[v6,14/17] aarch64: ilp32: use generic stat64 structure

Commit Message

Yury Norov Nov. 2, 2015, 11:30 p.m. UTC

Generic 32-bit and AARCH32 stat64 structures has same names.
ILP32 needs generic stat64. So we can either make ILP32 mutual
exclusive with AARCH32, or introduce __stat64, and where needed,
cast stat64 to it with #define.

Second option requires to duplicate cp_new_stat64 code. But we
choose it, because it's more flexible to have independend support
for ABIs.

Signed-off-by: Yury Norov <[e-mail]>
Reviewed-by: David Daney <[e-mail]>
---
 arch/arm64/kernel/sys_ilp32.c   | 57 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/asm-generic/stat.h |  8 +++---
 2 files changed, 62 insertions(+), 3 deletions(-)

Comments

Arnd Bergmann Nov. 5, 2015, 2:03 p.m. UTC | #1

On Tuesday 03 November 2015 02:30:43 Yury Norov wrote:
> Generic 32-bit and AARCH32 stat64 structures has same names.
> ILP32 needs generic stat64. So we can either make ILP32 mutual
> exclusive with AARCH32, or introduce __stat64, and where needed,
> cast stat64 to it with #define.
> 
> Second option requires to duplicate cp_new_stat64 code. But we
> choose it, because it's more flexible to have independend support
> for ABIs.
> 
> Signed-off-by: Yury Norov <[e-mail]>
> Reviewed-by: David Daney <[e-mail]>

I'm sorry I screwed up with the definition for stat64 in asm-generic,
by defining it to have too short st_{a,m,c}time members.

This means we have to introduce another 'struct stat64' variant already
to solve the y2038 problem, and I have patches for it already, to make
that implementation use the same structure as the 64-bit 'struct stat'
with 64-bit timestamps. There is also an ongoing effort from David Howells
to create a new 'struct statx' (or maybe xstat) system call with a
completely new layout.

I think here it would be better to avoid adding yet another version
for ilp32 mode, and we are better off defining 'struct stat64' in
the arm64 headers, and share either the normal arm32 syscall entry
(with the default asm-generic syscall) or the normal arm64 syscall
entry (as we will do for the future replacement).

	Arnd

Patch

diff --git a/arch/arm64/kernel/sys_ilp32.c b/arch/arm64/kernel/sys_ilp32.c
index 6c7d274..889f1d3 100644
--- a/arch/arm64/kernel/sys_ilp32.c
+++ b/arch/arm64/kernel/sys_ilp32.c
@@ -205,6 +205,63 @@  long ilp32_sys_sigaltstack(const stack_t __user *uss_ptr,
    for stack_t might not be non-zero. */
 #define sys_sigaltstack		ilp32_sys_sigaltstack
 
+/* fs */
+
+#define sys_fcntl		compat_sys_fcntl
+
+static long __cp_new_stat64(struct kstat *stat, struct __stat64 __user *statbuf)
+{
+	struct __stat64 tmp;
+
+	memset(&tmp, 0, sizeof(tmp));
+	tmp.st_dev = huge_encode_dev(stat->dev);
+	tmp.st_rdev = huge_encode_dev(stat->rdev);
+
+	tmp.st_ino = stat->ino;
+	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
+		return -EOVERFLOW;
+	tmp.st_mode = stat->mode;
+	tmp.st_nlink = stat->nlink;
+	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
+	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
+	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_size = stat->size;
+	tmp.st_blocks = stat->blocks;
+	tmp.st_blksize = stat->blksize;
+	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
+}
+
+long ilp32_sys_fstat64(int fd, struct __stat64 __user * statbuf)
+{
+	struct kstat stat;
+	int error = vfs_fstat(fd, &stat);
+
+	if (!error)
+		error = __cp_new_stat64(&stat, statbuf);
+
+	return error;
+}
+
+#define sys_newfstat ilp32_sys_fstat64
+
+long ilp32_sys_fstatat64(int dfd, const char __user * filename,
+		struct __stat64 __user * statbuf, int flag)
+{
+	struct kstat stat;
+	int error;
+
+	error = vfs_fstatat(dfd, filename, &stat, flag);
+	if (error)
+		return error;
+	return __cp_new_stat64(&stat, statbuf);
+}
+
+#define sys_newfstatat ilp32_sys_fstatat64
 
 #include <asm/syscall.h>
 
diff --git a/include/uapi/asm-generic/stat.h b/include/uapi/asm-generic/stat.h
index bd8cad2..ae81e73 100644
--- a/include/uapi/asm-generic/stat.h
+++ b/include/uapi/asm-generic/stat.h
@@ -43,9 +43,7 @@  struct stat {
 	unsigned int	__unused5;
 };
 
-/* This matches struct stat64 in glibc2.1. Only used for 32 bit. */
-#if __BITS_PER_LONG != 64 || defined(__ARCH_WANT_STAT64)
-struct stat64 {
+struct __stat64 {
 	unsigned long long st_dev;	/* Device.  */
 	unsigned long long st_ino;	/* File serial number.  */
 	unsigned int	st_mode;	/* File mode.  */
@@ -67,6 +65,10 @@  struct stat64 {
 	unsigned int	__unused4;
 	unsigned int	__unused5;
 };
+
+#if __BITS_PER_LONG != 64 || defined(__ARCH_WANT_STAT64)
+/* This matches struct stat64 in glibc2.1. Only used for 32 bit. */
+#define stat64 __stat64
 #endif
 
 #endif /* __ASM_GENERIC_STAT_H */