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? /Jarkko
