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RISC-V: relocate DTB if it's outside memory region

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In case the DTB provided by the bootloader/BootROM is before the kernel
image or outside /memory, we won't be able to access it through the
linear mapping, and get a segfault on setup_arch(). Currently OpenSBI
relocates DTB but that's not always the case (e.g. if FW_JUMP_FDT_ADDR
is not specified), and it's also not the most portable approach since
the default FW_JUMP_FDT_ADDR of the generic platform relocates the DTB
at a specific offset that may not be available. To avoid this situation
copy DTB so that it's visible through the linear mapping.

Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
Link: https://lore.kernel.org/r/20220322132839.3653682-1-mick@ics.forth.gr
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Fixes: f105aa940e ("riscv: add BUILTIN_DTB support for MMU-enabled targets")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Nick Kossifidis 2022-03-22 15:28:39 +02:00 committed by Palmer Dabbelt
parent ac0280a9ca
commit c6fe81191b
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1 changed files with 19 additions and 2 deletions
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21
arch/riscv/mm/init.c
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@ -208,8 +208,25 @@ static void __init setup_bootmem(void)
* early_init_fdt_reserve_self() since __pa() does
* not work for DTB pointers that are fixmap addresses
*/
if (!IS_ENABLED(CONFIG_BUILTIN_DTB))
memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
if (!IS_ENABLED(CONFIG_BUILTIN_DTB)) {
/*
* In case the DTB is not located in a memory region we won't
* be able to locate it later on via the linear mapping and
* get a segfault when accessing it via __va(dtb_early_pa).
* To avoid this situation copy DTB to a memory region.
* Note that memblock_phys_alloc will also reserve DTB region.
*/
if (!memblock_is_memory(dtb_early_pa)) {
size_t fdt_size = fdt_totalsize(dtb_early_va);
phys_addr_t new_dtb_early_pa = memblock_phys_alloc(fdt_size, PAGE_SIZE);
void *new_dtb_early_va = early_memremap(new_dtb_early_pa, fdt_size);
memcpy(new_dtb_early_va, dtb_early_va, fdt_size);
early_memunmap(new_dtb_early_va, fdt_size);
_dtb_early_pa = new_dtb_early_pa;
} else
memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va));
}
early_init_fdt_scan_reserved_mem();
dma_contiguous_reserve(dma32_phys_limit);