On Wednesday 11 May 2016 19:16:44 Zhangjian wrote: > Hi, > > On 2016/5/11 18:12, Zhangjian (Bamvor) wrote: > > Hi, Arnd > > > > On 2016/5/11 16:09, Arnd Bergmann wrote: > > > On Wednesday 11 May 2016 10:04:16 Zhangjian wrote: > > >>> I don't remember. It's probably not important whether we have the shift > > >>> in there, as long as it's independent of the actual kernel page size and > > >>> user space and kernel agree on the calling conventions. > > >> Well. I am ok with where to shift the pages size because we get the same > > >> result. I was just thinking if we should get rid of the name of mmap2 in our > > >> ILP32 porting. Actually, it is mmap but we name it as mmap2. User may confused > > >> if they do not know the implementations. > > > > > > That is a good point: If the implementation matches the mmap() behavior rather than > > > mmap2(), we should rename the macro by doing > > > > > > #undef __NR_mmap2 > > > #define __NR_mmap 222 > > > > > > in the uapi/asm/unistd.h file for ilp32 mode. > > Do you mean define the following things in kernel: > > ``` > > diff --git a/arch/arm64/include/uapi/asm/unistd.h b/arch/arm64/include/uapi/asm/unistd.h > > index 1caadc2..3f79640 100644 > > --- a/arch/arm64/include/uapi/asm/unistd.h > > +++ b/arch/arm64/include/uapi/asm/unistd.h > > @@ -14,3 +14,9 @@ > > * along with this program. If not, see <http://www.gnu.org/licenses/>. > > */ > > #include <asm-generic/unistd.h> > > + > > +#ifdef __ILP32__ > > +#undef __NR_mmap2 > > +#define __NR_mmap 222 > > +#endif /* #ifdef __ILP32__ */ > > + > > ``` > > Then glibc could call mmap instead of mmap2. > > I could not try it now. Because after change off_t to 64bit in glibc, stat > > is fail. I may need to revert the stat relative patch. > After revert stat relative patch in glibc, mmap01-mmap14 success. But mmap16 > success with segfault. I will investigate it later. > > There is pointer and size_t in mmap, so, IIUC, we need to clear the top halves > of register by using COMPAT_SYSCALL_WRAP6. Correct, good catch! > And after check the function in > arch/s390/kernel/compat_linux.c, I feel that we need to do the same thing for > pread64 and pwrite64. > > But I got following error when I try to add > COMPAT_SYSCALL_WRAP4(pread64, unsigned int, fd, char __user *, buf, > size_t, count, loff_t, pos); > COMPAT_SYSCALL_WRAP4(pwrite64, unsigned int, fd, const char __user *, buf, > size_t, count, loff_t, pos); > Hmm, that is indeed tricky. I think COMPAT_SYSCALL_WRAP4 rightfully refuses the loff_t argument here, as the common case is that this is not possible. Can you open-code this using a COMPAT_SYSCALL4 definition similar to what arch/tile has, but without the merging of the two halves of the argument? Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
