unicore32: switch to generic kernel_thread()/kernel_execve()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-and-Tested-by: Guan Xuetao <gxt@mprc.pku.edu.cn>

5 files changed, 23 insertions, 99 deletions

diff --git a/arch/unicore32/Kconfig b/arch/unicore32/Kconfig
index 5b95ba4e0c70..fda37c941c10 100644
--- a/arch/unicore32/Kconfig
+++ b/arch/unicore32/Kconfig
@@ -16,6 +16,8 @@ config UNICORE32
         select ARCH_WANT_FRAME_POINTERS
         select GENERIC_IOMAP
         select MODULES_USE_ELF_REL
+        select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
         help
           UniCore-32 is 32-bit Instruction Set Architecture,
           including a series of low-power-consumption RISC chip
diff --git a/arch/unicore32/include/asm/processor.h b/arch/unicore32/include/asm/processor.h
index 14382cb09657..4eaa42167667 100644
--- a/arch/unicore32/include/asm/processor.h
+++ b/arch/unicore32/include/asm/processor.h
@@ -72,11 +72,6 @@ unsigned long get_wchan(struct task_struct *p);
 
 #define cpu_relax()                     barrier()
 
-/*
- * Create a new kernel thread
- */
-extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-
 #define task_pt_regs(p) \
         ((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
 
diff --git a/arch/unicore32/kernel/entry.S b/arch/unicore32/kernel/entry.S
index dcb87ab19ddd..32648c99483a 100644
--- a/arch/unicore32/kernel/entry.S
+++ b/arch/unicore32/kernel/entry.S
@@ -573,17 +573,16 @@ ENDPROC(ret_to_user)
  */
 ENTRY(ret_from_fork)
         b.l     schedule_tail
-        get_thread_info tsk
-        ldw     r1, [tsk+], #TI_FLAGS           @ check for syscall tracing
-        mov     why, #1
-        cand.a  r1, #_TIF_SYSCALL_TRACE         @ are we tracing syscalls?
-        beq     ret_slow_syscall
-        mov     r1, sp
-        mov     r0, #1                          @ trace exit [IP = 1]
-        b.l     syscall_trace
         b       ret_slow_syscall
 ENDPROC(ret_from_fork)
 
+ENTRY(ret_from_kernel_thread)
+        b.l     schedule_tail
+        mov     r0, r5
+        adr     lr, ret_slow_syscall
+        mov     pc, r4
+ENDPROC(ret_from_kernel_thread)
+
 /*=============================================================================
  * SWI handler
  *-----------------------------------------------------------------------------
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index b008586dad75..a8fe265ce2c0 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -258,6 +258,7 @@ void release_thread(struct task_struct *dead_task)
 }
 
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
 
 int
 copy_thread(unsigned long clone_flags, unsigned long stack_start,
@@ -266,17 +267,22 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
         struct thread_info *thread = task_thread_info(p);
         struct pt_regs *childregs = task_pt_regs(p);
 
-        *childregs = *regs;
-        childregs->UCreg_00 = 0;
-        childregs->UCreg_sp = stack_start;
-
         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
         thread->cpu_context.sp = (unsigned long)childregs;
-        thread->cpu_context.pc = (unsigned long)ret_from_fork;
-
-        if (clone_flags & CLONE_SETTLS)
-                childregs->UCreg_16 = regs->UCreg_03;
+        if (unlikely(!regs)) {
+                thread->cpu_context.pc = (unsigned long)ret_from_kernel_thread;
+                thread->cpu_context.r4 = stack_start;
+                thread->cpu_context.r5 = stk_sz;
+                memset(childregs, 0, sizeof(struct pt_regs));
+        } else {
+                thread->cpu_context.pc = (unsigned long)ret_from_fork;
+                *childregs = *regs;
+                childregs->UCreg_00 = 0;
+                childregs->UCreg_sp = stack_start;
 
+                if (clone_flags & CLONE_SETTLS)
+                        childregs->UCreg_16 = regs->UCreg_03;
+        }
         return 0;
 }
 
@@ -305,42 +311,6 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fp)
 }
 EXPORT_SYMBOL(dump_fpu);
 
-/*
- * Shuffle the argument into the correct register before calling the
- * thread function.  r1 is the thread argument, r2 is the pointer to
- * the thread function, and r3 points to the exit function.
- */
-asm(".pushsection .text\n"
-"       .align\n"
-"       .type   kernel_thread_helper, #function\n"
-"kernel_thread_helper:\n"
-"       mov.a   asr, r7\n"
-"       mov     r0, r4\n"
-"       mov     lr, r6\n"
-"       mov     pc, r5\n"
-"       .size   kernel_thread_helper, . - kernel_thread_helper\n"
-"       .popsection");
-
-/*
- * 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.UCreg_04 = (unsigned long)arg;
-        regs.UCreg_05 = (unsigned long)fn;
-        regs.UCreg_06 = (unsigned long)do_exit;
-        regs.UCreg_07 = PRIV_MODE;
-        regs.UCreg_pc = (unsigned long)kernel_thread_helper;
-        regs.UCreg_asr = regs.UCreg_07 | PSR_I_BIT;
-
-        return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 unsigned long get_wchan(struct task_struct *p)
 {
         struct stackframe frame;
diff --git a/arch/unicore32/kernel/sys.c b/arch/unicore32/kernel/sys.c
index fabdee96110b..8b6e4cc57393 100644
--- a/arch/unicore32/kernel/sys.c
+++ b/arch/unicore32/kernel/sys.c
@@ -63,48 +63,6 @@ out:
         return error;
 }
 
-int kernel_execve(const char *filename,
-                  const char *const argv[],
-                  const char *const envp[])
-{
-        struct pt_regs regs;
-        int ret;
-
-        memset(&regs, 0, sizeof(struct pt_regs));
-        ret = do_execve(filename,
-                        (const char __user *const __user *)argv,
-                        (const char __user *const __user *)envp, &regs);
-        if (ret < 0)
-                goto out;
-
-        /*
-         * Save argc to the register structure for userspace.
-         */
-        regs.UCreg_00 = ret;
-
-        /*
-         * We were successful.  We won't be returning to our caller, but
-         * instead to user space by manipulating the kernel stack.
-         */
-        asm("add        r0, %0, %1\n\t"
-                "mov    r1, %2\n\t"
-                "mov    r2, %3\n\t"
-                "mov    r22, #0\n\t"    /* not a syscall */
-                "mov    r23, %0\n\t"    /* thread structure */
-                "b.l    memmove\n\t"    /* copy regs to top of stack */
-                "mov    sp, r0\n\t"     /* reposition stack pointer */
-                "b      ret_to_user"
-                :
-                : "r" (current_thread_info()),
-                  "Ir" (THREAD_START_SP - sizeof(regs)),
-                  "r" (&regs),
-                  "Ir" (sizeof(regs))
-                : "r0", "r1", "r2", "r3", "ip", "lr", "memory");
-
- out:
-        return ret;
-}
-
 /* Note: used by the compat code even in 64-bit Linux. */
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
                 unsigned long, prot, unsigned long, flags,