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c6x: add ret_from_kernel_thread(), simplify kernel_thread()

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Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Mark Salter 2012-09-21 12:26:37 -04:00 • committed by Al Viro
parent 61b7fbc3f4
commit 46f15067c0
2 changed files with 32 additions and 26 deletions
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20
arch/c6x/kernel/entry.S
View file

@ -400,6 +400,26 @@ ret_from_fork_2:
STW .D2T2 B0,*+SP(REGS_A4+8) STW .D2T2 B0,*+SP(REGS_A4+8)
ENDPROC(ret_from_fork) ENDPROC(ret_from_fork)
ENTRY(ret_from_kernel_thread)
#ifdef CONFIG_C6X_BIG_KERNEL
MVKL .S1 schedule_tail,A0
MVKH .S1 schedule_tail,A0
B .S2X A0
#else
B .S2 schedule_tail
#endif
LDW .D2T2 *+SP(REGS_A0+8),B10 /* get fn */
ADDKPC .S2 0f,B3,3
0:
B .S2 B10 /* call fn */
LDW .D2T1 *+SP(REGS_A1+8),A4 /* get arg */
MVKL .S2 sys_exit,B11
MVKH .S2 sys_exit,B11
ADDKPC .S2 0f,B3,1
0:
BNOP .S2 B11,5 /* jump to sys_exit */
ENDPROC(ret_from_kernel_thread)
;; ;;
;; These are the interrupt handlers, responsible for calling __do_IRQ() ;; These are the interrupt handlers, responsible for calling __do_IRQ()
;; int6 is used for syscalls (see _system_call entry) ;; int6 is used for syscalls (see _system_call entry)

38
arch/c6x/kernel/process.c
View file

@ -25,6 +25,7 @@ void (*c6x_restart)(void);
void (*c6x_halt)(void); void (*c6x_halt)(void);
extern asmlinkage void ret_from_fork(void); extern asmlinkage void ret_from_fork(void);
extern asmlinkage void ret_from_kernel_thread(void);
/* /*
* power off function, if any * power off function, if any
@ -103,36 +104,21 @@ void machine_power_off(void)
halt_loop(); halt_loop();
} }
static void kernel_thread_helper(int dummy, void *arg, int (*fn)(void *))
{
do_exit(fn(arg));
}
/* /*
* Create a kernel thread * Create a kernel thread
*/ */
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{ {
struct pt_regs regs; struct pt_regs regs = {
.a0 = (unsigned long)fn,
/* .a1 = (unsigned long)arg,
* copy_thread sets a4 to zero (child return from fork) .tsr = 0, /* kernel mode */
* so we can't just set things up to directly return to };
* fn.
*/
memset(&regs, 0, sizeof(regs));
regs.b4 = (unsigned long) arg;
regs.a6 = (unsigned long) fn;
regs.pc = (unsigned long) kernel_thread_helper;
local_save_flags(regs.csr);
regs.csr |= 1;
regs.tsr = 5; /* Set GEE and GIE in TSR */
/* Ok, create the new process.. */ /* Ok, create the new process.. */
return do_fork(flags | CLONE_VM | CLONE_UNTRACED, -1, &regs, return do_fork(flags | CLONE_VM | CLONE_UNTRACED, -1, &regs,
0, NULL, NULL); 0, NULL, NULL);
} }
EXPORT_SYMBOL(kernel_thread);
void flush_thread(void) void flush_thread(void)
{ {
@ -192,21 +178,21 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
childregs = task_pt_regs(p); childregs = task_pt_regs(p);
*childregs = *regs; *childregs = *regs;
childregs->a4 = 0;
if (usp == -1) if (usp == -1) {
/* case of __kernel_thread: we return to supervisor space */ /* case of __kernel_thread: we return to supervisor space */
childregs->sp = (unsigned long)(childregs + 1); childregs->sp = (unsigned long)(childregs + 1);
else p->thread.pc = (unsigned long) ret_from_kernel_thread;
} else {
/* Otherwise use the given stack */ /* Otherwise use the given stack */
childregs->sp = usp; childregs->sp = usp;
p->thread.pc = (unsigned long) ret_from_fork;
}
/* Set usp/ksp */ /* Set usp/ksp */
p->thread.usp = childregs->sp; p->thread.usp = childregs->sp;
/* switch_to uses stack to save/restore 14 callee-saved regs */
thread_saved_ksp(p) = (unsigned long)childregs - 8; thread_saved_ksp(p) = (unsigned long)childregs - 8;
p->thread.pc = (unsigned int) ret_from_fork; p->thread.wchan = p->thread.pc;
p->thread.wchan = (unsigned long) ret_from_fork;
#ifdef __DSBT__ #ifdef __DSBT__
{ {
unsigned long dp; unsigned long dp;