[mirror_ubuntu-artful-kernel.git] / arch / alpha / kernel / process.c

/*
 *  linux/arch/alpha/kernel/process.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 */

/*
 * This file handles the architecture-dependent parts of process handling.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/time.h>
#include <linux/major.h>
#include <linux/stat.h>
#include <linux/vt.h>
#include <linux/mman.h>
#include <linux/elfcore.h>
#include <linux/reboot.h>
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>

#include <asm/reg.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/hwrpb.h>
#include <asm/fpu.h>

#include "proto.h"
#include "pci_impl.h"

/*
 * Power off function, if any
 */
void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

struct halt_info {
	int mode;
	char *restart_cmd;
};

static void
common_shutdown_1(void *generic_ptr)
{
	struct halt_info *how = (struct halt_info *)generic_ptr;
	struct percpu_struct *cpup;
	unsigned long *pflags, flags;
	int cpuid = smp_processor_id();

	/* No point in taking interrupts anymore. */
	local_irq_disable();

	cpup = (struct percpu_struct *)
			((unsigned long)hwrpb + hwrpb->processor_offset
			 + hwrpb->processor_size * cpuid);
	pflags = &cpup->flags;
	flags = *pflags;

	/* Clear reason to "default"; clear "bootstrap in progress". */
	flags &= ~0x00ff0001UL;

#ifdef CONFIG_SMP
	/* Secondaries halt here. */
	if (cpuid != boot_cpuid) {
		flags |= 0x00040000UL; /* "remain halted" */
		*pflags = flags;
		set_cpu_present(cpuid, false);
		set_cpu_possible(cpuid, false);
		halt();
	}
#endif

	if (how->mode == LINUX_REBOOT_CMD_RESTART) {
		if (!how->restart_cmd) {
			flags |= 0x00020000UL; /* "cold bootstrap" */
		} else {
			/* For SRM, we could probably set environment
			   variables to get this to work.  We'd have to
			   delay this until after srm_paging_stop unless
			   we ever got srm_fixup working.

			   At the moment, SRM will use the last boot device,
			   but the file and flags will be the defaults, when
			   doing a "warm" bootstrap.  */
			flags |= 0x00030000UL; /* "warm bootstrap" */
		}
	} else {
		flags |= 0x00040000UL; /* "remain halted" */
	}
	*pflags = flags;

#ifdef CONFIG_SMP
	/* Wait for the secondaries to halt. */
	set_cpu_present(boot_cpuid, false);
	set_cpu_possible(boot_cpuid, false);
	while (cpumask_weight(cpu_present_mask))
		barrier();
#endif

	/* If booted from SRM, reset some of the original environment. */
	if (alpha_using_srm) {
#ifdef CONFIG_DUMMY_CONSOLE
		/* If we've gotten here after SysRq-b, leave interrupt
		   context before taking over the console. */
		if (in_interrupt())
			irq_exit();
		/* This has the effect of resetting the VGA video origin.  */
		take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
#endif
		pci_restore_srm_config();
		set_hae(srm_hae);
	}

	if (alpha_mv.kill_arch)
		alpha_mv.kill_arch(how->mode);

	if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
		/* Unfortunately, since MILO doesn't currently understand
		   the hwrpb bits above, we can't reliably halt the 
		   processor and keep it halted.  So just loop.  */
		return;
	}

	if (alpha_using_srm)
		srm_paging_stop();

	halt();
}

static void
common_shutdown(int mode, char *restart_cmd)
{
	struct halt_info args;
	args.mode = mode;
	args.restart_cmd = restart_cmd;
	on_each_cpu(common_shutdown_1, &args, 0);
}

void
machine_restart(char *restart_cmd)
{
	common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
}


void
machine_halt(void)
{
	common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
}


void
machine_power_off(void)
{
	common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
}


/* Used by sysrq-p, among others.  I don't believe r9-r15 are ever
   saved in the context it's used.  */

void
show_regs(struct pt_regs *regs)
{
	show_regs_print_info(KERN_DEFAULT);
	dik_show_regs(regs, NULL);
}

/*
 * Re-start a thread when doing execve()
 */
void
start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
	regs->pc = pc;
	regs->ps = 8;
	wrusp(sp);
}
EXPORT_SYMBOL(start_thread);

