From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Adds initial skeletal COMPAT Kbuild (Runing 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>
---
arch/riscv/Kconfig | 22 ++++++++++++++++++++++
arch/riscv/include/asm/elf.h | 8 ++++++++
arch/riscv/include/asm/processor.h | 3 +++
arch/riscv/kernel/Makefile | 2 ++
arch/riscv/kernel/compat_signal.c | 18 ++++++++++++++++++
arch/riscv/kernel/process.c | 10 ++++++++++
arch/riscv/kernel/ptrace.c | 9 +++++++++
arch/riscv/kernel/vdso.c | 8 ++++++++
8 files changed, 80 insertions(+)
create mode 100644 arch/riscv/kernel/compat_signal.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 821252b65f89..6c3515a492a8 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -72,6 +72,7 @@ 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
@@ -122,12 +123,18 @@ 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
@@ -427,6 +434,21 @@ config CRASH_DUMP
For more details see Documentation/admin-guide/kdump/kdump.rst
+config COMPAT
+ bool "Kernel support for 32-bit U-mode"
+ 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.
+
+config SYSVIPC_COMPAT
+ def_bool y
+ depends on COMPAT && SYSVIPC
+
endmenu
menu "Boot options"
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index 48c116f3c12d..37f1cbdaa242 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -129,5 +129,13 @@ do { if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
typedef compat_ulong_t compat_elf_greg_t;
typedef compat_elf_greg_t compat_elf_gregset_t[ELF_NGREG];
+#define compat_start_thread compat_start_thread
+
+
+extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+ int uses_interp);
+#define compat_arch_setup_additional_pages \
+ compat_arch_setup_additional_pages
+
#endif /* CONFIG_COMPAT */
#endif /* _ASM_RISCV_ELF_H */
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 8649436b8fcf..9544c138d9ce 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -62,6 +62,9 @@ extern void start_thread(struct pt_regs *regs,
unsigned long pc, unsigned long sp);
#ifdef CONFIG_COMPAT
+extern void compat_start_thread(struct pt_regs *regs,
+ unsigned long pc, unsigned long sp);
+
#define DEFAULT_MAP_WINDOW_64 TASK_SIZE_64
#else
#define DEFAULT_MAP_WINDOW_64 TASK_SIZE
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 3397ddac1a30..f83e22affd5f 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -65,3 +65,5 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
obj-$(CONFIG_EFI) += efi.o
+obj-$(CONFIG_COMPAT) += compat_syscall_table.o
+obj-$(CONFIG_COMPAT) += compat_signal.o
diff --git a/arch/riscv/kernel/compat_signal.c b/arch/riscv/kernel/compat_signal.c
new file mode 100644
index 000000000000..1ad3d348f37c
--- /dev/null
+++ b/arch/riscv/kernel/compat_signal.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/compat.h>
+#include <linux/signal.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/tracehook.h>
+#include <linux/linkage.h>
+
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+#include <asm/switch_to.h>
+#include <asm/csr.h>
+
+COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
+{
+ return 0;
+}
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 03ac3aa611f5..9ebf9a95e5ea 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -15,6 +15,7 @@
#include <linux/tick.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
+#include <uapi/linux/elf.h>
#include <asm/unistd.h>
#include <asm/processor.h>
@@ -99,6 +100,15 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
regs->sp = sp;
}
+#ifdef CONFIG_COMPAT
+void compat_start_thread(struct pt_regs *regs, unsigned long pc,
+ unsigned long sp)
+{
+ start_thread(regs, pc, sp);
+ regs->status |= SR_UXL_32;
+}
+#endif
+
void flush_thread(void)
{
#ifdef CONFIG_FPU
diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
index 9c0511119bad..55dd50f8a5cc 100644
--- a/arch/riscv/kernel/ptrace.c
+++ b/arch/riscv/kernel/ptrace.c
@@ -12,6 +12,7 @@
#include <asm/thread_info.h>
#include <asm/switch_to.h>
#include <linux/audit.h>
+#include <linux/compat.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
#include <linux/regset.h>
@@ -275,3 +276,11 @@ __visible void do_syscall_trace_exit(struct pt_regs *regs)
trace_sys_exit(regs, regs_return_value(regs));
#endif
}
+
+#ifdef CONFIG_COMPAT
+long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+ compat_ulong_t caddr, compat_ulong_t cdata)
+{
+ return 0;
+}
+#endif
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index a9436a65161a..4f523a23a5d1 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -253,6 +253,14 @@ static int __setup_additional_pages(struct mm_struct *mm,
return PTR_ERR(ret);
}
+#ifdef CONFIG_COMPAT
+int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+ int uses_interp)
+{
+ return 0;
+}
+#endif
+
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
--
2.25.1
