riscv: compat: Support TASK_SIZE for compat mode

Make TASK_SIZE from const to dynamic detect TIF_32BIT flag
function. Refer to arm64 to implement DEFAULT_MAP_WINDOW_64 for
efi-stub.

Limit 32-bit compatible process in 0-2GB virtual address range
(which is enough for real scenarios), because it could avoid
address sign extend problem when 32-bit enter 64-bit and ease
software design.

The standard 32-bit TASK_SIZE is 0x9dc00000:FIXADDR_START, and
compared to a compatible 32-bit, it increases 476MB for the
application's virtual address.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-11-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 046b442256239b05650ef19435de767bfb4eba71..e32d75fef068774a17a36c8d2602d001930c234e 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -707,8 +707,17 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
  * 63–48 all equal to bit 47, or else a page-fault exception will occur."
  */
 #ifdef CONFIG_64BIT
-#define TASK_SIZE      (PGDIR_SIZE * PTRS_PER_PGD / 2)
-#define TASK_SIZE_MIN  (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+#define TASK_SIZE_64   (PGDIR_SIZE * PTRS_PER_PGD / 2)
+#define TASK_SIZE_MIN  (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+
+#ifdef CONFIG_COMPAT
+#define TASK_SIZE_32   (_AC(0x80000000, UL) - PAGE_SIZE)
+#define TASK_SIZE      (test_thread_flag(TIF_32BIT) ? \
+                        TASK_SIZE_32 : TASK_SIZE_64)
+#else
+#define TASK_SIZE      TASK_SIZE_64
+#endif
+
 #else
 #define TASK_SIZE      FIXADDR_START
 #define TASK_SIZE_MIN  TASK_SIZE

diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 0749924d9e552dc26786a9b3be2d44d593d8fc07..21c8072dce17aaf5f818b1fdc6ead92279d60608 100644 (file)
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -19,7 +19,11 @@
 #define TASK_UNMAPPED_BASE     PAGE_ALIGN(TASK_SIZE / 3)
 
 #define STACK_TOP              TASK_SIZE
-#define STACK_TOP_MAX          STACK_TOP
+#ifdef CONFIG_64BIT
+#define STACK_TOP_MAX          TASK_SIZE_64
+#else
+#define STACK_TOP_MAX          TASK_SIZE
+#endif
 #define STACK_ALIGN            16
 
 #ifndef __ASSEMBLY__