[SLOF] [PATCH slof] tcgbios: Fix warnings

[Thomas Huth]

On 30/06/2021 05.16, Alexey Kardashevskiy wrote:
> This fixes gcc warnings from -Waddress-of-packed-member and -Wzero-length-bounds.
> 
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> 
> ---
> 
> tpm_drivers.c: In function ‘spapr_send_crq_and_wait’:
> tpm_drivers.c:153:2: warning: converting a packed ‘struct crq’ pointer (alignment 1) to a ‘uint64_t’ {aka ‘long long unsigned int’} pointer alignment 8) may result in an unaligned pointer value [-Waddress-of-packed-member]
>    153 |  rc = hv_send_crq(unit, (uint64_t *)crq);
>        |  ^~
> tpm_drivers.c:34:8: note: defined here
>     34 | struct crq {
>        |        ^~~
> tpm_drivers.c: In function ‘spapr_vtpm_senddata’:
> tpm_drivers.c:346:2: warning: converting a packed ‘struct crq’ pointer (alignment 1) to a ‘uint64_t’ {aka ‘long long unsigned int’} pointer (alignment 8) may result in an unaligned pointer value [-Waddress-of-packed-member]
>    346 |  rc = hv_send_crq(spapr_vtpm.unit, (uint64_t *)&crq);
>        |  ^~
> tpm_drivers.c:34:8: note: defined here
>     34 | struct crq {
>        |        ^~~
>          [CC]    common-libs
>          [CC]    common-libs
> tcgbios.c: In function ‘tpm20_write_EfiSpecIdEventStruct’:
> tcgbios.c:708:24: warning: array subscript ‘numAlgs’ is outside the bounds of an interior zero-length array ‘struct TCG_EfiSpecIdEventAlgorithmSize[0]’ [-Wzero-length-bounds]
>    708 |   event.hdr.digestSizes[numAlgs].algorithmId =
>        |   ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
> In file included from tpm_drivers.h:20,
>                   from tcgbios.c:27:
> tcgbios_int.h:92:4: note: while referencing ‘digestSizes’
>     92 |  } digestSizes[0];
>        |    ^~~~~~~~~~~
> tcgbios.c:710:24: warning: array subscript ‘numAlgs’ is outside the bounds of an interior zero-length array ‘struct TCG_EfiSpecIdEventAlgorithmSize[0]’ [-Wzero-length-bounds]
>    710 |   event.hdr.digestSizes[numAlgs].digestSize = cpu_to_log16(hsize);
>        |   ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
> In file included from tpm_drivers.h:20,
>                   from tcgbios.c:27:
> tcgbios_int.h:92:4: note: while referencing ‘digestSizes’
>     92 |  } digestSizes[0];
>        |    ^~~~~~~~~~~
> ---
>   lib/libtpm/tcgbios_int.h | 2 +-
>   lib/libtpm/tpm_drivers.c | 4 ++--
>   2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/libtpm/tcgbios_int.h b/lib/libtpm/tcgbios_int.h
> index 22df31dd504f..cc38455850f2 100644
> --- a/lib/libtpm/tcgbios_int.h
> +++ b/lib/libtpm/tcgbios_int.h
> @@ -89,7 +89,7 @@ struct TCG_EfiSpecIdEventStruct {
>   	struct TCG_EfiSpecIdEventAlgorithmSize {
>   		uint16_t algorithmId;
>   		uint16_t digestSize;
> -	} digestSizes[0];
> +	} digestSizes[];
>   	/*
>   	uint8_t vendorInfoSize;
>   	uint8_t vendorInfo[0];
> diff --git a/lib/libtpm/tpm_drivers.c b/lib/libtpm/tpm_drivers.c
> index 85cb3098712d..4a4fde89ade8 100644
> --- a/lib/libtpm/tpm_drivers.c
> +++ b/lib/libtpm/tpm_drivers.c
> @@ -150,7 +150,7 @@ static bool spapr_send_crq_and_wait(unsigned long unit,
>   
>   	vtpm_drv_state_set(state1, VTPM_DRV_ERROR_NO_FAILURE);
>   
> -	rc = hv_send_crq(unit, (uint64_t *)crq);
> +	rc = hv_send_crq(unit, (uint64_t *)&crq->valid);
>   	if (rc != H_SUCCESS) {
>   		vtpm_drv_state_set(VTPM_DRV_STATE_WAIT_INIT,
>   				   VTPM_DRV_ERROR_TPM_CRQ_ERROR);
> @@ -343,7 +343,7 @@ static bool spapr_vtpm_senddata(const uint8_t *const data, uint32_t len)
>   	vtpm_drv_state_set(VTPM_DRV_STATE_SEND_TPM_CMD,
>   			   VTPM_DRV_ERROR_NO_FAILURE);
>   
> -	rc = hv_send_crq(spapr_vtpm.unit, (uint64_t *)&crq);
> +	rc = hv_send_crq(spapr_vtpm.unit, (uint64_t *)&crq.valid);
>   
>   	if (rc == H_SUCCESS)
>   		vtpm_drv_state_set(VTPM_DRV_STATE_WAIT_TPM_RSP,
> 

All members of struct crq seem to be naturally aligned, so you could also 
simply remove the "packed" attribute there.
Anyway, taking the detour via the uint8_t valid field seems ok to me, too, so:

Reviewed-by: Thomas Huth <thuth at redhat.com>