On Wed, Jul 02, 2025 at 10:58:56PM -0500, Prachotan Bathi wrote:
> On 7/2/25 5:16 PM, Jarkko Sakkinen wrote:
>
> > On Thu, Jun 26, 2025 at 01:45:20PM -0500, Prachotan Bathi wrote:
> > > Add a memzero macro to simplify and standardize zeroing
> > > FF-A data args, replacing direct uses of memset for
> > > improved readability and maintainability.
> > >
> > > Signed-off-by: Prachotan Bathi <prachotan.ba...@arm.com>
> > > ---
> > > drivers/char/tpm/tpm_crb_ffa.c | 6 ++++--
> > > 1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm_crb_ffa.c
> > > b/drivers/char/tpm/tpm_crb_ffa.c
> > > index 089d1e54bb46..397cc3b0a478 100644
> > > --- a/drivers/char/tpm/tpm_crb_ffa.c
> > > +++ b/drivers/char/tpm/tpm_crb_ffa.c
> > > @@ -12,6 +12,8 @@
> > > #include <linux/arm_ffa.h>
> > > #include "tpm_crb_ffa.h"
> > > +#define memzero(s, n) memset((s), 0, (n))
> > > +
> > > /* TPM service function status codes */
> > > #define CRB_FFA_OK 0x05000001
> > > #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002
> > > @@ -192,7 +194,7 @@ static int __tpm_crb_ffa_send_receive(unsigned long
> > > func_id,
> > > msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops;
> > > if
> > > (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) {
> > > - memset(&tpm_crb_ffa->direct_msg_data2, 0x00,
> > > + memzero(&tpm_crb_ffa->direct_msg_data2,
> > > sizeof(struct ffa_send_direct_data2));
> > > tpm_crb_ffa->direct_msg_data2.data[0] = func_id;
> > > @@ -205,7 +207,7 @@ static int __tpm_crb_ffa_send_receive(unsigned long
> > > func_id,
> > > if (!ret)
> > > ret =
> > > tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]);
> > > } else {
> > > - memset(&tpm_crb_ffa->direct_msg_data, 0x00,
> > > + memzero(&tpm_crb_ffa->direct_msg_data,
> > > sizeof(struct ffa_send_direct_data));
> > > tpm_crb_ffa->direct_msg_data.data1 = func_id;
> > > --
> > > 2.43.0
> > >
> > It adds a ross-reference to the source code, meaning that you have to
> > jump back and forth in the source code just to see that there is a
> > function that wraps up a single memset() call.
> >
> > How does that map to "readability"?
> >
> > BR, Jarkko
>
> Hi Jarkko
>
> I've implemented this change post your feedback on v4 of the initial patch
> series, maybe this should've been a question at that point, but what was the
> reasoning for recommending that I use memzero instead? I'll use the same
> reasoning to rephrase the commit message.
OK I found what you were referring to:
https://lore.kernel.org/linux-integrity/aff-wnsoltdv9...@kernel.org/
Well, that was some truly misguided advice from my side so all the shame
here is on me :-) There's no global memzero() and neither explicit
version makes much sense here. Sorry about that.
I gave it now (actual) thought, and here's what I'd propose:
diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c
index 96746d5b03e3..e769f6143a7c 100644
--- a/drivers/char/tpm/tpm_crb_ffa.c
+++ b/drivers/char/tpm/tpm_crb_ffa.c
@@ -203,26 +203,20 @@ static int __tpm_crb_ffa_try_send_receive(unsigned long
func_id,
msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops;
if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) {
- memzero(&tpm_crb_ffa->direct_msg_data2,
- sizeof(struct ffa_send_direct_data2));
-
- tpm_crb_ffa->direct_msg_data2.data[0] = func_id;
- tpm_crb_ffa->direct_msg_data2.data[1] = a0;
- tpm_crb_ffa->direct_msg_data2.data[2] = a1;
- tpm_crb_ffa->direct_msg_data2.data[3] = a2;
+ tpm_crb_ffa->direct_msg_data2 = (struct ffa_send_direct_data2){
+ .data = { func_id, a0, a1, a2 },
+ };
ret = msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev,
&tpm_crb_ffa->direct_msg_data2);
if (!ret)
ret =
tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0]);
} else {
- memzero(&tpm_crb_ffa->direct_msg_data,
- sizeof(struct ffa_send_direct_data));
-
- tpm_crb_ffa->direct_msg_data.data1 = func_id;
- tpm_crb_ffa->direct_msg_data.data2 = a0;
- tpm_crb_ffa->direct_msg_data.data3 = a1;
- tpm_crb_ffa->direct_msg_data.data4 = a2;
+ tpm_crb_ffa->direct_msg_data = (struct ffa_send_direct_data){
+ .data1 = func_id,
+ .data2 = a0,
+ .data3 = a1,
+ };
ret = msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev,
&tpm_crb_ffa->direct_msg_data);
I tested the compilation with:
make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 tinyconfig && ./scripts/config
--file .config -e CONFIG_KEYS -e CONFIG_TCG_TPM -e CONFIG_64BIT -e
CONFIG_TRUSTED_KEYS -e CONFIG_TTY -e CONFIG_PROCFS -e CONFIG_SYSFS -e
CONFIG_TCG_VTPM_PROXY -e CONFIG_EFI -e CONFIG_ACPI -e CONFIG_ARM_FFA_TRANSPORT
-e CONFIG_TCG_CRB && yes '' | make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64
oldconfig && make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 -j$(nproc)
BR, Jarkko
