Alexandre Julliard : ntdll: Reimplement map_fixed_area() to avoid recursion and callbacks.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 33240c54651ca849e91e8de649c0c779db01d064
URL:    https://gitlab.winehq.org/wine/wine/-/commit/33240c54651ca849e91e8de649c0c77...

Author: Alexandre Julliard 
Date:   Wed Jun  7 12:00:14 2023 +0200

ntdll: Reimplement map_fixed_area() to avoid recursion and callbacks.

---

dlls/ntdll/unix/virtual.c | 110 ++++++++++++++--------------------------------
 1 file changed, 34 insertions(+), 76 deletions(-)

diff --git a/dlls/ntdll/unix/virtual.c b/dlls/ntdll/unix/virtual.c
index 074fe7a4559..f3362a8b6ef 100644
--- a/dlls/ntdll/unix/virtual.c
+++ b/dlls/ntdll/unix/virtual.c
@@ -1463,42 +1463,6 @@ static void remove_reserved_area( void *addr, size_t size )
 }

-struct area_boundary
-{
-    void  *base;
-    size_t size;
-    void  *boundary;
-};
-
-/***********************************************************************
- *           get_area_boundary_callback
- *
- * Get lowest boundary address between reserved area and non-reserved area
- * in the specified region. If no boundaries are found, result is NULL.
- * virtual_mutex must be held by caller.
- */
-static int get_area_boundary_callback( void *start, SIZE_T size, void *arg )
-{
-    struct area_boundary *area = arg;
-    void *end = (char *)start + size;
-
-    area->boundary = NULL;
-    if (area->base >= end) return 0;
-    if ((char *)start >= (char *)area->base + area->size) return 1;
-    if (area->base >= start)
-    {
-        if ((char *)area->base + area->size > (char *)end)
-        {
-            area->boundary = end;
-            return 1;
-        }
-        return 0;
-    }
-    area->boundary = start;
-    return 1;
-}
-
-
 /***********************************************************************
  *           unmap_area
  *
@@ -1918,52 +1882,48 @@ static int alloc_reserved_area_callback( void *start, SIZE_T size, void *arg )
 /***********************************************************************
  *           map_fixed_area
  *
- * mmap the fixed memory area.
+ * Map a memory area at a fixed address.
  * virtual_mutex must be held by caller.
  */
 static NTSTATUS map_fixed_area( void *base, size_t size, unsigned int vprot )
 {
-    void *ptr;
+    int unix_prot = get_unix_prot(vprot);
+    struct reserved_area *area;
+    NTSTATUS status;
+    char *start = base, *end = (char *)base + size;

-    switch (mmap_is_in_reserved_area( base, size ))
-    {
-    case -1: /* partially in a reserved area */
+    if (find_view_range( base, size )) return STATUS_CONFLICTING_ADDRESSES;
+
+    LIST_FOR_EACH_ENTRY( area, &reserved_areas, struct reserved_area, entry )
     {
-        NTSTATUS status;
-        struct area_boundary area;
-        size_t lower_size;
-        area.base = base;
-        area.size = size;
-        mmap_enum_reserved_areas( get_area_boundary_callback, &area, 0 );
-        assert( area.boundary );
-        lower_size = (char *)area.boundary - (char *)base;
-        status = map_fixed_area( base, lower_size, vprot );
-        if (status == STATUS_SUCCESS)
+        char *area_start = area->base;
+        char *area_end = area_start + area->size;
+
+        if (area_start >= end) break;
+        if (area_end <= start) continue;
+        if (area_start > start)
         {
-            status = map_fixed_area( area.boundary, size - lower_size, vprot);
-            if (status != STATUS_SUCCESS) unmap_area( base, lower_size );
+            if (anon_mmap_tryfixed( start, area_start - start, unix_prot, 0 ) == MAP_FAILED) goto failed;
+            start = area_start;
         }
-        return status;
-    }
-    case 0:  /* not in a reserved area, do a normal allocation */
-        if ((ptr = anon_mmap_tryfixed( base, size, get_unix_prot(vprot), 0 )) == MAP_FAILED)
+        if (area_end >= end)
         {
-            if (errno == ENOMEM) return STATUS_NO_MEMORY;
-            if (errno == EEXIST) return STATUS_CONFLICTING_ADDRESSES;
-            return STATUS_INVALID_PARAMETER;
+            if (anon_mmap_fixed( start, end - start, unix_prot, 0 ) == MAP_FAILED) goto failed;
+            return STATUS_SUCCESS;
         }
-        break;
-
-    default:
-    case 1:  /* in a reserved area, make sure the address is available */
-        if (find_view_range( base, size )) return STATUS_CONFLICTING_ADDRESSES;
-        /* replace the reserved area by our mapping */
-        if ((ptr = anon_mmap_fixed( base, size, get_unix_prot(vprot), 0 )) != base)
-            return STATUS_INVALID_PARAMETER;
-        break;
+        if (anon_mmap_fixed( start, area_end - start, unix_prot, 0 ) == MAP_FAILED) goto failed;
+        start = area_end;
     }
-    if (is_beyond_limit( ptr, size, working_set_limit )) working_set_limit = address_space_limit;
+
+    if (anon_mmap_tryfixed( start, end - start, unix_prot, 0 ) == MAP_FAILED) goto failed;
     return STATUS_SUCCESS;
+
+failed:
+    if (errno == ENOMEM) status = STATUS_NO_MEMORY;
+    else if (errno == EEXIST) status = STATUS_CONFLICTING_ADDRESSES;
+    else status = STATUS_INVALID_PARAMETER;
+    unmap_area( base, start - (char *)base );
+    return status;
 }

/***********************************************************************
@@ -1998,12 +1958,10 @@ static NTSTATUS map_view( struct file_view **view_ret, void *base, size_t size,

if (base)
     {
-        if (is_beyond_limit( base, size, address_space_limit ))
-            return STATUS_WORKING_SET_LIMIT_RANGE;
-        if (limit && is_beyond_limit( base, size, (void *)limit ))
-            return STATUS_CONFLICTING_ADDRESSES;
-        status = map_fixed_area( base, size, vprot );
-        if (status != STATUS_SUCCESS) return status;
+        if (is_beyond_limit( base, size, address_space_limit )) return STATUS_WORKING_SET_LIMIT_RANGE;
+        if (limit && is_beyond_limit( base, size, (void *)limit )) return STATUS_CONFLICTING_ADDRESSES;
+        if ((status = map_fixed_area( base, size, vprot ))) return status;
+        if (is_beyond_limit( base, size, working_set_limit )) working_set_limit = address_space_limit;
         ptr = base;
     }
     else