blackfin: convert kernel_thread() and kernel_execve() to generic ones

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

5 files changed, 27 insertions, 109 deletions

diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index b6f3ad5441c5..ab9ff4075f4d 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -45,6 +45,8 @@ config BLACKFIN
         select ARCH_USES_GETTIMEOFFSET if !GENERIC_CLOCKEVENTS
         select HAVE_MOD_ARCH_SPECIFIC
         select MODULES_USE_ELF_RELA
+        select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
 
 config GENERIC_CSUM
         def_bool y
diff --git a/arch/blackfin/include/asm/processor.h b/arch/blackfin/include/asm/processor.h
index 4ef7cfe43ceb..d0e72e9475a6 100644
--- a/arch/blackfin/include/asm/processor.h
+++ b/arch/blackfin/include/asm/processor.h
@@ -75,8 +75,6 @@ static inline void release_thread(struct task_struct *dead_task)
 {
 }
 
-extern int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags);
-
 /*
  * Free current thread data structures etc..
  */
diff --git a/arch/blackfin/kernel/entry.S b/arch/blackfin/kernel/entry.S
index f33792cc1a0d..78f4f637e155 100644
--- a/arch/blackfin/kernel/entry.S
+++ b/arch/blackfin/kernel/entry.S
@@ -46,22 +46,16 @@ ENTRY(_ret_from_fork)
         SP += -12;
         pseudo_long_call _schedule_tail, p5;
         SP += 12;
-        r0 = [sp + PT_IPEND];
-        cc = bittst(r0,1);
-        if cc jump .Lin_kernel;
+        p1 = [sp++];
+        r0 = [sp++];
+        cc = p1 == 0;
+        if cc jump .Lfork;
+        sp += -12;
+        call (p1);
+        sp += 12;
+.Lfork:
         RESTORE_CONTEXT
         rti;
-.Lin_kernel:
-        bitclr(r0,1);
-        [sp + PT_IPEND] = r0;
-        /* do a 'fake' RTI by jumping to [RETI]
-         * to avoid clearing supervisor mode in child
-         */
-        r0 = [sp + PT_PC];
-        [sp + PT_P0] = r0;
-
-        RESTORE_ALL_SYS
-        jump (p0);
 ENDPROC(_ret_from_fork)
 
 ENTRY(_sys_vfork)
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index bb1cc721fcf7..9945b94c63d4 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -102,40 +102,6 @@ void cpu_idle(void)
 }
 
 /*
- * This gets run with P1 containing the
- * function to call, and R1 containing
- * the "args".  Note P0 is clobbered on the way here.
- */
-void kernel_thread_helper(void);
-__asm__(".section .text\n"
-        ".align 4\n"
-        "_kernel_thread_helper:\n\t"
-        "\tsp += -12;\n\t"
-        "\tr0 = r1;\n\t" "\tcall (p1);\n\t" "\tcall _do_exit;\n" ".previous");
-
-/*
- * Create a kernel thread.
- */
-pid_t kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
-{
-        struct pt_regs regs;
-
-        memset(&regs, 0, sizeof(regs));
-
-        regs.r1 = (unsigned long)arg;
-        regs.p1 = (unsigned long)fn;
-        regs.pc = (unsigned long)kernel_thread_helper;
-        regs.orig_p0 = -1;
-        /* Set bit 2 to tell ret_from_fork we should be returning to kernel
-           mode.  */
-        regs.ipend = 0x8002;
-        __asm__ __volatile__("%0 = syscfg;":"=da"(regs.syscfg):);
-        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
-                       NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
-/*
  * Do necessary setup to start up a newly executed thread.
  *
  * pass the data segment into user programs if it exists,
@@ -193,13 +159,26 @@ copy_thread(unsigned long clone_flags,
             struct task_struct *p, struct pt_regs *regs)
 {
         struct pt_regs *childregs;
+        unsigned long *v;
 
         childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
-        *childregs = *regs;
-        childregs->r0 = 0;
+        v = ((unsigned long *)childregs) - 2;
+        if (unlikely(!regs)) {
+                memset(childregs, 0, sizeof(struct pt_regs));
+                v[0] = usp;
+                v[1] = topstk;
+                childregs->orig_p0 = -1;
+                childregs->ipend = 0x8000;
+                __asm__ __volatile__("%0 = syscfg;":"=da"(childregs->syscfg):);
+                p->thread.usp = 0;
+        } else {
+                *childregs = *regs;
+                childregs->r0 = 0;
+                p->thread.usp = usp;
+                v[0] = v[1] = 0;
+        }
 
-        p->thread.usp = usp;
-        p->thread.ksp = (unsigned long)childregs;
+        p->thread.ksp = (unsigned long)v;
         p->thread.pc = (unsigned long)ret_from_fork;
 
         return 0;
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index 1c3d2c5bb0bb..4a38c68e2dde 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -530,61 +530,6 @@ ENTRY(_trap) /* Exception: 4th entry into system event table(supervisor mode)*/
         jump .Lsyscall_really_exit;
 ENDPROC(_trap)
 
-ENTRY(_kernel_execve)
-        link SIZEOF_PTREGS;
-        p0 = sp;
-        r3 = SIZEOF_PTREGS / 4;
-        r4 = 0(x);
-.Lclear_regs:
-        [p0++] = r4;
-        r3 += -1;
-        cc = r3 == 0;
-        if !cc jump .Lclear_regs (bp);
-
-        p0 = sp;
-        sp += -16;
-        [sp + 12] = p0;
-        pseudo_long_call _do_execve, p5;
-        SP += 16;
-        cc = r0 == 0;
-        if ! cc jump .Lexecve_failed;
-        /* Success.  Copy our temporary pt_regs to the top of the kernel
-         * stack and do a normal exception return.
-         */
-        r1 = sp;
-        r0 = (-KERNEL_STACK_SIZE) (x);
-        r1 = r1 & r0;
-        p2 = r1;
-        p3 = [p2];
-        r0 = KERNEL_STACK_SIZE - 4 (z);
-        p1 = r0;
-        p1 = p1 + p2;
-
-        p0 = fp;
-        r4 = [p0--];
-        r3 = SIZEOF_PTREGS / 4;
-.Lcopy_regs:
-        r4 = [p0--];
-        [p1--] = r4;
-        r3 += -1;
-        cc = r3 == 0;
-        if ! cc jump .Lcopy_regs (bp);
-
-        r0 = (KERNEL_STACK_SIZE - SIZEOF_PTREGS) (z);
-        p1 = r0;
-        p1 = p1 + p2;
-        sp = p1;
-        r0 = syscfg;
-        [SP + PT_SYSCFG] = r0;
-        [p3 + (TASK_THREAD + THREAD_KSP)] = sp;
-
-        RESTORE_CONTEXT;
-        rti;
-.Lexecve_failed:
-        unlink;
-        rts;
-ENDPROC(_kernel_execve)
-
 ENTRY(_system_call)
         /* Store IPEND */
         p2.l = lo(IPEND);