From: Borislav Petkov <b...@suse.de>
Turn them into proper sentences. Add comments to
microcode_sanity_check() to explain what it does.
Signed-off-by: Borislav Petkov <b...@suse.de>
---
arch/x86/kernel/cpu/microcode/intel_lib.c | 36 ++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/intel_lib.c
b/arch/x86/kernel/cpu/microcode/intel_lib.c
index ffb1bbf45db0..23b1d92342e3 100644
--- a/arch/x86/kernel/cpu/microcode/intel_lib.c
+++ b/arch/x86/kernel/cpu/microcode/intel_lib.c
@@ -57,15 +57,16 @@ 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;
@@ -74,43 +75,58 @@ int microcode_sanity_check(void *mc, int print_err)
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 */
+ /*
+ * 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 / 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) / sizeof(u32);
while (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;
@@ -119,7 +135,7 @@ int microcode_sanity_check(void *mc, int print_err)
+ (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;
}
}
--
2.3.5