/*
 * Free current thread data structures etc..
 */
void
exit_thread(void)
{
}

void
flush_thread(void)
{
	/* Arrange for each exec'ed process to start off with a clean slate
	   with respect to the FPU.  This is all exceptions disabled.  */
	current_thread_info()->ieee_state = 0;
	wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));

	/* Clean slate for TLS.  */
	current_thread_info()->pcb.unique = 0;
}

void
release_thread(struct task_struct *dead_task)
{
}

/*
 * Copy an alpha thread..
 */

int
copy_thread(unsigned long clone_flags, unsigned long usp,
	    unsigned long arg,
	    struct task_struct *p)
{
	extern void ret_from_fork(void);
	extern void ret_from_kernel_thread(void);

	struct thread_info *childti = task_thread_info(p);
	struct pt_regs *childregs = task_pt_regs(p);
	struct pt_regs *regs = current_pt_regs();
	struct switch_stack *childstack, *stack;

	childstack = ((struct switch_stack *) childregs) - 1;
	childti->pcb.ksp = (unsigned long) childstack;
	childti->pcb.flags = 1;	/* set FEN, clear everything else */

	if (unlikely(p->flags & PF_KTHREAD)) {
		/* kernel thread */
		memset(childstack, 0,
			sizeof(struct switch_stack) + sizeof(struct pt_regs));
		childstack->r26 = (unsigned long) ret_from_kernel_thread;
		childstack->r9 = usp;	/* function */
		childstack->r10 = arg;
		childregs->hae = alpha_mv.hae_cache,
		childti->pcb.usp = 0;
		return 0;
	}
	/* Note: if CLONE_SETTLS is not set, then we must inherit the
	   value from the parent, which will have been set by the block
	   copy in dup_task_struct.  This is non-intuitive, but is
	   required for proper operation in the case of a threaded
	   application calling fork.  */
	if (clone_flags & CLONE_SETTLS)
		childti->pcb.unique = regs->r20;
	childti->pcb.usp = usp ?: rdusp();
	*childregs = *regs;
	childregs->r0 = 0;
	childregs->r19 = 0;
	childregs->r20 = 1;	/* OSF/1 has some strange fork() semantics.  */
	regs->r20 = 0;
	stack = ((struct switch_stack *) regs) - 1;
	*childstack = *stack;
	childstack->r26 = (unsigned long) ret_from_fork;
	return 0;
}

/*
 * Fill in the user structure for a ELF core dump.
 */
void
dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
{
	/* switch stack follows right below pt_regs: */
	struct switch_stack * sw = ((struct switch_stack *) pt) - 1;

	dest[ 0] = pt->r0;
	dest[ 1] = pt->r1;
	dest[ 2] = pt->r2;
	dest[ 3] = pt->r3;
	dest[ 4] = pt->r4;
	dest[ 5] = pt->r5;
	dest[ 6] = pt->r6;
	dest[ 7] = pt->r7;
	dest[ 8] = pt->r8;
	dest[ 9] = sw->r9;
	dest[10] = sw->r10;
	dest[11] = sw->r11;
	dest[12] = sw->r12;
	dest[13] = sw->r13;
	dest[14] = sw->r14;
	dest[15] = sw->r15;
	dest[16] = pt->r16;
	dest[17] = pt->r17;
	dest[18] = pt->r18;
	dest[19] = pt->r19;
	dest[20] = pt->r20;
	dest[21] = pt->r21;
	dest[22] = pt->r22;
	dest[23] = pt->r23;
	dest[24] = pt->r24;
	dest[25] = pt->r25;
	dest[26] = pt->r26;
	dest[27] = pt->r27;
	dest[28] = pt->r28;
	dest[29] = pt->gp;
	dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
	dest[31] = pt->pc;

	/* Once upon a time this was the PS value.  Which is stupid
	   since that is always 8 for usermode.  Usurped for the more
	   useful value of the thread's UNIQUE field.  */
	dest[32] = ti->pcb.unique;
}
EXPORT_SYMBOL(dump_elf_thread);

int
dump_elf_task(elf_greg_t *dest, struct task_struct *task)
{
	dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
	return 1;
}
EXPORT_SYMBOL(dump_elf_task);

int
dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
{
	struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
	memcpy(dest, sw->fp, 32 * 8);
	return 1;
}
EXPORT_SYMBOL(dump_elf_task_fp);

