signal/powerpc: Specialize _exception_pkey for handling pkey exceptions

Now that _exception no longer calls _exception_pkey it is no longer
necessary to handle any signal with any si_code.  All pkey exceptions
are SIGSEGV with paired with SEGV_PKUERR.  So just handle
that case and remove the now unnecessary parameters from _exception_pkey.
Reviewed-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

arch/powerpc/include/asm/bug.h

@@ -133,7 +133,7 @@ struct pt_regs;
 extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);
 extern void bad_page_fault(struct pt_regs *, unsigned long, int);
 extern void _exception(int, struct pt_regs *, int, unsigned long);
-extern void _exception_pkey(int, struct pt_regs *, int, unsigned long, int);
+extern void _exception_pkey(struct pt_regs *, unsigned long, int);
 extern void die(const char *, struct pt_regs *, long);
 extern bool die_will_crash(void);
 extern void panic_flush_kmsg_start(void);

arch/powerpc/kernel/traps.c

@@ -362,20 +362,20 @@ static bool exception_common(int signr, struct pt_regs *regs, int code,
 	return true;
 }
 
-void _exception_pkey(int signr, struct pt_regs *regs, int code, unsigned long addr, int key)
+void _exception_pkey(struct pt_regs *regs, unsigned long addr, int key)
 {
 	siginfo_t info;
 
-	if (!exception_common(signr, regs, code, addr))
+	if (!exception_common(SIGSEGV, regs, SEGV_PKUERR, addr))
 		return;
 
 	clear_siginfo(&info);
-	info.si_signo = signr;
-	info.si_code = code;
+	info.si_signo = SIGSEGV;
+	info.si_code = SEGV_PKUERR;
 	info.si_addr = (void __user *) addr;
 	info.si_pkey = key;
 
-	force_sig_info(signr, &info, current);
+	force_sig_info(info.si_signo, &info, current);
 }
 
 void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)

arch/powerpc/mm/fault.c

@@ -152,7 +152,7 @@ static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address,
 	if (!user_mode(regs))
 		return SIGSEGV;
 
-	_exception_pkey(SIGSEGV, regs, SEGV_PKUERR, address, pkey);
+	_exception_pkey(regs, address, pkey);
 
 	return 0;
 }