[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>

1 files changed, 17 insertions, 11 deletions

diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index a8b5b9d9c6ee..040cc1472bc7 100644
--- 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,