process.c

LINUX 2.6.17.4的源码

{
	discard_lazy_cpu_state();
}

void flush_thread(void)
{
#ifdef CONFIG_PPC64
	struct thread_info *t = current_thread_info();

	if (t->flags & _TIF_ABI_PENDING)
		t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
#endif

	discard_lazy_cpu_state();

#ifdef CONFIG_PPC64	/* for now */
	if (current->thread.dabr) {
		current->thread.dabr = 0;
		set_dabr(0);
	}
#endif
}

void
release_thread(struct task_struct *t)
{
}

/*
 * This gets called before we allocate a new thread and copy
 * the current task into it.
 */
void prepare_to_copy(struct task_struct *tsk)
{
	flush_fp_to_thread(current);
	flush_altivec_to_thread(current);
	flush_spe_to_thread(current);
}

/*
 * Copy a thread..
 */
int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
		unsigned long unused, struct task_struct *p,
		struct pt_regs *regs)
{
	struct pt_regs *childregs, *kregs;
	extern void ret_from_fork(void);
	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

	CHECK_FULL_REGS(regs);
	/* Copy registers */
	sp -= sizeof(struct pt_regs);
	childregs = (struct pt_regs *) sp;
	*childregs = *regs;
	if ((childregs->msr & MSR_PR) == 0) {
		/* for kernel thread, set `current' and stackptr in new task */
		childregs->gpr[1] = sp + sizeof(struct pt_regs);
#ifdef CONFIG_PPC32
		childregs->gpr[2] = (unsigned long) p;
#else
		clear_tsk_thread_flag(p, TIF_32BIT);
#endif
		p->thread.regs = NULL;	/* no user register state */
	} else {
		childregs->gpr[1] = usp;
		p->thread.regs = childregs;
		if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_PPC64
			if (!test_thread_flag(TIF_32BIT))
				childregs->gpr[13] = childregs->gpr[6];
			else
#endif
				childregs->gpr[2] = childregs->gpr[6];
		}
	}
	childregs->gpr[3] = 0;  /* Result from fork() */
	sp -= STACK_FRAME_OVERHEAD;

	/*
	 * The way this works is that at some point in the future
	 * some task will call _switch to switch to the new task.
	 * That will pop off the stack frame created below and start
	 * the new task running at ret_from_fork.  The new task will
	 * do some house keeping and then return from the fork or clone
	 * system call, using the stack frame created above.
	 */
	sp -= sizeof(struct pt_regs);
	kregs = (struct pt_regs *) sp;
	sp -= STACK_FRAME_OVERHEAD;
	p->thread.ksp = sp;

#ifdef CONFIG_PPC64
	if (cpu_has_feature(CPU_FTR_SLB)) {
		unsigned long sp_vsid = get_kernel_vsid(sp);
		unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;

		sp_vsid <<= SLB_VSID_SHIFT;
		sp_vsid |= SLB_VSID_KERNEL | llp;
		p->thread.ksp_vsid = sp_vsid;
	}

	/*
	 * The PPC64 ABI makes use of a TOC to contain function 
	 * pointers.  The function (ret_from_except) is actually a pointer
	 * to the TOC entry.  The first entry is a pointer to the actual
	 * function.
 	 */
	kregs->nip = *((unsigned long *)ret_from_fork);
#else
	kregs->nip = (unsigned long)ret_from_fork;
	p->thread.last_syscall = -1;
#endif

	return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
{
#ifdef CONFIG_PPC64
	unsigned long load_addr = regs->gpr[2];	/* saved by ELF_PLAT_INIT */
#endif

	set_fs(USER_DS);

	/*
	 * If we exec out of a kernel thread then thread.regs will not be
	 * set.  Do it now.
	 */
	if (!current->thread.regs) {
		struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
		current->thread.regs = regs - 1;
	}

	memset(regs->gpr, 0, sizeof(regs->gpr));
	regs->ctr = 0;
	regs->link = 0;
	regs->xer = 0;
	regs->ccr = 0;
	regs->gpr[1] = sp;

#ifdef CONFIG_PPC32
	regs->mq = 0;
	regs->nip = start;
	regs->msr = MSR_USER;
#else
	if (!test_thread_flag(TIF_32BIT)) {
		unsigned long entry, toc;

