Blackfin: initial tracehook support

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/syscall.h

@@ -0,0 +1,96 @@
+/*
+ * Magic syscall break down functions
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef __ASM_BLACKFIN_SYSCALL_H__
+#define __ASM_BLACKFIN_SYSCALL_H__
+
+/*
+ * Blackfin syscalls are simple:
+ *	enter:
+ *		p0: syscall number
+ *		r{0,1,2,3,4,5}: syscall args 0,1,2,3,4,5
+ *	exit:
+ *		r0: return/error value
+ */
+
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <asm/ptrace.h>
+
+static inline long
+syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
+{
+	return regs->p0;
+}
+
+static inline void
+syscall_rollback(struct task_struct *task, struct pt_regs *regs)
+{
+	regs->p0 = regs->orig_p0;
+}
+
+static inline long
+syscall_get_error(struct task_struct *task, struct pt_regs *regs)
+{
+	return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
+}
+
+static inline long
+syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
+{
+	return regs->r0;
+}
+
+static inline void
+syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
+                         int error, long val)
+{
+	regs->r0 = error ? -error : val;
+}
+
+/**
+ *	syscall_get_arguments()
+ *	@task:   unused
+ *	@regs:   the register layout to extract syscall arguments from
+ *	@i:      first syscall argument to extract
+ *	@n:      number of syscall arguments to extract
+ *	@args:   array to return the syscall arguments in
+ *
+ * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
+ */
+static inline void
+syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
+                      unsigned int i, unsigned int n, unsigned long *args)
+{
+	/*
+	 * Assume the ptrace layout doesn't change -- r5 is first in memory,
+	 * then r4, ..., then r0.  So we simply reverse the ptrace register
+	 * array in memory to store into the args array.
+	 */
+	long *aregs = &regs->r0 - i;
+
+	BUG_ON(i > 5 || i + n > 6);
+
+	while (n--)
+		*args++ = *aregs--;
+}
+
+/* See syscall_get_arguments() comments */
+static inline void
+syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
+                      unsigned int i, unsigned int n, const unsigned long *args)
+{
+	long *aregs = &regs->r0 - i;
+
+	BUG_ON(i > 5 || i + n > 6);
+
+	while (n--)
+		*aregs-- = *args++;
+}
+
+#endif