[RESEND,0/8] IIO: Alignment fixes part 3 - __aligned(8) used to ensure alignment

Message

Jonathan Cameron June 13, 2021, 3:22 p.m. UTC

From: Jonathan Cameron <[e-mail]>

Resent as none of these have had any comments since being sent out over
a month ago.  Note these are very straight forward, but I've messed up
such things in the past so really appreciate it if someone takes the time
to do a quick sanity check.

I have picked up those patches that did get review in first posting and
dropped them from this posting.

Cover letter from first posting.

I finally got around to do a manual audit of all the calls to
iio_push_to_buffers_with_timestamp() which has the somewhat odd requirements
of:
1. 8 byte alignment of the provided buffer.
2. space for an 8 byte naturally aligned timestamp to be inserted at the
   end.

Unfortunately there were rather a lot of these left, but time to bite the bullet
and clean them up.

As discussed previous in
https://lore.kernel.org/linux-iio/[e-mail]/
it is not easy to fix the alignment issue without requiring a bounce buffer
(see part 4 of the alignment fixes for a proposal for that where it is
absolutely necessary).

Part 3 contains the cases where the struct approach in part 2 did not seem
appropriate.  Normally there are two possible reasons for this.
1.  Would have required an additional memset operation to avoid any
    possibility of leaking kernel data.
2.  The location of the timestamp may depend on the channels enabled.
    This normally happens when the max sizeof channels is greater than
    8 bytes.

Once all cases are fixes, I'll take a look at hardening against any
accidental reintroductions. Note that on many platforms and usecases the
bug in question will never occur.

Cc: Eugen Hristev <[e-mail]>
Cc: Andreas Klinger <ak@it-klinger.d>
Cc: Song Qiang <[e-mail]>
Cc: Mathieu Othacehe <[e-mail]>
Cc: Parthiban Nallathambi <[e-mail]>

Jonathan Cameron (8):
  iio: adc: at91-sama5d2: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()
  iio: adc: hx711: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()
  iio: adc: mxs-lradc: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()
  iio: adc: ti-ads8688: Fix alignment of buffer in
    iio_push_to_buffers_with_timestamp()
  iio: magn: rm3100: Fix alignment of buffer in
    iio_push_to_buffers_with_timestamp()
  iio: light: vcnl4000: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()
  iio: light: vcnl4035: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()
  iio: prox: isl29501: Fix buffer alignment in
    iio_push_to_buffers_with_timestamp()

 drivers/iio/adc/at91-sama5d2_adc.c     | 3 ++-
 drivers/iio/adc/hx711.c                | 4 ++--
 drivers/iio/adc/mxs-lradc-adc.c        | 3 ++-
 drivers/iio/adc/ti-ads8688.c           | 3 ++-
 drivers/iio/light/vcnl4000.c           | 2 +-
 drivers/iio/light/vcnl4035.c           | 3 ++-
 drivers/iio/magnetometer/rm3100-core.c | 3 ++-
 drivers/iio/proximity/isl29501.c       | 2 +-
 8 files changed, 14 insertions(+), 9 deletions(-)

