arch/s390/kernel/process.c - kernel/skids - Git at Google

 /*
  * This file handles the architecture dependent parts of process handling.
  *
  *    Copyright IBM Corp. 1999,2009
  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
  *		 Hartmut Penner <hp@de.ibm.com>,
  *		 Denis Joseph Barrow,
  */

 #include <linux/compiler.h>
 #include <linux/cpu.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/smp.h>
 #include <linux/stddef.h>
 #include <linux/slab.h>
 #include <linux/unistd.h>
 #include <linux/ptrace.h>
 #include <linux/vmalloc.h>
 #include <linux/user.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/reboot.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/tick.h>
 #include <linux/elfcore.h>
 #include <linux/kernel_stat.h>
 #include <linux/syscalls.h>
 #include <linux/compat.h>
 #include <asm/compat.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/irq.h>
 #include <asm/timer.h>
 #include <asm/nmi.h>
 #include "entry.h"

 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");

 /*
  * Return saved PC of a blocked thread. used in kernel/sched.
  * resume in entry.S does not create a new stack frame, it
  * just stores the registers %r6-%r15 to the frame given by
  * schedule. We want to return the address of the caller of
  * schedule, so we have to walk the backchain one time to
  * find the frame schedule() store its return address.
  */
 unsigned long thread_saved_pc(struct task_struct *tsk)
 {
 	struct stack_frame *sf, *low, *high;

 	if (!tsk || !task_stack_page(tsk))
 		return 0;
 	low = task_stack_page(tsk);
 	high = (struct stack_frame *) task_pt_regs(tsk);
 	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
 	if (sf <= low || sf > high)
 		return 0;
 	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 	if (sf <= low || sf > high)
 		return 0;
 	return sf->gprs[8];
 }

 /*
  * The idle loop on a S390...
  */
 static void default_idle(void)
 {
 	/* CPU is going idle. */
 	local_irq_disable();
 	if (need_resched()) {
 		local_irq_enable();
 		return;
 	}
 #ifdef CONFIG_HOTPLUG_CPU
 	if (cpu_is_offline(smp_processor_id())) {
 		preempt_enable_no_resched();
 		cpu_die();
 	}
 #endif
 	local_mcck_disable();
 	if (test_thread_flag(TIF_MCCK_PENDING)) {
 		local_mcck_enable();
 		local_irq_enable();
 		s390_handle_mcck();
 		return;
 	}
 	trace_hardirqs_on();
 	/* Don't trace preempt off for idle. */
 	stop_critical_timings();
 	/* Stop virtual timer and halt the cpu. */
 	vtime_stop_cpu();
 	/* Reenable preemption tracer. */
 	start_critical_timings();
 }

 void cpu_idle(void)
 {
 	for (;;) {
 		tick_nohz_stop_sched_tick(1);
 		while (!need_resched())
 			default_idle();
 		tick_nohz_restart_sched_tick();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
 	}
 }

 extern void kernel_thread_starter(void);

 asm(
 	".align 4\n"
 	"kernel_thread_starter:\n"
 	"    la    2,0(10)\n"
 	"    basr  14,9\n"
 	"    la    2,0\n"
 	"    br    11\n");

 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 {
 	struct pt_regs regs;

 	memset(&regs, 0, sizeof(regs));
 	regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 	regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 	regs.gprs[9] = (unsigned long) fn;
 	regs.gprs[10] = (unsigned long) arg;
 	regs.gprs[11] = (unsigned long) do_exit;
 	regs.orig_gpr2 = -1;

 	/* Ok, create the new process.. */
 	return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 		       0, &regs, 0, NULL, NULL);
 }
 EXPORT_SYMBOL(kernel_thread);

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

 void flush_thread(void)
 {
 }

 void release_thread(struct task_struct *dead_task)
 {
 }

 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 		unsigned long unused,
 		struct task_struct *p, struct pt_regs *regs)
 {
 	struct thread_info *ti;
 	struct fake_frame
 	{
 		struct stack_frame sf;
 		struct pt_regs childregs;
 	} *frame;

 	frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 	p->thread.ksp = (unsigned long) frame;
 	/* Store access registers to kernel stack of new process. */
 	frame->childregs = *regs;
 	frame->childregs.gprs[2] = 0;	/* child returns 0 on fork. */
 	frame->childregs.gprs[15] = new_stackp;
 	frame->sf.back_chain = 0;

 	/* new return point is ret_from_fork */
 	frame->sf.gprs[8] = (unsigned long) ret_from_fork;

 	/* fake return stack for resume(), don't go back to schedule */
 	frame->sf.gprs[9] = (unsigned long) frame;

