[PATCH] uml: fix advanced sysemu check

cleanup and fix the check for advanced sysemu (PTRACE_SYSEMU_SINGLESTEP
option)

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index a8b5b9d..040cc14 100644 (file)
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -161,7 +161,7 @@ __uml_setup("nosysemu", nosysemu_cmd_param,
 static void __init check_sysemu(void)
 {
        void *stack;
-       int pid, syscall, n, status, count=0;
+       int pid, n, status, count=0;
 
        printk("Checking syscall emulation patch for ptrace...");
        sysemu_supported = 0;
@@ -192,6 +192,12 @@ static void __init check_sysemu(void)
 
        printk("Checking advanced syscall emulation patch for ptrace...");
        pid = start_ptraced_child(&stack);
+
+       if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
+                 (void *) PTRACE_O_TRACESYSGOOD) < 0)
+               panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d",
+                     errno);
+
        while(1){
                count++;
                if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
@@ -199,15 +205,10 @@ static void __init check_sysemu(void)
                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
                if(n < 0)
                        panic("check_ptrace : wait failed, errno = %d", errno);
-               if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
-                       panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), "
-                             "got status = %d", status);
-
-               syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
-                                0);
-               if(syscall == __NR_getpid){
+               if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
                        if (!count)
-                               panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep");
+                               panic("check_ptrace : SYSEMU_SINGLESTEP "
+                                     "doesn't singlestep");
                        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
                                   os_getpid());
                        if(n < 0)
@@ -215,6 +216,11 @@ static void __init check_sysemu(void)
                                      "call return, errno = %d", errno);
                        break;
                }
+               else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
+                       count++;
+               else
+                       panic("check_ptrace : expected SIGTRAP or "
+                             "(SIGTRAP|0x80), got status = %d", status);
        }
        if (stop_ptraced_child(pid, stack, 0, 0) < 0)
                goto fail_stopped;
@@ -250,8 +256,8 @@ static void __init check_ptrace(void)
                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
                if(n < 0)
                        panic("check_ptrace : wait failed, errno = %d", errno);
-               if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80))
-                       panic("check_ptrace : expected SIGTRAP + 0x80, "
+               if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80)))
+                       panic("check_ptrace : expected (SIGTRAP|0x80), "
                              "got status = %d", status);
 
                syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,