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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: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas 2012-10-05 12:31:20 +01:00
parent ddffeb8c4d
commit c34501d21b
4 changed files with 32 additions and 62 deletions
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1
arch/arm64/Kconfig
View File

@ -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

5
arch/arm64/include/asm/processor.h
View File

@ -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)

5
arch/arm64/kernel/entry.S
View File

@ -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)

83
arch/arm64/kernel/process.c
View File

@ -240,27 +240,35 @@ 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;
*childregs = *regs;
childregs->regs[0] = 0;
if (is_compat_thread(task_thread_info(p)))
childregs->compat_sp = stack_start;
else {
/*
* Read the current TLS pointer from tpidr_el0 as it may be
* out-of-sync with the saved value.
*/
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 (clone_flags & CLONE_SETTLS)
tls = regs->regs[3];
if (likely(regs)) {
*childregs = *regs;
childregs->regs[0] = 0;
if (is_compat_thread(task_thread_info(p))) {
childregs->compat_sp = stack_start;
} else {
/*
* Read the current TLS pointer from tpidr_el0 as it may be
* out-of-sync with the saved value.
*/
asm("mrs %0, tpidr_el0" : "=r" (tls));
childregs->sp = stack_start;
}
/*
* 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;