Subject: [PATCH V3 08/17] riscv: compat: syscall: Add compat_sys_call_table implementation

From: [email-masked]
Date: Thu, 20 Jan 2022 15:39:01 +0800

From: Guo Ren <[email-masked]>

Implement compat_syscall_table.c with compat_sys_call_table & fixup
system call such as truncate64,pread64,fallocate which need two
regs to indicate 64bit-arg (copied from arm64).

Signed-off-by: Guo Ren <[email-masked]>
Signed-off-by: Guo Ren <[email-masked]>
Cc: Arnd Bergmann <[email-masked]>
---
 arch/riscv/include/asm/syscall.h         |  3 +
 arch/riscv/include/uapi/asm/unistd.h     |  2 +-
 arch/riscv/kernel/Makefile               |  1 +
 arch/riscv/kernel/compat_syscall_table.c | 72 ++++++++++++++++++++++++
 arch/riscv/kernel/sys_riscv.c            |  6 +-
 5 files changed, 81 insertions(+), 3 deletions(-)
 create mode 100644 arch/riscv/kernel/compat_syscall_table.c

diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index 7ac6a0e275f2..4ff98a22ef24 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -16,6 +16,9 @@
 
 /* The array of function pointers for syscalls. */
 extern void * const sys_call_table[];
+#ifdef CONFIG_COMPAT
+extern void * const compat_sys_call_table[];
+#endif
 
 /*
  * Only the low 32 bits of orig_r0 are meaningful, so we return int.
diff --git a/arch/riscv/include/uapi/asm/unistd.h b/arch/riscv/include/uapi/asm/unistd.h
index 8062996c2dfd..c9e50eed14aa 100644
--- a/arch/riscv/include/uapi/asm/unistd.h
+++ b/arch/riscv/include/uapi/asm/unistd.h
@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-#ifdef __LP64__
+#if defined(__LP64__) && !defined(__SYSCALL_COMPAT)
 #define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SET_GET_RLIMIT
 #endif /* __LP64__ */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 3397ddac1a30..1f2111179615 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -65,3 +65,4 @@ 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
diff --git a/arch/riscv/kernel/compat_syscall_table.c b/arch/riscv/kernel/compat_syscall_table.c
new file mode 100644
index 000000000000..53905947678e
--- /dev/null
+++ b/arch/riscv/kernel/compat_syscall_table.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define __SYSCALL_COMPAT
+
+#include <linux/compat.h>
+#include <linux/syscalls.h>
+#include <asm-generic/mman-common.h>
+#include <asm-generic/syscalls.h>
+#include <asm/syscall.h>
+
+#define arg_u32p(name)  u32, name##_lo, u32, name##_hi
+
+#define arg_u64(name)   (((u64)name##_hi << 32) | \
+			 ((u64)name##_lo & 0xffffffff))
+
+COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
+		       arg_u32p(length))
+{
+	return ksys_truncate(pathname, arg_u64(length));
+}
+
+COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd, arg_u32p(length))
+{
+	return ksys_ftruncate(fd, arg_u64(length));
+}
+
+COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode,
+		       arg_u32p(offset), arg_u32p(len))
+{
+	return ksys_fallocate(fd, mode, arg_u64(offset), arg_u64(len));
+}
+
+COMPAT_SYSCALL_DEFINE5(pread64, unsigned int, fd, char __user *, buf,
+		       size_t, count, arg_u32p(pos))
+{
+	return ksys_pread64(fd, buf, count, arg_u64(pos));
+}
+
+COMPAT_SYSCALL_DEFINE5(pwrite64, unsigned int, fd,
+		       const char __user *, buf, size_t, count, arg_u32p(pos))
+{
+	return ksys_pwrite64(fd, buf, count, arg_u64(pos));
+}
+
+COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, arg_u32p(offset),
+		       arg_u32p(nbytes), unsigned int, flags)
+{
+	return ksys_sync_file_range(fd, arg_u64(offset), arg_u64(nbytes),
+				    flags);
+}
+
+COMPAT_SYSCALL_DEFINE4(readahead, int, fd, arg_u32p(offset),
+		       size_t, count)
+{
+	return ksys_readahead(fd, arg_u64(offset), count);
+}
+
+COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, int, advice, arg_u32p(offset),
+		       arg_u32p(len))
+{
+	return ksys_fadvise64_64(fd, arg_u64(offset), arg_u64(len), advice);
+}
+
+#undef __SYSCALL
+#define __SYSCALL(nr, call)      [nr] = (call),
+
+asmlinkage long compat_sys_rt_sigreturn(void);
+
+void * const compat_sys_call_table[__NR_syscalls] = {
+	[0 ... __NR_syscalls - 1] = sys_ni_syscall,
+#include <asm/unistd.h>
+};
diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index 12f8a7fce78b..9c0194f176fc 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -33,7 +33,9 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 {
 	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 0);
 }
-#else
+#endif
+
+#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
 SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 	unsigned long, prot, unsigned long, flags,
 	unsigned long, fd, off_t, offset)
@@ -44,7 +46,7 @@ SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
 	 */
 	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 12);
 }
-#endif /* !CONFIG_64BIT */
+#endif
 
 /*
  * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
-- 
2.25.1

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