Follow up to r15936.

Kernel allocates another page after fork and we have to
keep aspacemgr's point of view consistent.
n-i-bz


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15937

coregrind/m_aspacemgr/aspacemgr-linux.c

@@ -4057,6 +4057,51 @@ static void parse_procselfmaps (
       (*record_gap)(gap_start, Addr_MAX - gap_start + 1);
 }
 
+/* parse_procselfmaps() callbacks do not allow for easy thread safety. */
+static Addr found_addr;
+static SizeT found_size;
+static UInt found_prot;
+
+/* Reports a new mapping into variables above. */
+static void new_segment_found_callback(Addr addr, SizeT len, UInt prot,
+   ULong dev, ULong ino, Off64T offset, const HChar *filename)
+{
+   aspacem_assert(addr <= addr + len - 1); 
+
+   Int iLo = find_nsegment_idx(addr);
+   Int iHi = find_nsegment_idx(addr + len - 1);
+   aspacem_assert(iLo <= iHi);
+   aspacem_assert(nsegments[iLo].start <= addr);
+   aspacem_assert(nsegments[iHi].end   >= addr + len - 1);
+
+   /* Do not perform any sanity checks. That is done in other places.
+      Just find if a reported mapping is found in aspacemgr's book keeping. */
+   for (Int i = iLo; i <= iHi; i++) {
+      if ((nsegments[i].kind == SkFree) || (nsegments[i].kind == SkResvn)) {
+         found_addr = addr;
+         found_size = len;
+         found_prot = prot;
+         break;
+      }
+   }
+}
+
+/* Returns True if a new segment was found. */
+Bool VG_(am_search_for_new_segment)(Addr *addr, SizeT *size, UInt *prot)
+{
+   found_addr = 0;
+   parse_procselfmaps(new_segment_found_callback, NULL);
+
+   if (found_addr != 0) {
+      *addr = found_addr;
+      *size = found_size;
+      *prot = found_prot;
+      return True;
+   } else {
+      return False;
+   }
+}
+
 #endif // defined(VGO_solaris)
 
 /*------END-procmaps-parser-for-Solaris--------------------------*/

coregrind/m_syswrap/syswrap-solaris.c

@@ -6520,6 +6520,27 @@ PRE(sys_forksys)
       /* vfork */
       if (ARG1 == 2)
          VG_(close)(fds[1]);
+
+#     if defined(SOLARIS_PT_SUNDWTRACE_THRP)
+      /* Kernel can map a new page as a scratch space of the DTrace fasttrap
+         provider. There is no way we can directly get its address - it's all
+         private to the kernel. Fish it the slow way. */
+      Addr addr;
+      SizeT size;
+      UInt prot;
+      Bool found = VG_(am_search_for_new_segment)(&addr, &size, &prot);
+      if (found) {
+         VG_(debugLog)(1, "syswrap-solaris", "PRE(forksys), new segment: "
+                       "vaddr=%#lx, size=%#lx, prot=%#x\n", addr, size, prot);
+         vg_assert(prot == (VKI_PROT_READ | VKI_PROT_EXEC));
+         vg_assert(size == VKI_PAGE_SIZE);
+         ML_(notify_core_and_tool_of_mmap)(addr, size, prot, VKI_MAP_ANONYMOUS,
+                                           -1, 0);
+
+         /* Note: We don't notify the debuginfo reader about this mapping
+            because there is no debug information stored in this segment. */
+      }
+#     endif /* SOLARIS_PT_SUNDWTRACE_THRP */
    }
    else {
       VG_(do_atfork_parent)(tid);
@@ -9345,7 +9366,7 @@ POST(sys_door)
                                                  -1, 0);
 
                /* Note: We don't notify the debuginfo reader about this
-                  mapping because there are no debug information stored in
+                  mapping because there is no debug information stored in
                   this segment. */
             }
 

coregrind/pub_core_aspacemgr.h

@@ -378,6 +378,11 @@ extern Bool VG_(get_changed_segments)(
       Int css_size, /*OUT*/Int* css_used);
 #endif
 
+#if defined(VGO_solaris)
+extern Bool VG_(am_search_for_new_segment)(Addr *start, SizeT *size,
+                                           UInt *prot);
+#endif
+
 #endif   // __PUB_CORE_ASPACEMGR_H
 
 /*--------------------------------------------------------------------*/