[SeaBIOS] [PATCH v2 1/3] tcgbios: pass returnCode through many functions

[Stefan Berger]

On 01/16/2018 01:16 PM, Kevin O'Connor wrote:
> On Tue, Jan 16, 2018 at 11:41:01AM -0500, Stefan Berger wrote:
>> Pass the returnCode parameter through many of the functions so
>> that we can get the TPM return code from hwtpm_transmit, if needed.
>>
>> Signed-off-by: Stefan Berger <stefanb at linux.vnet.ibm.com>
>> ---
>>   src/hw/tpm_drivers.c |   8 ++-
>>   src/hw/tpm_drivers.h |   2 +-
>>   src/tcgbios.c        | 147 +++++++++++++++++++++++++++------------------------
>>   3 files changed, 86 insertions(+), 71 deletions(-)
>>
>> diff --git a/src/hw/tpm_drivers.c b/src/hw/tpm_drivers.c
>> index a137e62..25f4f36 100644
>> --- a/src/hw/tpm_drivers.c
>> +++ b/src/hw/tpm_drivers.c
>> @@ -377,7 +377,7 @@ tpmhw_is_present(void)
>>   int
>>   tpmhw_transmit(u8 locty, struct tpm_req_header *req,
>>                  void *respbuffer, u32 *respbufferlen,
>> -               enum tpmDurationType to_t)
>> +               enum tpmDurationType to_t, u32 *returnCode)
>>   {
>>       if (TPMHW_driver_to_use == TPM_INVALID_DRIVER)
>>           return -1;
>> @@ -408,6 +408,12 @@ tpmhw_transmit(u8 locty, struct tpm_req_header *req,
>>   
>>       td->ready();
>>   
>> +    if (returnCode && *respbufferlen >= sizeof(struct tpm_rsp_header)) {
>> +        struct tpm_rsp_header *r = respbuffer;
>> +
>> +        *returnCode = be32_to_cpu(r->errcode);
>> +    }
>> +
>>       return 0;
>>   }
> [...]
>> diff --git a/src/tcgbios.c b/src/tcgbios.c
>> index 40b3028..730b5e7 100644
>> --- a/src/tcgbios.c
>> +++ b/src/tcgbios.c
>> @@ -350,7 +350,8 @@ tpm_build_digest(struct tpm_log_entry *le, const u8 *sha1, int bigEndian)
>>   // optional parameter (0, 1, or 2 bytes) and have no special response.
>>   static int
>>   tpm_simple_cmd(u8 locty, u32 ordinal
>> -               , int param_size, u16 param, enum tpmDurationType to_t)
>> +               , int param_size, u16 param, enum tpmDurationType to_t
>> +               , u32 *returnCode)
>>   {
>>       struct {
>>           struct tpm_req_header trqh;
>> @@ -374,7 +375,8 @@ tpm_simple_cmd(u8 locty, u32 ordinal
>>       u32 obuffer_len = sizeof(obuffer);
>>       memset(obuffer, 0x0, sizeof(obuffer));
>>   
>> -    int ret = tpmhw_transmit(locty, &req.trqh, obuffer, &obuffer_len, to_t);
>> +    int ret = tpmhw_transmit(locty, &req.trqh, obuffer, &obuffer_len, to_t,
>> +                             returnCode);
>>       ret = ret ? -1 : be32_to_cpu(trsh->errcode);
> I'm not sure why this patch is necessary.  The callers of
> tpmhw_transmit() can already extract the errcode.  Indeed,
> tpm_simple_cmd() does just that and returns it to its callers via its
> return code (see the last line of code above).

We sometimes have code like this:

ret = tpm12...
if (ret)
     return -1;

This just maps a potential TPM error code to -1.

I guess the right thing to do is to avoid this mapping.

    Stefan
>
> -Kevin
>