* Correctly merge HEAD into cv-branch.

1 files changed, 55 insertions, 35 deletions

diff --git a/winsup/cygwin/mmap.cc b/winsup/cygwin/mmap.cc
index 97966515e..1c1afba57 100644
--- a/winsup/cygwin/mmap.cc
+++ b/winsup/cygwin/mmap.cc
@@ -900,44 +900,64 @@ map::del_list (unsigned i)
 }
 
 /* This function is called from exception_handler when a segmentation
-   violation has happened.  We have two cases to check here.
+   violation has occurred.  It should also be called from all Cygwin
+   functions that want to support passing noreserve mmap page addresses
+   to Windows system calls.  In that case, it should be called only after
+   a system call indicates that the application buffer passed had an
+   invalid virtual address to avoid any performance impact in non-noreserve
+   cases.
    
-   First, is it an address within "attached" mmap pages (indicated by
-   the __PROT_ATTACH protection, see there)?  In this case the function
-   returns 1 and the exception_handler raises SIGBUS, as demanded by the
-   memory protection extension described in SUSv3 (see the mmap man
-   page).
-   
-   Second, check if the address is within "noreserve" mmap pages
-   (indicated by MAP_NORESERVE flag).  If so, the function calls
-   VirtualAlloc to commit the page and returns 2.  The exception handler
-   then just returns with 0 and the affected application retries the
-   failing memory access.  If VirtualAlloc fails, the function returns
-   1, so that the exception handler raises a SIGBUS, as described in the
-   MAP_NORESERVE man pages for Linux and Solaris.
-   
-   In any other case 0 is returned and a normal SIGSEGV is raised. */
-int
-mmap_is_attached_or_noreserve_page (ULONG_PTR addr)
+   Check if the address range is all within noreserve mmap regions.  If so,
+   call VirtualAlloc to commit the pages and return MMAP_NORESERVE_COMMITED
+   on success.  If the page has __PROT_ATTACH (SUSv3 memory protection
+   extension), or if VirutalAlloc fails, return MMAP_RAISE_SIGBUS.
+   Otherwise, return MMAP_NONE if the address range is not covered by an
+   attached or noreserve map.
+
+   On MAP_NORESERVE_COMMITED, the exeception handler should return 0 to
+   allow the application to retry the memory access, or the calling Cygwin
+   function should retry the Windows system call. */
+mmap_region_status
+mmap_is_attached_or_noreserve (void *addr, size_t len)
 {
-  list *map_list;
-  long record_idx;
-  caddr_t u_addr;
-  DWORD u_len;
-  DWORD pagesize = getsystempagesize ();
+  list *map_list = mmapped_areas.get_list_by_fd (-1);
 
-  addr = rounddown (addr, pagesize);
-  if (!(map_list = mmapped_areas.get_list_by_fd (-1)))
-    return 0;
-  if ((record_idx = map_list->search_record ((caddr_t)addr, pagesize,
-					     u_addr, u_len, -1)) < 0)
-    return 0;
-  if (map_list->get_record (record_idx)->attached ())
-    return 1;
-  if (!map_list->get_record (record_idx)->noreserve ())
-    return 0;
-  DWORD new_prot = map_list->get_record (record_idx)->gen_protect ();
-  return VirtualAlloc ((void *)addr, pagesize, MEM_COMMIT, new_prot) ? 2 : 1;
+  size_t pagesize = getpagesize ();
+  caddr_t start_addr = (caddr_t) rounddown ((uintptr_t) addr, pagesize);
+  len += ((caddr_t) addr - start_addr);
+  len = roundup2 (len, pagesize);
+
+  if (map_list == NULL)
+    return MMAP_NONE;
+
+  while (len > 0) 
+    {
+      caddr_t u_addr;
+      DWORD u_len;
+      long record_idx = map_list->search_record (start_addr, len,
+						 u_addr, u_len, -1);
+      if (record_idx < 0)
+	return MMAP_NONE;
+
+      mmap_record *rec = map_list->get_record (record_idx);
+      if (rec->attached ())
+	return MMAP_RAISE_SIGBUS;
+      if (!rec->noreserve ())
+	return MMAP_NONE;
+
+      size_t commit_len = u_len - (start_addr - u_addr);
+      if (commit_len > len)
+	commit_len = len;
+
+      if (!VirtualAlloc (start_addr, commit_len, MEM_COMMIT,
+			 rec->gen_protect ()))
+	return MMAP_RAISE_SIGBUS;
+
+      start_addr += commit_len;
+      len -= commit_len;
+    }
+
+    return MMAP_NORESERVE_COMMITED;
 }
 
 static caddr_t