ACPI: Store valid ACPI tables passed via early initrd in reserved memblock areas

A later patch will compare them with ACPI tables that get loaded at boot or
runtime and if criteria match, a stored one is loaded.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Link: http://lkml.kernel.org/r/1349043837-22659-4-git-send-email-trenn@suse.de
Cc: Len Brown <lenb@kernel.org>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

4 files changed, 141 insertions, 0 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f4b9b80e1b95..764e543b2297 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -941,6 +941,8 @@ void __init setup_arch(char **cmdline_p)
 
         reserve_initrd();
 
+        acpi_initrd_override((void *)initrd_start, initrd_end - initrd_start);
+
         reserve_crashkernel();
 
         vsmp_init();
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 80998958cf45..8cf719547b51 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -261,6 +261,15 @@ config ACPI_CUSTOM_DSDT
         bool
         default ACPI_CUSTOM_DSDT_FILE != ""
 
+config ACPI_INITRD_TABLE_OVERRIDE
+        bool "ACPI tables can be passed via uncompressed cpio in initrd"
+        default n
+        help
+          This option provides functionality to override arbitrary ACPI tables
+          via initrd. No functional change if no ACPI tables are passed via
+          initrd, therefore it's safe to say Y.
+          See Documentation/acpi/initrd_table_override.txt for details
+
 config ACPI_BLACKLIST_YEAR
         int "Disable ACPI for systems before Jan 1st this year" if X86_32
         default 0
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9eaf708f5885..b20b07903218 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -534,6 +534,128 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
         return AE_OK;
 }
 
+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
+#include <linux/earlycpio.h>
+#include <linux/memblock.h>
+
+static u64 acpi_tables_addr;
+static int all_tables_size;
+
+/* Copied from acpica/tbutils.c:acpi_tb_checksum() */
+u8 __init acpi_table_checksum(u8 *buffer, u32 length)
+{
+        u8 sum = 0;
+        u8 *end = buffer + length;
+
+        while (buffer < end)
+                sum = (u8) (sum + *(buffer++));
+        return sum;
+}
+
+/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
+static const char * const table_sigs[] = {
+        ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
+        ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
+        ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
+        ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
+        ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
+        ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
+        ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
+        ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
+        ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL };
+
+/* Non-fatal errors: Affected tables/files are ignored */
+#define INVALID_TABLE(x, path, name)                                    \
+        { pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); continue; }
+
+#define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
+
+/* Must not increase 10 or needs code modification below */
+#define ACPI_OVERRIDE_TABLES 10
+
+void __init acpi_initrd_override(void *data, size_t size)
+{
+        int sig, no, table_nr = 0, total_offset = 0;
+        long offset = 0;
+        struct acpi_table_header *table;
+        char cpio_path[32] = "kernel/firmware/acpi/";
+        struct cpio_data file;
+        struct cpio_data early_initrd_files[ACPI_OVERRIDE_TABLES];
+        char *p;
+
+        if (data == NULL || size == 0)
+                return;
+
+        for (no = 0; no < ACPI_OVERRIDE_TABLES; no++) {
+                file = find_cpio_data(cpio_path, data, size, &offset);
+                if (!file.data)
+                        break;
+
+                data += offset;
+                size -= offset;
+
+                if (file.size < sizeof(struct acpi_table_header))
+                        INVALID_TABLE("Table smaller than ACPI header",
+                                      cpio_path, file.name);
+
+                table = file.data;
+
+                for (sig = 0; table_sigs[sig]; sig++)
+                        if (!memcmp(table->signature, table_sigs[sig], 4))
+                                break;
+
+                if (!table_sigs[sig])
+                        INVALID_TABLE("Unknown signature",
+                                      cpio_path, file.name);
+                if (file.size != table->length)
+                        INVALID_TABLE("File length does not match table length",
+                                      cpio_path, file.name);
+                if (acpi_table_checksum(file.data, table->length))
+                        INVALID_TABLE("Bad table checksum",
+                                      cpio_path, file.name);
+
+                pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n",
+                        table->signature, cpio_path, file.name, table->length);
+
+                all_tables_size += table->length;
+                early_initrd_files[table_nr].data = file.data;
+                early_initrd_files[table_nr].size = file.size;
+                table_nr++;
+        }
+        if (table_nr == 0)
+                return;
+
+        acpi_tables_addr =
+                memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
+                                       all_tables_size, PAGE_SIZE);
+        if (!acpi_tables_addr) {
+                WARN_ON(1);
+                return;
+        }
+        /*
+         * Only calling e820_add_reserve does not work and the
+         * tables are invalid (memory got used) later.
+         * memblock_reserve works as expected and the tables won't get modified.
+         * But it's not enough on X86 because ioremap will
+         * complain later (used by acpi_os_map_memory) that the pages
+         * that should get mapped are not marked "reserved".
+         * Both memblock_reserve and e820_add_region (via arch_reserve_mem_area)
+         * works fine.
+         */
+        memblock_reserve(acpi_tables_addr, acpi_tables_addr + all_tables_size);
+        arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
+
+        p = early_ioremap(acpi_tables_addr, all_tables_size);
+
+        for (no = 0; no < table_nr; no++) {
+                memcpy(p + total_offset, early_initrd_files[no].data,
+                       early_initrd_files[no].size);
+                total_offset += early_initrd_files[no].size;
+        }
+        early_iounmap(p, all_tables_size);
+}
+#endif /* CONFIG_ACPI_INITRD_TABLE_OVERRIDE */
+
 acpi_status
 acpi_os_table_override(struct acpi_table_header * existing_table,
                        struct acpi_table_header ** new_table)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 946fd1ea79ff..d14081c10c17 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -76,6 +76,14 @@ typedef int (*acpi_table_handler) (struct acpi_table_header *table);
 
 typedef int (*acpi_table_entry_handler) (struct acpi_subtable_header *header, const unsigned long end);
 
+#ifdef CONFIG_ACPI_INITRD_TABLE_OVERRIDE
+void acpi_initrd_override(void *data, size_t size);
+#else
+static inline void acpi_initrd_override(void *data, size_t size)
+{
+}
+#endif
+
 char * __acpi_map_table (unsigned long phys_addr, unsigned long size);
 void __acpi_unmap_table(char *map, unsigned long size);
 int early_acpi_boot_init(void);