/*
 * Return saved PC of a blocked thread.  This assumes the frame
 * pointer is the 6th saved long on the kernel stack and that the
 * saved return address is the first long in the frame.  This all
 * holds provided the thread blocked through a call to schedule() ($15
 * is the frame pointer in schedule() and $15 is saved at offset 48 by
 * entry.S:do_switch_stack).
 *
 * Under heavy swap load I've seen this lose in an ugly way.  So do
 * some extra sanity checking on the ranges we expect these pointers
 * to be in so that we can fail gracefully.  This is just for ps after
 * all.  -- r~
 */

unsigned long
thread_saved_pc(struct task_struct *t)
{
	unsigned long base = (unsigned long)task_stack_page(t);
	unsigned long fp, sp = task_thread_info(t)->pcb.ksp;

	if (sp > base && sp+6*8 < base + 16*1024) {
		fp = ((unsigned long*)sp)[6];
		if (fp > sp && fp < base + 16*1024)
			return *(unsigned long *)fp;
	}

	return 0;
}

unsigned long
get_wchan(struct task_struct *p)
{
	unsigned long schedule_frame;
	unsigned long pc;
	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;
	/*
	 * This one depends on the frame size of schedule().  Do a
	 * "disass schedule" in gdb to find the frame size.  Also, the
	 * code assumes that sleep_on() follows immediately after
	 * interruptible_sleep_on() and that add_timer() follows
	 * immediately after interruptible_sleep().  Ugly, isn't it?
	 * Maybe adding a wchan field to task_struct would be better,
	 * after all...
	 */

