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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/include/asm/i387.h
Initial import
Diffstat (limited to 'arch/x86/include/asm/i387.h')
-rw-r--r--arch/x86/include/asm/i387.h108
1 files changed, 108 insertions, 0 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
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+++ b/arch/x86/include/asm/i387.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 1994 Linus Torvalds
+ *
+ * Pentium III FXSR, SSE support
+ * General FPU state handling cleanups
+ * Gareth Hughes <gareth@valinux.com>, May 2000
+ * x86-64 work by Andi Kleen 2002
+ */
+
+#ifndef _ASM_X86_I387_H
+#define _ASM_X86_I387_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/sched.h>
+#include <linux/hardirq.h>
+
+struct pt_regs;
+struct user_i387_struct;
+
+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);
+
+extern bool irq_fpu_usable(void);
+
+/*
+ * Careful: __kernel_fpu_begin/end() must be called with preempt disabled
+ * and they don't touch the preempt state on their own.
+ * If you enable preemption after __kernel_fpu_begin(), preempt notifier
+ * should call the __kernel_fpu_end() to prevent the kernel/user FPU
+ * state from getting corrupted. KVM for example uses this model.
+ *
+ * All other cases use kernel_fpu_begin/end() which disable preemption
+ * during kernel FPU usage.
+ */
+extern void __kernel_fpu_begin(void);
+extern void __kernel_fpu_end(void);
+
+static inline void kernel_fpu_begin(void)
+{
+ preempt_disable();
+ WARN_ON_ONCE(!irq_fpu_usable());
+ __kernel_fpu_begin();
+}
+
+static inline void kernel_fpu_end(void)
+{
+ __kernel_fpu_end();
+ preempt_enable();
+}
+
+/* Must be called with preempt disabled */
+extern void kernel_fpu_disable(void);
+extern void kernel_fpu_enable(void);
+
+/*
+ * Some instructions like VIA's padlock instructions generate a spurious
+ * DNA fault but don't modify SSE registers. And these instructions
+ * get used from interrupt context as well. To prevent these kernel instructions
+ * in interrupt context interacting wrongly with other user/kernel fpu usage, we
+ * should use them only in the context of irq_ts_save/restore()
+ */
+static inline int irq_ts_save(void)
+{
+ /*
+ * If in process context and not atomic, we can take a spurious DNA fault.
+ * Otherwise, doing clts() in process context requires disabling preemption
+ * or some heavy lifting like kernel_fpu_begin()
+ */
+ if (!in_atomic())
+ return 0;
+
+ if (read_cr0() & X86_CR0_TS) {
+ clts();
+ return 1;
+ }
+
+ return 0;
+}
+
+static inline void irq_ts_restore(int TS_state)
+{
+ if (TS_state)
+ stts();
+}
+
+/*
+ * The question "does this thread have fpu access?"
+ * is slightly racy, since preemption could come in
+ * and revoke it immediately after the test.
+ *
+ * However, even in that very unlikely scenario,
+ * we can just assume we have FPU access - typically
+ * to save the FP state - we'll just take a #NM
+ * fault and get the FPU access back.
+ */
+static inline int user_has_fpu(void)
+{
+ return current->thread.fpu.has_fpu;
+}
+
+extern void unlazy_fpu(struct task_struct *tsk);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_I387_H */