Corrupt SV32 page table generation in the function setup_vm about riscv-linux

[aswaterman]

Thanks, Sebastian. Can you verify that 26e4369 works correctly for RV32?

[s-macke]

The patch is almost fine except that the PMD_SIZE is defined in asm-generic/pgtable-nopmd.h if no pmd is present. That was the main problem with the code. The code compiled and ran on 32-Bit but lead to a corrupt pagetable. The correct way is to use __PAGETABLE_PMD_FOLDED. This define is also used in arch/riscv/include/asm/pgalloc.h

index b7981d7065ea..2a6ce882081a 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -91,7 +91,7 @@ asmlinkage void __init setup_vm(void)
        BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
        BUG_ON((pa % (PAGE_SIZE * PTRS_PER_PTE)) != 0);

-#ifdef PMD_SIZE
+#ifndef __PAGETABLE_PMD_FOLDED
        trampoline_pg_dir[(PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD] =
                pfn_pgd(PFN_DOWN((uintptr_t)trampoline_pmd),
                        __pgprot(_PAGE_TABLE));

[aswaterman]

Ah, thanks, fixed in 8fa2c8f.