		/* start is a relocated pointer to the function descriptor for
		 * the elf _start routine.  The first entry in the function
		 * descriptor is the entry address of _start and the second
		 * entry is the TOC value we need to use.
		 */
		__get_user(entry, (unsigned long __user *)start);
		__get_user(toc, (unsigned long __user *)start+1);

		/* Check whether the e_entry function descriptor entries
		 * need to be relocated before we can use them.
		 */
		if (load_addr != 0) {
			entry += load_addr;
			toc   += load_addr;
		}
		regs->nip = entry;
		regs->gpr[2] = toc;
		regs->msr = MSR_USER64;
	} else {
		regs->nip = start;
		regs->gpr[2] = 0;
		regs->msr = MSR_USER32;
	}
#endif

	discard_lazy_cpu_state();
	memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
	current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC
	memset(current->thread.vr, 0, sizeof(current->thread.vr));
	memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
	current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
	current->thread.vrsave = 0;
	current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
	memset(current->thread.evr, 0, sizeof(current->thread.evr));
	current->thread.acc = 0;
	current->thread.spefscr = 0;
	current->thread.used_spe = 0;
#endif /* CONFIG_SPE */
}

#define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
		| PR_FP_EXC_RES | PR_FP_EXC_INV)

int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
	struct pt_regs *regs = tsk->thread.regs;

	/* This is a bit hairy.  If we are an SPE enabled  processor
	 * (have embedded fp) we store the IEEE exception enable flags in
	 * fpexc_mode.  fpexc_mode is also used for setting FP exception
	 * mode (asyn, precise, disabled) for 'Classic' FP. */
	if (val & PR_FP_EXC_SW_ENABLE) {
#ifdef CONFIG_SPE
		tsk->thread.fpexc_mode = val &
			(PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
		return 0;
#else
		return -EINVAL;
#endif
	}

	/* on a CONFIG_SPE this does not hurt us.  The bits that
	 * __pack_fe01 use do not overlap with bits used for
	 * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
	 * on CONFIG_SPE implementations are reserved so writing to
	 * them does not change anything */
	if (val > PR_FP_EXC_PRECISE)
		return -EINVAL;
	tsk->thread.fpexc_mode = __pack_fe01(val);
	if (regs != NULL && (regs->msr & MSR_FP) != 0)
		regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
			| tsk->thread.fpexc_mode;
	return 0;
}

int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
	unsigned int val;

	if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
#ifdef CONFIG_SPE
		val = tsk->thread.fpexc_mode;
#else
		return -EINVAL;
#endif
	else
		val = __unpack_fe01(tsk->thread.fpexc_mode);
	return put_user(val, (unsigned int __user *) adr);
}

#define TRUNC_PTR(x)	((typeof(x))(((unsigned long)(x)) & 0xffffffff))

int sys_clone(unsigned long clone_flags, unsigned long usp,
	      int __user *parent_tidp, void __user *child_threadptr,
	      int __user *child_tidp, int p6,
	      struct pt_regs *regs)
{
	CHECK_FULL_REGS(regs);
	if (usp == 0)
		usp = regs->gpr[1];	/* stack pointer for child */
#ifdef CONFIG_PPC64
	if (test_thread_flag(TIF_32BIT)) {
		parent_tidp = TRUNC_PTR(parent_tidp);
		child_tidp = TRUNC_PTR(child_tidp);
	}
#endif
 	return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
}

int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
	     unsigned long p4, unsigned long p5, unsigned long p6,
	     struct pt_regs *regs)
{
	CHECK_FULL_REGS(regs);
	return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
}

int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
	      unsigned long p4, unsigned long p5, unsigned long p6,
	      struct pt_regs *regs)
{
	CHECK_FULL_REGS(regs);
	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
			regs, 0, NULL, NULL);
}

int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
	       unsigned long a3, unsigned long a4, unsigned long a5,
	       struct pt_regs *regs)
{
	int error;
	char *filename;

	filename = getname((char __user *) a0);
	error = PTR_ERR(filename);
	if (IS_ERR(filename))
		goto out;
	flush_fp_to_thread(current);
	flush_altivec_to_thread(current);
	flush_spe_to_thread(current);
	error = do_execve(filename, (char __user * __user *) a1,
			  (char __user * __user *) a2, regs);
	if (error == 0) {
		task_lock(current);
		current->ptrace &= ~PT_DTRACE;
		task_unlock(current);
	}
	putname(filename);
out:
	return error;
}

int validate_sp(unsigned long sp, struct task_struct *p,
		       unsigned long nbytes)
{
	unsigned long stack_page = (unsigned long)task_stack_page(p);

