[PATCH 129] turn PTRACE_EVENT_SIGTRAP into PTRACE_EVENT_SIGNAL

[Oleg Nesterov]

Kill PTRACE_EVENT_SIGTRAP state, report PTRACE_EVENT_SIGNAL with
the valid ctx->siginfo instead.

Note: we can change ptrace_report_exec() to set ->signr = SIGTRAP
and return UTRACE_INTERRUPT too, instead of send_sig(SIGTRAP).
We can even change ptrace_resume(PTRACE_EVENT_SIGNAL) similarly,
but this needs more efforts.

---

 kernel/ptrace.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- PU/kernel/ptrace.c~129_KILL_PTRACE_EVENT_SIGTRAP    2009-11-02 
06:16:53.000000000 +0100
+++ PU/kernel/ptrace.c  2009-11-02 06:54:49.000000000 +0100
@@ -73,8 +73,7 @@ struct ptrace_context {
 
 #define PTRACE_EVENT_SYSCALL_ENTRY     (1 << 16)
 #define PTRACE_EVENT_SYSCALL_EXIT      (2 << 16)
-#define PTRACE_EVENT_SIGTRAP           (3 << 16)
-#define PTRACE_EVENT_SIGNAL            (4 << 16)
+#define PTRACE_EVENT_SIGNAL            (3 << 16)
 /* events visible to user-space */
 #define PTRACE_EVENT_MASK              0xFFFF
 
@@ -525,9 +524,12 @@ static u32 ptrace_report_signal(u32 acti
                        ctx->siginfo = NULL;
 
                if (resume != UTRACE_RESUME) {
-                       set_stop_code(ctx, PTRACE_EVENT_SIGTRAP);
-                       return UTRACE_STOP | UTRACE_SIGNAL_IGN;
+                       WARN_ON(resume != UTRACE_BLOCKSTEP &&
+                               resume != UTRACE_SINGLESTEP);
+                       WARN_ON(ctx->signr);
+                       ctx->signr = SIGTRAP;
                }
+               /* fallthrough */
 
        case UTRACE_SIGNAL_REPORT:
                if (!ctx->siginfo) {
@@ -535,7 +537,10 @@ static u32 ptrace_report_signal(u32 acti
                                return resume | UTRACE_SIGNAL_IGN;
 
                        WARN_ON(ctx->signr != SIGTRAP);
-                       /* set by ptrace_resume(PTRACE_EVENT_SYSCALL_EXIT) */
+                       /*
+                        * set by ptrace_resume(PTRACE_EVENT_SYSCALL_EXIT) or
+                        * by UTRACE_SIGNAL_HANDLER above.
+                        */
                        fill_sigtrap_info(task, info);
                        break;
                }