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riscv: compat: Support TASK_SIZE for compat mode

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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>
This commit is contained in:
Guo Ren 2022-04-05 15:13:04 +08:00 committed by Palmer Dabbelt
parent 06d0e37236
commit 01abdfeac8
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GPG Key ID: 2E1319F35FBB1889
2 changed files with 16 additions and 3 deletions
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13
arch/riscv/include/asm/pgtable.h
View File

@ -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

6
arch/riscv/include/asm/processor.h
View File

@ -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__