Merge branch 'kexec' into next

arch/powerpc/include/asm/kexec.h

@@ -49,7 +49,6 @@
 #define KEXEC_STATE_REAL_MODE 2
 
 #ifndef __ASSEMBLY__
-#include <linux/cpumask.h>
 #include <asm/reg.h>
 
 typedef void (*crash_shutdown_t)(void);
@@ -73,11 +72,6 @@ extern void kexec_smp_wait(void);	/* get and clear naca physid, wait for
 					  master to copy new code to 0 */
 extern int crashing_cpu;
 extern void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *));
-extern cpumask_t cpus_in_sr;
-static inline int kexec_sr_activated(int cpu)
-{
-	return cpumask_test_cpu(cpu, &cpus_in_sr);
-}
 
 struct kimage;
 struct pt_regs;
@@ -94,7 +88,6 @@ extern void reserve_crashkernel(void);
 extern void machine_kexec_mask_interrupts(void);
 
 #else /* !CONFIG_KEXEC */
-static inline int kexec_sr_activated(int cpu) { return 0; }
 static inline void crash_kexec_secondary(struct pt_regs *regs) { }
 
 static inline int overlaps_crashkernel(unsigned long start, unsigned long size)

arch/powerpc/include/asm/system.h

@@ -193,8 +193,8 @@ extern void cacheable_memzero(void *p, unsigned int nb);
 extern void *cacheable_memcpy(void *, const void *, unsigned int);
 extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);
 extern void bad_page_fault(struct pt_regs *, unsigned long, int);
-extern int die(const char *, struct pt_regs *, long);
 extern void _exception(int, struct pt_regs *, int, unsigned long);
+extern void die(const char *, struct pt_regs *, long);
 extern void _nmask_and_or_msr(unsigned long nmask, unsigned long or_val);
 
 #ifdef CONFIG_BOOKE_WDT

arch/powerpc/kernel/crash.c

@@ -10,85 +10,85 @@
  *
  */
 
-#undef DEBUG
-
 #include <linux/kernel.h>
 #include <linux/smp.h>
 #include <linux/reboot.h>
 #include <linux/kexec.h>
-#include <linux/bootmem.h>
 #include <linux/export.h>
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
-#include <linux/elf.h>
-#include <linux/elfcore.h>
 #include <linux/init.h>
 #include <linux/irq.h>
 #include <linux/types.h>
-#include <linux/memblock.h>
 
 #include <asm/processor.h>
 #include <asm/machdep.h>
 #include <asm/kexec.h>
 #include <asm/kdump.h>
 #include <asm/prom.h>
-#include <asm/firmware.h>
 #include <asm/smp.h>
 #include <asm/system.h>
 #include <asm/setjmp.h>
 
-#ifdef DEBUG
-#include <asm/udbg.h>
-#define DBG(fmt...) udbg_printf(fmt)
-#else
-#define DBG(fmt...)
-#endif
+/*
+ * The primary CPU waits a while for all secondary CPUs to enter. This is to
+ * avoid sending an IPI if the secondary CPUs are entering
+ * crash_kexec_secondary on their own (eg via a system reset).
+ *
+ * The secondary timeout has to be longer than the primary. Both timeouts are
+ * in milliseconds.
+ */
+#define PRIMARY_TIMEOUT		500
+#define SECONDARY_TIMEOUT	1000
 
-/* This keeps a track of which one is crashing cpu. */
+#define IPI_TIMEOUT		10000
+#define REAL_MODE_TIMEOUT	10000
+
+/* This keeps a track of which one is the crashing cpu. */
 int crashing_cpu = -1;
-static cpumask_t cpus_in_crash = CPU_MASK_NONE;
-cpumask_t cpus_in_sr = CPU_MASK_NONE;
+static atomic_t cpus_in_crash;
+static int time_to_dump;
 
 #define CRASH_HANDLER_MAX 3
 /* NULL terminated list of shutdown handles */
 static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
 static DEFINE_SPINLOCK(crash_handlers_lock);
 
