powerpc: split ret_from_fork

... and get rid of in-kernel syscalls in kernel_thread()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

8 files changed, 43 insertions, 84 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 352f416269ce..6e5a0979c085 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -139,6 +139,7 @@ config PPC
         select GENERIC_CLOCKEVENTS
         select GENERIC_STRNCPY_FROM_USER
         select GENERIC_STRNLEN_USER
+        select GENERIC_KERNEL_THREAD
 
 config EARLY_PRINTK
         bool
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 54b73a28c205..5376453d90cc 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -74,9 +74,6 @@ struct task_struct;
 void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp);
 void release_thread(struct task_struct *);
 
-/* Create a new kernel thread. */
-extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-
 /* Lazy FPU handling on uni-processor */
 extern struct task_struct *last_task_used_math;
 extern struct task_struct *last_task_used_altivec;
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index ead5016b02d0..6eb330a87c36 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -435,6 +435,17 @@ ret_from_fork:
         li      r3,0
         b       ret_from_syscall
 
+        .globl  ret_from_kernel_thread
+ret_from_kernel_thread:
+        REST_NVGPRS(r1)
+        bl      schedule_tail
+        mtlr    r14
+        mr      r3,r15
+        PPC440EP_ERR42
+        blrl
+        li      r3,0
+        b       do_exit         # no return
+
 /* Traced system call support */
 syscall_dotrace:
         SAVE_NVGPRS(r1)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index b40e0b4815b3..d7f4fafc7515 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -370,6 +370,16 @@ _GLOBAL(ret_from_fork)
         li      r3,0
         b       syscall_exit
 
+_GLOBAL(ret_from_kernel_thread)
+        bl      .schedule_tail
+        REST_NVGPRS(r1)
+        REST_GPR(2,r1)
+        mtlr    r14
+        mr      r3,r15
+        blrl
+        li      r3,0
+        b       .do_exit        # no return
+
         .section        ".toc","aw"
 DSCR_DEFAULT:
         .tc dscr_default[TC],dscr_default
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 407e293aad2f..19e096bd0e73 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -663,39 +663,6 @@ _GLOBAL(abs)
         sub     r3,r3,r4
         blr
 
-/*
- * Create a kernel thread
- *   kernel_thread(fn, arg, flags)
- */
-_GLOBAL(kernel_thread)
-        stwu    r1,-16(r1)
-        stw     r30,8(r1)
-        stw     r31,12(r1)
-        mr      r30,r3          /* function */
-        mr      r31,r4          /* argument */
-        ori     r3,r5,CLONE_VM  /* flags */
-        oris    r3,r3,CLONE_UNTRACED>>16
-        li      r4,0            /* new sp (unused) */
-        li      r0,__NR_clone
-        sc
-        bns+    1f              /* did system call indicate error? */
-        neg     r3,r3           /* if so, make return code negative */
-1:      cmpwi   0,r3,0          /* parent or child? */
-        bne     2f              /* return if parent */
-        li      r0,0            /* make top-level stack frame */
-        stwu    r0,-16(r1)
-        mtlr    r30             /* fn addr in lr */
-        mr      r3,r31          /* load arg and call fn */
-        PPC440EP_ERR42
-        blrl
-        li      r0,__NR_exit    /* exit if function returns */
-        li      r3,0
-        sc
-2:      lwz     r30,8(r1)
-        lwz     r31,12(r1)
-        addi    r1,r1,16
-        blr
-
 #ifdef CONFIG_SMP
 _GLOBAL(start_secondary_resume)
         /* Reset stack */
diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 565b78625a32..5cfa8008693b 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -407,40 +407,6 @@ _GLOBAL(scom970_write)
 
