Messages in this thread | | | Date | Wed, 23 Mar 2022 17:21:51 +0000 | Subject | Re: [PATCH] RISC-V-fixes: relocate DTB if it's outside memory region | From | Conor Dooley <> |
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On 22/03/2022 13:28, Nick Kossifidis wrote: > 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.
Ran into the same issue & have been carrying a hack for it, this looks *a lot* cleaner. I'll dig out the offending configuration tomorrow and try to give you a tested-by. Thanks, Conor.
> > Signed-off-by: Nick Kossifidis <mick@ics.forth.gr> > --- > arch/riscv/mm/init.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 0d588032d..697a9aed4 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -206,8 +206,25 @@ 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);
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