On Fri, Jul 02, 2021 at 11:42:39AM +0300, Jarkko Sakkinen wrote: > 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? What you should do, is to define two fields: - tpm_timeout_min - tpm_timeout_max And initialize these to TPM_TIMEOUT_USECS_MIN and TPM_TIMEOUT_USECS_MAX. Then fixup those for Atmel (with a simple if-statement, switch-case is overkill). The way you work out things right now is broken: 1. Before for non-Atmel: usleep_range(100, 500) 2. After for non-Atmel: usleep_range(200, 500) I.e. the patch changes code semantically that it should not touch in the first place. /Jarkko