 
 /*
- * Create a kernel thread
- *   kernel_thread(fn, arg, flags)
- */
-_GLOBAL(kernel_thread)
-        std     r29,-24(r1)
-        std     r30,-16(r1)
-        stdu    r1,-STACK_FRAME_OVERHEAD(r1)
-        mr      r29,r3
-        mr      r30,r4
-        ori     r3,r5,CLONE_VM  /* flags */
-        oris    r3,r3,(CLONE_UNTRACED>>16)
-        li      r4,0            /* new sp (unused) */
-        li      r0,__NR_clone
-        sc
-        bns+    1f              /* did system call indicate error? */
-        neg     r3,r3           /* if so, make return code negative */
-1:      cmpdi   0,r3,0          /* parent or child? */
-        bne     2f              /* return if parent */
-        li      r0,0
-        stdu    r0,-STACK_FRAME_OVERHEAD(r1)
-        ld      r2,8(r29)
-        ld      r29,0(r29)
-        mtlr    r29              /* fn addr in lr */
-        mr      r3,r30          /* load arg and call fn */
-        blrl
-        li      r0,__NR_exit    /* exit after child exits */
-        li      r3,0
-        sc
-2:      addi    r1,r1,STACK_FRAME_OVERHEAD
-        ld      r29,-24(r1)
-        ld      r30,-16(r1)
-        blr
-
-/*
  * disable_kernel_fp()
  * Disable the FPU.
  */
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 3e4031581c65..19e4288d8486 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -94,7 +94,6 @@ EXPORT_SYMBOL(pci_dram_offset);
 #endif /* CONFIG_PCI */
 
 EXPORT_SYMBOL(start_thread);
-EXPORT_SYMBOL(kernel_thread);
 
 EXPORT_SYMBOL(giveup_fpu);
 #ifdef CONFIG_ALTIVEC
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 1a1f2ddfb581..3b06898fa175 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -734,30 +734,39 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 extern unsigned long dscr_default; /* defined in arch/powerpc/kernel/sysfs.c */
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,
-                unsigned long unused, struct task_struct *p,
+                unsigned long arg, struct task_struct *p,
                 struct pt_regs *regs)
 {
         struct pt_regs *childregs, *kregs;
         extern void ret_from_fork(void);
+        extern void ret_from_kernel_thread(void);
+        void (*f)(void);
         unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 
-        CHECK_FULL_REGS(regs);
         /* Copy registers */
         sp -= sizeof(struct pt_regs);
         childregs = (struct pt_regs *) sp;
-        *childregs = *regs;
-        if ((childregs->msr & MSR_PR) == 0) {
+        if (!regs) {
                 /* for kernel thread, set `current' and stackptr in new task */
+                memset(childregs, 0, sizeof(struct pt_regs));
                 childregs->gpr[1] = sp + sizeof(struct pt_regs);
-#ifdef CONFIG_PPC32
-                childregs->gpr[2] = (unsigned long) p;
-#else
+#ifdef CONFIG_PPC64
+                childregs->gpr[14] = *(unsigned long *)usp;
+                childregs->gpr[2] = ((unsigned long *)usp)[1],
                 clear_tsk_thread_flag(p, TIF_32BIT);
+#else
+                childregs->gpr[14] = usp;       /* function */
+                childregs->gpr[2] = (unsigned long) p;
 #endif
+                childregs->gpr[15] = arg;
                 p->thread.regs = NULL;  /* no user register state */
+                f = ret_from_kernel_thread;
         } else {
+                CHECK_FULL_REGS(regs);
+                *childregs = *regs;
                 childregs->gpr[1] = usp;
                 p->thread.regs = childregs;
+                childregs->gpr[3] = 0;  /* Result from fork() */
                 if (clone_flags & CLONE_SETTLS) {
 #ifdef CONFIG_PPC64
                         if (!is_32bit_task())
@@ -766,8 +775,9 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 #endif
                                 childregs->gpr[2] = childregs->gpr[6];
                 }
+
+                f = ret_from_fork;
         }
-        childregs->gpr[3] = 0;  /* Result from fork() */
         sp -= STACK_FRAME_OVERHEAD;
 
         /*
@@ -806,19 +816,17 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
                 p->thread.dscr = current->thread.dscr;
         }
 #endif
-
         /*
          * The PPC64 ABI makes use of a TOC to contain function 
          * pointers.  The function (ret_from_except) is actually a pointer
          * to the TOC entry.  The first entry is a pointer to the actual
          * function.
-         */
+         */
 #ifdef CONFIG_PPC64
-        kregs->nip = *((unsigned long *)ret_from_fork);
+        kregs->nip = *((unsigned long *)f);
 #else
-        kregs->nip = (unsigned long)ret_from_fork;
+        kregs->nip = (unsigned long)f;
 #endif
-
         return 0;
 }