x86: split ret_from_fork

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

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8ec3a1a..d93eb9d 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -97,6 +97,7 @@ config X86
        select KTIME_SCALAR if X86_32
        select GENERIC_STRNCPY_FROM_USER
        select GENERIC_STRNLEN_USER
+       select GENERIC_KERNEL_THREAD
 
 config INSTRUCTION_DECODER
        def_bool (KPROBES || PERF_EVENTS || UPROBES)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index d048cad..078f3fd 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -589,11 +589,6 @@ typedef struct {
 } mm_segment_t;
 
 
-/*
- * create a kernel thread without removing it from tasklists
- */
-extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 623f288..ac11073 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -994,15 +994,20 @@ END(spurious_interrupt_bug)
  */
        .popsection
 
-ENTRY(kernel_thread_helper)
-       pushl $0                # fake return address for unwinder
+ENTRY(ret_from_kernel_thread)
        CFI_STARTPROC
-       movl %edi,%eax
-       call *%esi
+       pushl_cfi %eax
+       call schedule_tail
+       GET_THREAD_INFO(%ebp)
+       popl_cfi %eax
+       pushl_cfi $0x0202               # Reset kernel eflags
+       popfl_cfi
+       movl PT_EBP(%esp),%eax
+       call *PT_EBX(%esp)
        call do_exit
        ud2                     # padding for call trace
        CFI_ENDPROC
-ENDPROC(kernel_thread_helper)
+ENDPROC(ret_from_kernel_thread)
 
 #ifdef CONFIG_XEN
 /* Xen doesn't set %esp to be precisely what the normal sysenter

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 69babd8..5526d17 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -450,7 +450,7 @@ ENTRY(ret_from_fork)
        RESTORE_REST
 
        testl $3, CS-ARGOFFSET(%rsp)            # from kernel_thread?
-       jz   retint_restore_args
+       jz   1f
 
        testl $_TIF_IA32, TI_flags(%rcx)        # 32-bit compat task needs IRET
        jnz  int_ret_from_sys_call
@@ -458,6 +458,16 @@ ENTRY(ret_from_fork)
        RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
        jmp ret_from_sys_call                   # go to the SYSRET fastpath
 
+1:
+       subq $REST_SKIP, %rsp   # move the stack pointer back
+       CFI_ADJUST_CFA_OFFSET   REST_SKIP
+       movq %rbp, %rdi
+       call *%rbx
+       # exit
+       mov %eax, %edi
+       call do_exit
+       ud2                     # padding for call trace
+
        CFI_ENDPROC
 END(ret_from_fork)
 
@@ -1206,21 +1216,6 @@ bad_gs:
        jmp  2b
        .previous
 
-ENTRY(kernel_thread_helper)
-       pushq $0                # fake return address
-       CFI_STARTPROC
-       /*
-        * Here we are in the child and the registers are set as they were
-        * at kernel_thread() invocation in the parent.
-        */
-       call *%rsi
-       # exit
-       mov %eax, %edi
-       call do_exit
-       ud2                     # padding for call trace
-       CFI_ENDPROC
-END(kernel_thread_helper)
-
 /*
  * execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
  *

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 7162e9c..6947ec9 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -298,44 +298,6 @@ sys_clone(unsigned long clone_flags, unsigned long newsp,
        return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 }
 
-/*
- * This gets run with %si containing the
- * function to call, and %di containing
- * the "args".
- */
-extern void kernel_thread_helper(void);
-
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
-       struct pt_regs regs;
-
-       memset(&regs, 0, sizeof(regs));
-
-       regs.si = (unsigned long) fn;
-       regs.di = (unsigned long) arg;
-
-#ifdef CONFIG_X86_32
-       regs.ds = __USER_DS;
-       regs.es = __USER_DS;
-       regs.fs = __KERNEL_PERCPU;
-       regs.gs = __KERNEL_STACK_CANARY;
-#else
-       regs.ss = __KERNEL_DS;
-#endif
-
-       regs.orig_ax = -1;
-       regs.ip = (unsigned long) kernel_thread_helper;
-       regs.cs = __KERNEL_CS | get_kernel_rpl();
-       regs.flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
-
-       /* Ok, create the new process.. */
-       return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
 /*
  * sys_execve() executes a new program.
  */

