syscall_get_arch: add "struct task_struct *" argument

This argument is required to extend the generic ptrace API with
PTRACE_GET_SYSCALL_INFO request: syscall_get_arch() is going
to be called from ptrace_request() along with syscall_get_nr(),
syscall_get_arguments(), syscall_get_error(), and
syscall_get_return_value() functions with a tracee as their argument.

The primary intent is that the triple (audit_arch, syscall_nr, arg1..arg6)
should describe what system call is being called and what its arguments
are.

Reverts: 5e937a9ae9 ("syscall_get_arch: remove useless function arguments")
Reverts: 1002d94d30 ("syscall.h: fix doc text for syscall_get_arch()")
Reviewed-by: Andy Lutomirski <[email protected]> # for x86
Reviewed-by: Palmer Dabbelt <[email protected]>
Acked-by: Paul Moore <[email protected]>
Acked-by: Paul Burton <[email protected]> # MIPS parts
Acked-by: Michael Ellerman <[email protected]> (powerpc)
Acked-by: Kees Cook <[email protected]> # seccomp parts
Acked-by: Mark Salter <[email protected]> # for the c6x bit
Cc: Elvira Khabirova <[email protected]>
Cc: Eugene Syromyatnikov <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Dmitry V. Levin <[email protected]>
Signed-off-by: Paul Moore <[email protected]>

arch/openrisc/include/asm/syscall.h

@@ -72,7 +72,7 @@ syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 	memcpy(&regs->gpr[3 + i], args, n * sizeof(args[0]));
 }
 
-static inline int syscall_get_arch(void)
+static inline int syscall_get_arch(struct task_struct *task)
 {
 	return AUDIT_ARCH_OPENRISC;
 }