	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;

#ifdef CONFIG_IRQSTACKS
	stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;

	stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
	if (sp >= stack_page + sizeof(struct thread_struct)
	    && sp <= stack_page + THREAD_SIZE - nbytes)
		return 1;
#endif

	return 0;
}

#ifdef CONFIG_PPC64
#define MIN_STACK_FRAME	112	/* same as STACK_FRAME_OVERHEAD, in fact */
#define FRAME_LR_SAVE	2
#define INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD + 288)
#define REGS_MARKER	0x7265677368657265ul
#define FRAME_MARKER	12
#else
#define MIN_STACK_FRAME	16
#define FRAME_LR_SAVE	1
#define INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
#define REGS_MARKER	0x72656773ul
#define FRAME_MARKER	2
#endif

EXPORT_SYMBOL(validate_sp);

unsigned long get_wchan(struct task_struct *p)
{
	unsigned long ip, sp;
	int count = 0;

	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;

	sp = p->thread.ksp;
	if (!validate_sp(sp, p, MIN_STACK_FRAME))
		return 0;

	do {
		sp = *(unsigned long *)sp;
		if (!validate_sp(sp, p, MIN_STACK_FRAME))
			return 0;
		if (count > 0) {
			ip = ((unsigned long *)sp)[FRAME_LR_SAVE];
			if (!in_sched_functions(ip))
				return ip;
		}
	} while (count++ < 16);
	return 0;
}

static int kstack_depth_to_print = 64;

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
	unsigned long sp, ip, lr, newsp;
	int count = 0;
	int firstframe = 1;

	sp = (unsigned long) stack;
	if (tsk == NULL)
		tsk = current;
	if (sp == 0) {
		if (tsk == current)
			asm("mr %0,1" : "=r" (sp));
		else
			sp = tsk->thread.ksp;
	}

	lr = 0;
	printk("Call Trace:\n");
	do {
		if (!validate_sp(sp, tsk, MIN_STACK_FRAME))
			return;

		stack = (unsigned long *) sp;
		newsp = stack[0];
		ip = stack[FRAME_LR_SAVE];
		if (!firstframe || ip != lr) {
			printk("["REG"] ["REG"] ", sp, ip);
			print_symbol("%s", ip);
			if (firstframe)
				printk(" (unreliable)");
			printk("\n");
		}
		firstframe = 0;

		/*
		 * See if this is an exception frame.
		 * We look for the "regshere" marker in the current frame.
		 */
		if (validate_sp(sp, tsk, INT_FRAME_SIZE)
		    && stack[FRAME_MARKER] == REGS_MARKER) {
			struct pt_regs *regs = (struct pt_regs *)
				(sp + STACK_FRAME_OVERHEAD);
			printk("--- Exception: %lx", regs->trap);
			print_symbol(" at %s\n", regs->nip);
			lr = regs->link;
			print_symbol("    LR = %s\n", lr);
			firstframe = 1;
		}

		sp = newsp;
	} while (count++ < kstack_depth_to_print);
}

void dump_stack(void)
{
	show_stack(current, NULL);
}
EXPORT_SYMBOL(dump_stack);

#ifdef CONFIG_PPC64
void ppc64_runlatch_on(void)
{
	unsigned long ctrl;

	if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
		HMT_medium();

		ctrl = mfspr(SPRN_CTRLF);
		ctrl |= CTRL_RUNLATCH;
		mtspr(SPRN_CTRLT, ctrl);

		set_thread_flag(TIF_RUNLATCH);
	}
}

void ppc64_runlatch_off(void)
{
	unsigned long ctrl;

	if (cpu_has_feature(CPU_FTR_CTRL) && test_thread_flag(TIF_RUNLATCH)) {
		HMT_medium();

		clear_thread_flag(TIF_RUNLATCH);

		ctrl = mfspr(SPRN_CTRLF);
		ctrl &= ~CTRL_RUNLATCH;
		mtspr(SPRN_CTRLT, ctrl);
	}
}
#endif