[RFC PATCH v2 05/11] riscv: pgtable: Add custom protection_map init

guoren
2021-06-06T09:05:31Z

From: Guo Ren <guoren@linux.alibaba.com>

Some RISC-V CPU vendors have defined their own PTE attributes to
solve non-coherent DMA bus problems. That makes _P/SXXX definitions
contain global variables which could be initialized at the early
boot stage before setup_vm.

This patch is similar to 316d097c4cd4 (x86/pti: Filter at
vma->vm_page_prot population) which give a choice for arch custom
implementation.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
---
arch/riscv/Kconfig | 4 ++++
arch/riscv/mm/init.c | 22 ++++++++++++++++++++++
mm/mmap.c | 4 ++++
3 files changed, 30 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c5914e7..05c4976 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -25,6 +25,7 @@ config RISCV
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_KCOV
select ARCH_HAS_MMIOWB
+ select ARCH_HAS_PROTECTION_MAP_INIT
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_SET_MEMORY
@@ -198,6 +199,9 @@ config GENERIC_HWEIGHT
config FIX_EARLYCON_MEM
def_bool MMU

+config ARCH_HAS_PROTECTION_MAP_INIT
+ def_bool y
+
config PGTABLE_LEVELS
int
default 3 if 64BIT
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 4faf8bd..4b398c6 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -496,6 +496,26 @@ static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size)
}
#endif

+static void __init setup_protection_map(void)
+{
+ protection_map[0] = __P000;
+ protection_map[1] = __P001;
+ protection_map[2] = __P010;
+ protection_map[3] = __P011;
+ protection_map[4] = __P100;
+ protection_map[5] = __P101;
+ protection_map[6] = __P110;
+ protection_map[7] = __P111;
+ protection_map[8] = __S000;
+ protection_map[9] = __S001;
+ protection_map[10] = __S010;
+ protection_map[11] = __S011;
+ protection_map[12] = __S100;
+ protection_map[13] = __S101;
+ protection_map[14] = __S110;
+ protection_map[15] = __S111;
+}
+
asmlinkage void __init setup_vm(uintptr_t dtb_pa)
{
uintptr_t __maybe_unused pa;
@@ -504,6 +524,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
pmd_t fix_bmap_spmd, fix_bmap_epmd;
#endif

+ setup_protection_map();
+
#ifdef CONFIG_XIP_KERNEL
xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);
diff --git a/mm/mmap.c b/mm/mmap.c
index 0584e54..0a86059 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -100,10 +100,14 @@ static void unmap_region(struct mm_struct *mm,
* w: (no) no
* x: (yes) yes
*/
+#ifdef CONFIG_ARCH_HAS_PROTECTION_MAP_INIT
+pgprot_t protection_map[16] __ro_after_init;
+#else
pgprot_t protection_map[16] __ro_after_init = {
__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
};
+#endif

#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
--
2.7.4