/*
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg, struct task_struct *p)
{
struct thread_info *ti = task_thread_info(p);
struct hexagon_switch_stack *ss;
struct pt_regs *childregs;
asmlinkage void ret_from_fork(void);
childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
sizeof(*childregs));
ti->regs = childregs;
/*
* Establish kernel stack pointer and initial PC for new thread
* Note that unlike the usual situation, we do not copy the
* parent's callee-saved here; those are in pt_regs and whatever
* we leave here will be overridden on return to userland.
*/
ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
if (unlikely(p->flags & PF_KTHREAD)) {
memset(childregs, 0, sizeof(struct pt_regs));
/* r24 <- fn, r25 <- arg */
ss->r24 = usp;
ss->r25 = arg;
pt_set_kmode(childregs);
return 0;
}
memcpy(childregs, current_pt_regs(), sizeof(*childregs));
ss->r2524 = 0;
if (usp)
pt_set_rte_sp(childregs, usp);
/* Child sees zero return value */
childregs->r00 = 0;
/*
* The clone syscall has the C signature:
* int [r0] clone(int flags [r0],
* void *child_frame [r1],
* void *parent_tid [r2],
* void *child_tid [r3],
* void *thread_control_block [r4]);
* ugp is used to provide TLS support.
*/
if (clone_flags & CLONE_SETTLS)
childregs->ugp = childregs->r04;
/*
* Parent sees new pid -- not necessary, not even possible at
* this point in the fork process
* Might also want to set things like ti->addr_limit
*/
return 0;
}
/*
* Program thread launch. Often defined as a macro in processor.h,
* but we're shooting for a small footprint and it's not an inner-loop
* performance-critical operation.
*
* The Hexagon ABI specifies that R28 is zero'ed before program launch,
* so that gets automatically done here. If we ever stop doing that here,
* we'll probably want to define the ELF_PLAT_INIT macro.
*/
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
{
/* We want to zero all data-containing registers. Is this overkill? */
memset(regs, 0, sizeof(*regs));
/* We might want to also zero all Processor registers here */
pt_set_usermode(regs);
pt_set_elr(regs, pc);
pt_set_rte_sp(regs, sp);
}
/*
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long unused, struct task_struct *p,
struct pt_regs *regs)
{
struct thread_info *ti = task_thread_info(p);
struct hexagon_switch_stack *ss;
struct pt_regs *childregs;
asmlinkage void ret_from_fork(void);
childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
sizeof(*childregs));
memcpy(childregs, regs, sizeof(*childregs));
ti->regs = childregs;
/*
* Establish kernel stack pointer and initial PC for new thread
*/
ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
/* If User mode thread, set pt_reg stack pointer as per parameter */
if (user_mode(childregs)) {
pt_set_rte_sp(childregs, usp);
/* Child sees zero return value */
childregs->r00 = 0;
/*
* The clone syscall has the C signature:
* int [r0] clone(int flags [r0],
* void *child_frame [r1],
* void *parent_tid [r2],
* void *child_tid [r3],
* void *thread_control_block [r4]);
* ugp is used to provide TLS support.
*/
if (clone_flags & CLONE_SETTLS)
childregs->ugp = childregs->r04;
/*
* Parent sees new pid -- not necessary, not even possible at
* this point in the fork process
* Might also want to set things like ti->addr_limit
*/
} else {
/*
* If kernel thread, resume stack is kernel stack base.
* Note that this is pointer arithmetic on pt_regs *
*/
pt_set_rte_sp(childregs, (unsigned long)(childregs + 1));
/*
* We need the current thread_info fast path pointer
* set up in pt_regs. The register to be used is
* parametric for assembler code, but the mechanism
* doesn't drop neatly into C. Needs to be fixed.
*/
childregs->THREADINFO_REG = (unsigned long) ti;
}
/*
* thread_info pointer is pulled out of task_struct "stack"
* field on switch_to.
*/
p->stack = (void *)ti;
return 0;
}
