Merge branch 'drm-fixes' of master.kernel.org:/pub/scm/linux/kernel/git/airlied/drm-2.6

[linux-2.6-omap-h63xx.git] / arch / i386 / kernel / ptrace.c

diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 0da59b42843cffebc8d104d09376b734cb4ca948..340980203b095f9cda5113c14369799815dad1e5 100644 (file)
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -271,6 +271,8 @@ static void clear_singlestep(struct task_struct *child)
 void ptrace_disable(struct task_struct *child)
 { 
        clear_singlestep(child);
+       clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+       clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 }
 
 /*
@@ -509,15 +511,20 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
                  }
                  break;
 
+       case PTRACE_SYSEMU: /* continue and stop at next syscall, which will not be executed */
        case PTRACE_SYSCALL:    /* continue and stop at next (return from) syscall */
        case PTRACE_CONT:       /* restart after signal. */
                ret = -EIO;
                if (!valid_signal(data))
                        break;
-               if (request == PTRACE_SYSCALL) {
+               if (request == PTRACE_SYSEMU) {
+                       set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+                       clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+               } else if (request == PTRACE_SYSCALL) {
                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
-               }
-               else {
+                       clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+               } else {
+                       clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                }
                child->exit_code = data;
@@ -542,10 +549,17 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
                wake_up_process(child);
                break;
 
+       case PTRACE_SYSEMU_SINGLESTEP: /* Same as SYSEMU, but singlestep if not syscall */
        case PTRACE_SINGLESTEP: /* set the trap flag. */
                ret = -EIO;
                if (!valid_signal(data))
                        break;
+
+               if (request == PTRACE_SYSEMU_SINGLESTEP)
+                       set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+               else
+                       clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+
                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                set_singlestep(child);
                child->exit_code = data;
@@ -678,26 +692,52 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
  * - triggered by current->work.syscall_trace
  */
 __attribute__((regparm(3)))
-void do_syscall_trace(struct pt_regs *regs, int entryexit)
+int do_syscall_trace(struct pt_regs *regs, int entryexit)
 {
+       int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU), ret = 0;
+       /* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
+        * interception. */
+       int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
+
        /* do the secure computing check first */
        secure_computing(regs->orig_eax);
 
-       if (unlikely(current->audit_context) && entryexit)
-               audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+       if (unlikely(current->audit_context)) {
+               if (entryexit)
+                       audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+               /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
+                * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
+                * not used, entry.S will call us only on syscall exit, not
+                * entry; so when TIF_SYSCALL_AUDIT is used we must avoid
+                * calling send_sigtrap() on syscall entry.
+                *
+                * Note that when PTRACE_SYSEMU_SINGLESTEP is used,
+                * is_singlestep is false, despite his name, so we will still do
+                * the correct thing.
+                */
+               else if (is_singlestep)
+                       goto out;
+       }
 
        if (!(current->ptrace & PT_PTRACED))
                goto out;
 
+       /* If a process stops on the 1st tracepoint with SYSCALL_TRACE
+        * and then is resumed with SYSEMU_SINGLESTEP, it will come in
+        * here. We have to check this and return */
+       if (is_sysemu && entryexit)
+               return 0;
+
        /* Fake a debug trap */
-       if (test_thread_flag(TIF_SINGLESTEP))
+       if (is_singlestep)
                send_sigtrap(current, regs, 0);
 
-       if (!test_thread_flag(TIF_SYSCALL_TRACE))
+       if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu)
                goto out;
 
        /* the 0x80 provides a way for the tracing parent to distinguish
           between a syscall stop and SIGTRAP delivery */
+       /* Note that the debugger could change the result of test_thread_flag!*/
        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
 
        /*
@@ -709,9 +749,16 @@ void do_syscall_trace(struct pt_regs *regs, int entryexit)
                send_sig(current->exit_code, current, 1);
                current->exit_code = 0;
        }
+       ret = is_sysemu;
  out:
        if (unlikely(current->audit_context) && !entryexit)
                audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
                                    regs->ebx, regs->ecx, regs->edx, regs->esi);
+       if (ret == 0)
+               return 0;
 
+       regs->orig_eax = -1; /* force skip of syscall restarting */
+       if (unlikely(current->audit_context))
+               audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+       return 1;
 }