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 75fcad1..c993987 100644 (file)
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -57,6 +57,7 @@
 #include <asm/switch_to.h>
 
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");
 
 /*
  * Return saved PC of a blocked thread.
@@ -127,23 +128,39 @@ void release_thread(struct task_struct *dead_task)
 }
 
 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 pt_regs *childregs;
+       struct pt_regs *childregs = task_pt_regs(p);
        struct task_struct *tsk;
        int err;
 
-       childregs = task_pt_regs(p);
+       p->thread.sp = (unsigned long) childregs;
+       p->thread.sp0 = (unsigned long) (childregs+1);
+
+       if (unlikely(!regs)) {
+               /* kernel thread */
+               memset(childregs, 0, sizeof(struct pt_regs));
+               p->thread.ip = (unsigned long) ret_from_kernel_thread;
+               task_user_gs(p) = __KERNEL_STACK_CANARY;
+               childregs->ds = __USER_DS;
+               childregs->es = __USER_DS;
+               childregs->fs = __KERNEL_PERCPU;
+               childregs->bx = sp;     /* function */
+               childregs->bp = arg;
+               childregs->orig_ax = -1;
+               childregs->cs = __KERNEL_CS | get_kernel_rpl();
+               childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
+               p->fpu_counter = 0;
+               p->thread.io_bitmap_ptr = NULL;
+               memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+               return 0;
+       }
        *childregs = *regs;
        childregs->ax = 0;
        childregs->sp = sp;
 
-       p->thread.sp = (unsigned long) childregs;
-       p->thread.sp0 = (unsigned long) (childregs+1);
-
        p->thread.ip = (unsigned long) ret_from_fork;
-
        task_user_gs(p) = get_user_gs(regs);
 
        p->fpu_counter = 0;

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 0a980c9..937f2af 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -146,29 +146,18 @@ static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 }
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
-               unsigned long unused,
+               unsigned long arg,
        struct task_struct *p, struct pt_regs *regs)
 {
        int err;
        struct pt_regs *childregs;
        struct task_struct *me = current;
 
-       childregs = ((struct pt_regs *)
-                       (THREAD_SIZE + task_stack_page(p))) - 1;
-       *childregs = *regs;
-
-       childregs->ax = 0;
-       if (user_mode(regs))
-               childregs->sp = sp;
-       else
-               childregs->sp = (unsigned long)childregs;
-
+       p->thread.sp0 = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+       childregs = task_pt_regs(p);
        p->thread.sp = (unsigned long) childregs;
-       p->thread.sp0 = (unsigned long) (childregs+1);
        p->thread.usersp = me->thread.usersp;
-
        set_tsk_thread_flag(p, TIF_FORK);
-
        p->fpu_counter = 0;
        p->thread.io_bitmap_ptr = NULL;
 
@@ -178,6 +167,24 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
        p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
        savesegment(es, p->thread.es);
        savesegment(ds, p->thread.ds);
+       memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+
+       if (unlikely(!regs)) {
+               /* kernel thread */
+               memset(childregs, 0, sizeof(struct pt_regs));
+               childregs->sp = (unsigned long)childregs;
+               childregs->ss = __KERNEL_DS;
+               childregs->bx = sp; /* function */
+               childregs->bp = arg;
+               childregs->orig_ax = -1;
+               childregs->cs = __KERNEL_CS | get_kernel_rpl();
+               childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
+               return 0;
+       }
+       *childregs = *regs;
+
+       childregs->ax = 0;
+       childregs->sp = sp;
 
        err = -ENOMEM;
        memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));