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x86/fpu: Don't export __kernel_fpu_{begin,end}()
[ Upstream commit12209993e9
] There is one user of __kernel_fpu_begin() and before invoking it, it invokes preempt_disable(). So it could invoke kernel_fpu_begin() right away. The 32bit version of arch_efi_call_virt_setup() and arch_efi_call_virt_teardown() does this already. The comment above *kernel_fpu*() claims that before invoking __kernel_fpu_begin() preemption should be disabled and that KVM is a good example of doing it. Well, KVM doesn't do that since commitf775b13eed
("x86,kvm: move qemu/guest FPU switching out to vcpu_run") so it is not an example anymore. With EFI gone as the last user of __kernel_fpu_{begin|end}(), both can be made static and not exported anymore. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Rik van Riel <riel@surriel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm ML <kvm@vger.kernel.org> Cc: linux-efi <linux-efi@vger.kernel.org> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20181129150210.2k4mawt37ow6c2vq@linutronix.de Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
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commit
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3 changed files with 9 additions and 18 deletions
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@ -82,8 +82,7 @@ struct efi_scratch {
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#define arch_efi_call_virt_setup() \
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({ \
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efi_sync_low_kernel_mappings(); \
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preempt_disable(); \
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__kernel_fpu_begin(); \
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kernel_fpu_begin(); \
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firmware_restrict_branch_speculation_start(); \
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\
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if (efi_scratch.use_pgd) { \
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@ -104,8 +103,7 @@ struct efi_scratch {
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} \
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\
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firmware_restrict_branch_speculation_end(); \
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__kernel_fpu_end(); \
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preempt_enable(); \
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kernel_fpu_end(); \
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})
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extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size,
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@ -12,17 +12,12 @@
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#define _ASM_X86_FPU_API_H
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/*
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* Careful: __kernel_fpu_begin/end() must be called with preempt disabled
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* and they don't touch the preempt state on their own.
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* If you enable preemption after __kernel_fpu_begin(), preempt notifier
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* should call the __kernel_fpu_end() to prevent the kernel/user FPU
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* state from getting corrupted. KVM for example uses this model.
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*
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* All other cases use kernel_fpu_begin/end() which disable preemption
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* during kernel FPU usage.
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* Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
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* disables preemption so be careful if you intend to use it for long periods
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* of time.
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* If you intend to use the FPU in softirq you need to check first with
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* irq_fpu_usable() if it is possible.
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*/
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extern void __kernel_fpu_begin(void);
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extern void __kernel_fpu_end(void);
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extern void kernel_fpu_begin(void);
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extern void kernel_fpu_end(void);
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extern bool irq_fpu_usable(void);
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@ -93,7 +93,7 @@ bool irq_fpu_usable(void)
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}
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EXPORT_SYMBOL(irq_fpu_usable);
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void __kernel_fpu_begin(void)
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static void __kernel_fpu_begin(void)
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{
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struct fpu *fpu = ¤t->thread.fpu;
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@ -111,9 +111,8 @@ void __kernel_fpu_begin(void)
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__cpu_invalidate_fpregs_state();
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}
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}
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EXPORT_SYMBOL(__kernel_fpu_begin);
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void __kernel_fpu_end(void)
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static void __kernel_fpu_end(void)
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{
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struct fpu *fpu = ¤t->thread.fpu;
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@ -122,7 +121,6 @@ void __kernel_fpu_end(void)
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kernel_fpu_enable();
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}
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EXPORT_SYMBOL(__kernel_fpu_end);
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void kernel_fpu_begin(void)
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{
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