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-rw-r--r--viengoos/server.c269
1 files changed, 187 insertions, 82 deletions
diff --git a/viengoos/server.c b/viengoos/server.c
index 623b743..e26eeb8 100644
--- a/viengoos/server.c
+++ b/viengoos/server.c
@@ -52,7 +52,7 @@ struct trace_buffer rpc_trace = TRACE_BUFFER_INIT ("rpcs", 0,
/* Like debug but also prints the method id and saves to the trace
buffer if level is less than or equal to 4. */
-#define DEBUG(level, format, args...) \
+# define DEBUG(level, format, args...) \
do \
{ \
if (level <= 4) \
@@ -69,11 +69,92 @@ struct trace_buffer rpc_trace = TRACE_BUFFER_INIT ("rpcs", 0,
while (0)
#else
-#define DEBUG(level, format, args...) do {} while (0)
+# define DEBUG(level, format, args...) do {} while (0)
#endif
#define PAGEFAULT_METHOD 2
+struct fault_info
+{
+ struct object *page;
+ bool discarded;
+ bool writable;
+};
+
+/* Fault the page at PAGE_ADDR in thread THREAD's address space in.
+ Does not map it (but marks it as mapped). If there is no page or
+ some other error occurs, returns PAGE == 0. If the page is
+ discarded, sets DISCARDED to true. */
+static struct fault_info
+page_fault (struct activity *activity,
+ struct thread *thread,
+ l4_word_t page_addr,
+ bool require_writable)
+{
+ struct fault_info info;
+ memset (&info, 0, sizeof (info));
+
+ struct cap cap;
+ cap = as_object_lookup_rel (activity, &thread->aspace,
+ addr_chop (PTR_TO_ADDR (page_addr),
+ PAGESIZE_LOG2),
+ cap_rpage, &info.writable);
+ assert (cap.type == cap_void
+ || cap.type == cap_page
+ || cap.type == cap_rpage);
+
+ if (require_writable && ! info.writable)
+ {
+ debug (5, "Access fault at %x", page_addr);
+ return info;
+ }
+
+ if (! info.writable && cap.discardable)
+ {
+ debug (5, "Clearing discardable predicate for cap designating "
+ OID_FMT " (%s)",
+ OID_PRINTF (cap.oid), cap_type_string (cap.type));
+ cap.discardable = false;
+ }
+
+ struct object *page = cap_to_object_soft (activity, &cap);
+ if (! page && cap.type != cap_void)
+ /* It's not in-memory. See if it was discarded. If not,
+ load it using cap_to_object. */
+ {
+ int object = (cap.oid % (FOLIO_OBJECTS + 1)) - 1;
+ oid_t foid = cap.oid - object - 1;
+ struct folio *folio
+ = (struct folio *) object_find (activity, foid,
+ OBJECT_POLICY_DEFAULT);
+ assert (folio);
+ assert (object_type ((struct object *) folio) == cap_folio);
+
+ if (folio_object_discarded (folio, object))
+ {
+ debug (5, OID_FMT " (%s) was discarded",
+ OID_PRINTF (cap.oid),
+ cap_type_string (folio_object_type (folio,
+ object)));
+
+ assert (! folio_object_content (folio, object));
+
+ info.discarded = true;
+
+ debug (5, "Raising discarded fault at %x", page_addr);
+ }
+ else
+ page = cap_to_object (activity, &cap);
+ }
+
+ if (page)
+ object_to_object_desc (page)->mapped = true;
+
+ info.page = page;
+
+ return info;
+}
+
void
server_loop (void)
{
@@ -233,84 +314,20 @@ server_loop (void)
l4_word_t ip;
l4_word_t fault = l4_pagefault (msg_tag, &access, &ip);
bool w = !! (access & L4_FPAGE_WRITABLE);
