MIPS: Enable HAVE_ARCH_TRACEHOOK.

This enables /proc/<pid>/syscall and the ptrace PTRACE_GETREGSET and
PTRACE_SETREGSET operations.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 67 insertions, 0 deletions

diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index ab5effdc935d..00f2ffaaf293 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -1,14 +1,81 @@
 /*
+ * Access to user system call parameters and results
+ *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ *
  * Copyright (C) 2012 Ralf Baechle <ralf@linux-mips.org>
  */
 
 #ifndef __ASM_MIPS_SYSCALL_H
 #define __ASM_MIPS_SYSCALL_H
 
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <asm/ptrace.h>
+
+static inline long syscall_get_nr(struct task_struct *task,
+                                  struct pt_regs *regs)
+{
+        return regs->regs[2];
+}
+
+static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
+        struct task_struct *task, struct pt_regs *regs, unsigned int n)
+{
+        unsigned long usp = regs->regs[29];
+
+        switch (n) {
+        case 0: case 1: case 2: case 3:
+                *arg = regs->regs[4 + n];
+
+                return 0;
+
+#ifdef CONFIG_32BIT
+        case 4: case 5: case 6: case 7:
+                return get_user(*arg, (int *)usp + 4 * n);
+#endif
+
+#ifdef CONFIG_64BIT
+        case 4: case 5: case 6: case 7:
+#ifdef CONFIG_MIPS32_O32
+                if (test_thread_flag(TIF_32BIT_REGS))
+                        return get_user(*arg, (int *)usp + 4 * n);
+                else
+#endif
+                        *arg = regs->regs[4 + n];
+
+                return 0;
+#endif
+
+        default:
+                BUG();
+        }
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+                                         struct pt_regs *regs,
+                                         unsigned int i, unsigned int n,
+                                         unsigned long *args)
+{
+        unsigned long arg;
+        int ret;
+
+        while (n--)
+                ret |= mips_get_syscall_arg(&arg, task, regs, i++);
+
+        /*
+         * No way to communicate an error because this is a void function.
+         */
+#if 0
+        return ret;
+#endif
+}
+
 extern const unsigned long sys_call_table[];
 extern const unsigned long sys32_call_table[];
 extern const unsigned long sysn32_call_table[];