[ARM] 3109/1: old ABI compat: syscall wrappers for ABI impedance matching
Patch from Nicolas Pitre
The difference between EABI and the legacy ABI may affect either
structure member alignment and/or argument register selection.
The patch has the details.
Included are wrappers for the following syscalls:
sys_stat64
sys_lstat64
sys_fstat64
sys_fcntl64
sys_epoll_ctl
sys_epoll_wait
sys_ipc
sys_semop
sys_semtimedop
sys_pread64
sys_pwrite64
sys_truncate64
sys_ftruncate64
sys_readahead
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index de94b0f..2ce0e3a 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -20,6 +20,7 @@
obj-$(CONFIG_ISA_DMA) += dma-isa.o
obj-$(CONFIG_PCI) += bios32.o
obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
obj-$(CONFIG_IWMMXT) += iwmmxt.o
AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index ee63ee7..59ce1bc 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -288,3 +288,35 @@
str r5, [sp, #4]
b do_mmap2
#endif
+
+#ifdef CONFIG_OABI_COMPAT
+/*
+ * These are syscalls with argument register differences
+ */
+
+sys_oabi_pread64:
+ stmia sp, {r3, r4}
+ b sys_pread64
+
+sys_oabi_pwrite64:
+ stmia sp, {r3, r4}
+ b sys_pwrite64
+
+sys_oabi_truncate64:
+ mov r3, r2
+ mov r2, r1
+ b sys_truncate64
+
+sys_oabi_ftruncate64:
+ mov r3, r2
+ mov r2, r1
+ b sys_ftruncate64
+
+sys_oabi_readahead:
+ str r3, [sp]
+ mov r3, r2
+ mov r2, r1
+ b sys_readahead
+
+#endif
+
diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
new file mode 100644
index 0000000..eafa8e5
--- /dev/null
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -0,0 +1,339 @@
+/*
+ * arch/arm/kernel/sys_oabi-compat.c
+ *
+ * Compatibility wrappers for syscalls that are used from
+ * old ABI user space binaries with an EABI kernel.
+ *
+ * Author: Nicolas Pitre
+ * Created: Oct 7, 2005
+ * Copyright: MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * The legacy ABI and the new ARM EABI have different rules making some
+ * syscalls incompatible especially with structure arguments.
+ * Most notably, Eabi says 64-bit members should be 64-bit aligned instead of
+ * simply word aligned. EABI also pads structures to the size of the largest
+ * member it contains instead of the invariant 32-bit.
+ *
+ * The following syscalls are affected:
+ *
+ * sys_stat64:
+ * sys_lstat64:
+ * sys_fstat64:
+ *
+ * struct stat64 has different sizes and some members are shifted
+ * Compatibility wrappers are needed for them and provided below.
+ *
+ * sys_fcntl64:
+ *
+ * struct flock64 has different sizes and some members are shifted
+ * A compatibility wrapper is needed and provided below.
+ *
+ * sys_statfs64:
+ * sys_fstatfs64:
+ *
+ * struct statfs64 has extra padding with EABI growing its size from
+ * 84 to 88. This struct is now __attribute__((packed,aligned(4)))
+ * with a small assembly wrapper to force the sz argument to 84 if it is 88
+ * to avoid copying the extra padding over user space unexpecting it.
+ *
+ * sys_newuname:
+ *
+ * struct new_utsname has no padding with EABI. No problem there.
+ *
+ * sys_epoll_ctl:
+ * sys_epoll_wait:
+ *
+ * struct epoll_event has its second member shifted also affecting the
+ * structure size. Compatibility wrappers are needed and provided below.
+ *
+ * sys_ipc:
+ * sys_semop:
+ * sys_semtimedop:
+ *
+ * struct sembuf loses its padding with EABI. Since arrays of them are
+ * used they have to be copyed to remove the padding. Compatibility wrappers
+ * provided below.
