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| author | Anup Patel <anup.patel@wdc.com> | 2020-09-17 15:37:10 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-10-02 14:30:57 -0700 |
| commit | 8f3a2b4a96dc014e99e1df327db1450fdbbd5e15 (patch) | |
| tree | 5d1bcde041ee3609ec8e1e7081cbd76bf5574f32 /arch/riscv/mm | |
| parent | 8a3f30c4319dc70547f11c18da2e7b5987543aa1 (diff) | |
| download | linux-8f3a2b4a96dc014e99e1df327db1450fdbbd5e15.tar.bz2 | |
RISC-V: Move DT mapping outof fixmap
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>
Diffstat (limited to 'arch/riscv/mm')
| -rw-r--r-- | arch/riscv/mm/init.c | 26 |
1 files changed, 12 insertions, 14 deletions
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 787c75f751a5..2b651f63f5c4 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -28,7 +28,9 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] EXPORT_SYMBOL(empty_zero_page); extern char _start[]; -void *dtb_early_va; +#define DTB_EARLY_BASE_VA PGDIR_SIZE +void *dtb_early_va __initdata; +uintptr_t dtb_early_pa __initdata; static void __init zone_sizes_init(void) { @@ -141,8 +143,6 @@ disable: } #endif /* CONFIG_BLK_DEV_INITRD */ -static phys_addr_t dtb_early_pa __initdata; - void __init setup_bootmem(void) { struct memblock_region *reg; @@ -399,7 +399,7 @@ static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size) asmlinkage void __init setup_vm(uintptr_t dtb_pa) { - uintptr_t va, end_va; + uintptr_t va, pa, end_va; uintptr_t load_pa = (uintptr_t)(&_start); uintptr_t load_sz = (uintptr_t)(&_end) - load_pa; uintptr_t map_size = best_map_size(load_pa, MAX_EARLY_MAPPING_SIZE); @@ -448,16 +448,13 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) load_pa + (va - PAGE_OFFSET), map_size, PAGE_KERNEL_EXEC); - /* Create fixed mapping for early FDT parsing */ - end_va = __fix_to_virt(FIX_FDT) + FIX_FDT_SIZE; - for (va = __fix_to_virt(FIX_FDT); va < end_va; va += PAGE_SIZE) - create_pte_mapping(fixmap_pte, va, - dtb_pa + (va - __fix_to_virt(FIX_FDT)), - PAGE_SIZE, PAGE_KERNEL); - - /* Save pointer to DTB for early FDT parsing */ - dtb_early_va = (void *)fix_to_virt(FIX_FDT) + (dtb_pa & ~PAGE_MASK); - /* Save physical address for memblock reservation */ + /* Create two consecutive PGD mappings for FDT early scan */ + pa = dtb_pa & ~(PGDIR_SIZE - 1); + create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA, + pa, PGDIR_SIZE, PAGE_KERNEL); + create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA + PGDIR_SIZE, + pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL); + dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1)); dtb_early_pa = dtb_pa; } @@ -516,6 +513,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) #else dtb_early_va = (void *)dtb_pa; #endif + dtb_early_pa = dtb_pa; } static inline void setup_vm_final(void) |