RISC-V: Add support for rv32 userspace via COMPAT

The RISC-V port supports the rv32i and rv64i base ISAs, but provides no
mechanism to run 32-bit userspace on 64-bit systems.  This adds that
support, via the COMPAT framework.  As the RISC-V ISAs (and uABIs) were
developed concurrently, the resulting compat support is mostly generic.

This includes a handful of cleanups to the generic compat infrastructure
to more cleanly support RISC-V, followed by the RISC-V implementation.

* palmer/riscv-compat:
  riscv: compat: Add COMPAT Kbuild skeletal support
  riscv: compat: ptrace: Add compat_arch_ptrace implement
  riscv: compat: signal: Add rt_frame implementation
  riscv: compat: vdso: Add setup additional pages implementation
  riscv: compat: vdso: Add COMPAT_VDSO base code implementation
  riscv: compat: Add hw capability check for elf
  riscv: compat: Add elf.h implementation
  riscv: compat: process: Add UXL_32 support in start_thread
  riscv: compat: syscall: Add entry.S implementation
  riscv: compat: syscall: Add compat_sys_call_table implementation
  riscv: compat: Support TASK_SIZE for compat mode
  riscv: compat: Add basic compat data type implementation
  riscv: Fixup difference with defconfig
  syscalls: compat: Fix the missing part for __SYSCALL_COMPAT
  asm-generic: compat: Cleanup duplicate definitions
  fs: stat: compat: Add __ARCH_WANT_COMPAT_STAT
  arch: Add SYSVIPC_COMPAT for all architectures
  compat: consolidate the compat_flock{,64} definition
  uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
  uapi: simplify __ARCH_FLOCK{,64}_PAD a little

Author: palmer-dabbelt

arch/arm64/Kconfig

@@ -2122,10 +2122,6 @@ config DMI
 
 endmenu
 
-config SYSVIPC_COMPAT
-	def_bool y
-	depends on COMPAT && SYSVIPC
-
 menu "Power management options"
 
 source "kernel/power/Kconfig"

arch/arm64/include/asm/compat.h

@@ -8,6 +8,15 @@
 #define compat_mode_t compat_mode_t
 typedef u16		compat_mode_t;
 
+#define __compat_uid_t	__compat_uid_t
+typedef u16		__compat_uid_t;
+typedef u16		__compat_gid_t;
+
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16		compat_ipc_pid_t;
+
+#define compat_statfs	compat_statfs
+
 #include <asm-generic/compat.h>
 
 #ifdef CONFIG_COMPAT
@@ -19,21 +28,15 @@ typedef u16		compat_mode_t;
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 
-#define COMPAT_USER_HZ		100
 #ifdef __AARCH64EB__
 #define COMPAT_UTS_MACHINE	"armv8b\0\0"
 #else
 #define COMPAT_UTS_MACHINE	"armv8l\0\0"
 #endif
 
-typedef u16		__compat_uid_t;
-typedef u16		__compat_gid_t;
 typedef u16		__compat_uid16_t;
 typedef u16		__compat_gid16_t;
-typedef u32		compat_dev_t;
 typedef s32		compat_nlink_t;
-typedef u16		compat_ipc_pid_t;
-typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
 #ifdef __AARCH64EB__
@@ -65,26 +68,6 @@ struct compat_stat {
 	compat_ulong_t	__unused4[2];
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	compat_pid_t	l_pid;
-};
-
-#define F_GETLK64	12	/*  using 'struct flock64' */
-#define F_SETLK64	13
-#define F_SETLKW64	14
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
-
 struct compat_statfs {
 	int		f_type;
 	int		f_bsize;
@@ -107,64 +90,6 @@ struct compat_statfs {
 #define compat_user_stack_pointer() (user_stack_pointer(task_pt_regs(current)))
 #define COMPAT_MINSIGSTKSZ	2048
 