+ */
+
+#include <linux/syscalls.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/fcntl.h>
+#include <linux/eventpoll.h>
+#include <linux/sem.h>
+#include <asm/ipc.h>
+#include <asm/uaccess.h>
+
+struct oldabi_stat64 {
+ unsigned long long st_dev;
+ unsigned int __pad1;
+ unsigned long __st_ino;
+ unsigned int st_mode;
+ unsigned int st_nlink;
+
+ unsigned long st_uid;
+ unsigned long st_gid;
+
+ unsigned long long st_rdev;
+ unsigned int __pad2;
+
+ long long st_size;
+ unsigned long st_blksize;
+ unsigned long long st_blocks;
+
+ unsigned long st_atime;
+ unsigned long st_atime_nsec;
+
+ unsigned long st_mtime;
+ unsigned long st_mtime_nsec;
+
+ unsigned long st_ctime;
+ unsigned long st_ctime_nsec;
+
+ unsigned long long st_ino;
+} __attribute__ ((packed,aligned(4)));
+
+static long cp_oldabi_stat64(struct kstat *stat,
+ struct oldabi_stat64 __user *statbuf)
+{
+ struct oldabi_stat64 tmp;
+
+ tmp.st_dev = huge_encode_dev(stat->dev);
+ tmp.__pad1 = 0;
+ tmp.__st_ino = stat->ino;
+ tmp.st_mode = stat->mode;
+ tmp.st_nlink = stat->nlink;
+ tmp.st_uid = stat->uid;
+ tmp.st_gid = stat->gid;
+ tmp.st_rdev = huge_encode_dev(stat->rdev);
+ tmp.st_size = stat->size;
+ tmp.st_blocks = stat->blocks;
+ tmp.__pad2 = 0;
+ tmp.st_blksize = stat->blksize;
+ tmp.st_atime = stat->atime.tv_sec;
+ tmp.st_atime_nsec = stat->atime.tv_nsec;
+ tmp.st_mtime = stat->mtime.tv_sec;
+ tmp.st_mtime_nsec = stat->mtime.tv_nsec;
+ tmp.st_ctime = stat->ctime.tv_sec;
+ tmp.st_ctime_nsec = stat->ctime.tv_nsec;
+ tmp.st_ino = stat->ino;
+ return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
+}
+
+asmlinkage long sys_oabi_stat64(char __user * filename,
+ struct oldabi_stat64 __user * statbuf)
+{
+ struct kstat stat;
+ int error = vfs_stat(filename, &stat);
+ if (!error)
+ error = cp_oldabi_stat64(&stat, statbuf);
+ return error;
+}
+
+asmlinkage long sys_oabi_lstat64(char __user * filename,
+ struct oldabi_stat64 __user * statbuf)
+{
+ struct kstat stat;
+ int error = vfs_lstat(filename, &stat);
+ if (!error)
+ error = cp_oldabi_stat64(&stat, statbuf);
+ return error;
+}
+
+asmlinkage long sys_oabi_fstat64(unsigned long fd,
+ struct oldabi_stat64 __user * statbuf)
+{
+ struct kstat stat;
+ int error = vfs_fstat(fd, &stat);
+ if (!error)
+ error = cp_oldabi_stat64(&stat, statbuf);
+ return error;
+}
+
+struct oabi_flock64 {
+ short l_type;
+ short l_whence;
+ loff_t l_start;
+ loff_t l_len;
+ pid_t l_pid;
+} __attribute__ ((packed,aligned(4)));
+
+asmlinkage long sys_oabi_fcntl64(unsigned int fd, unsigned int cmd,
+ unsigned long arg)
+{
+ struct oabi_flock64 user;
+ struct flock64 kernel;
+ mm_segment_t fs = USER_DS; /* initialized to kill a warning */
+ unsigned long local_arg = arg;
+ int ret;
+
+ switch (cmd) {
+ case F_GETLK64:
+ case F_SETLK64:
+ case F_SETLKW64:
+ if (copy_from_user(&user, (struct oabi_flock64 __user *)arg,
+ sizeof(user)))
+ return -EFAULT;
+ kernel.l_type = user.l_type;
+ kernel.l_whence = user.l_whence;
+ kernel.l_start = user.l_start;
+ kernel.l_len = user.l_len;
+ kernel.l_pid = user.l_pid;
+ local_arg = (unsigned long)&kernel;
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ }
+
+ ret = sys_fcntl64(fd, cmd, local_arg);
+
+ switch (cmd) {
+ case F_GETLK64:
+ if (!ret) {
+ user.l_type = kernel.l_type;
+ user.l_whence = kernel.l_whence;
