[SeaBIOS] [PATCH v6 1/3] biostables: support looking up RSDP

[Michael S. Tsirkin]

Will be used when it's loaded from QEMU.

Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
---
 src/util.h          |  1 +
 src/fw/biostables.c | 40 +++++++++++++++++++++++++++++++++-------
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/src/util.h b/src/util.h
index 880c04a..bf983e5 100644
--- a/src/util.h
+++ b/src/util.h
@@ -72,6 +72,7 @@ void acpi_reboot(void);
 // fw/biostable.c
 void copy_smbios(void *pos);
 void copy_table(void *pos);
+void *find_acpi_rsdp(void);
 
 // fw/coreboot.c
 extern const char *CBvendor, *CBpart;
diff --git a/src/fw/biostables.c b/src/fw/biostables.c
index a3ee827..4c2f355 100644
--- a/src/fw/biostables.c
+++ b/src/fw/biostables.c
@@ -60,22 +60,34 @@ copy_mptable(void *pos)
     memcpy((void*)newpos + length, (void*)p->physaddr, mpclength);
 }
 
-static void
-copy_acpi_rsdp(void *pos)
+static bool
+test_acpi_rsdp(void *pos, unsigned size)
 {
-    if (RsdpAddr)
-        return;
     struct rsdp_descriptor *p = pos;
     if (p->signature != RSDP_SIGNATURE)
-        return;
+        return false;
     u32 length = 20;
+    if (length > size)
+        return false;
     if (checksum(pos, length) != 0)
-        return;
+        return false;
     if (p->revision > 1) {
         length = p->length;
+        if (length > size)
+            return false;
         if (checksum(pos, length) != 0)
-            return;
+            return false;
     }
+    return true;
+}
+
+static void
+copy_acpi_rsdp(void *pos)
+{
+    if (RsdpAddr)
+        return;
+    if (!test_acpi_rsdp(pos, -1))
+        return;
     void *newpos = malloc_fseg(length);
     if (!newpos) {
         warn_noalloc();
@@ -118,3 +130,17 @@ copy_table(void *pos)
     copy_acpi_rsdp(pos);
     copy_smbios(pos);
 }
+
+void *find_acpi_rsdp(void)
+{
+    extern u8 zonefseg_start[], zonefseg_end[];
+    unsigned long start = (unsigned long)zonefseg_start;
+    unsigned long end = (unsigned long)zonefseg_end;
+    unsigned long pos;
+
+    for (pos = ALIGN(start, 0x10); pos += 0x10; pos <= ALIGN_DOWN(end, 0x10))
+        if (test_acpi_rsdp((void *)pos, end - pos))
+            return (void *)pos;
+
+    return NULL;
+}
-- 
MST