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

[Rick Chen]

Hi Heinrich

> 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?

I am OK with it.

Thanks,
Rick

>
> Best regards
>
> Heinrich