Comments

Nuno Sa June 14, 2021, 8:03 a.m. UTC | #1

Hi Jonathan,

> From: Jonathan Cameron <[e-mail]>
> Sent: Sunday, June 13, 2021 5:23 PM
> To: [e-mail]
> Cc: Jonathan Cameron <[e-mail]>; Eugen
> Hristev <[e-mail]>; Andreas Klinger <ak@it-
> klinger.d>; Song Qiang <[e-mail]>; Mathieu
> Othacehe <[e-mail]>; Parthiban Nallathambi
> <[e-mail]>
> Subject: [PATCH RESEND 0/8] IIO: Alignment fixes part 3 - __aligned(8)
> used to ensure alignment
> 
> From: Jonathan Cameron <[e-mail]>
> 
> Resent as none of these have had any comments since being sent out
> over
> a month ago.  Note these are very straight forward, but I've messed up
> such things in the past so really appreciate it if someone takes the time
> to do a quick sanity check.
> 
> I have picked up those patches that did get review in first posting and
> dropped them from this posting.
> 
> Cover letter from first posting.
> 
> I finally got around to do a manual audit of all the calls to
> iio_push_to_buffers_with_timestamp() which has the somewhat odd
> requirements
> of:
> 1. 8 byte alignment of the provided buffer.
> 2. space for an 8 byte naturally aligned timestamp to be inserted at the
>    end.
> 
> Unfortunately there were rather a lot of these left, but time to bite
> the bullet
> and clean them up.
> 
> As discussed previous in
> https://urldefense.com/v3/__https://lore.kernel.org/linux-
> iio/20200920112742.170751-1-
> [e-mail]/__;!!A3Ni8CS0y2Y!uCn6NSpGUvHYdcFazn7flxxjh8RA
> RqPCumitrRDDgGAjXF7crgi911KY2v_iyw$
> it is not easy to fix the alignment issue without requiring a bounce
> buffer
> (see part 4 of the alignment fixes for a proposal for that where it is
> absolutely necessary).
> 
> Part 3 contains the cases where the struct approach in part 2 did not
> seem
> appropriate.  Normally there are two possible reasons for this.
> 1.  Would have required an additional memset operation to avoid any
>     possibility of leaking kernel data.
> 2.  The location of the timestamp may depend on the channels
> enabled.
>     This normally happens when the max sizeof channels is greater than
>     8 bytes.
> 
> Once all cases are fixes, I'll take a look at hardening against any
> accidental reintroductions. Note that on many platforms and usecases
> the
> bug in question will never occur.
> 
> Cc: Eugen Hristev <[e-mail]>
> Cc: Andreas Klinger <ak@it-klinger.d>
> Cc: Song Qiang <[e-mail]>
> Cc: Mathieu Othacehe <[e-mail]>
> Cc: Parthiban Nallathambi <[e-mail]>
> 
> Jonathan Cameron (8):
>   iio: adc: at91-sama5d2: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
>   iio: adc: hx711: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
>   iio: adc: mxs-lradc: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
>   iio: adc: ti-ads8688: Fix alignment of buffer in
>     iio_push_to_buffers_with_timestamp()
>   iio: magn: rm3100: Fix alignment of buffer in
>     iio_push_to_buffers_with_timestamp()
>   iio: light: vcnl4000: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
>   iio: light: vcnl4035: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
>   iio: prox: isl29501: Fix buffer alignment in
>     iio_push_to_buffers_with_timestamp()
> 
>  drivers/iio/adc/at91-sama5d2_adc.c     | 3 ++-
>  drivers/iio/adc/hx711.c                | 4 ++--
>  drivers/iio/adc/mxs-lradc-adc.c        | 3 ++-
>  drivers/iio/adc/ti-ads8688.c           | 3 ++-
>  drivers/iio/light/vcnl4000.c           | 2 +-
>  drivers/iio/light/vcnl4035.c           | 3 ++-
>  drivers/iio/magnetometer/rm3100-core.c | 3 ++-
>  drivers/iio/proximity/isl29501.c       | 2 +-
>  8 files changed, 14 insertions(+), 9 deletions(-)
> 
> --
> 2.32.0

LGTM. For the whole series:

Reviewed-by: Nuno Sá <[e-mail]>

- Nuno Sá

Jonathan Cameron June 14, 2021, 10:43 a.m. UTC | #2

On Mon, 14 Jun 2021 08:03:20 +0000
"Sa, Nuno" <[e-mail]> wrote:

> Hi Jonathan,
> 
> > From: Jonathan Cameron <[e-mail]>
> > Sent: Sunday, June 13, 2021 5:23 PM
> > To: [e-mail]
> > Cc: Jonathan Cameron <[e-mail]>; Eugen
> > Hristev <[e-mail]>; Andreas Klinger <ak@it-  
> > klinger.d>; Song Qiang <[e-mail]>; Mathieu  
> > Othacehe <[e-mail]>; Parthiban Nallathambi
> > <[e-mail]>
> > Subject: [PATCH RESEND 0/8] IIO: Alignment fixes part 3 - __aligned(8)
> > used to ensure alignment
> > 
> > From: Jonathan Cameron <[e-mail]>
> > 
> > Resent as none of these have had any comments since being sent out
> > over
> > a month ago.  Note these are very straight forward, but I've messed up
> > such things in the past so really appreciate it if someone takes the time
> > to do a quick sanity check.
> > 
> > I have picked up those patches that did get review in first posting and
> > dropped them from this posting.
> > 
> > Cover letter from first posting.
> > 
> > I finally got around to do a manual audit of all the calls to
> > iio_push_to_buffers_with_timestamp() which has the somewhat odd
> > requirements
> > of:
> > 1. 8 byte alignment of the provided buffer.
> > 2. space for an 8 byte naturally aligned timestamp to be inserted at the
> >    end.
> > 
> > Unfortunately there were rather a lot of these left, but time to bite
> > the bullet
> > and clean them up.
> > 
> > As discussed previous in
> > https://urldefense.com/v3/__https://lore.kernel.org/linux-
> > iio/20200920112742.170751-1-
> > [e-mail]/__;!!A3Ni8CS0y2Y!uCn6NSpGUvHYdcFazn7flxxjh8RA
> > RqPCumitrRDDgGAjXF7crgi911KY2v_iyw$
> > it is not easy to fix the alignment issue without requiring a bounce
> > buffer
> > (see part 4 of the alignment fixes for a proposal for that where it is
> > absolutely necessary).
> > 
> > Part 3 contains the cases where the struct approach in part 2 did not
> > seem
> > appropriate.  Normally there are two possible reasons for this.
> > 1.  Would have required an additional memset operation to avoid any
> >     possibility of leaking kernel data.
> > 2.  The location of the timestamp may depend on the channels
> > enabled.
> >     This normally happens when the max sizeof channels is greater than
> >     8 bytes.
> > 
> > Once all cases are fixes, I'll take a look at hardening against any
> > accidental reintroductions. Note that on many platforms and usecases
> > the
> > bug in question will never occur.
> > 
> > Cc: Eugen Hristev <[e-mail]>
> > Cc: Andreas Klinger <ak@it-klinger.d>
> > Cc: Song Qiang <[e-mail]>
> > Cc: Mathieu Othacehe <[e-mail]>
> > Cc: Parthiban Nallathambi <[e-mail]>
> > 
> > Jonathan Cameron (8):
> >   iio: adc: at91-sama5d2: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: adc: hx711: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: adc: mxs-lradc: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: adc: ti-ads8688: Fix alignment of buffer in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: magn: rm3100: Fix alignment of buffer in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: light: vcnl4000: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: light: vcnl4035: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> >   iio: prox: isl29501: Fix buffer alignment in
> >     iio_push_to_buffers_with_timestamp()
> > 
> >  drivers/iio/adc/at91-sama5d2_adc.c     | 3 ++-
> >  drivers/iio/adc/hx711.c                | 4 ++--
> >  drivers/iio/adc/mxs-lradc-adc.c        | 3 ++-
> >  drivers/iio/adc/ti-ads8688.c           | 3 ++-
> >  drivers/iio/light/vcnl4000.c           | 2 +-
> >  drivers/iio/light/vcnl4035.c           | 3 ++-
> >  drivers/iio/magnetometer/rm3100-core.c | 3 ++-
> >  drivers/iio/proximity/isl29501.c       | 2 +-
> >  8 files changed, 14 insertions(+), 9 deletions(-)
> > 
> > --
> > 2.32.0  
> 
> LGTM. For the whole series:
> 
> Reviewed-by: Nuno Sá <[e-mail]>
Thanks!

Given how long they've been sitting around on list...

Applied to the togreg branch of iio.git and pushed out as testing
for all the normal reasons.

Thanks,

Jonathan

> 
> - Nuno Sá