+static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
+static int crash_shutdown_cpu = -1;
+
+static int handle_fault(struct pt_regs *regs)
+{
+	if (crash_shutdown_cpu == smp_processor_id())
+		longjmp(crash_shutdown_buf, 1);
+	return 0;
+}
+
 #ifdef CONFIG_SMP
-static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
 
 void crash_ipi_callback(struct pt_regs *regs)
 {
+	static cpumask_t cpus_state_saved = CPU_MASK_NONE;
+
 	int cpu = smp_processor_id();
 
 	if (!cpu_online(cpu))
 		return;
 
 	hard_irq_disable();
-	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
+	if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
 		crash_save_cpu(regs, cpu);
-	cpumask_set_cpu(cpu, &cpus_in_crash);
-
-	/*
-	 * Entered via soft-reset - could be the kdump
-	 * process is invoked using soft-reset or user activated
-	 * it if some CPU did not respond to an IPI.
-	 * For soft-reset, the secondary CPU can enter this func
-	 * twice. 1 - using IPI, and 2. soft-reset.
-	 * Tell the kexec CPU that entered via soft-reset and ready
-	 * to go down.
-	 */
-	if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
-		cpumask_clear_cpu(cpu, &cpus_in_sr);
-		atomic_inc(&enter_on_soft_reset);
+		cpumask_set_cpu(cpu, &cpus_state_saved);
 	}
 
+	atomic_inc(&cpus_in_crash);
+	smp_mb__after_atomic_inc();
+
 	/*
 	 * Starting the kdump boot.
 	 * This barrier is needed to make sure that all CPUs are stopped.
-	 * If not, soft-reset will be invoked to bring other CPUs.
 	 */
-	while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
+	while (!time_to_dump)
 		cpu_relax();
 
 	if (ppc_md.kexec_cpu_down)
@@ -103,106 +103,99 @@ void crash_ipi_callback(struct pt_regs *regs)
 	/* NOTREACHED */
 }
 
-/*
- * Wait until all CPUs are entered via soft-reset.
- */
-static void crash_soft_reset_check(int cpu)
-{
-	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
-
-	cpumask_clear_cpu(cpu, &cpus_in_sr);
-	while (atomic_read(&enter_on_soft_reset) != ncpus)
-		cpu_relax();
-}
-
-
 static void crash_kexec_prepare_cpus(int cpu)
 {
 	unsigned int msecs;
-
 	unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+	int tries = 0;
+	int (*old_handler)(struct pt_regs *regs);
+
+	printk(KERN_EMERG "Sending IPI to other CPUs\n");
 
 	crash_send_ipi(crash_ipi_callback);
 	smp_wmb();
 
+again:
 	/*
 	 * FIXME: Until we will have the way to stop other CPUs reliably,
 	 * the crash CPU will send an IPI and wait for other CPUs to
 	 * respond.
-	 * Delay of at least 10 seconds.
 	 */
-	printk(KERN_EMERG "Sending IPI to other cpus...\n");
-	msecs = 10000;
-	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
-		cpu_relax();
+	msecs = IPI_TIMEOUT;
+	while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
 		mdelay(1);
-	}
 
 	/* Would it be better to replace the trap vector here? */
 
+	if (atomic_read(&cpus_in_crash) >= ncpus) {
+		printk(KERN_EMERG "IPI complete\n");
+		return;
+	}
+
+	printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
+		ncpus - atomic_read(&cpus_in_crash));
+
 	/*
-	 * FIXME: In case if we do not get all CPUs, one possibility: ask the
-	 * user to do soft reset such that we get all.
-	 * Soft-reset will be used until better mechanism is implemented.
+	 * If we have a panic timeout set then we can't wait indefinitely
+	 * for someone to activate system reset. We also give up on the
+	 * second time through if system reset fail to work.
 	 */
-	if (cpumask_weight(&cpus_in_crash) < ncpus) {
-		printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
-			ncpus - cpumask_weight(&cpus_in_crash));
-		printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
-		cpumask_clear(&cpus_in_sr);
-		atomic_set(&enter_on_soft_reset, 0);
-		while (cpumask_weight(&cpus_in_crash) < ncpus)
-			cpu_relax();
-	}
+	if ((panic_timeout > 0) || (tries > 0))
+		return;
+
 	/*
-	 * Make sure all CPUs are entered via soft-reset if the kdump is
-	 * invoked using soft-reset.
+	 * A system reset will cause all CPUs to take an 0x100 exception.
+	 * The primary CPU returns here via setjmp, and the secondary
+	 * CPUs reexecute the crash_kexec_secondary path.
 	 */
-	if (cpumask_test_cpu(cpu, &cpus_in_sr))
-		crash_soft_reset_check(cpu);
-	/* Leave the IPI callback set */
+	old_handler = __debugger;
+	__debugger = handle_fault;
+	crash_shutdown_cpu = smp_processor_id();
+
+	if (setjmp(crash_shutdown_buf) == 0) {
+		printk(KERN_EMERG "Activate system reset (dumprestart) "
+				  "to stop other cpu(s)\n");
+
+		/*
+		 * A system reset will force all CPUs to execute the
+		 * crash code again. We need to reset cpus_in_crash so we
+		 * wait for everyone to do this.
+		 */
+		atomic_set(&cpus_in_crash, 0);
+		smp_mb();
+
+		while (atomic_read(&cpus_in_crash) < ncpus)
+			cpu_relax();
+	}
+
+	crash_shutdown_cpu = -1;
+	__debugger = old_handler;
+
+	tries++;
+	goto again;
 }
 
