sparc32: switch to generic kernel_thread()

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

4 files changed, 56 insertions, 81 deletions

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index e47eb324d77a..edc4ede8ec3e 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -40,6 +40,7 @@ config SPARC
         select GENERIC_STRNCPY_FROM_USER
         select GENERIC_STRNLEN_USER
         select MODULES_USE_ELF_RELA
+        select GENERIC_KERNEL_THREAD
 
 config SPARC32
         def_bool !64BIT
@@ -74,7 +75,6 @@ config SPARC64
         select ARCH_HAVE_NMI_SAFE_CMPXCHG
         select HAVE_C_RECORDMCOUNT
         select NO_BOOTMEM
-        select GENERIC_KERNEL_THREAD
         select GENERIC_KERNEL_EXECVE
 
 config ARCH_DEFCONFIG
diff --git a/arch/sparc/include/asm/processor_32.h b/arch/sparc/include/asm/processor_32.h
index f74ac9ee33a8..c1e01914fd98 100644
--- a/arch/sparc/include/asm/processor_32.h
+++ b/arch/sparc/include/asm/processor_32.h
@@ -106,7 +106,6 @@ static inline void start_thread(struct pt_regs * regs, unsigned long pc,
 
 /* Free all resources held by a thread. */
 #define release_thread(tsk)             do { } while(0)
-extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long get_wchan(struct task_struct *);
 
diff --git a/arch/sparc/kernel/entry.S b/arch/sparc/kernel/entry.S
index dc089702e00a..6114672a1b0e 100644
--- a/arch/sparc/kernel/entry.S
+++ b/arch/sparc/kernel/entry.S
@@ -983,6 +983,16 @@ ret_from_fork:
         b       ret_sys_call
          ld     [%sp + STACKFRAME_SZ + PT_I0], %o0
 
+        .globl  ret_from_kernel_thread
+ret_from_kernel_thread:
+        call    schedule_tail
+         ld     [%g3 + TI_TASK], %o0
+        ld      [%sp + STACKFRAME_SZ + PT_G1], %l0
+        call    %l0
+         ld     [%sp + STACKFRAME_SZ + PT_G2], %o0
+        call    do_exit /* won't return */
+         clr    %o0
+
         /* Linux native system calls enter here... */
         .align  4
         .globl  linux_sparc_syscall
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 487bffb36f5e..72764356d308 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -316,9 +316,10 @@ asmlinkage int sparc_do_fork(unsigned long clone_flags,
  * XXX See comment above sys_vfork in sparc64. todo.
  */
 extern void ret_from_fork(void);
+extern void ret_from_kernel_thread(void);
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
-                unsigned long unused,
+                unsigned long arg,
                 struct task_struct *p, struct pt_regs *regs)
 {
         struct thread_info *ti = task_thread_info(p);
@@ -336,16 +337,13 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
         }
 
         /*
-         *  p->thread_info         new_stack   childregs
-         *  !                      !           !             {if(PSR_PS) }
-         *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
-         *  +----- - - - - - ------+===========+============={+==========}+
+         *  p->thread_info         new_stack   childregs stack bottom
+         *  !                      !           !             !
+         *  V                      V (stk.fr.) V  (pt_regs)  V
+         *  +----- - - - - - ------+===========+=============+
          */
         new_stack = task_stack_page(p) + THREAD_SIZE;
-        if (regs->psr & PSR_PS)
-                new_stack -= STACKFRAME_SZ;
         new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
-        memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
         childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);
 
         /*
@@ -356,55 +354,58 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
          * Thus, kpsr|=PSR_PIL.
          */
         ti->ksp = (unsigned long) new_stack;
+        p->thread.kregs = childregs;
+
+        if (unlikely(p->flags & PF_KTHREAD)) {
+                extern int nwindows;
+                unsigned long psr;
+                memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
+                p->thread.flags |= SPARC_FLAG_KTHREAD;
+                p->thread.current_ds = KERNEL_DS;
+                ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
+                childregs->u_regs[UREG_G1] = sp; /* function */
+                childregs->u_regs[UREG_G2] = arg;
+                psr = childregs->psr = get_psr();
+                ti->kpsr = psr | PSR_PIL;
+                ti->kwim = 1 << (((psr & PSR_CWP) + 1) % nwindows);
+                return 0;
+        }
+        memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
+        childregs->u_regs[UREG_FP] = sp;
+        p->thread.flags &= ~SPARC_FLAG_KTHREAD;
+        p->thread.current_ds = USER_DS;
         ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
         ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
         ti->kwim = current->thread.fork_kwim;
 
