[PATCH V9 10/20] riscv: compat: Re-implement TASK_SIZE for COMPAT_32BIT
From: guoren@kernel.org
Date: 2022-03-22 14:42:24
Also in:
linux-arch, linux-arm-kernel, linux-mips, linux-riscv, linux-s390, lkml, sparclinux
Subsystem:
risc-v architecture, the rest · Maintainers:
Paul Walmsley, Palmer Dabbelt, Albert Ou, Linus Torvalds
From: Guo Ren <redacted> 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 <redacted> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Heiko Stuebner <heiko@sntech.de> --- arch/riscv/include/asm/pgtable.h | 13 +++++++++++-- arch/riscv/include/asm/processor.h | 6 +++++- 2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index e3549e50de95..afdc9ece2ba4 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h@@ -705,8 +705,17 @@ 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 0749924d9e55..21c8072dce17 100644
--- 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__
--
2.25.1