test: use a non system PCR for testing PCR extend

We currently use PCR 0 for testing the PCR read/extend functionality in
our selftests.  How ever those PCRs are defined by the TCG spec for
platform use.  For example if the tests run *after* the efi subsystem
initialization, which extends PCRs 0 & 7 it will give a false positive.

So let's switch over to a PCR which is more suitable and is defined for
OS use.  It's worth noting that we are using PCR10 here, since PCR9 is
used internally by U-Boot if we choose to measure the loaded DTB

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

1 files changed, 8 insertions, 8 deletions

diff --git a/test/py/tests/test_tpm2.py b/test/py/tests/test_tpm2.py
index c2579fa02c..47392b87a9 100644
--- a/test/py/tests/test_tpm2.py
+++ b/test/py/tests/test_tpm2.py
@@ -239,7 +239,7 @@ def test_tpm2_dam_parameters(u_boot_console):
 def test_tpm2_pcr_read(u_boot_console):
     """Execute a TPM2_PCR_Read command.
 
-    Perform a PCR read of the 0th PCR. Must be zero.
+    Perform a PCR read of the 10th PCR. Must be zero.
     """
     if is_sandbox(u_boot_console):
         tpm2_sandbox_init(u_boot_console)
@@ -247,7 +247,7 @@ def test_tpm2_pcr_read(u_boot_console):
     force_init(u_boot_console)
     ram = u_boot_utils.find_ram_base(u_boot_console)
 
-    read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % ram)
+    read_pcr = u_boot_console.run_command('tpm2 pcr_read 10 0x%x' % ram)
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
 
@@ -257,7 +257,7 @@ def test_tpm2_pcr_read(u_boot_console):
     updates = int(re.findall(r'\d+', str)[0])
 
     # Check the output value
-    assert 'PCR #0 content' in read_pcr
+    assert 'PCR #10 content' in read_pcr
     assert '00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00' in read_pcr
 
 @pytest.mark.buildconfigspec('cmd_tpm_v2')
@@ -275,19 +275,19 @@ def test_tpm2_pcr_extend(u_boot_console):
     force_init(u_boot_console)
     ram = u_boot_utils.find_ram_base(u_boot_console)
 
-    read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % (ram + 0x20))
+    read_pcr = u_boot_console.run_command('tpm2 pcr_read 10 0x%x' % (ram + 0x20))
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
     str = re.findall(r'\d+ known updates', read_pcr)[0]
     updates = int(re.findall(r'\d+', str)[0])
 
-    u_boot_console.run_command('tpm2 pcr_extend 0 0x%x' % ram)
+    u_boot_console.run_command('tpm2 pcr_extend 10 0x%x' % ram)
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
 
     # Read the value back into a different place so we can still use 'ram' as
     # our zero bytes
-    read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % (ram + 0x20))
+    read_pcr = u_boot_console.run_command('tpm2 pcr_read 10 0x%x' % (ram + 0x20))
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
     assert 'f5 a5 fd 42 d1 6a 20 30 27 98 ef 6e d3 09 97 9b' in read_pcr
@@ -297,11 +297,11 @@ def test_tpm2_pcr_extend(u_boot_console):
     new_updates = int(re.findall(r'\d+', str)[0])
     assert (updates + 1) == new_updates
 
-    u_boot_console.run_command('tpm2 pcr_extend 0 0x%x' % ram)
+    u_boot_console.run_command('tpm2 pcr_extend 10 0x%x' % ram)
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
 
-    read_pcr = u_boot_console.run_command('tpm2 pcr_read 0 0x%x' % (ram + 0x20))
+    read_pcr = u_boot_console.run_command('tpm2 pcr_read 10 0x%x' % (ram + 0x20))
     output = u_boot_console.run_command('echo $?')
     assert output.endswith('0')
     assert '7a 05 01 f5 95 7b df 9c b3 a8 ff 49 66 f0 22 65' in read_pcr