MIPS: Fix syscall tracing interface

Fix pointer computation for stack-based arguments.

Signed-off-by: Lars Persson <larper@axis.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6620/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/syscall.h

@@ -40,14 +40,14 @@ static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
 
 #ifdef CONFIG_32BIT
  case 4: case 5: case 6: case 7:
- return get_user(*arg, (int *)usp + 4 * n);
+ return get_user(*arg, (int *)usp + 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);
+ return get_user(*arg, (int *)usp + n);
  else
 #endif
  *arg = regs->regs[4 + n];