-        if(regs->psr & PSR_PS) {
-                extern struct pt_regs fake_swapper_regs;
+        if (sp != regs->u_regs[UREG_FP]) {
+                struct sparc_stackf __user *childstack;
+                struct sparc_stackf __user *parentstack;
 
-                p->thread.kregs = &fake_swapper_regs;
-                new_stack += STACKFRAME_SZ + TRACEREG_SZ;
-                childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
-                p->thread.flags |= SPARC_FLAG_KTHREAD;
-                p->thread.current_ds = KERNEL_DS;
-                memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
-                childregs->u_regs[UREG_G6] = (unsigned long) ti;
-        } else {
-                p->thread.kregs = childregs;
-                childregs->u_regs[UREG_FP] = sp;
-                p->thread.flags &= ~SPARC_FLAG_KTHREAD;
-                p->thread.current_ds = USER_DS;
-
-                if (sp != regs->u_regs[UREG_FP]) {
-                        struct sparc_stackf __user *childstack;
-                        struct sparc_stackf __user *parentstack;
-
-                        /*
-                         * This is a clone() call with supplied user stack.
-                         * Set some valid stack frames to give to the child.
-                         */
-                        childstack = (struct sparc_stackf __user *)
-                                (sp & ~0xfUL);
-                        parentstack = (struct sparc_stackf __user *)
-                                regs->u_regs[UREG_FP];
+                /*
+                 * This is a clone() call with supplied user stack.
+                 * Set some valid stack frames to give to the child.
+                 */
+                childstack = (struct sparc_stackf __user *)
+                        (sp & ~0xfUL);
+                parentstack = (struct sparc_stackf __user *)
+                        regs->u_regs[UREG_FP];
 
 #if 0
-                        printk("clone: parent stack:\n");
-                        show_stackframe(parentstack);
+                printk("clone: parent stack:\n");
+                show_stackframe(parentstack);
 #endif
 
-                        childstack = clone_stackframe(childstack, parentstack);
-                        if (!childstack)
-                                return -EFAULT;
+                childstack = clone_stackframe(childstack, parentstack);
+                if (!childstack)
+                        return -EFAULT;
 
 #if 0
-                        printk("clone: child stack:\n");
-                        show_stackframe(childstack);
+                printk("clone: child stack:\n");
+                show_stackframe(childstack);
 #endif
 
-                        childregs->u_regs[UREG_FP] = (unsigned long)childstack;
-                }
+                childregs->u_regs[UREG_FP] = (unsigned long)childstack;
         }
 
 #ifdef CONFIG_SMP
@@ -503,41 +504,6 @@ out:
         return error;
 }
 
-/*
- * This is the mechanism for creating a new kernel thread.
- *
- * NOTE! Only a kernel-only process(ie the swapper or direct descendants
- * who haven't done an "execve()") should use this: it will work within
- * a system call from a "real" process, but the process memory space will
- * not be freed until both the parent and the child have exited.
- */
-pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
-        long retval;
-
-        __asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
-                             "mov %5, %%g3\n\t"    /* and arg. */
-                             "mov %1, %%g1\n\t"
-                             "mov %2, %%o0\n\t"    /* Clone flags. */
-                             "mov 0, %%o1\n\t"     /* usp arg == 0 */
-                             "t 0x10\n\t"          /* Linux/Sparc clone(). */
-                             "cmp %%o1, 0\n\t"
-                             "be 1f\n\t"           /* The parent, just return. */
-                             " nop\n\t"            /* Delay slot. */
-                             "jmpl %%g2, %%o7\n\t" /* Call the function. */
-                             " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
-                             "mov %3, %%g1\n\t"
-                             "t 0x10\n\t"          /* Linux/Sparc exit(). */
-                             /* Notreached by child. */
-                             "1: mov %%o0, %0\n\t" :
-                             "=r" (retval) :
-                             "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
-                             "i" (__NR_exit),  "r" (fn), "r" (arg) :
-                             "g1", "g2", "g3", "o0", "o1", "memory", "cc");
-        return retval;
-}
-EXPORT_SYMBOL(kernel_thread);
-
 unsigned long get_wchan(struct task_struct *task)
 {
         unsigned long pc, fp, bias = 0;