Commit 97185c95 authored by Ingo Molnar's avatar Ingo Molnar

x86/fpu: Split an fpstate_alloc_init() function out of init_fpu()

Most init_fpu() users don't want the register-saving aspect of the
function, they are calling it for 'current' and when FPU registers
are not allocated and initialized yet.

Split out a simplified API that does just that (and add debug-checks
for these conditions): fpstate_alloc_init().

Use it where appropriate.
Reviewed-by: default avatarBorislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 68ad8b9f
......@@ -18,7 +18,10 @@
struct pt_regs;
struct user_i387_struct;
extern int fpstate_alloc_init(struct task_struct *curr);
extern int init_fpu(struct task_struct *child);
extern void fpu_finit(struct fpu *fpu);
extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
extern void math_state_restore(void);
......
......@@ -246,6 +246,37 @@ void fpu_finit(struct fpu *fpu)
}
EXPORT_SYMBOL_GPL(fpu_finit);
/*
* Allocate the backing store for the current task's FPU registers
* and initialize the registers themselves as well.
*
* Can fail.
*/
int fpstate_alloc_init(struct task_struct *curr)
{
int ret;
if (WARN_ON_ONCE(curr != current))
return -EINVAL;
if (WARN_ON_ONCE(curr->flags & PF_USED_MATH))
return -EINVAL;
/*
* Memory allocation at the first usage of the FPU and other state.
*/
ret = fpu_alloc(&curr->thread.fpu);
if (ret)
return ret;
fpu_finit(&curr->thread.fpu);
/* Safe to do for the current task: */
curr->flags |= PF_USED_MATH;
return 0;
}
EXPORT_SYMBOL_GPL(fpstate_alloc_init);
/*
* The _current_ task is using the FPU for the first time
* so initialize it and set the mxcsr to its default
......
......@@ -159,7 +159,7 @@ void flush_thread(void)
} else {
if (!tsk_used_math(tsk)) {
/* kthread execs. TODO: cleanup this horror. */
if (WARN_ON(init_fpu(tsk)))
if (WARN_ON(fpstate_alloc_init(tsk)))
force_sig(SIGKILL, tsk);
user_fpu_begin();
}
......
......@@ -846,7 +846,7 @@ void math_state_restore(void)
/*
* does a slab alloc which can sleep
*/
if (init_fpu(tsk)) {
if (fpstate_alloc_init(tsk)) {
/*
* ran out of memory!
*/
......
......@@ -349,7 +349,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
if (!access_ok(VERIFY_READ, buf, size))
return -EACCES;
if (!used_math() && init_fpu(tsk))
if (!used_math() && fpstate_alloc_init(tsk))
return -1;
if (!static_cpu_has(X86_FEATURE_FPU))
......
......@@ -6600,7 +6600,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
int r;
sigset_t sigsaved;
if (!tsk_used_math(current) && init_fpu(current))
if (!tsk_used_math(current) && fpstate_alloc_init(current))
return -ENOMEM;
if (vcpu->sigset_active)
......
......@@ -149,7 +149,7 @@ void math_emulate(struct math_emu_info *info)
struct desc_struct code_descriptor;
if (!used_math()) {
if (init_fpu(current)) {
if (fpstate_alloc_init(current)) {
do_group_exit(SIGKILL);
return;
}
......
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