	pc = thread_saved_pc(p);
	if (in_sched_functions(pc)) {
		schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
		return ((unsigned long *)schedule_frame)[12];
	}
	return pc;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/alpha/kernel/process.c
	3	*
	4	* Copyright (C) 1995 Linus Torvalds
	5	*/
	6
	7	/*
	8	* This file handles the architecture-dependent parts of process handling.
	9	*/
	10
1da177e4 LT	11	#include <linux/errno.h>
	12	#include <linux/module.h>
	13	#include <linux/sched.h>
	14	#include <linux/kernel.h>
	15	#include <linux/mm.h>
	16	#include <linux/smp.h>
1da177e4 LT	17	#include <linux/stddef.h>
	18	#include <linux/unistd.h>
	19	#include <linux/ptrace.h>
1da177e4	20	#include <linux/user.h>
1da177e4 LT	21	#include <linux/time.h>
	22	#include <linux/major.h>
	23	#include <linux/stat.h>
a8f340e3	24	#include <linux/vt.h>
1da177e4 LT	25	#include <linux/mman.h>
	26	#include <linux/elfcore.h>
	27	#include <linux/reboot.h>
	28	#include <linux/tty.h>
	29	#include <linux/console.h>
5a0e3ad6	30	#include <linux/slab.h>
4c94cada	31	#include <linux/rcupdate.h>
1da177e4 LT	32
	33	#include <asm/reg.h>
	34	#include <asm/uaccess.h>
1da177e4 LT	35	#include <asm/io.h>
	36	#include <asm/pgtable.h>
	37	#include <asm/hwrpb.h>
	38	#include <asm/fpu.h>
	39
	40	#include "proto.h"
	41	#include "pci_impl.h"
	42
5e38291d EB	43	/*
	44	* Power off function, if any
	45	*/
	46	void (*pm_power_off)(void) = machine_power_off;
89eb1693	47	EXPORT_SYMBOL(pm_power_off);
5e38291d	48
1da177e4 LT	49	struct halt_info {
	50	int mode;
	51	char *restart_cmd;
	52	};
	53
	54	static void
	55	common_shutdown_1(void *generic_ptr)
	56	{
	57	struct halt_info how = (struct halt_info )generic_ptr;
	58	struct percpu_struct *cpup;
	59	unsigned long *pflags, flags;
	60	int cpuid = smp_processor_id();
	61
	62	/* No point in taking interrupts anymore. */
	63	local_irq_disable();
	64
	65	cpup = (struct percpu_struct *)
	66	((unsigned long)hwrpb + hwrpb->processor_offset
	67	+ hwrpb->processor_size * cpuid);
	68	pflags = &cpup->flags;
	69	flags = *pflags;
	70
	71	/* Clear reason to "default"; clear "bootstrap in progress". */
	72	flags &= ~0x00ff0001UL;
	73
	74	#ifdef CONFIG_SMP
	75	/* Secondaries halt here. */
	76	if (cpuid != boot_cpuid) {
	77	flags \|= 0x00040000UL; /* "remain halted" */
	78	*pflags = flags;
1371be0f RR	79	set_cpu_present(cpuid, false);
1371be0f RR	80	set_cpu_possible(cpuid, false);
1da177e4 LT	81	halt();
	82	}
	83	#endif
	84
	85	if (how->mode == LINUX_REBOOT_CMD_RESTART) {
	86	if (!how->restart_cmd) {
	87	flags \|= 0x00020000UL; /* "cold bootstrap" */
	88	} else {
	89	/* For SRM, we could probably set environment
	90	variables to get this to work. We'd have to
	91	delay this until after srm_paging_stop unless
	92	we ever got srm_fixup working.
	93
	94	At the moment, SRM will use the last boot device,
	95	but the file and flags will be the defaults, when
	96	doing a "warm" bootstrap. */
	97	flags \|= 0x00030000UL; /* "warm bootstrap" */
	98	}
	99	} else {
	100	flags \|= 0x00040000UL; /* "remain halted" */
	101	}
	102	*pflags = flags;
	103
	104	#ifdef CONFIG_SMP
	105	/* Wait for the secondaries to halt. */
1371be0f RR	106	set_cpu_present(boot_cpuid, false);
1371be0f RR	107	set_cpu_possible(boot_cpuid, false);
81740fc6	108	while (cpumask_weight(cpu_present_mask))
1da177e4 LT	109	barrier();
	110	#endif
	111
	112	/* If booted from SRM, reset some of the original environment. */
	113	if (alpha_using_srm) {
	114	#ifdef CONFIG_DUMMY_CONSOLE
4b3c86a7 IK	115	/* If we've gotten here after SysRq-b, leave interrupt
	116	context before taking over the console. */
	117	if (in_interrupt())
	118	irq_exit();
1da177e4 LT	119	/* This has the effect of resetting the VGA video origin. */
	120	take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
	121	#endif
	122	pci_restore_srm_config();
	123	set_hae(srm_hae);
	124	}
	125
	126	if (alpha_mv.kill_arch)
	127	alpha_mv.kill_arch(how->mode);
	128
	129	if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
