Thank you Vicky and Joy for the clarification. This patch mainly
converts the fields in the tcpa_event structure. I see the code converts
everytime it accesses the event fields. Would it be more efficient if you
do the conversion once and reuse them when needed? Could
convert_to_host_format(x) takes x as a tcpa_event structure?
If not you still can convert individual fields and reuse them. I'm aware
that the pcr_value field is type u8 and it does not need the conversion
but if convert_to_host_format() can convert the structure it shouldn't convert
u8 type I think.
static const char* tcpa_event_type_strings[] = {
"PREBOOT",
@@ -82,9 +87,11 @@ static void *tpm_bios_measurements_start(struct seq_file *m,
loff_t *pos)
event = addr;
if ((addr + sizeof(struct tcpa_event)) < limit) {
- if (event->event_type == 0 && event->event_size == 0)
+ if ((convert_to_host_format(event->event_type) == 0) &&
+ (convert_to_host_format(event->event_size) == 0))
return NULL;
- addr += sizeof(struct tcpa_event) + event->event_size;
+ addr += (sizeof(struct tcpa_event) +
+ convert_to_host_format(event->event_size));
}
}
@@ -94,8 +101,11 @@ static void *tpm_bios_measurements_start(struct seq_file
*m, loff_t *pos)
event = addr;
- if ((event->event_type == 0 && event->event_size == 0) ||
- ((addr + sizeof(struct tcpa_event) + event->event_size) >= limit))
+ if (((convert_to_host_format(event->event_type) == 0) &&
+ (convert_to_host_format(event->event_size) == 0))
+ ||
+ ((addr + sizeof(struct tcpa_event) +
+ convert_to_host_format(event->event_size)) >= limit))
return NULL;
return addr;
In this function, event_type and event_size can be converted
once and reuse.
case SEPARATOR:
case ACTION:
- if (MAX_TEXT_EVENT > event->event_size) {
+ if (MAX_TEXT_EVENT >
+ convert_to_host_format(event->event_size)) {
name = event_entry;
- n_len = event->event_size;
+ n_len = convert_to_host_format(event->event_size);
}
break;
case EVENT_TAG:
Same here.
@@ -208,11 +229,43 @@ static int tpm_binary_bios_measurements_show(struct
seq_file *m, void *v)
struct tcpa_event *event = v;
char *data = v;
int i;
-
- for (i = 0; i < sizeof(struct tcpa_event) + event->event_size; i++)
+ u32 x;
+ char tmp[4];
+
+ /* PCR */
+ x = convert_to_host_format(event->pcr_index);
+ memcpy(tmp, &x, 4);
+ for (i = 0; i < 4; i++)
+ seq_putc(m, tmp[i]);
+ data += 4;
+
+ /* Event Type */
+ x = convert_to_host_format(event->event_type);
+ memcpy(tmp, &x, 4);
+ for (i = 0; i < 4; i++)
+ seq_putc(m, tmp[i]);
+ data += 4;
+
+ /* HASH */
+ for (i = 0; i < 20; i++)
seq_putc(m, data[i]);
+ data += 20;
+
+ /* Size */
+ x = convert_to_host_format(event->event_size);
+ memcpy(tmp, &x, 4);
+ for (i = 0; i < 4; i++)
+ seq_putc(m, tmp[i]);
+ data += 4;
+
+ /* Data */
+ if (convert_to_host_format(event->event_size)) {
+ for (i = 0; i < convert_to_host_format(event->event_size); i++)
+ seq_putc(m, data[i]);
+ }
return 0;
+
}
If the tcpa_event structure is converted, you may be able to get away
with memcpy and the for loop.
Thanks,
--Ashley Lai
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