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frv: split ret_from_fork, simplify kernel_thread() a lot 

Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-09-18 22:18:51 -04:00
parent d878d6dace
commit 02ce496f15
5 changed files with 30 additions and 98 deletions
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2
arch/frv/kernel/Makefile
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@ -7,7 +7,7 @@ heads-$(CONFIG_MMU) := head-mmu-fr451.o
extra-y:= head.o vmlinux.lds
obj-y := $(heads-y) entry.o entry-table.o break.o switch_to.o kernel_thread.o \
obj-y := $(heads-y) entry.o entry-table.o break.o switch_to.o \
kernel_execve.o process.o traps.o ptrace.o signal.o dma.o \
sys_frv.o time.o setup.o frv_ksyms.o \
debug-stub.o irq.o sleep.o uaccess.o

8
arch/frv/kernel/entry.S
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@ -863,6 +863,14 @@ ret_from_fork:
setlos.p #0,gr8
bra __syscall_exit
.globl ret_from_kernel_thread
ret_from_kernel_thread:
lddi.p @(gr28,#REG_GR(8)),gr20
call schedule_tail
or.p gr20,gr20,gr8
calll @(gr21,gr0)
bra sys_exit
###################################################################################################
#
# Return to user mode is not as complex as all this looks,

1
arch/frv/kernel/frv_ksyms.c
View File

@ -30,7 +30,6 @@ EXPORT_SYMBOL(ip_fast_csum);
EXPORT_SYMBOL(local_irq_count);
EXPORT_SYMBOL(local_bh_count);
#endif
EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(__res_bus_clock_speed_HZ);
EXPORT_SYMBOL(__page_offset);

77
arch/frv/kernel/kernel_thread.S
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@ -1,77 +0,0 @@
/* kernel_thread.S: kernel thread creation
*
* Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/linkage.h>
#include <linux/kern_levels.h>
#include <asm/unistd.h>
#define CLONE_VM 0x00000100 /* set if VM shared between processes */
.section .rodata
kernel_thread_emsg:
.asciz KERN_ERR "failed to create kernel thread: error=%d\n"
.text
.balign 4
###############################################################################
#
# Create a kernel thread
#
# int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
#
###############################################################################
.globl kernel_thread
.type kernel_thread,@function
kernel_thread:
or.p gr8,gr0,gr4
or gr9,gr0,gr5
# start by forking the current process, but with shared VM
setlos.p #__NR_clone,gr7 ; syscall number
ori gr10,#CLONE_VM,gr8 ; first syscall arg [clone_flags]
sethi.p #0xe4e4,gr9 ; second syscall arg [newsp]
setlo #0xe4e4,gr9
setlos.p #0,gr10 ; third syscall arg [parent_tidptr]
setlos #0,gr11 ; fourth syscall arg [child_tidptr]
tira gr0,#0
setlos.p #4095,gr7
andcc gr8,gr8,gr0,icc0
addcc.p gr8,gr7,gr0,icc1
bnelr icc0,#2
bc icc1,#0,kernel_thread_error
# now invoke the work function
or gr5,gr0,gr8
calll @(gr4,gr0)
# and finally exit the thread
setlos #__NR_exit,gr7 ; syscall number
tira gr0,#0
kernel_thread_error:
subi sp,#8,sp
movsg lr,gr4
sti gr8,@(sp,#0)
sti.p gr4,@(sp,#4)
or gr8,gr0,gr9
sethi.p %hi(kernel_thread_emsg),gr8
setlo %lo(kernel_thread_emsg),gr8
call printk
ldi @(sp,#4),gr4
ldi @(sp,#0),gr8
subi sp,#8,sp
jmpl @(gr4,gr0)
.size kernel_thread,.-kernel_thread

40
arch/frv/kernel/process.c
View File

@ -37,6 +37,7 @@
#include "local.h"
asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);
#include <asm/pgalloc.h>
@ -172,29 +173,21 @@ int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long topstk,
struct task_struct *p, struct pt_regs *regs)
{
struct pt_regs *childregs0, *childregs, *regs0;
struct pt_regs *childregs;
regs0 = __kernel_frame0_ptr;
childregs0 = (struct pt_regs *)
childregs = (struct pt_regs *)
(task_stack_page(p) + THREAD_SIZE - FRV_FRAME0_SIZE);
childregs = childregs0;
/* set up the userspace frame (the only place that the USP is stored) */
*childregs0 = *regs0;
*childregs = *regs;
childregs0->gr8 = 0;
childregs0->sp = usp;
childregs0->next_frame = NULL;
childregs->sp = usp;
childregs->next_frame = NULL;
/* set up the return kernel frame if called from kernel_thread() */
if (regs != regs0) {
childregs--;
*childregs = *regs;
childregs->sp = (unsigned long) childregs0;
childregs->next_frame = childregs0;
childregs->gr15 = (unsigned long) task_thread_info(p);
childregs->gr29 = (unsigned long) p;
}
if (unlikely(!user_mode(regs)))
p->thread.pc = (unsigned long) ret_from_kernel_thread;
else
p->thread.pc = (unsigned long) ret_from_fork;
p->set_child_tid = p->clear_child_tid = NULL;
@ -203,8 +196,7 @@ int copy_thread(unsigned long clone_flags,
p->thread.sp = (unsigned long) childregs;
p->thread.fp = 0;
p->thread.lr = 0;
p->thread.pc = (unsigned long) ret_from_fork;
p->thread.frame0 = childregs0;
p->thread.frame0 = childregs;
/* the new TLS pointer is passed in as arg #5 to sys_clone() */
if (clone_flags & CLONE_SETTLS)
@ -347,3 +339,13 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
sizeof(current->thread.user->f));
return 1;
}
int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
struct pt_regs regs = {
.gr8 = (unsigned long)arg;
.gr9 = (unsigned long)fn;
.psr = PSR_S;
};
return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}