Re: [PATCH 02/12] tpm: move buffer handling from static inlines to real functions

[Jarkko Sakkinen <jarkko@kernel.org>]

On Thu, Feb 16, 2023 at 03:14:00PM -0500, James Bottomley wrote:
> separate out the tpm_buf_... handling functions from static inlines in
> tpm.h and move them to their own tpm-buf.c file.  This is a precursor
> to adding new functions for other TPM type handling because the amount
> of code will grow from the current 70 lines in tpm.h to about 200
> lines when the additions are done.  200 lines of inline functions is a
> bit too much to keep in a header file.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> 
> ---
> v3: make tpm_buf_tag static
> ---
>  drivers/char/tpm/Makefile  |  1 +
>  drivers/char/tpm/tpm-buf.c | 95 ++++++++++++++++++++++++++++++++++++++
>  include/linux/tpm.h        | 86 ++++------------------------------
>  3 files changed, 105 insertions(+), 77 deletions(-)
>  create mode 100644 drivers/char/tpm/tpm-buf.c
> 
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 0222b1ddb310..ad3594e383e1 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -15,6 +15,7 @@ tpm-y += tpm-sysfs.o
>  tpm-y += eventlog/common.o
>  tpm-y += eventlog/tpm1.o
>  tpm-y += eventlog/tpm2.o
> +tpm-y += tpm-buf.o
>  
>  tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o
>  tpm-$(CONFIG_EFI) += eventlog/efi.o
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> new file mode 100644
> index 000000000000..ca59b92e0f95
> --- /dev/null
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0
> +

This empty line should be removed.

> +/*
> + * Handing for tpm_buf structures to facilitate the building of commands
> + */
> +
> +#include <linux/module.h>
> +#include <linux/tpm.h>
> +

Now that symbols are compiled and also exported, it would be good to add
also kdoc's while at it, e.g.

/*
 * tpm_buf_init - Init a buffer for a TPM command
 * @buf:        uninitialized buffer
 * @tag:        tag of a TPM command
 * @ordinal:    number of a TPM command
 *
 * Allocate a page sized buffer from heap for a TPM command, and initialize
 * the command header.
 */

It is probably better to have an additional patch for this, as this one
should just move code around.

> +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
> +{
> +	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
> +	if (!buf->data)
> +		return -ENOMEM;
> +
> +	buf->flags = 0;
> +	tpm_buf_reset(buf, tag, ordinal);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_init);
> +
> +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)

Ditto.

I guess you can fill these out. I just put an example to give a rough
idea what to put.

> +{
> +	struct tpm_header *head = (struct tpm_header *) buf->data;
> +
> +	head->tag = cpu_to_be16(tag);
> +	head->length = cpu_to_be32(sizeof(*head));
> +	head->ordinal = cpu_to_be32(ordinal);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_reset);
> +
> +void tpm_buf_destroy(struct tpm_buf *buf)

Ditto.

> +{
> +	free_page((unsigned long)buf->data);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_destroy);
> +
> +u32 tpm_buf_length(struct tpm_buf *buf)

Ditto.

> +{
> +	struct tpm_header *head = (struct tpm_header *)buf->data;
> +
> +	return be32_to_cpu(head->length);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_length);
> +
> +static u16 tpm_buf_tag(struct tpm_buf *buf)

Ditto.

> +{
> +	struct tpm_header *head = (struct tpm_header *)buf->data;
> +
> +	return be16_to_cpu(head->tag);
> +}
> +
> +void tpm_buf_append(struct tpm_buf *buf,
> +		    const unsigned char *new_data,
> +		    unsigned int new_len)
> +{
> +	struct tpm_header *head = (struct tpm_header *) buf->data;
> +	u32 len = tpm_buf_length(buf);
> +
> +	/* Return silently if overflow has already happened. */
> +	if (buf->flags & TPM_BUF_OVERFLOW)
> +		return;
> +
> +	if ((len + new_len) > PAGE_SIZE) {
> +		WARN(1, "tpm_buf: overflow\n");
> +		buf->flags |= TPM_BUF_OVERFLOW;
> +		return;
> +	}
> +
> +	memcpy(&buf->data[len], new_data, new_len);
> +	head->length = cpu_to_be32(len + new_len);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_append);
> +
> +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)

Ditto.

> +{
> +	tpm_buf_append(buf, &value, 1);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_append_u8);
> +
> +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)

Ditto.

