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Subject[tip: x86/fpu] x86/fpu: Provide a proper function for ex_handler_fprestore()
The following commit has been merged into the x86/fpu branch of tip:

Commit-ID: 079ec41b22b952cdf3126527d735e373c9125f6d
Gitweb: https://git.kernel.org/tip/079ec41b22b952cdf3126527d735e373c9125f6d
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 15 Oct 2021 03:16:41 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 20 Oct 2021 15:27:29 +02:00

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

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
---
arch/x86/include/asm/fpu/api.h | 4 +---
arch/x86/kernel/fpu/core.c | 5 +++++
arch/x86/kernel/fpu/internal.h | 2 ++
arch/x86/mm/extable.c | 5 ++---
4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index c691f07..9263d70 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -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);

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 9bb0c1c..79f2e8d 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -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)
{
diff --git a/arch/x86/kernel/fpu/internal.h b/arch/x86/kernel/fpu/internal.h
index bd7f813..479f2db 100644
--- a/arch/x86/kernel/fpu/internal.h
+++ b/arch/x86/kernel/fpu/internal.h
@@ -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)
{
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 79c2e30..5cd2a88 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -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;
}

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