From 6dd677a044e606fd343e31c2108b13d74aec1ca5 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 3 Apr 2019 18:41:31 +0200 Subject: [PATCH] x86/fpu: Remove fpu__restore() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are no users of fpu__restore() so it is time to remove it. The comment regarding fpu__restore() and TS bit is stale since commit b3b0870ef3ffe ("i387: do not preload FPU state at task switch time") and has no meaning since. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Aubrey Li Cc: Babu Moger Cc: "Chang S. Bae" Cc: Dmitry Safonov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jann Horn Cc: "Jason A. Donenfeld" Cc: Joerg Roedel Cc: Jonathan Corbet Cc: kvm ML Cc: linux-doc@vger.kernel.org Cc: Nicolai Stange Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Rik van Riel Cc: x86-ml Link: https://lkml.kernel.org/r/20190403164156.19645-3-bigeasy@linutronix.de --- Documentation/preempt-locking.txt | 1 - arch/x86/include/asm/fpu/internal.h | 1 - arch/x86/kernel/fpu/core.c | 24 ------------------------ arch/x86/kernel/process_32.c | 4 +--- arch/x86/kernel/process_64.c | 4 +--- 5 files changed, 2 insertions(+), 32 deletions(-) diff --git a/Documentation/preempt-locking.txt b/Documentation/preempt-locking.txt index 509f5a422d57..dce336134e54 100644 --- a/Documentation/preempt-locking.txt +++ b/Documentation/preempt-locking.txt @@ -52,7 +52,6 @@ preemption must be disabled around such regions. Note, some FPU functions are already explicitly preempt safe. For example, kernel_fpu_begin and kernel_fpu_end will disable and enable preemption. -However, fpu__restore() must be called with preemption disabled. RULE #3: Lock acquire and release must be performed by same task diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index fb04a3ded7dd..75a1d5f712ee 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -28,7 +28,6 @@ extern void fpu__initialize(struct fpu *fpu); extern void fpu__prepare_read(struct fpu *fpu); extern void fpu__prepare_write(struct fpu *fpu); extern void fpu__save(struct fpu *fpu); -extern void fpu__restore(struct fpu *fpu); extern int fpu__restore_sig(void __user *buf, int ia32_frame); extern void fpu__drop(struct fpu *fpu); extern int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu); diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 2e5003fef51a..1d3ae7988f7f 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -303,30 +303,6 @@ void fpu__prepare_write(struct fpu *fpu) } } -/* - * 'fpu__restore()' is called to copy FPU registers from - * the FPU fpstate to the live hw registers and to activate - * access to the hardware registers, so that FPU instructions - * can be used afterwards. - * - * Must be called with kernel preemption disabled (for example - * with local interrupts disabled, as it is in the case of - * do_device_not_available()). - */ -void fpu__restore(struct fpu *fpu) -{ - fpu__initialize(fpu); - - /* Avoid __kernel_fpu_begin() right after fpregs_activate() */ - kernel_fpu_disable(); - trace_x86_fpu_before_restore(fpu); - fpregs_activate(fpu); - copy_kernel_to_fpregs(&fpu->state); - trace_x86_fpu_after_restore(fpu); - kernel_fpu_enable(); -} -EXPORT_SYMBOL_GPL(fpu__restore); - /* * Drops current FPU state: deactivates the fpregs and * the fpstate. NOTE: it still leaves previous contents diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index e471d8e6f0b2..7888a41a03cd 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -267,9 +267,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) /* * Leave lazy mode, flushing any hypercalls made here. * This must be done before restoring TLS segments so - * the GDT and LDT are properly updated, and must be - * done before fpu__restore(), so the TS bit is up - * to date. + * the GDT and LDT are properly updated. */ arch_end_context_switch(next_p); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 6a62f4af9fcf..e1983b3a16c4 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -538,9 +538,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) /* * Leave lazy mode, flushing any hypercalls made here. This * must be done after loading TLS entries in the GDT but before - * loading segments that might reference them, and and it must - * be done before fpu__restore(), so the TS bit is up to - * date. + * loading segments that might reference them. */ arch_end_context_switch(next_p);