libpci: ecam: Fix scanning of Extended BIOS Data Area for ACPI RSDP

[pciutils.git] / lib / ecam.c

diff --git a/lib/ecam.c b/lib/ecam.c
index 7f73d51e98b9d12534827a5cc5cb91a9e3b398dd..fdeec0786f6978891564f8d6db0e303894e2c8ed 100644 (file)
--- a/lib/ecam.c
+++ b/lib/ecam.c
@@ -221,9 +221,11 @@ find_rsdp_address(struct pci_access *a, const char *efisystab, int use_bsd UNUSE
 #if defined(__amd64__) || defined(__i386__)
   struct ecam_access *eacc = a->backend_data;
   struct physmem *physmem = eacc->physmem;
+  long pagesize = eacc->pagesize;
   u64 rsdp_addr;
   u64 addr;
   void *map;
+  u64 ebda;
 #endif
   size_t len;
   FILE *f;
@@ -305,23 +307,39 @@ find_rsdp_address(struct pci_access *a, const char *efisystab, int use_bsd UNUSE
       rsdp_addr = 0;
 
       /* Scan first kB of Extended BIOS Data Area */
-      a->debug("scanning first kB of EBDA...");
-      map = physmem_map(physmem, 0, 0x40E + 1024, 0);
+      a->debug("reading EBDA location from BDA...");
+      map = physmem_map(physmem, 0, 0x40E + 2, 0);
       if (map != (void *)-1)
         {
-          for (addr = 0x40E; addr < 0x40E + 1024; addr += 16)
+          ebda = (u64)physmem_readw((unsigned char *)map + 0x40E) << 4;
+          if (physmem_unmap(physmem, map, 0x40E + 2) != 0)
+            a->debug("unmapping of BDA failed: %s...", strerror(errno));
+          if (ebda >= 0x400)
             {
-              if (check_rsdp((struct acpi_rsdp *)((unsigned char *)map + addr)))
+              a->debug("scanning first kB of EBDA at 0x%" PCI_U64_FMT_X "...", ebda);
+              map = physmem_map(physmem, ebda & ~(pagesize-1), 1024 + (ebda & (pagesize-1)), 0);
+              if (map != (void *)-1)
                 {
-                  rsdp_addr = addr;
-                  break;
+                  for (addr = ebda & (pagesize-1); addr < (ebda & (pagesize-1)) + 1024; addr += 16)
+                    {
+                      if (check_rsdp((struct acpi_rsdp *)((unsigned char *)map + addr)))
+                        {
+                          rsdp_addr = (ebda & ~(pagesize-1)) + addr;
+                          break;
+                        }
+                    }
+                  if (physmem_unmap(physmem, map, 1024 + (ebda & (pagesize-1))) != 0)
+                    a->debug("unmapping of EBDA failed: %s...", strerror(errno));
                 }
+              else
+                a->debug("mapping of EBDA failed: %s...", strerror(errno));
             }
-          if (physmem_unmap(physmem, map, 0x40E + 1024) != 0)
-            a->debug("unmapping of EBDA failed: %s...", strerror(errno));
+          else
+            a->debug("EBDA location 0x%" PCI_U64_FMT_X " is insane...", ebda);
         }
       else
-        a->debug("mapping of EBDA failed: %s...", strerror(errno));
+        a->debug("mapping of BDA failed: %s...", strerror(errno));
+
 
       if (rsdp_addr)
         return rsdp_addr;