[PATCH] Remove safe_smp_processor_id()

And replace all users with ordinary smp_processor_id.  The function
was originally added to get some basic oops information out even
if the GS register was corrupted. However that didn't
work for some anymore because printk is needed to print the oops
and it uses smp_processor_id() already. Also GS register corruptions
are not particularly common anymore.

This also helps the Xen port which would otherwise need to
do this in a special way because it can't access the local APIC.

Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>

arch/x86_64/kernel/mce.c

@@ -182,7 +182,7 @@ void do_machine_check(struct pt_regs * regs, long error_code)
 		goto out2;
 
 	memset(&m, 0, sizeof(struct mce));
-	m.cpu = safe_smp_processor_id();
+	m.cpu = smp_processor_id();
 	rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
 	if (!(m.mcgstatus & MCG_STATUS_RIPV))
 		kill_it = 1;

arch/x86_64/kernel/smp.c

@@ -522,26 +522,3 @@ asmlinkage void smp_call_function_interrupt(void)
 	}
 }
 
-int safe_smp_processor_id(void)
-{
-	unsigned apicid, i;
-
-	if (disable_apic || !apic_mapped)
-		return 0;
-
-	apicid = hard_smp_processor_id();
-	if (apicid < NR_CPUS && x86_cpu_to_apicid[apicid] == apicid)
-		return apicid;
-
-	for (i = 0; i < NR_CPUS; ++i) {
-		if (x86_cpu_to_apicid[i] == apicid)
-			return i;
-	}
-
-	/* No entries in x86_cpu_to_apicid?  Either no MPS|ACPI,
-	 * or called too early.  Either way, we must be CPU 0. */
-      	if (x86_cpu_to_apicid[0] == BAD_APICID)
-		return 0;
-
-	return 0; /* Should not happen */
-}

arch/x86_64/kernel/traps.c

@@ -264,7 +264,7 @@ static int dump_trace_unwind(struct unwind_frame_info *info, void *context)
 void dump_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * stack,
 		struct stacktrace_ops *ops, void *data)
 {
-	const unsigned cpu = safe_smp_processor_id();
+	const unsigned cpu = smp_processor_id();
 	unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
 	unsigned used = 0;
 
@@ -429,7 +429,7 @@ _show_stack(struct task_struct *tsk, struct pt_regs *regs, unsigned long *rsp)
 {
 	unsigned long *stack;
 	int i;
-	const int cpu = safe_smp_processor_id();
+	const int cpu = smp_processor_id();
 	unsigned long *irqstack_end = (unsigned long *) (cpu_pda(cpu)->irqstackptr);
 	unsigned long *irqstack = (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);
 
@@ -483,7 +483,7 @@ void show_registers(struct pt_regs *regs)
 	int i;
 	int in_kernel = !user_mode(regs);
 	unsigned long rsp;
-	const int cpu = safe_smp_processor_id(); 
+	const int cpu = smp_processor_id();
 	struct task_struct *cur = cpu_pda(cpu)->pcurrent;
 
 		rsp = regs->rsp;
@@ -558,7 +558,7 @@ static unsigned int die_nest_count;
 
 unsigned __kprobes long oops_begin(void)
 {
-	int cpu = safe_smp_processor_id();
+	int cpu = smp_processor_id();
 	unsigned long flags;
 
 	oops_enter();
@@ -636,7 +636,7 @@ void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
 	 * We are in trouble anyway, lets at least try
 	 * to get a message out.
 	 */
-	printk(str, safe_smp_processor_id());
+	printk(str, smp_processor_id());
 	show_registers(regs);
 	if (kexec_should_crash(current))
 		crash_kexec(regs);

include/asm-x86_64/smp.h

@@ -66,7 +66,6 @@ static inline int hard_smp_processor_id(void)
 	return GET_APIC_ID(*(unsigned int *)(APIC_BASE+APIC_ID));
 }
 
-extern int safe_smp_processor_id(void);
 extern int __cpu_disable(void);
 extern void __cpu_die(unsigned int cpu);
 extern void prefill_possible_map(void);
@@ -100,7 +99,6 @@ static inline int cpu_present_to_apicid(int mps_cpu)
 
 #ifndef CONFIG_SMP
 #define stack_smp_processor_id() 0
-#define safe_smp_processor_id() 0
 #define cpu_logical_map(x) (x)
 #else
 #include <asm/thread_info.h>