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xtensa: switch to generic kernel_thread()

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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Max Filippov 2012-10-25 11:10:50 +04:00 committed by Chris Zankel
parent 6ebe7da25b
commit 3306a72669
5 changed files with 61 additions and 63 deletions
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1
arch/xtensa/Kconfig
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@ -13,6 +13,7 @@ config XTENSA
select GENERIC_CPU_DEVICES
select MODULES_USE_ELF_RELA
select GENERIC_PCI_IOMAP
select GENERIC_KERNEL_THREAD
select ARCH_WANT_OPTIONAL_GPIOLIB
help
Xtensa processors are 32-bit RISC machines designed by Tensilica

4
arch/xtensa/include/asm/processor.h
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@ -152,6 +152,7 @@ struct thread_struct {
/* Clearing a0 terminates the backtrace. */
#define start_thread(regs, new_pc, new_sp) \
memset(regs, 0, sizeof(*regs)); \
regs->pc = new_pc; \
regs->ps = USER_PS_VALUE; \
regs->areg[1] = new_sp; \
@ -168,9 +169,6 @@ struct mm_struct;
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)
/* Create a kernel thread without removing it from tasklists */
extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
/* Copy and release all segment info associated with a VM */
#define copy_segments(p, mm) do { } while(0)
#define release_segments(mm) do { } while(0)

41
arch/xtensa/kernel/entry.S
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@ -1832,34 +1832,6 @@ ENTRY(system_call)
retw
/*
* Create a kernel thread
*
* int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
* a2 a2 a3 a4
*/
ENTRY(kernel_thread)
entry a1, 16
mov a5, a2 # preserve fn over syscall
mov a7, a3 # preserve args over syscall
movi a3, _CLONE_VM | _CLONE_UNTRACED
movi a2, __NR_clone
or a6, a4, a3 # arg0: flags
mov a3, a1 # arg1: sp
syscall
beq a3, a1, 1f # branch if parent
mov a6, a7 # args
callx4 a5 # fn(args)
movi a2, __NR_exit
syscall # return value of fn(args) still in a6
1: retw
/*
* Do a system call from kernel instead of calling sys_execve, so we end up
* with proper pt_regs.
@ -1958,3 +1930,16 @@ ENTRY(ret_from_fork)
j common_exception_return
/*
* Kernel thread creation helper
* On entry, set up by copy_thread: a2 = thread_fn, a3 = thread_fn arg
* left from _switch_to: a6 = prev
*/
ENTRY(ret_from_kernel_thread)
call4 schedule_tail
mov a6, a3
callx4 a2
call4 do_exit
ENDPROC(ret_from_kernel_thread)

77
arch/xtensa/kernel/process.c
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@ -45,6 +45,7 @@
#include <asm/regs.h>
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);
struct task_struct *current_set[NR_CPUS] = {&init_task, };
@ -158,18 +159,30 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
/*
* Copy thread.
*
* There are two modes in which this function is called:
* 1) Userspace thread creation,
* regs != NULL, usp_thread_fn is userspace stack pointer.
* It is expected to copy parent regs (in case CLONE_VM is not set
* in the clone_flags) and set up passed usp in the childregs.
* 2) Kernel thread creation,
* regs == NULL, usp_thread_fn is the function to run in the new thread
* and thread_fn_arg is its parameter.
* childregs are not used for the kernel threads.
*
* The stack layout for the new thread looks like this:
*
* +------------------------+ <- sp in childregs (= tos)
* +------------------------+
* | childregs |
* +------------------------+ <- thread.sp = sp in dummy-frame
* | dummy-frame | (saved in dummy-frame spill-area)
* +------------------------+
*
* We create a dummy frame to return to ret_from_fork:
* a0 points to ret_from_fork (simulating a call4)
* We create a dummy frame to return to either ret_from_fork or
* ret_from_kernel_thread:
* a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
* sp points to itself (thread.sp)
* a2, a3 are unused.
* a2, a3 are unused for userspace threads,
* a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
*
* Note: This is a pristine frame, so we don't need any spill region on top of
* childregs.
@ -185,41 +198,37 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
* involved. Much simpler to just not copy those live frames across.
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long unused,
struct task_struct * p, struct pt_regs * regs)
int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
unsigned long thread_fn_arg,
struct task_struct *p, struct pt_regs *unused)
{
struct pt_regs *childregs;
unsigned long tos;
int user_mode = user_mode(regs);
struct pt_regs *childregs = task_pt_regs(p);
#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
struct thread_info *ti;
#endif
/* Set up new TSS. */
tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
if (user_mode)
childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
else
childregs = (struct pt_regs*)tos - 1;
/* This does not copy all the regs. In a bout of brilliance or madness,
ARs beyond a0-a15 exist past the end of the struct. */
*childregs = *regs;
/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
*((int*)childregs - 3) = (unsigned long)childregs;
*((int*)childregs - 4) = 0;
childregs->areg[2] = 0;
p->set_child_tid = p->clear_child_tid = NULL;
p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
p->thread.sp = (unsigned long)childregs;
if (user_mode(regs)) {
if (!(p->flags & PF_KTHREAD)) {
struct pt_regs *regs = current_pt_regs();
unsigned long usp = usp_thread_fn ?
usp_thread_fn : regs->areg[1];
p->thread.ra = MAKE_RA_FOR_CALL(
(unsigned long)ret_from_fork, 0x1);
/* This does not copy all the regs.
* In a bout of brilliance or madness,
* ARs beyond a0-a15 exist past the end of the struct.
*/
*childregs = *regs;
childregs->areg[1] = usp;
childregs->areg[2] = 0;
/* When sharing memory with the parent thread, the child
usually starts on a pristine stack, so we have to reset
@ -254,11 +263,19 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
// FIXME: we need to set THREADPTR in thread_info...
if (clone_flags & CLONE_SETTLS)
childregs->areg[2] = childregs->areg[6];
} else {
/* In kernel space, we start a new thread with a new stack. */
childregs->wmask = 1;
childregs->areg[1] = tos;
p->thread.ra = MAKE_RA_FOR_CALL(
(unsigned long)ret_from_kernel_thread, 1);
/* pass parameters to ret_from_kernel_thread:
* a2 = thread_fn, a3 = thread_fn arg
*/
*((int *)childregs - 1) = thread_fn_arg;
*((int *)childregs - 2) = usp_thread_fn;
/* Childregs are only used when we're going to userspace
* in which case start_thread will set them up.
*/
}
#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
@ -354,8 +371,6 @@ long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
void __user *child_tid, long a5,
struct pt_regs *regs)
{
if (!newsp)
newsp = regs->areg[1];
return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
}

1
arch/xtensa/kernel/xtensa_ksyms.c
View File

@ -43,7 +43,6 @@ EXPORT_SYMBOL(__strncpy_user);
EXPORT_SYMBOL(clear_page);
EXPORT_SYMBOL(copy_page);
EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(empty_zero_page);
/*