Re: [PATCH v6 02/11] DIGEST: NEWS

[Ulf Samuelsson <binutils@emagii.com>]

On 2023-03-01 15:47, Ulf Samuelsson via Binutils wrote:
> From: Ulf Samuelsson <ulf@emagii.com>
>
> Signed-off-by: Ulf Samuelsson <ulf@emagii.com>
> ---
>   ld/NEWS | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>   1 file changed, 76 insertions(+), 4 deletions(-)
>
> diff --git a/ld/NEWS b/ld/NEWS
> index 4b91f2c3b0a..e245d3da4dc 100644
> --- a/ld/NEWS
> +++ b/ld/NEWS
> @@ -1,5 +1,77 @@
>   -*- text -*-
>   
> +* The linker script has a new command to insert a timestamp
> +  TIMESTAMP
> +  inserts the current time (seconds since Epoch) as a 64-bit value
> +
> +* The linker script syntax has new commands for debugging a linker script
> +  DEBUG ON  turns on debugging
> +  DEBUG OFF turns off debugging
> +
> +* The linker script syntax has new commands for handling CRC-32/64 calculations
> +  on the '.text' section
> +  It uses code from https://www.libcrc.org/
> +
> +  DIGEST "<label>[.BE]" "CRC32"              (start, end)
> +  DIGEST "<label>[.BE]" "CRC64-ECMA"         (start, end)
> +  DIGEST "<label>[.BE]" "CRC64-GO-ISO"       (start, end)
> +  DIGEST "<label>[.BE]" "CRC64-GO-ISO-R"     (start, end)
> +  DIGEST "<label>[.BE]" "CRC64-WE"           (start, end)
> +  DIGEST "<label>[.BE]" "CRC64-XZ"           (start, end)
> +  DIGEST "<label>[.BE]"  POLY (<params>)     (start, end)
> +  DIGEST TABLE "<label>[.BE]"
> +  DIGEST SECTION "<section>"
> +
> +  The CRC32, CRC64-ECMA, CRC64-ISO, CRC64-WE and POLY defines
> +  the polynome to use and reserves space for the 32/64-bit CRC in the
> +  current section (default ".text"). It also defines a label "<label>".
> +
> +  When generating a custom polynome you have to supply parameters
> +  in the  following order
> +  * size            {32 | 64 }
> +  * polynome
> +  * initial         initial value of crc
> +  * xor value       xor with this before returning result
> +  * input reflect   bitreverse input data
> +  * output reflect  bitreverse result
> +  * reciprocal      bitreverse polynome
> +
> +  These terms are explained at
> +  http://www.sunshine2k.de/articles/coding/crc/understanding_crc.html
> +
> +  The checksum is generated in little endian format, but this
> +  can be overridden by adding a ".BE" modifier to the label string.
> +  The generated label does not include the modifier.
> +
> +  The user can do the CRC check in another section through the
> +  DIGEST SECTION command by specifying the name of the section.
> +
> +  The 32 bit DIGEST <polynome> command defines some global symbols.
> +  ___CRC32___ is the address of the CRC64 checksum
> +  ___CRC32_START___ is the address where CRC calculation starts
> +  ___CRC32_END___ The CRC calculation ends before this address.
> +
> +  The 64-bit DIGEST <polynome> command defines some global symbols.
> +  ___CRC64___ is the address of the CRC64 checksum
> +  ___CRC64_START___ is the address where CRC calculation starts
> +  ___CRC64_END___ The CRC calculation ends before this address.
> +
> +  All three symbols must refer to addresses in the selected section.
> +  If they are defined at the end of the linking process, then
> +  the CRC## will be calculated between
> +
> +    ___CRC##_START___ .. ___CRC##_END___ -1
> +
> +  and the result will be inserted at ___CRC##___.
> +
> +  ___CRC##___ must be outside the region where CRC is calculated
> +
> +  The DIGEST TABLE command generates a table for CRC generation.
> +  A table is not neccessary, but will speed up the calculation.
> +  It defines the ___CRC##_TABLE___ symbol at the start of the table.
> +  The user may choose to add this table to his code instead of using
> +  the linker.
> +
>   * The linker script syntax has two new commands for inserting text into output
>     sections:
>       ASCII (<size>) "string"'
The stuff below was added unintentionally.

Do not know where is comes from...

Should have done a rebase before sending...

Best Regards
Ulf Samuelsson

> @@ -41,16 +113,16 @@ Changes in 2.39:
>     re-enabled via the --warn-rwx-segments option.
>   
>     New configure options can also control these new features:
> -
> +
>     --enable-warn-execstack=no
>        will disable the warnings about creating an executable stack.
> -
> +
>     --enable-warn-execstack=yes
>        will make --warn-execstack enabled by default.
> -
> +
>     --enable-warn-rwx-segments=no
>        will make --no-warn-rwx-segments enabled by default.
> -
> +
>     --enable-default-execstack=no
>        will stop the creation of an executable stack simply because an input file
>        is missing a .note.GNU-stack section, even on architectures where this