Unverified Commit 01abdfea authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

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: default avatarGuo Ren <guoren@linux.alibaba.com>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-11-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 06d0e372

arch/riscv/include/asm/pgtable.h

+11 −2
Original line number Diff line number Diff line
@@ -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_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

arch/riscv/include/asm/processor.h

+5 −1
Original line number Diff line number Diff line
@@ -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__