> +{
> +	__be16 value2 = cpu_to_be16(value);
> +
> +	tpm_buf_append(buf, (u8 *) &value2, 2);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_append_u16);
> +
> +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)

Ditto.

> +{
> +	__be32 value2 = cpu_to_be32(value);
> +
> +	tpm_buf_append(buf, (u8 *) &value2, 4);
> +}
> +EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index dfeb25a0362d..150b39b6190e 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -322,84 +322,16 @@ struct tpm2_hash {
>  	unsigned int tpm_id;
>  };
>  
> -static inline void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
> -{
> -	struct tpm_header *head = (struct tpm_header *)buf->data;
> -
> -	head->tag = cpu_to_be16(tag);
> -	head->length = cpu_to_be32(sizeof(*head));
> -	head->ordinal = cpu_to_be32(ordinal);
> -}
> -
> -static inline int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
> -{
> -	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
> -	if (!buf->data)
> -		return -ENOMEM;
> -
> -	buf->flags = 0;
> -	tpm_buf_reset(buf, tag, ordinal);
> -	return 0;
> -}
> -
> -static inline void tpm_buf_destroy(struct tpm_buf *buf)
> -{
> -	free_page((unsigned long)buf->data);
> -}
> -
> -static inline u32 tpm_buf_length(struct tpm_buf *buf)
> -{
> -	struct tpm_header *head = (struct tpm_header *)buf->data;
> -
> -	return be32_to_cpu(head->length);
> -}
> -
> -static inline u16 tpm_buf_tag(struct tpm_buf *buf)
> -{
> -	struct tpm_header *head = (struct tpm_header *)buf->data;
> -
> -	return be16_to_cpu(head->tag);
> -}
> -
> -static inline void tpm_buf_append(struct tpm_buf *buf,
> -				  const unsigned char *new_data,
> -				  unsigned int new_len)
> -{
> -	struct tpm_header *head = (struct tpm_header *)buf->data;
> -	u32 len = tpm_buf_length(buf);
> -
> -	/* Return silently if overflow has already happened. */
> -	if (buf->flags & TPM_BUF_OVERFLOW)
> -		return;
> -
> -	if ((len + new_len) > PAGE_SIZE) {
> -		WARN(1, "tpm_buf: overflow\n");
> -		buf->flags |= TPM_BUF_OVERFLOW;
> -		return;
> -	}
>  
> -	memcpy(&buf->data[len], new_data, new_len);
> -	head->length = cpu_to_be32(len + new_len);
> -}
> -
> -static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)
> -{
> -	tpm_buf_append(buf, &value, 1);
> -}
> -
> -static inline void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)
> -{
> -	__be16 value2 = cpu_to_be16(value);
> -
> -	tpm_buf_append(buf, (u8 *) &value2, 2);
> -}
> -
> -static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
> -{
> -	__be32 value2 = cpu_to_be32(value);
> -
> -	tpm_buf_append(buf, (u8 *) &value2, 4);
> -}
> +int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
> +void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
> +void tpm_buf_destroy(struct tpm_buf *buf);
> +u32 tpm_buf_length(struct tpm_buf *buf);
> +void tpm_buf_append(struct tpm_buf *buf, const unsigned char *new_data,
> +		    unsigned int new_len);
> +void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
> +void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value);
> +void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
>  
>  /*
>   * Check if TPM device is in the firmware upgrade mode.
> -- 
> 2.35.3
> 

Since you are now moving things around, I think we should make best of it.

I'd consider a subsequent patch after this to further clean up the flow:

struct tpm_buf *tpm_buf_init(u16 tag, u32 ordinal)
{
        struct tpm_buf *buf;

        buf = kzalloc(sizeof(*buf), GFP_KERNEL);
        if (!buf)
                goto err_alloc_buf;

	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
	if (!buf->data)
                goto err_alloc_page;

	buf->flags = 0;
	tpm_buf_reset(buf, tag, ordinal);

	return 0;
        
err_alloc_page:
        kfree(buf);

err_alloc_buf:
        return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(tpm_buf_init);

void tpm_buf_destroy(struct tpm_buf *buf)
{
	free_page((unsigned long)buf->data);
        kfree(buf);
}

There is 28 call sites for tpm_buf_init() buf the change is
fairly trival as tpm_buf_destroy() calls can stay as they are.

BR, Jarkko