	130	/* Unfortunately, since MILO doesn't currently understand
	131	the hwrpb bits above, we can't reliably halt the
	132	processor and keep it halted. So just loop. */
	133	return;
	134	}
	135
	136	if (alpha_using_srm)
	137	srm_paging_stop();
	138
	139	halt();
	140	}
	141
	142	static void
	143	common_shutdown(int mode, char *restart_cmd)
	144	{
	145	struct halt_info args;
	146	args.mode = mode;
	147	args.restart_cmd = restart_cmd;
15c8b6c1	148	on_each_cpu(common_shutdown_1, &args, 0);
1da177e4 LT	149	}
	150
	151	void
	152	machine_restart(char *restart_cmd)
	153	{
	154	common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
	155	}
	156
1da177e4 LT	157
	158	void
	159	machine_halt(void)
	160	{
	161	common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
	162	}
	163
1da177e4 LT	164
	165	void
	166	machine_power_off(void)
	167	{
	168	common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
	169	}
	170
1da177e4 LT	171
	172	/* Used by sysrq-p, among others. I don't believe r9-r15 are ever
	173	saved in the context it's used. */
	174
	175	void
	176	show_regs(struct pt_regs *regs)
	177	{
a43cb95d	178	show_regs_print_info(KERN_DEFAULT);
1da177e4 LT	179	dik_show_regs(regs, NULL);
	180	}
	181
	182	/*
	183	* Re-start a thread when doing execve()
	184	*/
	185	void
	186	start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
	187	{
1da177e4 LT	188	regs->pc = pc;
	189	regs->ps = 8;
	190	wrusp(sp);
	191	}
cff52daf	192	EXPORT_SYMBOL(start_thread);
1da177e4 LT	193
	194	/*
	195	* Free current thread data structures etc..
	196	*/
	197	void
	198	exit_thread(void)
	199	{
	200	}
	201
	202	void
	203	flush_thread(void)
	204	{
	205	/* Arrange for each exec'ed process to start off with a clean slate
	206	with respect to the FPU. This is all exceptions disabled. */
	207	current_thread_info()->ieee_state = 0;
	208	wrfpcr(FPCR_DYN_NORMAL \| ieee_swcr_to_fpcr(0));
	209
	210	/* Clean slate for TLS. */
	211	current_thread_info()->pcb.unique = 0;
	212	}
	213
	214	void
	215	release_thread(struct task_struct *dead_task)
	216	{
	217	}
	218
1da177e4 LT	219	/*
1da177e4 LT	220	* Copy an alpha thread..
1da177e4 LT	221	*/
	222
	223	int
6f2c55b8	224	copy_thread(unsigned long clone_flags, unsigned long usp,
cba1ec7e	225	unsigned long arg,
afa86fc4	226	struct task_struct *p)
1da177e4 LT	227	{
1da177e4 LT	228	extern void ret_from_fork(void);
cba1ec7e	229	extern void ret_from_kernel_thread(void);
1da177e4	230
27f45130	231	struct thread_info *childti = task_thread_info(p);
cba1ec7e	232	struct pt_regs *childregs = task_pt_regs(p);
25906730	233	struct pt_regs *regs = current_pt_regs();
cba1ec7e	234	struct switch_stack childstack, stack;
cba1ec7e AV	235
cba1ec7e AV	236	childstack = ((struct switch_stack *) childregs) - 1;
25906730 AV	237	childti->pcb.ksp = (unsigned long) childstack;
	238	childti->pcb.flags = 1; /* set FEN, clear everything else */
	239
	240	if (unlikely(p->flags & PF_KTHREAD)) {
cba1ec7e AV	241	/* kernel thread */
	242	memset(childstack, 0,
	243	sizeof(struct switch_stack) + sizeof(struct pt_regs));
	244	childstack->r26 = (unsigned long) ret_from_kernel_thread;
	245	childstack->r9 = usp; /* function */
	246	childstack->r10 = arg;
	247	childregs->hae = alpha_mv.hae_cache,
	248	childti->pcb.usp = 0;
cba1ec7e AV	249	return 0;
cba1ec7e AV	250	}
25906730 AV	251	/* Note: if CLONE_SETTLS is not set, then we must inherit the
	252	value from the parent, which will have been set by the block
	253	copy in dup_task_struct. This is non-intuitive, but is
	254	required for proper operation in the case of a threaded
	255	application calling fork. */
	256	if (clone_flags & CLONE_SETTLS)
	257	childti->pcb.unique = regs->r20;
	258	childti->pcb.usp = usp ?: rdusp();
1da177e4	259	childregs = regs;
1da177e4 LT	260	childregs->r0 = 0;
	261	childregs->r19 = 0;
	262	childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
	263	regs->r20 = 0;
	264	stack = ((struct switch_stack *) regs) - 1;
1da177e4 LT	265	childstack = stack;
1da177e4 LT	266	childstack->r26 = (unsigned long) ret_from_fork;