 	/* Save access registers to new thread structure. */
 	save_access_regs(&p->thread.acrs[0]);

 #ifndef CONFIG_64BIT
 	/*
 	 * save fprs to current->thread.fp_regs to merge them with
 	 * the emulated registers and then copy the result to the child.
 	 */
 	save_fp_regs(&current->thread.fp_regs);
 	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 	       sizeof(s390_fp_regs));
 	/* Set a new TLS ?  */
 	if (clone_flags & CLONE_SETTLS)
 		p->thread.acrs[0] = regs->gprs[6];
 #else /* CONFIG_64BIT */
 	/* Save the fpu registers to new thread structure. */
 	save_fp_regs(&p->thread.fp_regs);
 	/* Set a new TLS ?  */
 	if (clone_flags & CLONE_SETTLS) {
 		if (is_compat_task()) {
 			p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 		} else {
 			p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 			p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 		}
 	}
 #endif /* CONFIG_64BIT */
 	/* start new process with ar4 pointing to the correct address space */
 	p->thread.mm_segment = get_fs();
 	/* Don't copy debug registers */
 	memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
 	clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 	/* Initialize per thread user and system timer values */
 	ti = task_thread_info(p);
 	ti->user_timer = 0;
 	ti->system_timer = 0;
 	return 0;
 }

 SYSCALL_DEFINE0(fork)
 {
 	struct pt_regs *regs = task_pt_regs(current);
 	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 }

 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
 		int __user *, parent_tidptr, int __user *, child_tidptr)
 {
 	struct pt_regs *regs = task_pt_regs(current);

 	if (!newsp)
 		newsp = regs->gprs[15];
 	return do_fork(clone_flags, newsp, regs, 0,
 		       parent_tidptr, child_tidptr);
 }

 /*
  * This is trivial, and on the face of it looks like it
  * could equally well be done in user mode.
  *
  * Not so, for quite unobvious reasons - register pressure.
  * In user mode vfork() cannot have a stack frame, and if
  * done by calling the "clone()" system call directly, you
  * do not have enough call-clobbered registers to hold all
  * the information you need.
  */
 SYSCALL_DEFINE0(vfork)
 {
 	struct pt_regs *regs = task_pt_regs(current);
 	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 		       regs->gprs[15], regs, 0, NULL, NULL);
 }

 asmlinkage void execve_tail(void)
 {
 	current->thread.fp_regs.fpc = 0;
 	if (MACHINE_HAS_IEEE)
 		asm volatile("sfpc %0,%0" : : "d" (0));
 }

 /*
  * sys_execve() executes a new program.
  */
 SYSCALL_DEFINE3(execve, char __user *, name, char __user * __user *, argv,
 		char __user * __user *, envp)
 {
 	struct pt_regs *regs = task_pt_regs(current);
 	char *filename;
 	long rc;

 	filename = getname(name);
 	rc = PTR_ERR(filename);
 	if (IS_ERR(filename))
 		return rc;
 	rc = do_execve(filename, argv, envp, regs);
 	if (rc)
 		goto out;
 	execve_tail();
 	rc = regs->gprs[2];
 out:
 	putname(filename);
 	return rc;
 }

 /*
  * fill in the FPU structure for a core dump.
  */
 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 {
 #ifndef CONFIG_64BIT
 	/*
 	 * save fprs to current->thread.fp_regs to merge them with
 	 * the emulated registers and then copy the result to the dump.
 	 */
 	save_fp_regs(&current->thread.fp_regs);
 	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 #else /* CONFIG_64BIT */
 	save_fp_regs(fpregs);
 #endif /* CONFIG_64BIT */
 	return 1;
 }
 EXPORT_SYMBOL(dump_fpu);

 unsigned long get_wchan(struct task_struct *p)
 {
 	struct stack_frame *sf, *low, *high;
 	unsigned long return_address;
 	int count;

 	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 		return 0;
 	low = task_stack_page(p);
 	high = (struct stack_frame *) task_pt_regs(p);
 	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 	if (sf <= low || sf > high)
 		return 0;
 	for (count = 0; count < 16; count++) {
 		sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 		if (sf <= low || sf > high)
 			return 0;
 		return_address = sf->gprs[8] & PSW_ADDR_INSN;
 		if (!in_sched_functions(return_address))
 			return return_address;
 	}
 	return 0;
 }
	/*
	* This file handles the architecture dependent parts of process handling.
	*
	* Copyright IBM Corp. 1999,2009
	* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
	* Hartmut Penner <hp@de.ibm.com>,
	* Denis Joseph Barrow,
	*/

