x86, um: convert to saner kernel_execve() semantics

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

diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index 5d9ab0c..62435a0 100644 (file)
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -26,7 +26,6 @@ struct thread_struct {
        jmp_buf *fault_catcher;
        struct task_struct *prev_sched;
        unsigned long temp_stack;
-       jmp_buf *exec_buf;
        struct arch_thread arch;
        jmp_buf switch_buf;
        int mm_count;
@@ -54,7 +53,6 @@ struct thread_struct {
        .fault_addr             = NULL, \
        .prev_sched             = NULL, \
        .temp_stack             = 0, \
-       .exec_buf               = NULL, \
        .arch                   = INIT_ARCH_THREAD, \
        .request                = { 0 } \
 }

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 89b686c..25dbd37 100644 (file)
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -191,7 +191,6 @@ extern int os_getpid(void);
 extern int os_getpgrp(void);
 
 extern void init_new_thread_signals(void);
-extern int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr);
 
 extern int os_map_memory(void *virt, int fd, unsigned long long off,
                         unsigned long len, int r, int w, int x);

diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index e427301..565ca39 100644 (file)
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -47,8 +47,3 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
 #endif
 }
 EXPORT_SYMBOL(start_thread);
-
-void __noreturn ret_from_kernel_execve(struct pt_regs *unused)
-{
-       UML_LONGJMP(current->thread.exec_buf, 1);
-}

diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index a1b50ad..94b0d8b 100644 (file)
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -135,14 +135,10 @@ void new_thread_handler(void)
        arg = current->thread.request.u.thread.arg;
 
        /*
-        * The return value is 1 if the kernel thread execs a process,
-        * 0 if it just exits
+        * callback returns only if the kernel thread execs a process
         */
-       n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
-       if (n == 1)
-               userspace(&current->thread.regs.regs);
-       else
-               do_exit(0);
+       n = fn(arg);
+       userspace(&current->thread.regs.regs);
 }
 
 /* Called magically, see new_thread_handler above */

diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 307f173..a04ec16 100644 (file)
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -244,16 +244,3 @@ void init_new_thread_signals(void)
        signal(SIGWINCH, SIG_IGN);
        signal(SIGTERM, SIG_DFL);
 }
-
-int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr)
-{
-       jmp_buf buf;
-       int n;
-
-       *jmp_ptr = &buf;
-       n = UML_SETJMP(&buf);
-       if (n != 0)
-               return n;
-       (*fn)(arg);
-       return 0;
-}

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d93eb9d..45edcba 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -98,6 +98,7 @@ config X86
        select GENERIC_STRNCPY_FROM_USER
        select GENERIC_STRNLEN_USER
        select GENERIC_KERNEL_THREAD
+       select GENERIC_KERNEL_EXECVE
 
 config INSTRUCTION_DECODER
        def_bool (KPROBES || PERF_EVENTS || UPROBES)

diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h
index 55d1555..16f3fc6 100644 (file)
--- a/arch/x86/include/asm/unistd.h
+++ b/arch/x86/include/asm/unistd.h
@@ -51,7 +51,6 @@
 # define __ARCH_WANT_SYS_UTIME
 # define __ARCH_WANT_SYS_WAITPID
 # define __ARCH_WANT_SYS_EXECVE
-# define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index fe4cc30..91d2959 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -298,12 +298,20 @@ ENTRY(ret_from_fork)
        CFI_ENDPROC
 END(ret_from_fork)
 
-ENTRY(ret_from_kernel_execve)
-       movl %eax, %esp
-       movl $0,PT_EAX(%esp)
+ENTRY(ret_from_kernel_thread)
+       CFI_STARTPROC
+       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)
+       movl $0,PT_EAX(%esp)
        jmp syscall_exit
-END(ret_from_kernel_execve)
+       CFI_ENDPROC
+ENDPROC(ret_from_kernel_thread)
 
 /*
  * Interrupt exit functions should be protected against kprobes
@@ -994,21 +1002,6 @@ END(spurious_interrupt_bug)
  */
        .popsection
 
-ENTRY(ret_from_kernel_thread)
-       CFI_STARTPROC
-       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(ret_from_kernel_thread)
-
 #ifdef CONFIG_XEN
 /* Xen doesn't set %esp to be precisely what the normal sysenter
    entrypoint expects, so fix it up before using the normal path. */

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 053c955..e1f98c2 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -459,15 +459,13 @@ ENTRY(ret_from_fork)
        jmp ret_from_sys_call                   # go to the SYSRET fastpath
 
 1:
-       subq $REST_SKIP, %rsp   # move the stack pointer back
+       subq $REST_SKIP, %rsp   # leave space for volatiles
        CFI_ADJUST_CFA_OFFSET   REST_SKIP
        movq %rbp, %rdi
        call *%rbx
-       # exit
-       mov %eax, %edi
-       call do_exit
-       ud2                     # padding for call trace
-
+       movl $0, RAX(%rsp)
+       RESTORE_REST
+       jmp int_ret_from_sys_call
        CFI_ENDPROC
 END(ret_from_fork)
 
@@ -1214,20 +1212,6 @@ bad_gs:
        jmp  2b
        .previous
 
-ENTRY(ret_from_kernel_execve)
-       movq %rdi, %rsp
-       movl $0, RAX(%rsp)
-       // RESTORE_REST
-       movq 0*8(%rsp), %r15
-       movq 1*8(%rsp), %r14
-       movq 2*8(%rsp), %r13
-       movq 3*8(%rsp), %r12
-       movq 4*8(%rsp), %rbp
-       movq 5*8(%rsp), %rbx
-       addq $(6*8), %rsp
-       jmp int_ret_from_sys_call
-END(ret_from_kernel_execve)
-
 /* Call softirq on interrupt stack. Interrupts are off. */
 ENTRY(call_softirq)
        CFI_STARTPROC

diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index da85b6f..cab8eb8 100644 (file)
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -14,6 +14,7 @@ config UML_X86
        def_bool y
        select GENERIC_FIND_FIRST_BIT
        select GENERIC_KERNEL_THREAD
+       select GENERIC_KERNEL_EXECVE
 
 config 64BIT
        bool "64-bit kernel" if SUBARCH = "x86"