linux-kernel - Re: [PATCH] tpm: Add reserved memory event log

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Message-ID: <Y8T0VxQiCQH5sDEs@kernel.org>
Date:   Mon, 16 Jan 2023 08:53:11 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jgg@...pe.ca, peterhuewe@....de, joel@....id.au
Subject: Re: [PATCH] tpm: Add reserved memory event log

On Tue, Jan 03, 2023 at 10:20:10AM -0600, Eddie James wrote:
> Some platforms may desire to pass the event log up to linux in the
> form of a reserved memory region. Add support for this in the TPM
> core to find the reserved memory region and map it.
> 
> Signed-off-by: Eddie James <eajames@...ux.ibm.com>

Which platforms? 

I do not see information of 

+	void (*release)(void *ptr);

in the commit message. The description of the implemenation approach is
missing.


> ---
>  drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
>  drivers/char/tpm/tpm-chip.c    |  3 ++-
>  include/linux/tpm.h            |  1 +
>  3 files changed, 40 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
> index a9ce66d09a75..0455d7f61c10 100644
> --- a/drivers/char/tpm/eventlog/of.c
> +++ b/drivers/char/tpm/eventlog/of.c
> @@ -11,12 +11,48 @@
>   */
>  
>  #include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/tpm_eventlog.h>
>  
>  #include "../tpm.h"
>  #include "common.h"
>  
> +static int tpm_read_log_memory_region(struct tpm_chip *chip)
> +{
> +	struct device_node *node;
> +	struct resource res;
> +	int rc;
> +
> +	node = of_parse_phandle(chip->dev.parent->of_node, "memory-region", 0);
> +	if (!node) {
> +		dev_info(&chip->dev, "no phandle\n");
> +		return -ENODEV;
> +	}
> +
> +	rc = of_address_to_resource(node, 0, &res);
> +	of_node_put(node);
> +	if (rc) {
> +		dev_info(&chip->dev, "no mem\n");
> +		return rc;
> +	}
> +
> +	chip->log.bios_event_log = memremap(res.start, resource_size(&res), MEMREMAP_WB);
> +	if (!chip->log.bios_event_log) {
> +		dev_info(&chip->dev, "err memremap\n");
> +		return -ENOMEM;
> +	}
> +
> +	chip->log.release = memunmap;
> +	chip->log.bios_event_log_end = chip->log.bios_event_log + resource_size(&res);
> +
> +	return chip->flags & TPM_CHIP_FLAG_TPM2 ? EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 :
> +		EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> +}

We do not want to support TPM 1.2 for new features.

> +
>  int tpm_read_log_of(struct tpm_chip *chip)
>  {
>  	struct device_node *np;
> @@ -38,7 +74,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	sizep = of_get_property(np, "linux,sml-size", NULL);
>  	basep = of_get_property(np, "linux,sml-base", NULL);
>  	if (sizep == NULL && basep == NULL)
> -		return -ENODEV;
> +		return tpm_read_log_memory_region(chip);
>  	if (sizep == NULL || basep == NULL)
>  		return -EIO;
>  
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 741d8f3e8fb3..09ea8145d7c6 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -267,7 +267,7 @@ static void tpm_dev_release(struct device *dev)
>  	idr_remove(&dev_nums_idr, chip->dev_num);
>  	mutex_unlock(&idr_lock);
>  
> -	kfree(chip->log.bios_event_log);
> +	chip->log.release(chip->log.bios_event_log);
>  	kfree(chip->work_space.context_buf);
>  	kfree(chip->work_space.session_buf);
>  	kfree(chip->allocated_banks);
> @@ -324,6 +324,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>  	init_rwsem(&chip->ops_sem);
>  
>  	chip->ops = ops;
> +	chip->log.release = (void(*)(void *))kfree;

Why do you need this cast?

>  
>  	mutex_lock(&idr_lock);
>  	rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index dfeb25a0362d..f1c0b0eb20a5 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -109,6 +109,7 @@ struct tpm_space {
>  struct tpm_bios_log {
>  	void *bios_event_log;
>  	void *bios_event_log_end;
> +	void (*release)(void *ptr);
>  };
>  
>  struct tpm_chip_seqops {
> -- 
> 2.31.1
> 

BR, Jarkko