ACPI: make some IO ports off-limits to AML

ACPICA exports acpi_os_validate_address() so the OS
can prevent BIOS AML from accessing specified addresses.

Start using this interface to prevent AML from accessing
some well known IO addresses that the OS "owns".

Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 6729a4992f2b..4fb01b0133c7 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1317,6 +1317,54 @@ acpi_os_validate_interface (char *interface)
         return AE_SUPPORT;
 }
 
+#ifdef  CONFIG_X86
+
+struct aml_port_desc {
+        uint    start;
+        uint    end;
+        char*   name;
+        char    warned;
+};
+
+static struct aml_port_desc aml_invalid_port_list[] = {
+        {0x20, 0x21, "PIC0", 0},
+        {0xA0, 0xA1, "PIC1", 0},
+        {0x4D0, 0x4D1, "ELCR", 0}
+};
+
+/*
+ * valid_aml_io_address()
+ *
+ * if valid, return true
+ * else invalid, warn once, return false
+ */
+static bool valid_aml_io_address(uint address, uint length)
+{
+        int i;
+        int entries = sizeof(aml_invalid_port_list) / sizeof(struct aml_port_desc);
+
+        for (i = 0; i < entries; ++i) {
+                if ((address >= aml_invalid_port_list[i].start &&
+                        address <= aml_invalid_port_list[i].end) ||
+                        (address + length >= aml_invalid_port_list[i].start &&
+                        address  + length <= aml_invalid_port_list[i].end))
+                {
+                        if (!aml_invalid_port_list[i].warned)
+                        {
+                                printk(KERN_ERR "ACPI: Denied BIOS AML access"
+                                        " to invalid port 0x%x+0x%x (%s)\n",
+                                        address, length,
+                                        aml_invalid_port_list[i].name);
+                                aml_invalid_port_list[i].warned = 1;
+                        }
+                        return false;   /* invalid */
+                }
+        }
+        return true;    /* valid */
+}
+#else
+static inline bool valid_aml_io_address(uint address, uint length) { return true; }
+#endif
 /******************************************************************************
  *
  * FUNCTION:    acpi_os_validate_address
@@ -1346,6 +1394,8 @@ acpi_os_validate_address (
 
         switch (space_id) {
         case ACPI_ADR_SPACE_SYSTEM_IO:
+                if (!valid_aml_io_address(address, length))
+                        return AE_AML_ILLEGAL_ADDRESS;
         case ACPI_ADR_SPACE_SYSTEM_MEMORY:
                 /* Only interference checks against SystemIO and SytemMemory
                    are needed */