 /*
- * This function will be called by secondary cpus or by kexec cpu
- * if soft-reset is activated to stop some CPUs.
+ * This function will be called by secondary cpus.
  */
 void crash_kexec_secondary(struct pt_regs *regs)
 {
-	int cpu = smp_processor_id();
 	unsigned long flags;
-	int msecs = 5;
+	int msecs = SECONDARY_TIMEOUT;
 
 	local_irq_save(flags);
-	/* Wait 5ms if the kexec CPU is not entered yet. */
+
+	/* Wait for the primary crash CPU to signal its progress */
 	while (crashing_cpu < 0) {
 		if (--msecs < 0) {
-			/*
-			 * Either kdump image is not loaded or
-			 * kdump process is not started - Probably xmon
-			 * exited using 'x'(exit and recover) or
-			 * kexec_should_crash() failed for all running tasks.
-			 */
-			cpumask_clear_cpu(cpu, &cpus_in_sr);
+			/* No response, kdump image may not have been loaded */
 			local_irq_restore(flags);
 			return;
 		}
+
 		mdelay(1);
-		cpu_relax();
-	}
-	if (cpu == crashing_cpu) {
-		/*
-		 * Panic CPU will enter this func only via soft-reset.
-		 * Wait until all secondary CPUs entered and
-		 * then start kexec boot.
-		 */
-		crash_soft_reset_check(cpu);
-		cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
-		if (ppc_md.kexec_cpu_down)
-			ppc_md.kexec_cpu_down(1, 0);
-		machine_kexec(kexec_crash_image);
-		/* NOTREACHED */
 	}
+
 	crash_ipi_callback(regs);
 }
 
@@ -211,7 +204,7 @@ void crash_kexec_secondary(struct pt_regs *regs)
 static void crash_kexec_prepare_cpus(int cpu)
 {
 	/*
-	 * move the secondarys to us so that we can copy
+	 * move the secondaries to us so that we can copy
 	 * the new kernel 0-0x100 safely
 	 *
 	 * do this if kexec in setup.c ?
@@ -225,7 +218,6 @@ static void crash_kexec_prepare_cpus(int cpu)
 
 void crash_kexec_secondary(struct pt_regs *regs)
 {
-	cpumask_clear(&cpus_in_sr);
 }
 #endif	/* CONFIG_SMP */
 
@@ -236,7 +228,7 @@ static void crash_kexec_wait_realmode(int cpu)
 	unsigned int msecs;
 	int i;
 
-	msecs = 10000;
+	msecs = REAL_MODE_TIMEOUT;
 	for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
 		if (i == cpu)
 			continue;
@@ -308,22 +300,11 @@ int crash_shutdown_unregister(crash_shutdown_t handler)
 }
 EXPORT_SYMBOL(crash_shutdown_unregister);
 
-static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
-static int crash_shutdown_cpu = -1;
-
-static int handle_fault(struct pt_regs *regs)
-{
-	if (crash_shutdown_cpu == smp_processor_id())
-		longjmp(crash_shutdown_buf, 1);
-	return 0;
-}
-
 void default_machine_crash_shutdown(struct pt_regs *regs)
 {
 	unsigned int i;
 	int (*old_handler)(struct pt_regs *regs);
 
-
 	/*
 	 * This function is only called after the system
 	 * has panicked or is otherwise in a critical state.
@@ -341,15 +322,26 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	 * such that another IPI will not be sent.
 	 */
 	crashing_cpu = smp_processor_id();
-	crash_save_cpu(regs, crashing_cpu);
+
+	/*
+	 * If we came in via system reset, wait a while for the secondary
+	 * CPUs to enter.
+	 */
+	if (TRAP(regs) == 0x100)
+		mdelay(PRIMARY_TIMEOUT);
+
 	crash_kexec_prepare_cpus(crashing_cpu);
-	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
+
+	crash_save_cpu(regs, crashing_cpu);
+
+	time_to_dump = 1;
+
 	crash_kexec_wait_realmode(crashing_cpu);
 
 	machine_kexec_mask_interrupts();
 
