x86/microcode/intel: Drop orig_sum from ext signature checksum

[linux-2.6-block.git] / arch / x86 / kernel / cpu / microcode / intel_lib.c

diff --git a/arch/x86/kernel/cpu/microcode/intel_lib.c b/arch/x86/kernel/cpu/microcode/intel_lib.c
index b96896bcbdaf1ac88d4dcfa2a7ce3a98d291ccad..2ce1a7dc45b730cde0097e77353b9c426f3782b8 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/intel_lib.c
+++ b/arch/x86/kernel/cpu/microcode/intel_lib.c
@@ -49,7 +49,7 @@ int microcode_sanity_check(void *mc, int print_err)
        unsigned long total_size, data_size, ext_table_size;
        struct microcode_header_intel *mc_header = mc;
        struct extended_sigtable *ext_header = NULL;
-       int sum, orig_sum, ext_sigcount = 0, i;
+       u32 sum, orig_sum, ext_sigcount = 0, i;
        struct extended_signature *ext_sig;
 
        total_size = get_totalsize(mc_header);
@@ -57,69 +57,85 @@ int microcode_sanity_check(void *mc, int print_err)
 
        if (data_size + MC_HEADER_SIZE > total_size) {
                if (print_err)
-                       pr_err("error! Bad data size in microcode data file\n");
+                       pr_err("Error: bad microcode data file size.\n");
                return -EINVAL;
        }
 
        if (mc_header->ldrver != 1 || mc_header->hdrver != 1) {
                if (print_err)
-                       pr_err("error! Unknown microcode update format\n");
+                       pr_err("Error: invalid/unknown microcode update format.\n");
                return -EINVAL;
        }
+
        ext_table_size = total_size - (MC_HEADER_SIZE + data_size);
        if (ext_table_size) {
+               u32 ext_table_sum = 0;
+               u32 *ext_tablep;
+
                if ((ext_table_size < EXT_HEADER_SIZE)
                 || ((ext_table_size - EXT_HEADER_SIZE) % EXT_SIGNATURE_SIZE)) {
                        if (print_err)
-                               pr_err("error! Small exttable size in microcode data file\n");
+                               pr_err("Error: truncated extended signature table.\n");
                        return -EINVAL;
                }
+
                ext_header = mc + MC_HEADER_SIZE + data_size;
                if (ext_table_size != exttable_size(ext_header)) {
                        if (print_err)
-                               pr_err("error! Bad exttable size in microcode data file\n");
+                               pr_err("Error: extended signature table size mismatch.\n");
                        return -EFAULT;
                }
+
                ext_sigcount = ext_header->count;
-       }
 
-       /* check extended table checksum */
-       if (ext_table_size) {
-               int ext_table_sum = 0;
-               int *ext_tablep = (int *)ext_header;
+               /*
+                * Check extended table checksum: the sum of all dwords that
+                * comprise a valid table must be 0.
+                */
+               ext_tablep = (u32 *)ext_header;
 
-               i = ext_table_size / DWSIZE;
+               i = ext_table_size / sizeof(u32);
                while (i--)
                        ext_table_sum += ext_tablep[i];
+
                if (ext_table_sum) {
                        if (print_err)
-                               pr_warn("aborting, bad extended signature table checksum\n");
+                               pr_warn("Bad extended signature table checksum, aborting.\n");
                        return -EINVAL;
                }
        }
 
-       /* calculate the checksum */
+       /*
+        * Calculate the checksum of update data and header. The checksum of
+        * valid update data and header including the extended signature table
+        * must be 0.
+        */
        orig_sum = 0;
-       i = (MC_HEADER_SIZE + data_size) / DWSIZE;
+       i = (MC_HEADER_SIZE + data_size) / sizeof(u32);
        while (i--)
-               orig_sum += ((int *)mc)[i];
+               orig_sum += ((u32 *)mc)[i];
+
        if (orig_sum) {
                if (print_err)
-                       pr_err("aborting, bad checksum\n");
+                       pr_err("Bad microcode data checksum, aborting.\n");
                return -EINVAL;
        }
+
        if (!ext_table_size)
                return 0;
-       /* check extended signature checksum */
+
+       /*
+        * Check extended signature checksum: 0 => valid.
+        */
        for (i = 0; i < ext_sigcount; i++) {
                ext_sig = (void *)ext_header + EXT_HEADER_SIZE +
                          EXT_SIGNATURE_SIZE * i;
-               sum = orig_sum
-                       - (mc_header->sig + mc_header->pf + mc_header->cksum)
-                       + (ext_sig->sig + ext_sig->pf + ext_sig->cksum);
+
+               sum = (mc_header->sig + mc_header->pf + mc_header->cksum) -
+                     (ext_sig->sig + ext_sig->pf + ext_sig->cksum);
                if (sum) {
                        if (print_err)
-                               pr_err("aborting, bad checksum\n");
+                               pr_err("Bad extended signature checksum, aborting.\n");
                        return -EINVAL;
                }
        }