sparc64: switch to generic kernel_thread()

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

5 files changed, 42 insertions, 82 deletions

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index b6b442b0d793..ab8bd62b8dbe 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -74,6 +74,7 @@ config SPARC64
         select ARCH_HAVE_NMI_SAFE_CMPXCHG
         select HAVE_C_RECORDMCOUNT
         select NO_BOOTMEM
+        select GENERIC_KERNEL_THREAD
 
 config ARCH_DEFCONFIG
         string
diff --git a/arch/sparc/include/asm/processor_64.h b/arch/sparc/include/asm/processor_64.h
index 4e5a483122a0..5d81ff6b6933 100644
--- a/arch/sparc/include/asm/processor_64.h
+++ b/arch/sparc/include/asm/processor_64.h
@@ -188,8 +188,6 @@ do { \
 /* 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 *task);
 
 #define task_pt_regs(tsk) (task_thread_info(tsk)->kregs)
diff --git a/arch/sparc/include/asm/ptrace.h b/arch/sparc/include/asm/ptrace.h
index 5b6019e327e5..7a4075003e76 100644
--- a/arch/sparc/include/asm/ptrace.h
+++ b/arch/sparc/include/asm/ptrace.h
@@ -32,6 +32,9 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
 #define arch_ptrace_stop(exit_code, info) \
         synchronize_user_stack()
 
+#define current_pt_regs() \
+        ((struct pt_regs *)((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
+
 struct global_reg_snapshot {
         unsigned long           tstate;
         unsigned long           tpc;
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 4c864c796507..e37512319296 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -538,64 +538,56 @@ asmlinkage long sparc_do_fork(unsigned long clone_flags,
  * Child  -->  %o0 == parents pid, %o1 == 1
  */
 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 *t = task_thread_info(p);
         struct sparc_stackf *parent_sf;
         unsigned long child_stack_sz;
         char *child_trap_frame;
-        int kernel_thread;
-
-        kernel_thread = (regs->tstate & TSTATE_PRIV) ? 1 : 0;
-        parent_sf = ((struct sparc_stackf *) regs) - 1;
 
         /* Calculate offset to stack_frame & pt_regs */
-        child_stack_sz = ((STACKFRAME_SZ + TRACEREG_SZ) +
-                          (kernel_thread ? STACKFRAME_SZ : 0));
+        child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ);
         child_trap_frame = (task_stack_page(p) +
                             (THREAD_SIZE - child_stack_sz));
-        memcpy(child_trap_frame, parent_sf, child_stack_sz);
 
-        __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 
-                (regs->tstate + 1) & TSTATE_CWP;
         t->new_child = 1;
         t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
         t->kregs = (struct pt_regs *) (child_trap_frame +
                                        sizeof(struct sparc_stackf));
         t->fpsaved[0] = 0;
 
-        if (kernel_thread) {
-                struct sparc_stackf *child_sf = (struct sparc_stackf *)
-                        (child_trap_frame + (STACKFRAME_SZ + TRACEREG_SZ));
-
-                /* Zero terminate the stack backtrace.  */
-                child_sf->fp = NULL;
-                t->kregs->u_regs[UREG_FP] =
-                  ((unsigned long) child_sf) - STACK_BIAS;
-
+        if (unlikely(p->flags & PF_KTHREAD)) {
+                memset(child_trap_frame, 0, child_stack_sz);
+                __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 
+                        (current_pt_regs()->tstate + 1) & TSTATE_CWP;
                 t->current_ds = ASI_P;
-                t->kregs->u_regs[UREG_G6] = (unsigned long) t;
-                t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
-        } else {
-                if (t->flags & _TIF_32BIT) {
-                        sp &= 0x00000000ffffffffUL;
-                        regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
-                }
-                t->kregs->u_regs[UREG_FP] = sp;
-                t->current_ds = ASI_AIUS;
-                if (sp != regs->u_regs[UREG_FP]) {
-                        unsigned long csp;
-
-                        csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
-                        if (!csp)
-                                return -EFAULT;
-                        t->kregs->u_regs[UREG_FP] = csp;
-                }
-                if (t->utraps)
-                        t->utraps[0]++;
+                t->kregs->u_regs[UREG_G1] = sp; /* function */
+                t->kregs->u_regs[UREG_G2] = arg;
+                return 0;
         }
 