 	/*
-	 * Call registered shutdown routines savely.  Swap out
+	 * Call registered shutdown routines safely.  Swap out
 	 * __debugger_fault_handler, and replace on exit.
 	 */
 	old_handler = __debugger_fault_handler;

arch/powerpc/kernel/traps.c

@@ -98,18 +98,14 @@ static void pmac_backlight_unblank(void)
 static inline void pmac_backlight_unblank(void) { }
 #endif
 
-int die(const char *str, struct pt_regs *regs, long err)
+static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+static int die_owner = -1;
+static unsigned int die_nest_count;
+static int die_counter;
+
+static unsigned __kprobes long oops_begin(struct pt_regs *regs)
 {
-	static struct {
-		raw_spinlock_t lock;
-		u32 lock_owner;
-		int lock_owner_depth;
-	} die = {
-		.lock =			__RAW_SPIN_LOCK_UNLOCKED(die.lock),
-		.lock_owner =		-1,
-		.lock_owner_depth =	0
-	};
-	static int die_counter;
+	int cpu;
 	unsigned long flags;
 
 	if (debugger(regs))
@@ -117,19 +113,76 @@ int die(const char *str, struct pt_regs *regs, long err)
 
 	oops_enter();
 
-	if (die.lock_owner != raw_smp_processor_id()) {
+	/* racy, but better than risking deadlock. */
+	raw_local_irq_save(flags);
+	cpu = smp_processor_id();
+	if (!arch_spin_trylock(&die_lock)) {
+		if (cpu == die_owner)
+			/* nested oops. should stop eventually */;
+		else
+			arch_spin_lock(&die_lock);
+	}
+	die_nest_count++;
+	die_owner = cpu;
 	console_verbose();
-		raw_spin_lock_irqsave(&die.lock, flags);
-		die.lock_owner = smp_processor_id();
-		die.lock_owner_depth = 0;
 	bust_spinlocks(1);
 	if (machine_is(powermac))
 		pmac_backlight_unblank();
-	} else {
-		local_save_flags(flags);
+	return flags;
+}
+
+static void __kprobes oops_end(unsigned long flags, struct pt_regs *regs,
+			       int signr)
+{
+	bust_spinlocks(0);
+	die_owner = -1;
+	add_taint(TAINT_DIE);
+	die_nest_count--;
+	oops_exit();
+	printk("\n");
+	if (!die_nest_count)
+		/* Nest count reaches zero, release the lock. */
+		arch_spin_unlock(&die_lock);
+	raw_local_irq_restore(flags);
+
+	/*
+	 * A system reset (0x100) is a request to dump, so we always send
+	 * it through the crashdump code.
+	 */
+	if (kexec_should_crash(current) || (TRAP(regs) == 0x100)) {
+		crash_kexec(regs);
+
+		/*
+		 * We aren't the primary crash CPU. We need to send it
+		 * to a holding pattern to avoid it ending up in the panic
+		 * code.
+		 */
+		crash_kexec_secondary(regs);
+	}
+
+	if (!signr)
+		return;
+
+	/*
+	 * While our oops output is serialised by a spinlock, output
+	 * from panic() called below can race and corrupt it. If we
+	 * know we are going to panic, delay for 1 second so we have a
+	 * chance to get clean backtraces from all CPUs that are oopsing.
+	 */
+	if (in_interrupt() || panic_on_oops || !current->pid ||
+	    is_global_init(current)) {
+		mdelay(MSEC_PER_SEC);
 	}
 
-	if (++die.lock_owner_depth < 3) {
+	if (in_interrupt())
+		panic("Fatal exception in interrupt");
+	if (panic_on_oops)
+		panic("Fatal exception");
+	do_exit(signr);
+}
+
+static int __kprobes __die(const char *str, struct pt_regs *regs, long err)
+{
 	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 #ifdef CONFIG_PREEMPT
 	printk("PREEMPT ");
@@ -145,36 +198,22 @@ int die(const char *str, struct pt_regs *regs, long err)
 #endif
 	printk("%s\n", ppc_md.name ? ppc_md.name : "");
 
