diff options
| author | Palmer Dabbelt <palmer@sifive.com> | 2019-03-26 17:40:24 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@sifive.com> | 2019-05-16 20:42:13 -0700 |
| commit | 4c3aeb82a0f4612bf0d94fbf74c3738db2c32fe5 (patch) | |
| tree | 3a20f1f44c668fe3118550c2bb0a319ba8b9da96 /arch | |
| parent | 9a6e7af02f7fcc8c68e9d6ce167ee6ab0052cb60 (diff) | |
RISC-V: Avoid using invalid intermediate translations
This is almost entirely a comment.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/riscv/kernel/head.S | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index 987d4648aad9..370c66ce187a 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -96,7 +96,9 @@ relocate: /* * Load trampoline page directory, which will cause us to trap to - * stvec if VA != PA, or simply fall through if VA == PA + * stvec if VA != PA, or simply fall through if VA == PA. We need a + * full fence here because setup_vm() just wrote these PTEs and we need + * to ensure the new translations are in use. */ la a0, trampoline_pg_dir srl a0, a0, PAGE_SHIFT @@ -115,8 +117,14 @@ relocate: la gp, __global_pointer$ .option pop - /* Switch to kernel page tables */ + /* + * Switch to kernel page tables. A full fence is necessary in order to + * avoid using the trampoline translations, which are only correct for + * the first superpage. Fetching the fence is guarnteed to work + * because that first superpage is translated the same way. + */ csrw CSR_SATP, a2 + sfence.vma ret |