[SeaBIOS] [PATCH v10 3/6] Support for BIOS interrupt handler

[Kevin O'Connor]

On Mon, Mar 23, 2015 at 02:22:17PM -0400, Stefan Berger wrote:
> This patch implements the TCG BIOS interrupt handler 1ah. It is for
> example used by trusted grub.
> 
> This patch adds an implementation of SHA1 (following NIST specs., IETF RFC 3147
> and Wikipedia) for speeding up measurements of code. Trusted Grub for example
> makes use of this interface and measures (calculates SHA1) of the Linux kernel
> and initrd. Those files can be rather large and hunting their bytes through
> the TIS interface as part of the int handler commands invoked by trusted grub
> does take quite some time due to the many vmexits the interface is creating
> (one per byte).
> 
> There is also a threshold for the size of data to hash (100k) below which
> the TPM is used and above the internal faster SHA1 algorithm is used.
> 
> This patch for example enables trusted grub to interact with the TPM
> and take additional measurements.
[...]
> --- /dev/null
> +++ b/src/sha1.c
> @@ -0,0 +1,145 @@
> +//  Support for Calculation of SHA1 in SW
> +//
> +//  Copyright (C) 2006-2011 IBM Corporation
> +//
> +//  Authors:
> +//      Stefan Berger <stefanb at linux.vnet.ibm.com>
> +//
> +//  See: http://www.itl.nist.gov/fipspubs/fip180-1.htm
> +//       RFC3174, Wikipedia's SHA1 alogrithm description
> +//

This file needs an LGPLv3 license statement.

[...]
> --- a/src/x86.h
> +++ b/src/x86.h
> @@ -129,6 +129,13 @@ static inline u32 getesp(void) {
>      return esp;
>  }
>  
> +static inline u32 rol(u32 val, u16 rol) {
> +    u32 res;
> +    asm volatile("rol %%cl, %%eax"
> +                 : "=a" (res) : "a" (val), "c" (rol));
> +    return res;
> +}

Because of the mixed 16bit/32bit code in SeaBIOS, all assembler must
use size suffixes - so the above should be "roll" instead of "rol".

As before - both issues are minor and can be addressed after merge (as
long as there is agreement that the sha1.c file can be licensed as
LGPLv3).

-Kevin