1da177e4 LT	267	return 0;
	268	}
	269
1da177e4 LT	270	/*
	271	* Fill in the user structure for a ELF core dump.
	272	*/
	273	void
	274	dump_elf_thread(elf_greg_t dest, struct pt_regs pt, struct thread_info *ti)
	275	{
	276	/* switch stack follows right below pt_regs: */
	277	struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
	278
	279	dest[ 0] = pt->r0;
	280	dest[ 1] = pt->r1;
	281	dest[ 2] = pt->r2;
	282	dest[ 3] = pt->r3;
	283	dest[ 4] = pt->r4;
	284	dest[ 5] = pt->r5;
	285	dest[ 6] = pt->r6;
	286	dest[ 7] = pt->r7;
	287	dest[ 8] = pt->r8;
	288	dest[ 9] = sw->r9;
	289	dest[10] = sw->r10;
	290	dest[11] = sw->r11;
	291	dest[12] = sw->r12;
	292	dest[13] = sw->r13;
	293	dest[14] = sw->r14;
	294	dest[15] = sw->r15;
	295	dest[16] = pt->r16;
	296	dest[17] = pt->r17;
	297	dest[18] = pt->r18;
	298	dest[19] = pt->r19;
	299	dest[20] = pt->r20;
	300	dest[21] = pt->r21;
	301	dest[22] = pt->r22;
	302	dest[23] = pt->r23;
	303	dest[24] = pt->r24;
	304	dest[25] = pt->r25;
	305	dest[26] = pt->r26;
	306	dest[27] = pt->r27;
	307	dest[28] = pt->r28;
	308	dest[29] = pt->gp;
32163f4b	309	dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
1da177e4 LT	310	dest[31] = pt->pc;
	311
	312	/* Once upon a time this was the PS value. Which is stupid
	313	since that is always 8 for usermode. Usurped for the more
	314	useful value of the thread's UNIQUE field. */
	315	dest[32] = ti->pcb.unique;
	316	}
cff52daf	317	EXPORT_SYMBOL(dump_elf_thread);
1da177e4 LT	318
	319	int
	320	dump_elf_task(elf_greg_t dest, struct task_struct task)
	321	{
e52f4ca2	322	dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
1da177e4 LT	323	return 1;
1da177e4 LT	324	}
cff52daf	325	EXPORT_SYMBOL(dump_elf_task);
1da177e4 LT	326
	327	int
	328	dump_elf_task_fp(elf_fpreg_t dest, struct task_struct task)
	329	{
e52f4ca2	330	struct switch_stack sw = (struct switch_stack )task_pt_regs(task) - 1;
1da177e4	331	memcpy(dest, sw->fp, 32 * 8);
1da177e4 LT	332	return 1;
1da177e4 LT	333	}
cff52daf	334	EXPORT_SYMBOL(dump_elf_task_fp);
1da177e4	335
1da177e4 LT	336	/*
	337	* Return saved PC of a blocked thread. This assumes the frame
	338	* pointer is the 6th saved long on the kernel stack and that the
	339	* saved return address is the first long in the frame. This all
	340	* holds provided the thread blocked through a call to schedule() ($15
	341	* is the frame pointer in schedule() and $15 is saved at offset 48 by
	342	* entry.S:do_switch_stack).
	343	*
	344	* Under heavy swap load I've seen this lose in an ugly way. So do
	345	* some extra sanity checking on the ranges we expect these pointers
	346	* to be in so that we can fail gracefully. This is just for ps after
	347	* all. -- r~
	348	*/
	349
	350	unsigned long
36c8b586	351	thread_saved_pc(struct task_struct *t)
1da177e4	352	{
27f45130	353	unsigned long base = (unsigned long)task_stack_page(t);
37bfbaf9	354	unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
1da177e4 LT	355
	356	if (sp > base && sp+68 < base + 161024) {
	357	fp = ((unsigned long*)sp)[6];
	358	if (fp > sp && fp < base + 16*1024)
	359	return (unsigned long )fp;
	360	}
	361
	362	return 0;
	363	}
	364
	365	unsigned long
	366	get_wchan(struct task_struct *p)
	367	{
	368	unsigned long schedule_frame;
	369	unsigned long pc;
	370	if (!p \|\| p == current \|\| p->state == TASK_RUNNING)
	371	return 0;
	372	/*
	373	* This one depends on the frame size of schedule(). Do a
	374	* "disass schedule" in gdb to find the frame size. Also, the
	375	* code assumes that sleep_on() follows immediately after
	376	* interruptible_sleep_on() and that add_timer() follows
	377	* immediately after interruptible_sleep(). Ugly, isn't it?
	378	* Maybe adding a wchan field to task_struct would be better,
	379	* after all...
	380	*/
	381
	382	pc = thread_saved_pc(p);
	383	if (in_sched_functions(pc)) {
37bfbaf9	384	schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
1da177e4 LT	385	return ((unsigned long *)schedule_frame)[12];
	386	}
	387	return pc;
	388	}