- enum cap_type type = w ? cap_page : cap_rpage;
DEBUG (4, "%s fault at %x (ip = %x)",
w ? "Write" : "Read", fault, ip);
- l4_word_t page_addr = fault & ~(PAGESIZE - 1);
-
- bool writable;
- struct cap cap;
- struct object *page = NULL;
-
- bool raise_fault = false;
- bool discarded = false;
-
- cap = as_object_lookup_rel (activity, &thread->aspace,
- addr_chop (PTR_TO_ADDR (page_addr),
- PAGESIZE_LOG2),
- type, &writable);
- assert (cap.type == cap_void
- || cap.type == cap_page
- || cap.type == cap_rpage);
-
- if (! writable && cap.discardable)
- {
- debug (5, "Clearing discardable predicate for cap designating "
- OID_FMT " (%s)",
- OID_PRINTF (cap.oid), cap_type_string (cap.type));
- cap.discardable = false;
- }
-
- page = cap_to_object_soft (activity, &cap);
- if (! page && cap.type != cap_void)
- /* It's not in-memory. See if it was discarded. If not,
- load it using cap_to_object. */
- {
- int object = (cap.oid % (FOLIO_OBJECTS + 1)) - 1;
- oid_t foid = cap.oid - object - 1;
- struct folio *folio
- = (struct folio *) object_find (activity, foid,
- OBJECT_POLICY_DEFAULT);
- assert (folio);
- assert (object_type ((struct object *) folio) == cap_folio);
-
- if (folio_object_discarded (folio, object))
- {
- debug (5, OID_FMT " (%s) was discarded",
- OID_PRINTF (cap.oid),
- cap_type_string (folio_object_type (folio,
- object)));
-
- assert (! folio_object_content (folio, object));
- raise_fault = true;
- discarded = true;
-
- DEBUG (5, "Raising discarded fault at %x", page_addr);
- }
- else
- page = cap_to_object (activity, &cap);
- }
+ l4_word_t page_addr = fault & ~(PAGESIZE - 1);
- if (! page)
- {
- raise_fault = true;
- DEBUG (5, "fault (ip: %x; fault: %x.%c)!",
- ip, fault, w ? 'w' : 'r');
- }
- else if (w && ! writable)
- /* Only allow permitted writes through. */
- {
- raise_fault = true;
- DEBUG (5, "access fault (ip: %x; fault: %x.%c)!",
- ip, fault, w ? 'w' : 'r');
- }
+ struct fault_info fault_info
+ = page_fault (activity, thread, page_addr, w);
- if (raise_fault)
+ if (fault_info.discarded || ! fault_info.page)
{
DEBUG (4, "Reflecting fault (ip: %x; fault: %x.%c%s)!",
- ip, fault, w ? 'w' : 'r', discarded ? " discarded" : "");
+ ip, fault, w ? 'w' : 'r',
+ fault_info.discarded ? " discarded" : "");
l4_word_t c = _L4_XCHG_REGS_DELIVER;
l4_thread_id_t targ = thread->tid;
@@ -321,8 +338,9 @@ server_loop (void)
struct exception_info info;
info.access = access;
- info.type = type;
- info.discarded = discarded;
+ info.type = w ? cap_page : cap_rpage;
+
+ info.discarded = fault_info.discarded;
l4_msg_t msg;
exception_fault_send_marshal (&msg, PTR_TO_ADDR (fault),
@@ -333,15 +351,19 @@ server_loop (void)
continue;
}
- DEBUG (4, "%s fault at %x (ip=%x), replying with %p (" OID_FMT ")",
- w ? "Write" : "Read", fault, ip, page, OID_PRINTF (cap.oid));
- l4_map_item_t map_item
- = l4_map_item (l4_fpage_add_rights (l4_fpage ((uintptr_t) page,
- PAGESIZE),
- access),
- page_addr);
+ access = L4_FPAGE_READABLE;
+ if (fault_info.writable)
+ access |= L4_FPAGE_WRITABLE;
- object_to_object_desc (page)->mapped = true;