-		if (notify_die(DIE_OOPS, str, regs, err, 255,
-			       SIGSEGV) == NOTIFY_STOP)
+	if (notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV) == NOTIFY_STOP)
 		return 1;
 
 	print_modules();
 	show_regs(regs);
-	} else {
-		printk("Recursive die() failure, output suppressed\n");
-	}
-
-	bust_spinlocks(0);
-	die.lock_owner = -1;
-	add_taint(TAINT_DIE);
-	raw_spin_unlock_irqrestore(&die.lock, flags);
 
-	if (kexec_should_crash(current) ||
-		kexec_sr_activated(smp_processor_id()))
-		crash_kexec(regs);
-	crash_kexec_secondary(regs);
-
-	if (in_interrupt())
-		panic("Fatal exception in interrupt");
-
-	if (panic_on_oops)
-		panic("Fatal exception");
+	return 0;
+}
 
-	oops_exit();
-	do_exit(err);
+void die(const char *str, struct pt_regs *regs, long err)
+{
+	unsigned long flags = oops_begin(regs);
 
-	return 0;
+	if (__die(str, regs, err))
+		err = 0;
+	oops_end(flags, regs, err);
 }
 
 void user_single_step_siginfo(struct task_struct *tsk,
@@ -195,10 +234,11 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 			"at %016lx nip %016lx lr %016lx code %x\n";
 
 	if (!user_mode(regs)) {
-		if (die("Exception in kernel mode", regs, signr))
+		die("Exception in kernel mode", regs, signr);
 		return;
-	} else if (show_unhandled_signals &&
-		   unhandled_signal(current, signr)) {
+	}
+
+	if (show_unhandled_signals && unhandled_signal(current, signr)) {
 		printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
 				   current->comm, current->pid, signr,
 				   addr, regs->nip, regs->link, code);
@@ -220,25 +260,8 @@ void system_reset_exception(struct pt_regs *regs)
 			return;
 	}
 
-#ifdef CONFIG_KEXEC
-	cpumask_set_cpu(smp_processor_id(), &cpus_in_sr);
-#endif
-
 	die("System Reset", regs, SIGABRT);
 
-	/*
-	 * Some CPUs when released from the debugger will execute this path.
-	 * These CPUs entered the debugger via a soft-reset. If the CPU was
-	 * hung before entering the debugger it will return to the hung
-	 * state when exiting this function.  This causes a problem in
-	 * kdump since the hung CPU(s) will not respond to the IPI sent
-	 * from kdump. To prevent the problem we call crash_kexec_secondary()
-	 * here. If a kdump had not been initiated or we exit the debugger
-	 * with the "exit and recover" command (x) crash_kexec_secondary()
-	 * will return after 5ms and the CPU returns to its previous state.
-	 */
-	crash_kexec_secondary(regs);
-
 	/* Must die if the interrupt is not recoverable */
 	if (!(regs->msr & MSR_RI))
 		panic("Unrecoverable System Reset");

arch/powerpc/platforms/pseries/setup.c

@@ -366,6 +366,8 @@ static void pSeries_idle(void)
 
 static void __init pSeries_setup_arch(void)
 {
+	panic_timeout = 10;
+
 	/* Discover PIC type and setup ppc_md accordingly */
 	pseries_discover_pic();
 

arch/powerpc/sysdev/xics/icp-hv.c

@@ -41,23 +41,24 @@ static inline unsigned int icp_hv_get_xirr(unsigned char cppr)
 	return ret;
 }
 
-static inline void icp_hv_set_xirr(unsigned int value)
+static inline void icp_hv_set_cppr(u8 value)
 {
-	long rc = plpar_hcall_norets(H_EOI, value);
+	long rc = plpar_hcall_norets(H_CPPR, value);
 	if (rc != H_SUCCESS) {
-		pr_err("%s: bad return code eoi xirr=0x%x returned %ld\n",
+		pr_err("%s: bad return code cppr cppr=0x%x returned %ld\n",
 			__func__, value, rc);
 		WARN_ON_ONCE(1);
 	}
 }
 
-static inline void icp_hv_set_cppr(u8 value)
+static inline void icp_hv_set_xirr(unsigned int value)
 {
-	long rc = plpar_hcall_norets(H_CPPR, value);
+	long rc = plpar_hcall_norets(H_EOI, value);
 	if (rc != H_SUCCESS) {
-		pr_err("%s: bad return code cppr cppr=0x%x returned %ld\n",
+		pr_err("%s: bad return code eoi xirr=0x%x returned %ld\n",
 			__func__, value, rc);
 		WARN_ON_ONCE(1);
+		icp_hv_set_cppr(value >> 24);
 	}
 }