arm64: __show_regs: strip PAC from lr in printk

lr is printed with %pS which will try to find an entry in kallsyms.
After enabling pointer authentication, this match will fail due to
PAC present in the lr.

Strip PAC from the lr to display the correct symbol name.
Suggested-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: NVincenzo Frascino <Vincenzo.Frascino@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/process.c

@@ -262,7 +262,7 @@ void __show_regs(struct pt_regs *regs)
 
 	if (!user_mode(regs)) {
 		printk("pc : %pS\n", (void *)regs->pc);
-		printk("lr : %pS\n", (void *)lr);
+		printk("lr : %pS\n", (void *)ptrauth_strip_insn_pac(lr));
 	} else {
 		printk("pc : %016llx\n", regs->pc);
 		printk("lr : %016llx\n", lr);