riscv: Don't use PGD entries for the linear mapping

Propagating changes at this level is cumbersome as we need to go through
all the page tables when that happens (either when changing the
permissions or when splitting the mapping).

Note that this prevents the use of 4MB mapping for sv32 and 1GB mapping for
sv39 in the linear mapping.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20231108075930.7157-2-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
[backport of the commit 629db01c64ff6cea08fc61b52426362689ef8618 from mainline]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Change-Id: I4b122a6d6e66d5454be7596746957942b3df01e8

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index ec02ea86aa39fa3be6ec9bde87784cc583cda3c2..5f136be9a390a9afd6fdfcc69a658c72c9e2dde8 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -667,16 +667,16 @@ void __init create_pgd_mapping(pgd_t *pgdp,
 static uintptr_t __init best_map_size(phys_addr_t pa, uintptr_t va,
                                      phys_addr_t size)
 {
-       if (!(pa & (PGDIR_SIZE - 1)) && !(va & (PGDIR_SIZE - 1)) && size >= PGDIR_SIZE)
-               return PGDIR_SIZE;
-
-       if (!(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
+       if (pgtable_l5_enabled &&
+           !(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
                return P4D_SIZE;
 
-       if (!(pa & (PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
+       if (pgtable_l4_enabled &&
+           !(pa & (PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
                return PUD_SIZE;
 
-       if (!(pa & (PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
+       if (IS_ENABLED(CONFIG_64BIT) &&
+           !(pa & (PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
                return PMD_SIZE;
 
        return PAGE_SIZE;