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Commit c34501d2 authored by Catalin Marinas's avatar Catalin Marinas
Browse files

arm64: Use generic kernel_thread() implementation 



This patch enables CONFIG_GENERIC_KERNEL_THREAD on arm64, changes
copy_threads to cope with kernel threads creation and adapts
ret_from_fork accordingly. The arm64-specific kernel_thread
implementation is no longer needed.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent ddffeb8c

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ config ARM64 
	select GENERIC_IOMAP

	select GENERIC_IRQ_PROBE

	select GENERIC_IRQ_SHOW

	select GENERIC_KERNEL_THREAD

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_TIME_VSYSCALL

	select HARDIRQS_SW_RESEND

arch/arm64/include/asm/processor.h

+0 −5
Original line number Diff line number Diff line
@@ -136,11 +136,6 @@ unsigned long get_wchan(struct task_struct *p); 
extern struct task_struct *cpu_switch_to(struct task_struct *prev,

					 struct task_struct *next);



/*

 * Create a new kernel thread

 */

extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);



#define task_pt_regs(p) \

	((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)

arch/arm64/kernel/entry.S

+4 −1
Original line number Diff line number Diff line
@@ -611,7 +611,10 @@ ENDPROC(ret_to_user) 
 */

ENTRY(ret_from_fork)

	bl	schedule_tail

	get_thread_info tsk

	cbz	x19, 1f				// not a kernel thread

	mov	x0, x20

	blr	x19

1:	get_thread_info tsk

	b	ret_to_user

ENDPROC(ret_from_fork)

arch/arm64/kernel/process.c

+24 −53
Original line number Diff line number Diff line
@@ -240,12 +240,14 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, 
	struct pt_regs *childregs = task_pt_regs(p);

	unsigned long tls = p->thread.tp_value;



	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));



	if (likely(regs)) {

		*childregs = *regs;

		childregs->regs[0] = 0;



	if (is_compat_thread(task_thread_info(p)))

		if (is_compat_thread(task_thread_info(p))) {

			childregs->compat_sp = stack_start;

	else {

		} else {

			/*

			 * Read the current TLS pointer from tpidr_el0 as it may be

			 * out-of-sync with the saved value.
@@ -253,14 +255,20 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, 
			asm("mrs %0, tpidr_el0" : "=r" (tls));

			childregs->sp = stack_start;

		}



	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));

	p->thread.cpu_context.sp = (unsigned long)childregs;

	p->thread.cpu_context.pc = (unsigned long)ret_from_fork;



	/* If a TLS pointer was passed to clone, use that for the new thread. */

		/*

		 * If a TLS pointer was passed to clone (4th argument), use it

		 * for the new thread.

		 */

		if (clone_flags & CLONE_SETTLS)

			tls = regs->regs[3];

	} else {

		memset(childregs, 0, sizeof(struct pt_regs));

		childregs->pstate = PSR_MODE_EL1h;

		p->thread.cpu_context.x19 = stack_start;

		p->thread.cpu_context.x20 = stk_sz;

	}

	p->thread.cpu_context.pc = (unsigned long)ret_from_fork;

	p->thread.cpu_context.sp = (unsigned long)childregs;

	p->thread.tp_value = tls;



	ptrace_hw_copy_thread(p);
@@ -327,43 +335,6 @@ int dump_fpu (struct pt_regs *regs, struct user_fp *fp) 
}

EXPORT_SYMBOL(dump_fpu);



/*

 * Shuffle the argument into the correct register before calling the

 * thread function.  x1 is the thread argument, x2 is the pointer to

 * the thread function, and x3 points to the exit function.

 */

extern void kernel_thread_helper(void);

asm(	".section .text\n"

"	.align\n"

"	.type	kernel_thread_helper, #function\n"

"kernel_thread_helper:\n"

"	mov	x0, x1\n"

"	mov	x30, x3\n"

"	br	x2\n"

"	.size	kernel_thread_helper, . - kernel_thread_helper\n"

"	.previous");



#define kernel_thread_exit	do_exit



/*

 * Create a kernel thread.

 */

pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)

{

	struct pt_regs regs;



	memset(&regs, 0, sizeof(regs));



	regs.regs[1] = (unsigned long)arg;

	regs.regs[2] = (unsigned long)fn;

	regs.regs[3] = (unsigned long)kernel_thread_exit;

	regs.pc = (unsigned long)kernel_thread_helper;

	regs.pstate = PSR_MODE_EL1h;



	return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);

}

EXPORT_SYMBOL(kernel_thread);



unsigned long get_wchan(struct task_struct *p)

{

	struct stackframe frame;