1 files changed, 115 insertions, 0 deletions
diff --git a/arch/mips/include/asm/dsemul.h b/arch/mips/include/asm/dsemul.h
new file mode 100644
index 000000000..08bfe8fa3
--- /dev/null
+++ b/arch/mips/include/asm/dsemul.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.com>
+ */
+
+#ifndef __MIPS_ASM_DSEMUL_H__
+#define __MIPS_ASM_DSEMUL_H__
+
+#include <asm/break.h>
+#include <asm/inst.h>
+
+/* Break instruction with special math emu break code set */
+#define BREAK_MATH(micromips)	(((micromips) ? 0x7 : 0xd) | (BRK_MEMU << 16))
+
+/* When used as a frame index, indicates the lack of a frame */
+#define BD_EMUFRAME_NONE	((int)BIT(31))
+
+struct mm_struct;
+struct pt_regs;
+struct task_struct;
+
+/**
+ * mips_dsemul() - 'Emulate' an instruction from a branch delay slot
+ * @regs:	User thread register context.
+ * @ir:		The instruction to be 'emulated'.
+ * @branch_pc:	The PC of the branch instruction.
+ * @cont_pc:	The PC to continue at following 'emulation'.
+ *
+ * Emulate or execute an arbitrary MIPS instruction within the context of
+ * the current user thread. This is used primarily to handle instructions
+ * in the delay slots of emulated branch instructions, for example FP
+ * branch instructions on systems without an FPU.
+ *
+ * Return: Zero on success, negative if ir is a NOP, signal number on failure.
+ */
+extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
+		       unsigned long branch_pc, unsigned long cont_pc);
+
+/**
+ * do_dsemulret() - Return from a delay slot 'emulation' frame
+ * @xcp:	User thread register context.
+ *
+ * Call in response to the BRK_MEMU break instruction used to return to
+ * the kernel from branch delay slot 'emulation' frames following a call
+ * to mips_dsemul(). Restores the user thread PC to the value that was
+ * passed as the cpc parameter to mips_dsemul().
+ *
+ * Return: True if an emulation frame was returned from, else false.
+ */
+#ifdef CONFIG_MIPS_FP_SUPPORT
+extern bool do_dsemulret(struct pt_regs *xcp);
+#else
+static inline bool do_dsemulret(struct pt_regs *xcp)
+{
+	return false;
+}
+#endif
+
+/**
+ * dsemul_thread_cleanup() - Cleanup thread 'emulation' frame
+ * @tsk: The task structure associated with the thread
+ *
+ * If the thread @tsk has a branch delay slot 'emulation' frame
+ * allocated to it then free that frame.
+ *
+ * Return: True if a frame was freed, else false.
+ */
+#ifdef CONFIG_MIPS_FP_SUPPORT
+extern bool dsemul_thread_cleanup(struct task_struct *tsk);
+#else
+static inline bool dsemul_thread_cleanup(struct task_struct *tsk)
+{
+	return false;
+}
+#endif
+/**
+ * dsemul_thread_rollback() - Rollback from an 'emulation' frame
+ * @regs:	User thread register context.
+ *
+ * If the current thread, whose register context is represented by @regs,
+ * is executing within a delay slot 'emulation' frame then exit that
+ * frame. The PC will be rolled back to the branch if the instruction
+ * that was being 'emulated' has not yet executed, or advanced to the
+ * continuation PC if it has.
+ *
+ * Return: True if a frame was exited, else false.
+ */
+#ifdef CONFIG_MIPS_FP_SUPPORT
+extern bool dsemul_thread_rollback(struct pt_regs *regs);
+#else
+static inline bool dsemul_thread_rollback(struct pt_regs *regs)
+{
+	return false;
+}
+#endif
+
+/**
+ * dsemul_mm_cleanup() - Cleanup per-mm delay slot 'emulation' state
+ * @mm:		The struct mm_struct to cleanup state for.
+ *
+ * Cleanup state for the given @mm, ensuring that any memory allocated
+ * for delay slot 'emulation' book-keeping is freed. This is to be called
+ * before @mm is freed in order to avoid memory leaks.
+ */
+#ifdef CONFIG_MIPS_FP_SUPPORT
+extern void dsemul_mm_cleanup(struct mm_struct *mm);
+#else
+static inline void dsemul_mm_cleanup(struct mm_struct *mm)
+{
+	/* no-op */
+}
+#endif
+
+#endif /* __MIPS_ASM_DSEMUL_H__ */