49a3fb69
commit ab05214025
7 changed files with 1 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
arch/x86/Kconfig
View File

@ -1633,33 +1633,6 @@ 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 <file:arch/x86/math-emu/README>.
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

1
arch/x86/Kconfig.cpufeatures
View File

@ -70,7 +70,6 @@ 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

1
arch/x86/Makefile
View File

@ -276,7 +276,6 @@ 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

6
arch/x86/include/asm/fpu/api.h
View File

@ -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);

5
arch/x86/kernel/fpu/core.c
View File

@ -558,11 +558,6 @@ 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))

9
arch/x86/kernel/fpu/init.c
View File

@ -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
}
/*

14
arch/x86/kernel/traps.c
View File

@ -1543,20 +1543,6 @@ 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. */