Unverified Commit 9be84592 authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

riscv: compat: Add COMPAT Kbuild skeletal support 



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: 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/20220405071314.3225832-21-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 4608c159

arch/riscv/Kconfig

+19 −0
Original line number Diff line number Diff line
@@ -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



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