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. 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 for the time being only work on MMU-enabled
kernels.
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
[Alex: Rebase on top of "Move kernel mapping outside the linear mapping" ]
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
[Palmer: disable XIP for allyesconfig]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Currently, RISC-V reserves 1MB of fixmap memory for device tree. However,
it maps only single PMD (2MB) space for fixmap which leaves only < 1MB space
left for other kernel features such as early ioremap which requires fixmap
as well. The fixmap size can be increased by another 2MB but it brings
additional complexity and changes the virtual memory layout as well.
If we require some additional feature requiring fixmap again, it has to be
moved again.
Technically, DT doesn't need a fixmap as the memory occupied by the DT is
only used during boot. That's why, We map device tree in early page table
using two consecutive PGD mappings at lower addresses (< PAGE_OFFSET).
This frees lot of space in fixmap and also makes maximum supported
device tree size supported as PGDIR_SIZE. Thus, init memory section can be used
for the same purpose as well. This simplifies fixmap implementation.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Add prototypes for assembly language functions defined in head.S,
and include these prototypes into C source files that call those
functions.
This patch resolves the following warnings from sparse:
arch/riscv/kernel/setup.c:39:10: warning: symbol 'hart_lottery' was not declared. Should it be static?
arch/riscv/kernel/setup.c:42:13: warning: symbol 'parse_dtb' was not declared. Should it be static?
arch/riscv/kernel/smpboot.c:33:6: warning: symbol '__cpu_up_stack_pointer' was not declared. Should it be static?
arch/riscv/kernel/smpboot.c:34:6: warning: symbol '__cpu_up_task_pointer' was not declared. Should it be static?
arch/riscv/mm/fault.c:25:17: warning: symbol 'do_page_fault' was not declared. Should it be static?
This change should have no functional impact.
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
