[PATCH 2/2] tpm: get tpm event log from bloblist

[Simon Glass]

Hi Raymond,

On Mon, 16 Dec 2024 at 07:52, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Hi Simon,
>
> On Sun, 15 Dec 2024 at 19:25, Simon Glass <sjg at chromium.org> wrote:
>>
>> Hi Raymond,
>>
>> On Fri, 13 Dec 2024 at 15:56, Raymond Mao <raymond.mao at linaro.org> wrote:
>> >
>> > Get tpm event log from bloblist instead of FDT when bloblist is
>> > enabled and valid from previous boot stage.
>> >
>> > Note:
>> > This patch depends on:
>> > [PATCH 1/2] bloblist: Introduce BLOBLIST_PRIOR_STAGE options
>> > https://lore.kernel.org/u-boot/20241212151142.1562825-1-trini@konsulko.com/
>> >
>> > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
>> > ---
>> >  lib/tpm_tcg2.c | 7 +++++++
>> >  1 file changed, 7 insertions(+)
>> >
>> > diff --git a/lib/tpm_tcg2.c b/lib/tpm_tcg2.c
>> > index 7f868cc883..acaf0acb88 100644
>> > --- a/lib/tpm_tcg2.c
>> > +++ b/lib/tpm_tcg2.c
>> > @@ -19,6 +19,7 @@
>> >  #include <linux/unaligned/generic.h>
>> >  #include <linux/unaligned/le_byteshift.h>
>> >  #include "tpm-utils.h"
>> > +#include <bloblist.h>
>> >
>> >  int tcg2_get_pcr_info(struct udevice *dev, u32 *supported_pcr, u32 *active_pcr,
>> >                       u32 *pcr_banks)
>> > @@ -672,6 +673,12 @@ __weak int tcg2_platform_get_log(struct udevice *dev, void **addr, u32 *size)
>> >         *addr = NULL;
>> >         *size = 0;
>> >
>> > +       if (CONFIG_IS_ENABLED(BLOBLIST_PRIOR_STAGE) && !bloblist_maybe_init()) {
>>
>> Please drop the second term...the bloblist is inited by U-Boot already.
>>
>
> As an independent library, from the tpm library's angle, whether the bloblist init was already called or not is agnostic.
> I think this is the purpose of the "maybe" function.

No. U-Boot does init at the start. We don't want each subsystem
'maybe' initing each other subsystem that it uses. If you want to
check whether bloblist is available, you can use the GD flag.

>
>>
>> Also please drop the first term. If you find it in the bloblist, just use it.
>>
>
> I think here we should have the same logic as the existing one in fdtdec:
> If bloblist is not enabled or errors observed, do a fallback to the original process.
> At least I want to keep the same logic in different places before everything is ready from TF-A to U-boot.

Yes, your second line is right. But PRIOR_STAGE doesn't exist, nor
should it. Nor do you need it, since you can just check the bloblist
for what you want. If you don't find it, fall back.

>
> [snip]

REgards,
Simon