-struct compat_ipc64_perm {
-	compat_key_t key;
-	__compat_uid32_t uid;
-	__compat_gid32_t gid;
-	__compat_uid32_t cuid;
-	__compat_gid32_t cgid;
-	unsigned short mode;
-	unsigned short __pad1;
-	unsigned short seq;
-	unsigned short __pad2;
-	compat_ulong_t unused1;
-	compat_ulong_t unused2;
-};
-
-struct compat_semid64_ds {
-	struct compat_ipc64_perm sem_perm;
-	compat_ulong_t sem_otime;
-	compat_ulong_t sem_otime_high;
-	compat_ulong_t sem_ctime;
-	compat_ulong_t sem_ctime_high;
-	compat_ulong_t sem_nsems;
-	compat_ulong_t __unused3;
-	compat_ulong_t __unused4;
-};
-
-struct compat_msqid64_ds {
-	struct compat_ipc64_perm msg_perm;
-	compat_ulong_t msg_stime;
-	compat_ulong_t msg_stime_high;
-	compat_ulong_t msg_rtime;
-	compat_ulong_t msg_rtime_high;
-	compat_ulong_t msg_ctime;
-	compat_ulong_t msg_ctime_high;
-	compat_ulong_t msg_cbytes;
-	compat_ulong_t msg_qnum;
-	compat_ulong_t msg_qbytes;
-	compat_pid_t   msg_lspid;
-	compat_pid_t   msg_lrpid;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
-struct compat_shmid64_ds {
-	struct compat_ipc64_perm shm_perm;
-	compat_size_t  shm_segsz;
-	compat_ulong_t shm_atime;
-	compat_ulong_t shm_atime_high;
-	compat_ulong_t shm_dtime;
-	compat_ulong_t shm_dtime_high;
-	compat_ulong_t shm_ctime;
-	compat_ulong_t shm_ctime_high;
-	compat_pid_t   shm_cpid;
-	compat_pid_t   shm_lpid;
-	compat_ulong_t shm_nattch;
-	compat_ulong_t __unused4;
-	compat_ulong_t __unused5;
-};
-
 static inline int is_compat_task(void)
 {
 	return test_thread_flag(TIF_32BIT);

arch/arm64/include/asm/unistd.h

@@ -3,6 +3,7 @@
  * Copyright (C) 2012 ARM Ltd.
  */
 #ifdef CONFIG_COMPAT
+#define __ARCH_WANT_COMPAT_STAT
 #define __ARCH_WANT_COMPAT_STAT64
 #define __ARCH_WANT_SYS_GETHOSTNAME
 #define __ARCH_WANT_SYS_PAUSE

arch/mips/Kconfig

@@ -3198,16 +3198,12 @@ config MIPS32_COMPAT
 config COMPAT
 	bool
 
-config SYSVIPC_COMPAT
-	bool
-
 config MIPS32_O32
 	bool "Kernel support for o32 binaries"
 	depends on 64BIT
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT
 	select MIPS32_COMPAT
-	select SYSVIPC_COMPAT if SYSVIPC
 	help
 	  Select this option if you want to run o32 binaries.  These are pure
 	  32-bit binaries as used by the 32-bit Linux/MIPS port.  Most of
@@ -3221,7 +3217,6 @@ config MIPS32_N32
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 	select COMPAT
 	select MIPS32_COMPAT
-	select SYSVIPC_COMPAT if SYSVIPC
 	help
 	  Select this option if you want to run n32 binaries.  These are
 	  64-bit binaries using 32-bit quantities for addressing and certain

arch/mips/include/asm/compat.h

@@ -9,28 +9,28 @@
 #include <asm/page.h>
 #include <asm/ptrace.h>
 
+#define __compat_uid_t	__compat_uid_t
 typedef s32		__compat_uid_t;
 typedef s32		__compat_gid_t;
+
 typedef __compat_uid_t	__compat_uid32_t;
 typedef __compat_gid_t	__compat_gid32_t;
 #define __compat_uid32_t __compat_uid32_t
-#define __compat_gid32_t __compat_gid32_t
+
+#define compat_statfs		compat_statfs
+#define compat_ipc64_perm	compat_ipc64_perm
 
 #define _COMPAT_NSIG		128		/* Don't ask !$@#% ...	*/
 #define _COMPAT_NSIG_BPW	32
 typedef u32		compat_sigset_word;
 
+#define COMPAT_RLIM_INFINITY	0x7fffffffUL
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"mips\0\0\0"
 
-typedef u32		compat_dev_t;
 typedef u32		compat_nlink_t;
-typedef s32		compat_ipc_pid_t;
-typedef struct {
-	s32	val[2];
-} compat_fsid_t;
 
 struct compat_stat {
 	compat_dev_t	st_dev;
@@ -55,27 +55,8 @@ struct compat_stat {
 	s32		st_pad4[14];
 };
 
-struct compat_flock {
-	short		l_type;
-	short		l_whence;
-	compat_off_t	l_start;
-	compat_off_t	l_len;
-	s32		l_sysid;
-	compat_pid_t	l_pid;
-	s32		pad[4];
-};
-
-#define F_GETLK64	33
-#define F_SETLK64	34
-#define F_SETLKW64	35
-
-struct compat_flock64 {
-	short		l_type;
-	short		l_whence;
-	compat_loff_t	l_start;
-	compat_loff_t	l_len;
-	compat_pid_t	l_pid;
-};
+#define __ARCH_COMPAT_FLOCK_EXTRA_SYSID		s32 l_sysid;
+#define __ARCH_COMPAT_FLOCK_PAD			s32 pad[4];
 
 struct compat_statfs {
 	int		f_type;
@@ -92,10 +73,6 @@ struct compat_statfs {
 	int		f_spare[5];
 };
 
