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openrisc: use generic kernel_thread/kernel_execve

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Signed-off-by: Jonas Bonn <jonas@southpole.se>
This commit is contained in:
Jonas Bonn 2012-10-19 18:07:44 +02:00
parent 287ad220cd
commit cbf23cf1b9
3 changed files with 69 additions and 103 deletions
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2
arch/openrisc/Kconfig
View File

@ -22,6 +22,8 @@ config OPENRISC
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select MODULES_USE_ELF_RELA
select GENERIC_KERNEL_THREAD
select GENERIC_KERNEL_EXECVE
config MMU
def_bool y

30
arch/openrisc/kernel/entry.S
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@ -894,6 +894,16 @@ ENTRY(ret_from_fork)
l.jal schedule_tail
l.nop
/* Check if we are a kernel thread */
l.sfeqi r20,0
l.bf 1f
l.nop
/* ...we are a kernel thread so invoke the requested callback */
l.jalr r20
l.or r3,r22,r0
1:
/* _syscall_returns expect r11 to contain return value */
l.lwz r11,PT_GPR11(r1)
@ -915,26 +925,6 @@ ENTRY(ret_from_fork)
l.j _syscall_return
l.nop
/* Since syscalls don't save call-clobbered registers, the args to
* kernel_thread_helper will need to be passed through callee-saved
* registers and copied to the parameter registers when the thread
* begins running.
*
* See arch/openrisc/kernel/process.c:
* The args are passed as follows:
* arg1 (r3) : passed in r20
* arg2 (r4) : passed in r22
*/
ENTRY(_kernel_thread_helper)
l.or r3,r20,r0
l.or r4,r22,r0
l.movhi r31,hi(kernel_thread_helper)
l.ori r31,r31,lo(kernel_thread_helper)
l.jr r31
l.nop
/* ========================================================[ switch ] === */
/*

140
arch/openrisc/kernel/process.c
View File

@ -109,65 +109,82 @@ void release_thread(struct task_struct *dead_task)
*/
extern asmlinkage void ret_from_fork(void);
/*
* copy_thread
* @clone_flags: flags
* @usp: user stack pointer or fn for kernel thread
* @arg: arg to fn for kernel thread; always NULL for userspace thread
* @p: the newly created task
* @regs: CPU context to copy for userspace thread; always NULL for kthread
*
* At the top of a newly initialized kernel stack are two stacked pt_reg
* structures. The first (topmost) is the userspace context of the thread.
* The second is the kernelspace context of the thread.
*
* A kernel thread will not be returning to userspace, so the topmost pt_regs
* struct can be uninitialized; it _does_ need to exist, though, because
* a kernel thread can become a userspace thread by doing a kernel_execve, in
* which case the topmost context will be initialized and used for 'returning'
* to userspace.
*
* The second pt_reg struct needs to be initialized to 'return' to
* ret_from_fork. A kernel thread will need to set r20 to the address of
* a function to call into (with arg in r22); userspace threads need to set
* r20 to NULL in which case ret_from_fork will just continue a return to
* userspace.
*
* A kernel thread 'fn' may return; this is effectively what happens when
* kernel_execve is called. In that case, the userspace pt_regs must have
* been initialized (which kernel_execve takes care of, see start_thread
* below); ret_from_fork will then continue its execution causing the
* 'kernel thread' to return to userspace as a userspace thread.
*/
int
copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long unused, struct task_struct *p, struct pt_regs *regs)
unsigned long arg, struct task_struct *p, struct pt_regs *regs)
{
struct pt_regs *childregs;
struct pt_regs *userregs;
struct pt_regs *kregs;
unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
struct thread_info *ti;
unsigned long top_of_kernel_stack;
top_of_kernel_stack = sp;
p->set_child_tid = p->clear_child_tid = NULL;
/* Copy registers */
/* redzone */
sp -= STACK_FRAME_OVERHEAD;
/* Locate userspace context on stack... */
sp -= STACK_FRAME_OVERHEAD; /* redzone */
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *)sp;
userregs = (struct pt_regs *) sp;
/* Copy parent registers */
*childregs = *regs;
if ((childregs->sr & SPR_SR_SM) == 1) {
/* for kernel thread, set `current_thread_info'
* and stackptr in new task
*/
childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
childregs->gpr[10] = (unsigned long)task_thread_info(p);
} else {
childregs->sp = usp;
}
childregs->gpr[11] = 0; /* Result from fork() */
/*
* 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.
*/
/* redzone */
sp -= STACK_FRAME_OVERHEAD;
/* ...and kernel context */
sp -= STACK_FRAME_OVERHEAD; /* redzone */
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *)sp;
ti = task_thread_info(p);
ti->ksp = sp;
if (unlikely(p->flags & PF_KTHREAD)) {
memset(kregs, 0, sizeof(struct pt_regs));
kregs->gpr[20] = usp; /* fn, kernel thread */
kregs->gpr[22] = arg;
} else {
*userregs = *regs;
/* kregs->sp must store the location of the 'pre-switch' kernel stack
* pointer... for a newly forked process, this is simply the top of
* the kernel stack.
userregs->sp = usp;
userregs->gpr[11] = 0; /* Result from fork() */
kregs->gpr[20] = 0; /* Userspace thread */
}
/*
* _switch wants the kernel stack page in pt_regs->sp so that it
* can restore it to thread_info->ksp... see _switch for details.
*/
kregs->sp = top_of_kernel_stack;
kregs->gpr[10] = (unsigned long)task_thread_info(p);
kregs->gpr[9] = (unsigned long)ret_from_fork;
task_thread_info(p)->ksp = (unsigned long)kregs;
return 0;
}
@ -176,16 +193,14 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
*/
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
{
unsigned long sr = regs->sr & ~SPR_SR_SM;
unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
set_fs(USER_DS);
memset(regs->gpr, 0, sizeof(regs->gpr));
memset(regs, 0, sizeof(struct pt_regs));
regs->pc = pc;
regs->sr = sr;
regs->sp = sp;
/* printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
}
/* Fill in the fpu structure for a core dump. */
@ -236,31 +251,6 @@ void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
dest[35] = 0;
}
extern void _kernel_thread_helper(void);
void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)
{
do_exit(fn(arg));
}
/*
* Create a kernel thread.
*/
int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
{
struct pt_regs regs;
memset(&regs, 0, sizeof(regs));
regs.gpr[20] = (unsigned long)fn;
regs.gpr[22] = (unsigned long)arg;
regs.sr = mfspr(SPR_SR);
regs.pc = (unsigned long)_kernel_thread_helper;
return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
0, &regs, 0, NULL, NULL);
}
/*
* sys_execve() executes a new program.
*/
@ -291,19 +281,3 @@ unsigned long get_wchan(struct task_struct *p)
return 0;
}
int kernel_execve(const char *filename, char *const argv[], char *const envp[])
{
register long __res asm("r11") = __NR_execve;
register long __a asm("r3") = (long)(filename);
register long __b asm("r4") = (long)(argv);
register long __c asm("r5") = (long)(envp);
__asm__ volatile ("l.sys 1"
: "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
: "0"(__res), "1"(__a), "2"(__b), "3"(__c)
: "r6", "r7", "r8", "r12", "r13", "r15",
"r17", "r19", "r21", "r23", "r25", "r27",
"r29", "r31");
__asm__ volatile ("l.nop");
return __res;
}