[PATCH v2 1/1] riscv: restore global data pointer in trap handler

[Heinrich Schuchardt]

On 28.09.20 09:45, Rick Chen wrote:
>> From: Heinrich Schuchardt [mailto:xypron.glpk at gmx.de]
>> Sent: Sunday, September 27, 2020 4:24 PM
>> To: Rick Jian-Zhi Chen(陳建志)
>> Cc: Simon Glass; Sean Anderson; Bin Meng; u-boot at lists.denx.de; Alexander Graf; Abner Chang; Heinrich Schuchardt
>> Subject: [PATCH v2 1/1] riscv: restore global data pointer in trap handler
>>
>> The gp register is used to store U-Boot's global data pointer. We should
>> not assume that an UEFI application leaves the gp register unchanged as
>> the UEFI specifications does not define who is the owner of the gp and tp
>> registers.
>>
>> So the following sequence should be followed in the trap handler:
>>
>> * save the caller's gp register
>> * restore the global data pointer
>> * serve interrupts or print crash dump and reset
>> * restore the caller's gp register
>>
>> Cc: Abner Chang <abner.chang at hpe.com>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>> v2:
>>         Saving and restoring the caller's x3 is already handled in mtrap.S.
>>         efi_loader.h provides an empty fallback efi_restore_gd() function
>>         if CONFIG_EFI_LOADER=n.
>> ---
>>  arch/riscv/lib/interrupts.c | 3 +++
>>  1 file changed, 3 insertions(+)
>
> Reviewed-by: Rick Chen <rick at andestech.com>
>

Hello Rick,

I have two other corrections for the UEFI sub-system and would like to
add this patch to my pull-request for v2020.10. Is that ok with you?

Best regards

Heinrich