acpi: build_xsdt: use acpi_table_begin()/acpi_table_end() instead of build_header()

it replaces error-prone pointer arithmetic for build_header() API,
with 2 calls to start and finish table creation,
which hides offsets magic from API user.

While at it switch to build_append_int_noprefix() to build
entries to other tables (which also removes some manual offset
calculations).

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210924122802.1455362-4-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 15 insertions, 16 deletions

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index 616a292..86b8322 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -1912,33 +1912,32 @@ build_rsdt(GArray *table_data, BIOSLinker *linker, GArray *table_offsets,
     acpi_table_end(linker, &table);
 }
 
-/* Build xsdt table */
+/*
+ * ACPI 2.0 eXtended System Description Table (XSDT)
+ */
 void
 build_xsdt(GArray *table_data, BIOSLinker *linker, GArray *table_offsets,
            const char *oem_id, const char *oem_table_id)
 {
     int i;
-    unsigned xsdt_entries_offset;
-    AcpiXsdtDescriptorRev2 *xsdt;
-    int xsdt_start = table_data->len;
-    const unsigned table_data_len = (sizeof(uint64_t) * table_offsets->len);
-    const unsigned xsdt_entry_size = sizeof(xsdt->table_offset_entry[0]);
-    const size_t xsdt_len = sizeof(*xsdt) + table_data_len;
-
-    xsdt = acpi_data_push(table_data, xsdt_len);
-    xsdt_entries_offset = (char *)xsdt->table_offset_entry - table_data->data;
+    AcpiTable table = { .sig = "XSDT", .rev = 1,
+                        .oem_id = oem_id, .oem_table_id = oem_table_id };
+
+    acpi_table_begin(&table, table_data);
+
     for (i = 0; i < table_offsets->len; ++i) {
         uint64_t ref_tbl_offset = g_array_index(table_offsets, uint32_t, i);
-        uint64_t xsdt_entry_offset = xsdt_entries_offset + xsdt_entry_size * i;
+        uint64_t xsdt_entry_offset = table.array->len;
 
-        /* xsdt->table_offset_entry to be filled by Guest linker */
+        /* reserve space for entry */
+        build_append_int_noprefix(table.array, 0, 8);
+
+        /* mark position of RSDT entry to be filled by Guest linker */
         bios_linker_loader_add_pointer(linker,
-            ACPI_BUILD_TABLE_FILE, xsdt_entry_offset, xsdt_entry_size,
+            ACPI_BUILD_TABLE_FILE, xsdt_entry_offset, 8,
             ACPI_BUILD_TABLE_FILE, ref_tbl_offset);
     }
-    build_header(linker, table_data,
-                 (void *)(table_data->data + xsdt_start),
-                 "XSDT", xsdt_len, 1, oem_id, oem_table_id);
+    acpi_table_end(linker, &table);
 }
 
 void build_srat_memory(AcpiSratMemoryAffinity *numamem, uint64_t base,