Merge linux-2.6 with linux-acpi-2.6

1 files changed, 55 insertions, 8 deletions

diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 0da59b42843c..340980203b09 100644
--- 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;
 }