From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Adds initial skeletal COMPAT Kbuild (Running 32bit U-mode on 64bit S-mode) support. - Setup kconfig & dummy functions for compiling. - Implement compat_start_thread by the way. Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> Tested-by: Heiko Stuebner <heiko@xxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> --- arch/riscv/Kconfig | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 00fd9c548f26..def9798e9675 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -76,6 +76,7 @@ config RISCV select HAVE_ARCH_KGDB if !XIP_KERNEL select HAVE_ARCH_KGDB_QXFER_PKT select HAVE_ARCH_MMAP_RND_BITS if MMU + select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU @@ -127,12 +128,18 @@ config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT default 8 +config ARCH_MMAP_RND_COMPAT_BITS_MIN + default 8 + # max bits determined by the following formula: # VA_BITS - PAGE_SHIFT - 3 config ARCH_MMAP_RND_BITS_MAX default 24 if 64BIT # SV39 based default 17 +config ARCH_MMAP_RND_COMPAT_BITS_MAX + default 17 + # set if we run in machine mode, cleared if we run in supervisor mode config RISCV_M_MODE bool @@ -394,6 +401,18 @@ config CRASH_DUMP For more details see Documentation/admin-guide/kdump/kdump.rst +config COMPAT + bool "Kernel support for 32-bit U-mode" + default 64BIT + depends on 64BIT && MMU + help + This option enables support for a 32-bit U-mode running under a 64-bit + kernel at S-mode. riscv32-specific components such as system calls, + the user helper functions (vdso), signal rt_frame functions and the + ptrace interface are handled appropriately by the kernel. + + If you want to execute 32-bit userspace applications, say Y. + endmenu menu "Boot options" -- 2.25.1