+ user.l_start = kernel.l_start;
+ user.l_len = kernel.l_len;
+ user.l_pid = kernel.l_pid;
+ if (copy_to_user((struct oabi_flock64 __user *)arg,
+ &user, sizeof(user)))
+ ret = -EFAULT;
+ }
+ case F_SETLK64:
+ case F_SETLKW64:
+ set_fs(fs);
+ }
+
+ return ret;
+}
+
+struct oabi_epoll_event {
+ __u32 events;
+ __u64 data;
+} __attribute__ ((packed,aligned(4)));
+
+asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
+ struct oabi_epoll_event __user *event)
+{
+ struct oabi_epoll_event user;
+ struct epoll_event kernel;
+ mm_segment_t fs;
+ long ret;
+
+ if (op == EPOLL_CTL_DEL)
+ return sys_epoll_ctl(epfd, op, fd, NULL);
+ if (copy_from_user(&user, event, sizeof(user)))
+ return -EFAULT;
+ kernel.events = user.events;
+ kernel.data = user.data;
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = sys_epoll_ctl(epfd, op, fd, &kernel);
+ set_fs(fs);
+ return ret;
+}
+
+asmlinkage long sys_oabi_epoll_wait(int epfd,
+ struct oabi_epoll_event __user *events,
+ int maxevents, int timeout)
+{
+ struct epoll_event *kbuf;
+ mm_segment_t fs;
+ long ret, err, i;
+
+ if (maxevents <= 0 || maxevents > (INT_MAX/sizeof(struct epoll_event)))
+ return -EINVAL;
+ kbuf = kmalloc(sizeof(*kbuf) * maxevents, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout);
+ set_fs(fs);
+ err = 0;
+ for (i = 0; i < ret; i++) {
+ __put_user_error(kbuf[i].events, &events->events, err);
+ __put_user_error(kbuf[i].data, &events->data, err);
+ events++;
+ }
+ kfree(kbuf);
+ return err ? -EFAULT : ret;
+}
+
+struct oabi_sembuf {
+ unsigned short sem_num;
+ short sem_op;
+ short sem_flg;
+ unsigned short __pad;
+};
+
+asmlinkage long sys_oabi_semtimedop(int semid,
+ struct oabi_sembuf __user *tsops,
+ unsigned nsops,
+ const struct timespec __user *timeout)
+{
+ struct sembuf *sops;
+ struct timespec local_timeout;
+ long err;
+ int i;
+
+ if (nsops < 1)
+ return -EINVAL;
+ sops = kmalloc(sizeof(*sops) * nsops, GFP_KERNEL);
+ if (!sops)
+ return -ENOMEM;
+ err = 0;
+ for (i = 0; i < nsops; i++) {
+ __get_user_error(sops[i].sem_num, &tsops->sem_num, err);
+ __get_user_error(sops[i].sem_op, &tsops->sem_op, err);
+ __get_user_error(sops[i].sem_flg, &tsops->sem_flg, err);
+ tsops++;
+ }
+ if (timeout) {
+ /* copy this as well before changing domain protection */
+ err |= copy_from_user(&local_timeout, timeout, sizeof(*timeout));
+ timeout = &local_timeout;
+ }
+ if (err) {
+ err = -EFAULT;
+ } else {
+ mm_segment_t fs = get_fs();
+ set_fs(KERNEL_DS);
+ err = sys_semtimedop(semid, sops, nsops, timeout);
+ set_fs(fs);
+ }
+ kfree(sops);
+ return err;
+}
+
+asmlinkage long sys_oabi_semop(int semid, struct oabi_sembuf __user *tsops,
+ unsigned nsops)
+{
+ return sys_oabi_semtimedop(semid, tsops, nsops, NULL);
+}
+
+extern asmlinkage int sys_ipc(uint call, int first, int second, int third,
+ void __user *ptr, long fifth);
+
+asmlinkage int sys_oabi_ipc(uint call, int first, int second, int third,
+ void __user *ptr, long fifth)
+{
+ switch (call & 0xffff) {
+ case SEMOP:
+ return sys_oabi_semtimedop(first,
+ (struct oabi_sembuf __user *)ptr,
+ second, NULL);
+ case SEMTIMEDOP:
+ return sys_oabi_semtimedop(first,
+ (struct oabi_sembuf __user *)ptr,
+ second,
+ (const struct timespec __user *)fifth);
+ default:
+ return sys_ipc(call, first, second, third, ptr, fifth);
+ }
+}