	#include <linux/compiler.h>
	#include <linux/cpu.h>
	#include <linux/errno.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/fs.h>
	#include <linux/smp.h>
	#include <linux/stddef.h>
	#include <linux/slab.h>
	#include <linux/unistd.h>
	#include <linux/ptrace.h>
	#include <linux/vmalloc.h>
	#include <linux/user.h>
	#include <linux/interrupt.h>
	#include <linux/delay.h>
	#include <linux/reboot.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/notifier.h>
	#include <linux/tick.h>
	#include <linux/elfcore.h>
	#include <linux/kernel_stat.h>
	#include <linux/syscalls.h>
	#include <linux/compat.h>
	#include <asm/compat.h>
	#include <asm/uaccess.h>
	#include <asm/pgtable.h>
	#include <asm/system.h>
	#include <asm/io.h>
	#include <asm/processor.h>
	#include <asm/irq.h>
	#include <asm/timer.h>
	#include <asm/nmi.h>
	#include "entry.h"

	asmlinkage void ret_from_fork(void) asm ("ret_from_fork");

	/*
	* Return saved PC of a blocked thread. used in kernel/sched.
	* resume in entry.S does not create a new stack frame, it
	* just stores the registers %r6-%r15 to the frame given by
	* schedule. We want to return the address of the caller of
	* schedule, so we have to walk the backchain one time to
	* find the frame schedule() store its return address.
	*/
	unsigned long thread_saved_pc(struct task_struct *tsk)
	{
	struct stack_frame sf, low, *high;

	if (!tsk \|\| !task_stack_page(tsk))
	return 0;
	low = task_stack_page(tsk);
	high = (struct stack_frame *) task_pt_regs(tsk);
	sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
	if (sf <= low \|\| sf > high)
	return 0;
	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
	if (sf <= low \|\| sf > high)
	return 0;
	return sf->gprs[8];
	}

	/*
	* The idle loop on a S390...
	*/
	static void default_idle(void)
	{
	/* CPU is going idle. */
	local_irq_disable();
	if (need_resched()) {
	local_irq_enable();
	return;
	}
	#ifdef CONFIG_HOTPLUG_CPU
	if (cpu_is_offline(smp_processor_id())) {
	preempt_enable_no_resched();
	cpu_die();
	}
	#endif
	local_mcck_disable();
	if (test_thread_flag(TIF_MCCK_PENDING)) {
	local_mcck_enable();
	local_irq_enable();
	s390_handle_mcck();
	return;
	}
	trace_hardirqs_on();
	/* Don't trace preempt off for idle. */
	stop_critical_timings();
	/* Stop virtual timer and halt the cpu. */
	vtime_stop_cpu();
	/* Reenable preemption tracer. */
	start_critical_timings();
	}

	void cpu_idle(void)
	{
	for (;;) {
	tick_nohz_stop_sched_tick(1);
	while (!need_resched())
	default_idle();
	tick_nohz_restart_sched_tick();
	preempt_enable_no_resched();
	schedule();
	preempt_disable();
	}
	}

	extern void kernel_thread_starter(void);

	asm(
	".align 4\n"
	"kernel_thread_starter:\n"
	" la 2,0(10)\n"
	" basr 14,9\n"
	" la 2,0\n"
	" br 11\n");

	int kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
	{
	struct pt_regs regs;

	memset(&regs, 0, sizeof(regs));
	regs.psw.mask = psw_kernel_bits \| PSW_MASK_IO \| PSW_MASK_EXT;
	regs.psw.addr = (unsigned long) kernel_thread_starter \| PSW_ADDR_AMODE;
	regs.gprs[9] = (unsigned long) fn;
	regs.gprs[10] = (unsigned long) arg;
	regs.gprs[11] = (unsigned long) do_exit;
	regs.orig_gpr2 = -1;

	/* Ok, create the new process.. */
	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED,
	0, &regs, 0, NULL, NULL);
	}
	EXPORT_SYMBOL(kernel_thread);

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

	void flush_thread(void)
	{
	}

	void release_thread(struct task_struct *dead_task)
	{
	}

	int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
	unsigned long unused,
	struct task_struct p, struct pt_regs regs)
	{
	struct thread_info *ti;
	struct fake_frame
	{
	struct stack_frame sf;
	struct pt_regs childregs;
	} *frame;

	frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
	p->thread.ksp = (unsigned long) frame;
	/* Store access registers to kernel stack of new process. */
	frame->childregs = *regs;
	frame->childregs.gprs[2] = 0; /* child returns 0 on fork. */
	frame->childregs.gprs[15] = new_stackp;
	frame->sf.back_chain = 0;

	/* new return point is ret_from_fork */
	frame->sf.gprs[8] = (unsigned long) ret_from_fork;

