[PATCH v3] RISC-V: enable XIP

[Bin Meng]

Hi Vitaly,

On Tue, Dec 22, 2020 at 4:39 AM Vitaly Wool <vitaly.wool at konsulko.com> wrote:
>
> Introduce XIP (eXecute In Place) support for RISC-V platforms.
> It allows code to be executed directly from non-volatile storage
> directly addressable by the CPU, such as QSPI NOR flash which can
> be found on many RISC-V platforms. This makes way for significant
> optimization of RAM footprint. The XIP kernel is not compressed
> since it has to run directly from flash, so it will occupy more
> space on the non-volatile storage to The physical flash address
> used to link the kernel object files and for storing it has to
> be known at compile time and is represented by a Kconfig option.
>
> XIP on RISC-V will currently only work on MMU-enabled kernels.
>
> Changed in v2:
> - dedicated macro for XIP address fixup when MMU is not enabled yet
>   o both for 32-bit and 64-bit RISC-V
> - SP is explicitly set to a safe place in RAM before __copy_data call
> - removed redundant alignment requirements in vmlinux-xip.lds.S
> - changed long -> uintptr_t typecast in __XIP_FIXUP macro.
>
> Changed in v3:
> - rebased against latest for-next
> - XIP address fixup macro now takes an argument
> - SMP related fixes

The above changelogs should go below ---

> Signed-off-by: Vitaly Wool <vitaly.wool at konsulko.com>
> ---
>  arch/riscv/Kconfig                  |  46 ++++++++-
>  arch/riscv/Makefile                 |   8 +-
>  arch/riscv/boot/Makefile            |  13 +++
>  arch/riscv/include/asm/pgtable.h    |  56 +++++++++--
>  arch/riscv/kernel/cpu_ops_sbi.c     |   3 +
>  arch/riscv/kernel/head.S            |  69 +++++++++++++-
>  arch/riscv/kernel/head.h            |   3 +
>  arch/riscv/kernel/setup.c           |   8 +-
>  arch/riscv/kernel/vmlinux-xip.lds.S | 132 ++++++++++++++++++++++++++
>  arch/riscv/kernel/vmlinux.lds.S     |   6 ++
>  arch/riscv/mm/init.c                | 142 +++++++++++++++++++++++++---
>  11 files changed, 460 insertions(+), 26 deletions(-)
>  create mode 100644 arch/riscv/kernel/vmlinux-xip.lds.S
>

Regards,
Bin