-#define COMPAT_RLIM_INFINITY	0x7fffffffUL
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 struct compat_ipc64_perm {
 	compat_key_t key;
 	__compat_uid32_t uid;

arch/mips/include/asm/unistd.h

@@ -50,6 +50,8 @@
 # ifdef CONFIG_32BIT
 #  define __ARCH_WANT_STAT64
 #  define __ARCH_WANT_SYS_TIME32
+# else
+#  define __ARCH_WANT_COMPAT_STAT
 # endif
 # ifdef CONFIG_MIPS32_O32
 #  define __ARCH_WANT_SYS_TIME32

arch/mips/include/uapi/asm/fcntl.h

@@ -44,36 +44,16 @@
 #define F_SETOWN	24	/*  for sockets. */
 #define F_GETOWN	23	/*  for sockets. */
 
-#ifndef __mips64
+#if __BITS_PER_LONG == 32 || defined(__KERNEL__)
 #define F_GETLK64	33	/*  using 'struct flock64' */
 #define F_SETLK64	34
 #define F_SETLKW64	35
-#endif
-
-/*
- * The flavours of struct flock.  "struct flock" is the ABI compliant
- * variant.  Finally struct flock64 is the LFS variant of struct flock.	 As
- * a historic accident and inconsistence with the ABI definition it doesn't
- * contain all the same fields as struct flock.
- */
+#endif /* __BITS_PER_LONG == 32 || defined(__KERNEL__) */
 
 #if _MIPS_SIM != _MIPS_SIM_ABI64
-
-#include <linux/types.h>
-
-struct flock {
-	short	l_type;
-	short	l_whence;
-	__kernel_off_t	l_start;
-	__kernel_off_t	l_len;
-	long	l_sysid;
-	__kernel_pid_t l_pid;
-	long	pad[4];
-};
-
-#define HAVE_ARCH_STRUCT_FLOCK
-
-#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
+#define __ARCH_FLOCK_EXTRA_SYSID	long l_sysid;
+#define __ARCH_FLOCK_PAD		long pad[4];
+#endif
 
 #include <asm-generic/fcntl.h>
 

arch/parisc/Kconfig

@@ -331,10 +331,6 @@ config COMPAT
 	def_bool y
 	depends on 64BIT
 
-config SYSVIPC_COMPAT
-	def_bool y
-	depends on COMPAT && SYSVIPC
-
 config AUDIT_ARCH
 	def_bool y
 

arch/parisc/include/asm/compat.h

@@ -11,16 +11,16 @@
 #define compat_mode_t compat_mode_t
 typedef u16	compat_mode_t;
 
+#define compat_ipc_pid_t compat_ipc_pid_t
+typedef u16	compat_ipc_pid_t;
+
+#define compat_ipc64_perm compat_ipc64_perm
+
 #include <asm-generic/compat.h>
 
-#define COMPAT_USER_HZ 		100
 #define COMPAT_UTS_MACHINE	"parisc\0\0"
 
-typedef u32	__compat_uid_t;
-typedef u32	__compat_gid_t;
-typedef u32	compat_dev_t;
 typedef u16	compat_nlink_t;
-typedef u16	compat_ipc_pid_t;
 
 struct compat_stat {
 	compat_dev_t		st_dev;	/* dev_t is 32 bits on parisc */
@@ -53,37 +53,6 @@ struct compat_stat {
 	u32			st_spare4[3];
 };
 
-struct compat_flock {
-	short			l_type;
-	short			l_whence;
-	compat_off_t		l_start;
-	compat_off_t		l_len;
-	compat_pid_t		l_pid;
-};
-
-struct compat_flock64 {
-	short			l_type;
-	short			l_whence;
-	compat_loff_t		l_start;
-	compat_loff_t		l_len;
-	compat_pid_t		l_pid;
-};
-
-struct compat_statfs {
-	s32		f_type;
-	s32		f_bsize;
-	s32		f_blocks;
-	s32		f_bfree;
-	s32		f_bavail;
-	s32		f_files;
-	s32		f_ffree;
-	__kernel_fsid_t	f_fsid;
-	s32		f_namelen;
-	s32		f_frsize;
-	s32		f_flags;
-	s32		f_spare[4];
-};
-
 struct compat_sigcontext {
 	compat_int_t sc_flags;
 	compat_int_t sc_gr[32]; /* PSW in sc_gr[0] */
@@ -93,10 +62,6 @@ struct compat_sigcontext {
 	compat_int_t sc_sar; /* cr11 */
 };
 
-#define COMPAT_RLIM_INFINITY 0xffffffff
-
-#define COMPAT_OFF_T_MAX	0x7fffffff
-
 struct compat_ipc64_perm {
 	compat_key_t key;
 	__compat_uid_t uid;

arch/parisc/include/asm/unistd.h

@@ -164,6 +164,7 @@ type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4, type5 arg5)	\
 #define __ARCH_WANT_SYS_CLONE
 #define __ARCH_WANT_SYS_CLONE3
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
+#define __ARCH_WANT_COMPAT_STAT
 
 #ifdef CONFIG_64BIT
 #define __ARCH_WANT_SYS_TIME