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Commit 9e14f828 authored by Al Viro's avatar Al Viro
Browse files

arm: split ret_from_fork, simplify kernel_thread() [based on patch by rmk] 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 38b983b3

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ config ARM 
	select GENERIC_STRNCPY_FROM_USER

	select GENERIC_STRNLEN_USER

	select DCACHE_WORD_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && !CPU_BIG_ENDIAN

	select GENERIC_KERNEL_THREAD

	help

	  The ARM series is a line of low-power-consumption RISC chip designs

	  licensed by ARM Ltd and targeted at embedded applications and

arch/arm/include/asm/processor.h

+0 −5
Original line number Diff line number Diff line
@@ -85,11 +85,6 @@ unsigned long get_wchan(struct task_struct *p); 
#define cpu_relax()			barrier()

#endif



/*

 * 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/arm/kernel/entry-common.S

+12 −0
Original line number Diff line number Diff line
@@ -91,6 +91,18 @@ ENTRY(ret_from_fork) 
	b	ret_slow_syscall

ENDPROC(ret_from_fork)



ENTRY(ret_from_kernel_thread)

 UNWIND(.fnstart)

 UNWIND(.cantunwind)

	bl	schedule_tail

	mov	r0, r4

	adr	lr, BSYM(1f)	@ kernel threads should not exit

	mov	pc, r5

1:	bl	do_exit

	nop

 UNWIND(.fnend)

ENDPROC(ret_from_kernel_thread)



	.equ NR_syscalls,0

#define CALL(x) .equ NR_syscalls,NR_syscalls+1

#include "calls.S"

arch/arm/kernel/process.c

+13 −62
Original line number Diff line number Diff line
@@ -373,6 +373,7 @@ void release_thread(struct task_struct *dead_task) 
}



asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");



int

copy_thread(unsigned long clone_flags, unsigned long stack_start,
@@ -381,13 +382,20 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start, 
	struct thread_info *thread = task_thread_info(p);

	struct pt_regs *childregs = task_pt_regs(p);



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



	if (likely(regs)) {

		*childregs = *regs;

		childregs->ARM_r0 = 0;

		childregs->ARM_sp = stack_start;



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

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

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

	} else {

		thread->cpu_context.r4 = stk_sz;

		thread->cpu_context.r5 = stack_start;

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

		childregs->ARM_cpsr = SVC_MODE;

	}

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



	clear_ptrace_hw_breakpoint(p);
@@ -423,63 +431,6 @@ 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.  r4 is the thread argument, r5 is the pointer to

 * the thread function, and r6 points to the exit function.

 */

extern void kernel_thread_helper(void);

asm(	".pushsection .text\n"

"	.align\n"

"	.type	kernel_thread_helper, #function\n"

"kernel_thread_helper:\n"

#ifdef CONFIG_TRACE_IRQFLAGS

"	bl	trace_hardirqs_on\n"

#endif

"	msr	cpsr_c, r7\n"

"	mov	r0, r4\n"

"	mov	lr, r6\n"

"	mov	pc, r5\n"

"	.size	kernel_thread_helper, . - kernel_thread_helper\n"

"	.popsection");



#ifdef CONFIG_ARM_UNWIND

extern void kernel_thread_exit(long code);

asm(	".pushsection .text\n"

"	.align\n"

"	.type	kernel_thread_exit, #function\n"

"kernel_thread_exit:\n"

"	.fnstart\n"

"	.cantunwind\n"

"	bl	do_exit\n"

"	nop\n"

"	.fnend\n"

"	.size	kernel_thread_exit, . - kernel_thread_exit\n"

"	.popsection");

#else

#define kernel_thread_exit	do_exit

#endif



/*

 * 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.ARM_r4 = (unsigned long)arg;

	regs.ARM_r5 = (unsigned long)fn;

	regs.ARM_r6 = (unsigned long)kernel_thread_exit;

	regs.ARM_r7 = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;

	regs.ARM_pc = (unsigned long)kernel_thread_helper;

	regs.ARM_cpsr = regs.ARM_r7 | PSR_I_BIT;



	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;