On Fri, Jul 02, 2021 at 12:59:18AM -0700, Hao Wu wrote: > > On Jul 2, 2021, at 12:45 AM, Jarkko Sakkinen <jarkko@xxxxxxxxxx> wrote: > > > > On Fri, Jul 02, 2021 at 12:33:15AM -0700, Hao Wu wrote: > >> > >> > >>> On Jul 1, 2021, at 11:35 PM, Jarkko Sakkinen <jarkko@xxxxxxxxxx> wrote: > >>> > >>> On Tue, Jun 29, 2021 at 09:22:05PM -0700, Hao Wu wrote: > >>>> This is a fix for the ATMEL TPM crash bug reported in > >>>> https://patchwork.kernel.org/project/linux-integrity/patch/20200926223150.109645-1-hao.wu@xxxxxxxxxx/ > >>>> > >>>> According to the discussions in the original thread, > >>>> we don't want to revert the timeout of wait_for_tpm_stat > >>>> for non-ATMEL chips, which brings back the performance cost. > >>>> For investigation and analysis of why wait_for_tpm_stat > >>>> caused the issue, and how the regression was introduced, > >>>> please read the original thread above. > >>>> > >>>> Thus the proposed fix here is to only revert the timeout > >>>> for ATMEL chips by checking the vendor ID. > >>>> > >>>> Signed-off-by: Hao Wu <hao.wu@xxxxxxxxxx> > >>>> Fixes: 9f3fc7bcddcb ("tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers") > >>> > >>> Fixes tag should be before SOB. > >>> > >>>> --- > >>>> Test Plan: > >>>> - Run fixed kernel with ATMEL TPM chips and see crash > >>>> has been fixed. > >>>> - Run fixed kernel with non-ATMEL TPM chips, and confirm > >>>> the timeout has not been changed. > >>>> > >>>> drivers/char/tpm/tpm.h | 9 ++++++++- > >>>> drivers/char/tpm/tpm_tis_core.c | 19 +++++++++++++++++-- > >>>> include/linux/tpm.h | 2 ++ > >>>> 3 files changed, 27 insertions(+), 3 deletions(-) > >>>> > >>>> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > >>>> index 283f78211c3a..bc6aa7f9e119 100644 > >>>> --- a/drivers/char/tpm/tpm.h > >>>> +++ b/drivers/char/tpm/tpm.h > >>>> @@ -42,7 +42,9 @@ enum tpm_timeout { > >>>> TPM_TIMEOUT_RANGE_US = 300, /* usecs */ > >>>> TPM_TIMEOUT_POLL = 1, /* msecs */ > >>>> TPM_TIMEOUT_USECS_MIN = 100, /* usecs */ > >>>> - TPM_TIMEOUT_USECS_MAX = 500 /* usecs */ > >>>> + TPM_TIMEOUT_USECS_MAX = 500, /* usecs */ > >>> > >>> What is this change? > >> Need to add the tailing comma > >> > >>> > >>>> + TPM_TIMEOUT_WAIT_STAT = 500, /* usecs */ > >>>> + TPM_ATML_TIMEOUT_WAIT_STAT = 15000 /* usecs */ > >>>> }; > >>>> > >>>> /* TPM addresses */ > >>>> @@ -189,6 +191,11 @@ static inline void tpm_msleep(unsigned int delay_msec) > >>>> delay_msec * 1000); > >>>> }; > >>>> > >>>> +static inline void tpm_usleep(unsigned int delay_usec) > >>>> +{ > >>>> + usleep_range(delay_usec - TPM_TIMEOUT_RANGE_US, delay_usec); > >>>> +}; > >>> > >>> Please remove this, and open code. > >> Ok, will do > >> > >>>> + > >>>> int tpm_chip_start(struct tpm_chip *chip); > >>>> void tpm_chip_stop(struct tpm_chip *chip); > >>>> struct tpm_chip *tpm_find_get_ops(struct tpm_chip *chip); > >>>> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > >>>> index 55b9d3965ae1..9ddd4edfe1c2 100644 > >>>> --- a/drivers/char/tpm/tpm_tis_core.c > >>>> +++ b/drivers/char/tpm/tpm_tis_core.c > >>>> @@ -80,8 +80,12 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, > >>>> } > >>>> } else { > >>>> do { > >>>> - usleep_range(TPM_TIMEOUT_USECS_MIN, > >>>> - TPM_TIMEOUT_USECS_MAX); > >>>> + if (chip->timeout_wait_stat && > >>>> + chip->timeout_wait_stat >= TPM_TIMEOUT_WAIT_STAT) { > >>>> + tpm_usleep((unsigned int)(chip->timeout_wait_stat)); > >>>> + } else { > >>>> + tpm_usleep((unsigned int)(TPM_TIMEOUT_WAIT_STAT)); > >>>> + } > >>> > >>> Invalid use of braces. Please read > >>> > >>> https://www.kernel.org/doc/html/v5.13/process/coding-style.html > >>> > >>> Why do you have to use this field conditionally anyway? Why doesn't > >>> it always contain a legit value? > >> The field is legit now, but doesn’t hurt to do addition check for robustness > >> to ensure no crash ? Just in case the value is updated below TPM_TIMEOUT_WAIT_STAT ? > >> > >> Can remove if we think it is not needed. > > > > A simple question: why you use it conditionally? Can the field contain invalid value? > > > There are two checks > - chip->timeout_wait_stat >= TPM_TIMEOUT_WAIT_STAT > It could be invalid when future developer set it to some value less than `TPM_TIMEOUT_USECS_MIN`, > and crash the usleep I don't understand this. Why you don't set to appropriate value? /Jarkko
