[Qemu-devel] [v2 PATCH 04/13] SMBIOS: Use bitmaps to check for smbios table collisions

["Gabriel L. Somlo" <gsomlo@gmail.com>]

From: "Gabriel L. Somlo" <somlo@cmu.edu>

Replace existing smbios_check_collision() functionality with
a pair of bitmaps: have_binfile_bitmap and have_fields_bitmap.
Bits corresponding to each smbios type are set by smbios_entry_add(),
which also uses the bitmaps to ensure that binary blobs and field
values are never accepted for the same type.

These bitmaps will also be used in the future to decide whether
or not to build a full table for a given smbios type.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
---
 hw/i386/smbios.c         | 51 ++++++++++++++++++++----------------------------
 include/hw/i386/smbios.h |  2 ++
 2 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/hw/i386/smbios.c b/hw/i386/smbios.c
index f4ee7b4..6889332 100644
--- a/hw/i386/smbios.c
+++ b/hw/i386/smbios.c
@@ -49,11 +49,8 @@ static size_t smbios_entries_len;
 static int smbios_type4_count = 0;
 static bool smbios_immutable;
 
-static struct {
-    bool seen;
-    int headertype;
-    Location loc;
-} first_opt[2];
+static DECLARE_BITMAP(have_binfile_bitmap, SMBIOS_MAX_TYPE+1);
+static DECLARE_BITMAP(have_fields_bitmap, SMBIOS_MAX_TYPE+1);
 
 static struct {
     const char *vendor, *version, *date;
@@ -164,29 +161,6 @@ static void smbios_validate_table(void)
     }
 }
 
-/*
- * To avoid unresolvable overlaps in data, don't allow both
- * tables and fields for the same smbios type.
- */
-static void smbios_check_collision(int type, int entry)
-{
-    if (type < ARRAY_SIZE(first_opt)) {
-        if (first_opt[type].seen) {
-            if (first_opt[type].headertype != entry) {
-                error_report("Can't mix file= and type= for same type");
-                loc_push_restore(&first_opt[type].loc);
-                error_report("This is the conflicting setting");
-                loc_pop(&first_opt[type].loc);
-                exit(1);
-            }
-        } else {
-            first_opt[type].seen = true;
-            first_opt[type].headertype = entry;
-            loc_save(&first_opt[type].loc);
-        }
-    }
-}
-
 static void smbios_add_field(int type, int offset, const void *data, size_t len)
 {
     struct smbios_field *field;
@@ -331,7 +305,14 @@ void smbios_entry_add(QemuOpts *opts)
         }
 
         header = (struct smbios_structure_header *)(table->data);
-        smbios_check_collision(header->type, SMBIOS_TABLE_ENTRY);
+
+        if (test_bit(header->type, have_fields_bitmap)) {
+            error_report("Can't add binary type %d table! "
+                         "(fields already specified)", header->type);
+            exit(1);
+        }
+        set_bit(header->type, have_binfile_bitmap);
+
         if (header->type == 4) {
             smbios_type4_count++;
         }
@@ -346,7 +327,17 @@ void smbios_entry_add(QemuOpts *opts)
     if (val) {
         unsigned long type = strtoul(val, NULL, 0);
 
-        smbios_check_collision(type, SMBIOS_FIELD_ENTRY);
+        if (type > SMBIOS_MAX_TYPE) {
+            error_report("smbios type (%ld) out of range!", type);
+            exit(1);
+        }
+
+        if (test_bit(type, have_binfile_bitmap)) {
+            error_report("Can't add fields for type %ld table! "
+                         "(binary file already loaded)", type);
+            exit(1);
+        }
+        set_bit(type, have_fields_bitmap);
 
         switch (type) {
         case 0:
diff --git a/include/hw/i386/smbios.h b/include/hw/i386/smbios.h
index a7ec973..8b63441 100644
--- a/include/hw/i386/smbios.h
+++ b/include/hw/i386/smbios.h
@@ -15,6 +15,8 @@
 
 #include "qemu/option.h"
 
+#define SMBIOS_MAX_TYPE 127
+
 void smbios_entry_add(QemuOpts *opts);
 void smbios_set_defaults(const char *manufacturer,
                          const char *product, const char *version);
-- 
1.8.1.4