[PATCH 1/2] unicore32: switch to generic kernel_thread()/kernel_execve()

From: Guan Xuetao
Date: Fri Oct 19 2012 - 04:45:53 EST

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Acked-and-Tested-by: Guan Xuetao <gxt@xxxxxxxxxxxxxxx>
---
arch/unicore32/Kconfig | 2 +
arch/unicore32/include/asm/processor.h | 5 ---
arch/unicore32/kernel/entry.S | 15 ++++----
arch/unicore32/kernel/process.c | 58 ++++++++------------------------
arch/unicore32/kernel/sys.c | 42 -----------------------
5 files changed, 23 insertions(+), 99 deletions(-)

diff --git a/arch/unicore32/Kconfig b/arch/unicore32/Kconfig
index 5b95ba4..fda37c9 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 14382cb..4eaa421 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 dcb87ab..32648c9 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 b008586..a8fe265 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 fabdee9..8b6e4cc 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,
--
1.7.0.4

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