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x86/fpu: Provide a proper function for ex_handler_fprestore()

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To make upcoming changes for support of dynamically enabled features
simpler, provide a proper function for the exception handler which removes
exposure of FPU internals.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011540.053515012@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-10-15 03:16:41 +02:00 committed by Borislav Petkov
parent b56d2795b2
commit 079ec41b22
4 changed files with 10 additions and 6 deletions
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4
arch/x86/include/asm/fpu/api.h
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@ -113,6 +113,7 @@ static inline void update_pasid(void) { }
/* Trap handling */
extern int fpu__exception_code(struct fpu *fpu, int trap_nr);
extern void fpu_sync_fpstate(struct fpu *fpu);
extern void fpu_reset_from_exception_fixup(void);
/* Boot, hotplug and resume */
extern void fpu__init_cpu(void);
@ -129,9 +130,6 @@ static inline void fpstate_init_soft(struct swregs_state *soft) {}
/* State tracking */
DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
/* fpstate */
extern union fpregs_state init_fpstate;
/* fpstate-related functions which are exported to KVM */
extern void fpu_init_fpstate_user(struct fpu *fpu);

5
arch/x86/kernel/fpu/core.c
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@ -155,6 +155,11 @@ void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
}
}
void fpu_reset_from_exception_fixup(void)
{
restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());
}
#if IS_ENABLED(CONFIG_KVM)
void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask)
{

2
arch/x86/kernel/fpu/internal.h
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@ -2,6 +2,8 @@
#ifndef __X86_KERNEL_FPU_INTERNAL_H
#define __X86_KERNEL_FPU_INTERNAL_H
extern union fpregs_state init_fpstate;
/* CPU feature check wrappers */
static __always_inline __pure bool use_xsave(void)
{

5
arch/x86/mm/extable.c
View File

@ -4,8 +4,7 @@
#include <linux/sched/debug.h>
#include <xen/xen.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/xstate.h>
#include <asm/fpu/api.h>
#include <asm/sev.h>
#include <asm/traps.h>
#include <asm/kdebug.h>
@ -48,7 +47,7 @@ static bool ex_handler_fprestore(const struct exception_table_entry *fixup,
WARN_ONCE(1, "Bad FPU state detected at %pB, reinitializing FPU registers.",
(void *)instruction_pointer(regs));
restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());
fpu_reset_from_exception_fixup();
return true;
}