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>
mariux64 · Oct 1, 2012 · 02ce496 · 02ce496
1 parent d878d6d
commit 02ce496
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Showing 5 changed files with 32 additions and 100 deletions.
diff --git a/arch/frv/kernel/Makefile b/arch/frv/kernel/Makefile
@@ -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

diff --git a/arch/frv/kernel/entry.S b/arch/frv/kernel/entry.S
@@ -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,

diff --git a/arch/frv/kernel/frv_ksyms.c b/arch/frv/kernel/frv_ksyms.c
@@ -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);

diff --git a/arch/frv/kernel/kernel_thread.S b/arch/frv/kernel/kernel_thread.S
diff --git a/arch/frv/kernel/process.c b/arch/frv/kernel/process.c
@@ -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;
-
-	childregs0->gr8		= 0;
-	childregs0->sp		= usp;
-	childregs0->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;
-	}
+	*childregs = *regs;
+
+	childregs->sp		= usp;
+	childregs->next_frame	= NULL;
+
+	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);
+}