mirror of https://github.com/torvalds/linux.git
2c7387ef99
The existing asm-generic/stat.h specifies st_mtime, etc., as a 32-value, and works well for 32-bit architectures (currently microblaze, score, and 32-bit tile). However, for 64-bit architectures it isn't sufficient to return 32 bits of time_t; this isn't good insurance against the 2037 rollover. (It also makes glibc support less convenient, since we can't use glibc's handy STAT_IS_KERNEL_STAT mode.) This change extends the two "timespec" fields for each of the three atime, mtime, and ctime fields from "int" to "long". As a result, on 32-bit platforms nothing changes, and 64-bit platforms will now work as expected. The only wrinkle is 32-bit userspace under 64-bit kernels taking advantage of COMPAT mode. For these, we leave the "struct stat64" definitions with the "int" versions of the time_t and nsec fields, so that architectures can implement compat_sys_stat64() and friends with sys_stat64(), etc., and get the expected 32-bit structure layout. This requires a field-by-field copy in the kernel, implemented by the code guarded under __ARCH_WANT_STAT64. This does mean that the shape of the "struct stat" and "struct stat64" structures is different on a 64-bit kernel, but only one of the two structures should ever be used by any given process: "struct stat" is meant for 64-bit userspace only, and "struct stat64" for 32-bit userspace only. (On a 32-bit kernel the two structures continue to have the same shape, since "long" is 32 bits.) The alternative is keeping the two structures the same shape on 64-bit kernels, which means a 64-bit time_t in "struct stat64" for 32-bit processes. This is a little unnatural since 32-bit userspace can't do anything with 64 bits of time_t information, since time_t is just "long", not "int64_t"; and in any case 32-bit userspace might expect to be running under a 32-bit kernel, which can't provide the high 32 bits anyway. In the case of a 32-bit kernel we'd then be extending the kernel's 32-bit time_t to 64 bits, then truncating it back to 32 bits again in userspace, for no particular reason. And, as mentioned above, if we have 64-bit time_t for 32-bit processes we can't easily use glibc's STAT_IS_KERNEL_STAT, since glibc's stat structure requires an embedded "struct timespec", which is a pair of "long" (32-bit) values in a 32-bit userspace. "Inventive" solutions are possible, but are pretty hacky. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Acked-by: Arnd Bergmann <arnd@arndb.de> |
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| .. | ||
| Kbuild | ||
| asm-offsets.h | ||
| atomic.h | ||
| atomic_32.h | ||
| auxvec.h | ||
| backtrace.h | ||
| bitops.h | ||
| bitops_32.h | ||
| bitsperlong.h | ||
| bug.h | ||
| bugs.h | ||
| byteorder.h | ||
| cache.h | ||
| cacheflush.h | ||
| checksum.h | ||
| compat.h | ||
| cputime.h | ||
| current.h | ||
| delay.h | ||
| device.h | ||
| div64.h | ||
| dma-mapping.h | ||
| dma.h | ||
| elf.h | ||
| emergency-restart.h | ||
| errno.h | ||
| fcntl.h | ||
| fixmap.h | ||
| ftrace.h | ||
| futex.h | ||
| hardirq.h | ||
| hardwall.h | ||
| highmem.h | ||
| homecache.h | ||
| hugetlb.h | ||
| hv_driver.h | ||
| hw_irq.h | ||
| ide.h | ||
| io.h | ||
| ioctl.h | ||
| ioctls.h | ||
| ipc.h | ||
| ipcbuf.h | ||
| irq.h | ||
| irq_regs.h | ||
| irqflags.h | ||
| kdebug.h | ||
| kexec.h | ||
| kmap_types.h | ||
| linkage.h | ||
| local.h | ||
| memprof.h | ||
| mman.h | ||
| mmu.h | ||
| mmu_context.h | ||
| mmzone.h | ||
| module.h | ||
| msgbuf.h | ||
| mutex.h | ||
| opcode-tile.h | ||
| opcode-tile_32.h | ||
| opcode-tile_64.h | ||
| opcode_constants.h | ||
| opcode_constants_32.h | ||
| opcode_constants_64.h | ||
| page.h | ||
| param.h | ||
| pci-bridge.h | ||
| pci.h | ||
| percpu.h | ||
| pgalloc.h | ||
| pgtable.h | ||
| pgtable_32.h | ||
| poll.h | ||
| posix_types.h | ||
| processor.h | ||
| ptrace.h | ||
| resource.h | ||
| scatterlist.h | ||
| sections.h | ||
| sembuf.h | ||
| setup.h | ||
| shmbuf.h | ||
| shmparam.h | ||
| sigcontext.h | ||
| sigframe.h | ||
| siginfo.h | ||
| signal.h | ||
| smp.h | ||
| socket.h | ||
| sockios.h | ||
| spinlock.h | ||
| spinlock_32.h | ||
| spinlock_types.h | ||
| stack.h | ||
| stat.h | ||
| statfs.h | ||
| string.h | ||
| swab.h | ||
| syscall.h | ||
| syscalls.h | ||
| system.h | ||
| termbits.h | ||
| termios.h | ||
| thread_info.h | ||
| timex.h | ||
| tlb.h | ||
| tlbflush.h | ||
| topology.h | ||
| traps.h | ||
| types.h | ||
| uaccess.h | ||
| ucontext.h | ||
| unaligned.h | ||
| unistd.h | ||
| user.h | ||
| xor.h | ||