x86/dumpstack: Fix printk_address for direct addresses

Consider a kernel crash in a module, simulated the following way:

static int my_init(void)
{
char *map = (void *)0x5;
*map = 3;
return 0;
}
module_init(my_init);

When we turn off FRAME_POINTERs, the very first instruction in
that function causes a BUG. The problem is that we print IP in
the BUG report using %pB (from printk_address). And %pB
decrements the pointer by one to fix printing addresses of
functions with tail calls.

This was added in commit 71f9e59800e5ad4 ("x86, dumpstack: Use
%pB format specifier for stack trace") to fix the call stack
printouts.

So instead of correct output:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
IP: [<ffffffffa01ac000>] my_init+0x0/0x10 [pb173]

We get:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
IP: [<ffffffffa0152000>] 0xffffffffa0151fff

To fix that, we use %pS only for stack addresses printouts (via
newly added printk_stack_address) and %pB for regs->ip (via
printk_address). I.e. we revert to the old behaviour for all
except call stacks. And since from all those reliable is 1, we
remove that parameter from printk_address.

Signed-off-by: Jiri Slaby <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/kdebug.h

···
 	DIE_NMIUNKNOWN,
 };
 
-extern void printk_address(unsigned long address, int reliable);
+extern void printk_address(unsigned long address);
 extern void die(const char *, struct pt_regs *,long);
 extern int __must_check __die(const char *, struct pt_regs *, long);
 extern void show_trace(struct task_struct *t, struct pt_regs *regs,

arch/x86/kernel/dumpstack.c

···
 int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
 static int die_counter;
 
-void printk_address(unsigned long address, int reliable)
+static void printk_stack_address(unsigned long address, int reliable)
 {
 	pr_cont(" [<%p>] %s%pB\n",
 		(void *)address, reliable ? "" : "? ", (void *)address);
+}
+
+void printk_address(unsigned long address)
+{
+	pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
 }
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
···
 {
 	touch_nmi_watchdog();
 	printk(data);
-	printk_address(addr, reliable);
+	printk_stack_address(addr, reliable);
 }
 
 static const struct stacktrace_ops print_trace_ops = {
···
 #else
 	/* Executive summary in case the oops scrolled away */
 	printk(KERN_ALERT "RIP ");
-	printk_address(regs->ip, 1);
+	printk_address(regs->ip);
 	printk(" RSP <%016lx>\n", regs->sp);
 #endif
 	return 0;

arch/x86/kernel/process_64.c

···
 	unsigned int ds, cs, es;
 
 	printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
-	printk_address(regs->ip, 1);
+	printk_address(regs->ip);
 	printk(KERN_DEFAULT "RSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss,
 			regs->sp, regs->flags);
 	printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",

arch/x86/mm/fault.c

···
 
 	printk(KERN_CONT " at %p\n", (void *) address);
 	printk(KERN_ALERT "IP:");
-	printk_address(regs->ip, 1);
+	printk_address(regs->ip);
 
 	dump_pagetable(address);
 }

arch/x86/platform/uv/uv_nmi.c

···
 	printk(KERN_DEFAULT "UV: %4d %6d %-32.32s ",
 		cpu, current->pid, current->comm);
 
-	printk_address(regs->ip, 1);
+	printk_address(regs->ip);
 }
 
 /* Dump this cpu's state */