parisc: define syscall_get_error()

syscall_get_error() is required to be implemented on all architectures in
addition to already implemented syscall_get_nr(), syscall_get_arguments(),
syscall_get_return_value(), and syscall_get_arch() functions in order to
extend the generic ptrace API with PTRACE_GET_SYSCALL_INFO request.

Link: http://lkml.kernel.org/r/20190510152812.GD28558@altlinux.org
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Acked-by: Helge Deller <deller@gmx.de>	[parisc]
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Elvira Khabirova <lineprinter@altlinux.org>
Cc: Eugene Syromyatnikov <esyr@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Greentime Hu <greentime@andestech.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: kbuild test robot <lkp@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/parisc/include/asm/syscall.h

@@ -29,6 +29,13 @@ static inline void syscall_get_arguments(struct task_struct *tsk,
 	args[0] = regs->gr[26];
 }
 
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->gr[28];
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
 static inline long syscall_get_return_value(struct task_struct *task,
 						struct pt_regs *regs)
 {