[PATCH v7] Add support for stack-protector

[Alex Sadovsky]

Dear Joel,

> Add support for stack protector for UBOOT, SPL, and TPL
> as well as new pytest for stackprotector
>
> Signed-off-by: Joel Peshkin <joel.peshkin at broadcom.com>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
>
> Changes for v7:
>    - Fix commit message
>    - add __builtin_extract_return_addr() calls
> Changes for v6:
>    - Fix commit message
> Changes for v5:
>    - Rebase
> Changes for v4:
>    - Exclude EFI from stackprotector
>    - Cleanups of extra includes and declaration
> Changes for v3:
>    - Move test command to cmd/
>    - Update Kconfig names and depends
>    - clean up default canary initialization
> Changes for v2:
>    - Add test command and corresponding config
>    - Fixed incorrect description in Kconfig
>    - Add unit test
> ---
> ---

Patch changelog is not a part of commit message, it's placed below the '---' mark. I hope this guide will help you:
https://www.denx.de/wiki/view/U-Boot/Patches#Sending_updated_patch_versions

> [...]
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +unsigned long __stack_chk_guard = (long)(0xfeedf00ddeadbeef & ~0L);

'long' and 'unsigned long' are slightly different types. I suggest you the following form (please, note the UL instead of L):

unsigned long __stack_chk_guard = (unsigned long)(0xfeedf00ddeadbeef & ~0UL)

Else gcc will complain like this:

> warning: unsigned conversion from ‘long int’ to ‘long long unsigned int’ changes value from ‘-1’ to ‘18446744073709551615’ [-Wsign-conversion]
> unsigned long __stack_chk_guard = (long)(0xfeedf00ddeadbeef & ~0L);
> warning: unsigned conversion from ‘long int’ to ‘long unsigned int’ changes value from ‘-559038737’ to ‘3735928559’ [-Wsign-conversion]

I hope you'll find -Wconversion compiler flag useful, it's one of the flags that often help me to spot some corner cases with potential bugs. IMHO it should be enabled by default.