# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1617660840 -7200
# Node ID 866eb2a8fc8bb82cd9ad9552c9a6c30417c67174
# Parent  13e188dd5a9362939f10a348716c64f902c0b400
Employ map request flags instead of the maximal flags when sending flexpages.
Otherwise, mappings may be established with inappropriate permissions.

diff -r 13e188dd5a93 -r 866eb2a8fc8b generic/pager.cc
--- a/generic/pager.cc	Sun Apr 04 01:19:22 2021 +0200
+++ b/generic/pager.cc	Tue Apr 06 00:14:00 2021 +0200
@@ -4,6 +4,9 @@
 
 
 
+/* Initialise the pager with a page mapper and the given flags controlling
+   access to a file. */
+
 Pager::Pager(PageMapper *mapper, flags_t flags)
 : _start(0), _size(0), _mapper(mapper), _flags(flags)
 {
@@ -66,7 +69,8 @@
 
     /* Issue the flexpage via the IPC system. */
 
-    long err = ipc_prepare_flexpage(flexpage, file_offset, max_offset, hot_spot, region);
+    long err = ipc_prepare_flexpage(flexpage, file_offset, max_offset, hot_spot,
+                                    flags, region);
 
     if (!err)
       err = complete_Dataspace_map(*region);
diff -r 13e188dd5a93 -r 866eb2a8fc8b generic/simple_pager.cc
--- a/generic/simple_pager.cc	Sun Apr 04 01:19:22 2021 +0200
+++ b/generic/simple_pager.cc	Tue Apr 06 00:14:00 2021 +0200
@@ -38,7 +38,8 @@
 
     /* Send the flexpage explicitly. */
 
-    long err = ipc_prepare_flexpage(&flexpage, offset, _region->size(), hot_spot, region);
+    long err = ipc_prepare_flexpage(&flexpage, offset, _region->size(),
+                                    hot_spot, flags, region);
 
     if (err)
         return err;
diff -r 13e188dd5a93 -r 866eb2a8fc8b mapping/flexpage.cc
--- a/mapping/flexpage.cc	Sun Apr 04 01:19:22 2021 +0200
+++ b/mapping/flexpage.cc	Tue Apr 06 00:14:00 2021 +0200
@@ -73,6 +73,10 @@
     return (base_offset <= position) && (position < (base_offset + size));
 }
 
+/* Upgrade the flags involved with this flexpage. This is used to track the
+   maximal flags employed by the different pagers, with the result being used in
+   unmap operations. */
+
 void Flexpage::upgrade(flags_t flags)
 {
     if (flags && (flags != _flags))
@@ -82,7 +86,8 @@
 /* Return a "send" flexpage for an access to 'offset' by positioning it relative
    to 'hot_spot' for the receive flexpage window. */
 
-SendFlexpage Flexpage::to_send(offset_t offset, offset_t hot_spot, offset_t max_offset)
+SendFlexpage Flexpage::to_send(offset_t offset, offset_t hot_spot,
+                               flags_t flags, offset_t max_offset)
 {
     /* The dataspace offset of the flexpage base is a multiple of the flexpage
        size. */
@@ -108,7 +113,7 @@
         receive_size = size;
 
     if (!receive_size)
-        return SendFlexpage(base_addr, page_order(0), _flags);
+        return SendFlexpage(base_addr, page_order(0), flags);
 
     offset_t receive_page_offset = hot_spot % receive_size;
 
@@ -124,7 +129,7 @@
 
     offset_t adjustment = page_offset - receive_page_offset;
 
-    return SendFlexpage(base_addr + adjustment, page_order(receive_size), _flags);
+    return SendFlexpage(base_addr + adjustment, page_order(receive_size), flags);
 }
 
 /* Return a representation of the flexpage for unmapping. */
diff -r 13e188dd5a93 -r 866eb2a8fc8b mapping/flexpage.h
--- a/mapping/flexpage.h	Sun Apr 04 01:19:22 2021 +0200
+++ b/mapping/flexpage.h	Tue Apr 06 00:14:00 2021 +0200
@@ -46,7 +46,8 @@
 
     void upgrade(flags_t flags);
 
-    SendFlexpage to_send(offset_t offset, offset_t hot_spot, offset_t max_offset=0);
+    SendFlexpage to_send(offset_t offset, offset_t hot_spot, flags_t flags,
+                         offset_t max_offset=0);
 
     SendFlexpage to_unmap();
 };
diff -r 13e188dd5a93 -r 866eb2a8fc8b mapping/ipc.cc
--- a/mapping/ipc.cc	Sun Apr 04 01:19:22 2021 +0200
+++ b/mapping/ipc.cc	Tue Apr 06 00:14:00 2021 +0200
@@ -19,9 +19,10 @@
 
 long ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
                           unsigned long max_offset, l4_addr_t hot_spot,
-                          l4_snd_fpage_t *region)
+                          flags_t flags, l4_snd_fpage_t *region)
 {
-    SendFlexpage send_flexpage = flexpage->to_send(offset, hot_spot, max_offset);
+    SendFlexpage send_flexpage = flexpage->to_send(offset, hot_spot, flags,
+                                                   max_offset);
 
     /* NOTE: Consider l4_fpage_invalid() as the fpage here. */
 
diff -r 13e188dd5a93 -r 866eb2a8fc8b mapping/ipc.h
--- a/mapping/ipc.h	Sun Apr 04 01:19:22 2021 +0200
+++ b/mapping/ipc.h	Tue Apr 06 00:14:00 2021 +0200
@@ -8,7 +8,7 @@
 
 long ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
                           unsigned long max_offset, l4_addr_t hot_spot,
-                          l4_snd_fpage_t *region);
+                          flags_t flags, l4_snd_fpage_t *region);
 
 void ipc_unmap_flexpage(Flexpage *flexpage);