tpm: Reduce duplication in a few functions

Update tpm2_clear() and tpm2_pcr_extend() so that the command size
is not repeated twice. Add a small comment to the latter.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 1f3deb0..c4e869e 100644 (file)
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -47,9 +47,11 @@ u32 tpm2_self_test(struct udevice *dev, enum tpm2_yes_no full_test)
 u32 tpm2_clear(struct udevice *dev, u32 handle, const char *pw,
               const ssize_t pw_sz)
 {
+       /* Length of the message header, up to start of password */
+       uint offset = 27;
        u8 command_v2[COMMAND_BUFFER_SIZE] = {
                tpm_u16(TPM2_ST_SESSIONS),      /* TAG */
-               tpm_u32(27 + pw_sz),            /* Length */
+               tpm_u32(offset + pw_sz),        /* Length */
                tpm_u32(TPM2_CC_CLEAR),         /* Command code */
 
                /* HANDLE */
@@ -64,7 +66,6 @@ u32 tpm2_clear(struct udevice *dev, u32 handle, const char *pw,
                tpm_u16(pw_sz),                 /* Size of <hmac/password> */
                /* STRING(pw)                      <hmac/password> (if any) */
        };
-       unsigned int offset = 27;
        int ret;
 
        /*
@@ -83,9 +84,11 @@ u32 tpm2_clear(struct udevice *dev, u32 handle, const char *pw,
 u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
                    const u8 *digest, u32 digest_len)
 {
+       /* Length of the message header, up to start of digest */
+       uint offset = 33;
        u8 command_v2[COMMAND_BUFFER_SIZE] = {
                tpm_u16(TPM2_ST_SESSIONS),      /* TAG */
-               tpm_u32(33 + digest_len),       /* Length */
+               tpm_u32(offset + digest_len),   /* Length */
                tpm_u32(TPM2_CC_PCR_EXTEND),    /* Command code */
 
                /* HANDLE */
@@ -99,11 +102,12 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
                0,                              /* Attributes: Cont/Excl/Rst */
                tpm_u16(0),                     /* Size of <hmac/password> */
                                                /* <hmac/password> (if any) */
+
+               /* hashes */
                tpm_u32(1),                     /* Count (number of hashes) */
                tpm_u16(algorithm),     /* Algorithm of the hash */
                /* STRING(digest)                  Digest */
        };
-       unsigned int offset = 33;
        int ret;
 
        /*
@@ -112,7 +116,6 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
         */
        ret = pack_byte_string(command_v2, sizeof(command_v2), "s",
                               offset, digest, digest_len);
-       offset += digest_len;
        if (ret)
                return TPM_LIB_ERROR;