+ DEBUG (4, "%s fault at %x (ip=%x), replying with %p(r%s)",
+ w ? "Write" : "Read", fault, ip, fault_info.page,
+ fault_info.writable ? "w" : "");
+ l4_map_item_t map_item
+ = l4_map_item
+ (l4_fpage_add_rights (l4_fpage ((uintptr_t) fault_info.page,
+ PAGESIZE),
+ access),
+ page_addr);
/* Formulate the reply message. */
l4_pagefault_reply_formulate_in (msg, &map_item);
@@ -975,6 +997,47 @@ server_loop (void)
break;
case RM_cap_copy:
rm_cap_copy_reply_marshal (&msg);
+
+ if (ADDR_IS_VOID (target_as_addr)
+ && cap_types_compatible (target->type, cap_page)
+ && (addr_depth (target_addr) + CAP_GUARD_BITS (target)
+ == ADDR_BITS - PAGESIZE_LOG2))
+ /* The target address space is the caller's. The target
+ object appears to be a page. It seems to be
+ installed at a point where it would appear in the
+ hardware address space. If this is really the case,
+ then we can map it now and save a fault later. */
+ {
+ profile_region ("cap_copy(prefault)");
+
+ l4_word_t page_addr
+ = addr_prefix (addr_extend (target_addr,
+ CAP_GUARD_BITS (target),
+ CAP_GUARD (target)));
+ struct fault_info fault_info
+ = page_fault (principal, thread, page_addr, false);
+ if (fault_info.page)
+ {
+ assert (! fault_info.discarded);
+
+ l4_fpage_t fpage
+ = l4_fpage ((uintptr_t) fault_info.page, PAGESIZE);
+
+ if (fault_info.writable)
+ fpage = l4_fpage_add_rights (fpage,
+ L4_FPAGE_READABLE
+ | L4_FPAGE_WRITABLE);
+ else
+ fpage = l4_fpage_add_rights (fpage,
+ L4_FPAGE_READABLE);
+
+ l4_map_item_t map_item = l4_map_item (fpage, page_addr);
+ l4_msg_append_map_item (msg, map_item);
+ }
+
+ profile_region_end ();
+ }
+
break;
}
break;
@@ -1112,9 +1175,51 @@ server_loop (void)
if (folio_object_version (folio, idx) != cap.version)
REPLY (ENOENT);
+ bool was_discarded = folio_object_discarded (folio, idx);
folio_object_discarded_set (folio, idx, false);
rm_object_discarded_clear_reply_marshal (&msg);
+
+ if (was_discarded
+ && cap_types_compatible (cap.type, cap_page)
+ && (addr_depth (object_addr) + CAP_GUARD_BITS (&cap)
+ == ADDR_BITS - PAGESIZE_LOG2))
+ /* The target object was discarded, appears to be a page
+ and seems to be installed at a point where it would
+ appear in the hardware address space. If this is
+ really the case, then we can map it now and save a
+ fault later. */
+ {
+ profile_region ("object_discard(prefault)");
+
+ l4_word_t page_addr
+ = addr_prefix (addr_extend (object_addr,
+ CAP_GUARD_BITS (&cap),
+ CAP_GUARD (&cap)));
+ struct fault_info fault_info
+ = page_fault (principal, thread, page_addr, false);
+ if (fault_info.page)
+ {
+ assert (! fault_info.discarded);
+
+ l4_fpage_t fpage
+ = l4_fpage ((uintptr_t) fault_info.page, PAGESIZE);
+
+ if (fault_info.writable)
+ fpage = l4_fpage_add_rights (fpage,
+ L4_FPAGE_READABLE
+ | L4_FPAGE_WRITABLE);
+ else
+ fpage = l4_fpage_add_rights (fpage,
+ L4_FPAGE_READABLE);
+
+ l4_map_item_t map_item = l4_map_item (fpage, page_addr);
+ l4_msg_append_map_item (msg, map_item);
+ }
+
+ profile_region_end ();
+ }
+
break;
}
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