+        parent_sf = ((struct sparc_stackf *) regs) - 1;
+        memcpy(child_trap_frame, parent_sf, child_stack_sz);
+        if (t->flags & _TIF_32BIT) {
+                sp &= 0x00000000ffffffffUL;
+                regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
+        }
+        t->kregs->u_regs[UREG_FP] = sp;
+        __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 
+                (regs->tstate + 1) & TSTATE_CWP;
+        t->current_ds = ASI_AIUS;
+        if (sp != regs->u_regs[UREG_FP]) {
+                unsigned long csp;
+
+                csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
+                if (!csp)
+                        return -EFAULT;
+                t->kregs->u_regs[UREG_FP] = csp;
+        }
+        if (t->utraps)
+                t->utraps[0]++;
+
         /* Set the return value for the child. */
         t->kregs->u_regs[UREG_I0] = current->pid;
         t->kregs->u_regs[UREG_I1] = 1;
@@ -609,45 +601,6 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
         return 0;
 }
 
-/*
- * 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;
-
-        /* If the parent runs before fn(arg) is called by the child,
-         * the input registers of this function can be clobbered.
-         * So we stash 'fn' and 'arg' into global registers which
-         * will not be modified by the parent.
-         */
-        __asm__ __volatile__("mov %4, %%g2\n\t"    /* Save FN into global */
-                             "mov %5, %%g3\n\t"    /* Save ARG into global */
-                             "mov %1, %%g1\n\t"    /* Clone syscall nr. */
-                             "mov %2, %%o0\n\t"    /* Clone flags. */
-                             "mov 0, %%o1\n\t"     /* usp arg == 0 */
-                             "t 0x6d\n\t"          /* Linux/Sparc clone(). */
-                             "brz,a,pn %%o1, 1f\n\t" /* Parent, just return. */
-                             " mov %%o0, %0\n\t"
-                             "jmpl %%g2, %%o7\n\t"   /* Call the function. */
-                             " mov %%g3, %%o0\n\t"   /* Set arg in delay. */
-                             "mov %3, %%g1\n\t"
-                             "t 0x6d\n\t"          /* Linux/Sparc exit(). */
-                             /* Notreached by child. */
-                             "1:" :
-                             "=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);
-
 typedef struct {
         union {
                 unsigned int    pr_regs[32];
diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S
index b0ac10306425..624f34162c38 100644
--- a/arch/sparc/kernel/syscalls.S
+++ b/arch/sparc/kernel/syscalls.S
@@ -112,11 +112,16 @@ sys_clone:
 ret_from_syscall:
         /* Clear current_thread_info()->new_child. */
         stb     %g0, [%g6 + TI_NEW_CHILD]
-        ldx     [%g6 + TI_FLAGS], %l0
         call    schedule_tail
          mov    %g7, %o0
-        ba,pt   %xcc, ret_sys_call
-         ldx    [%sp + PTREGS_OFF + PT_V9_I0], %o0
+        ldx     [%sp + PTREGS_OFF + PT_V9_I0], %o0
+        brnz,a,pt       %o0, ret_sys_call
+         ldx    [%g6 + TI_FLAGS], %l0
+        ldx     [%sp + PTREGS_OFF + PT_V9_G1], %l0
+        call    %l0
+         ldx    [%sp + PTREGS_OFF + PT_V9_G2], %o0
+        call    do_exit ! will not return
+         mov    0,%o0
 
         .globl  sparc_exit
         .type   sparc_exit,#function