	/* fake return stack for resume(), don't go back to schedule */
	frame->sf.gprs[9] = (unsigned long) frame;

	/* Save access registers to new thread structure. */
	save_access_regs(&p->thread.acrs[0]);

	#ifndef CONFIG_64BIT
	/*
	* save fprs to current->thread.fp_regs to merge them with
	* the emulated registers and then copy the result to the child.
	*/
	save_fp_regs(&current->thread.fp_regs);
	memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
	sizeof(s390_fp_regs));
	/* Set a new TLS ? */
	if (clone_flags & CLONE_SETTLS)
	p->thread.acrs[0] = regs->gprs[6];
	#else /* CONFIG_64BIT */
	/* Save the fpu registers to new thread structure. */
	save_fp_regs(&p->thread.fp_regs);
	/* Set a new TLS ? */
	if (clone_flags & CLONE_SETTLS) {
	if (is_compat_task()) {
	p->thread.acrs[0] = (unsigned int) regs->gprs[6];
	} else {
	p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
	p->thread.acrs[1] = (unsigned int) regs->gprs[6];
	}
	}
	#endif /* CONFIG_64BIT */
	/* start new process with ar4 pointing to the correct address space */
	p->thread.mm_segment = get_fs();
	/* Don't copy debug registers */
	memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
	clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
	/* Initialize per thread user and system timer values */
	ti = task_thread_info(p);
	ti->user_timer = 0;
	ti->system_timer = 0;
	return 0;
	}

	SYSCALL_DEFINE0(fork)
	{
	struct pt_regs *regs = task_pt_regs(current);
	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
	}

	SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
	int __user , parent_tidptr, int __user , child_tidptr)
	{
	struct pt_regs *regs = task_pt_regs(current);

	if (!newsp)
	newsp = regs->gprs[15];
	return do_fork(clone_flags, newsp, regs, 0,
	parent_tidptr, child_tidptr);
	}

	/*
	* This is trivial, and on the face of it looks like it
	* could equally well be done in user mode.
	*
	* Not so, for quite unobvious reasons - register pressure.
	* In user mode vfork() cannot have a stack frame, and if
	* done by calling the "clone()" system call directly, you
	* do not have enough call-clobbered registers to hold all
	* the information you need.
	*/
	SYSCALL_DEFINE0(vfork)
	{
	struct pt_regs *regs = task_pt_regs(current);
	return do_fork(CLONE_VFORK \| CLONE_VM \| SIGCHLD,
	regs->gprs[15], regs, 0, NULL, NULL);
	}

	asmlinkage void execve_tail(void)
	{
	current->thread.fp_regs.fpc = 0;
	if (MACHINE_HAS_IEEE)
	asm volatile("sfpc %0,%0" : : "d" (0));
	}

	/*
	* sys_execve() executes a new program.
	*/
	SYSCALL_DEFINE3(execve, char __user , name, char __user __user *, argv,
	char __user * __user *, envp)
	{
	struct pt_regs *regs = task_pt_regs(current);
	char *filename;
	long rc;

	filename = getname(name);
	rc = PTR_ERR(filename);
	if (IS_ERR(filename))
	return rc;
	rc = do_execve(filename, argv, envp, regs);
	if (rc)
	goto out;
	execve_tail();
	rc = regs->gprs[2];
	out:
	putname(filename);
	return rc;
	}

	/*
	* fill in the FPU structure for a core dump.
	*/
	int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
	{
	#ifndef CONFIG_64BIT
	/*
	* save fprs to current->thread.fp_regs to merge them with
	* the emulated registers and then copy the result to the dump.
	*/
	save_fp_regs(&current->thread.fp_regs);
	memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
	#else /* CONFIG_64BIT */
	save_fp_regs(fpregs);
	#endif /* CONFIG_64BIT */
	return 1;
	}
	EXPORT_SYMBOL(dump_fpu);

	unsigned long get_wchan(struct task_struct *p)
	{
	struct stack_frame sf, low, *high;
	unsigned long return_address;
	int count;

	if (!p \|\| p == current \|\| p->state == TASK_RUNNING \|\| !task_stack_page(p))
	return 0;
	low = task_stack_page(p);
	high = (struct stack_frame *) task_pt_regs(p);
	sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
	if (sf <= low \|\| sf > high)
	return 0;
	for (count = 0; count < 16; count++) {
	sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
	if (sf <= low \|\| sf > high)
	return 0;
	return_address = sf->gprs[8] & PSW_ADDR_INSN;
	if (!in_sched_functions(return_address))
	return return_address;
	}
	return 0;
	}