On Wed, May 11, 2016 at 12:55:01PM +0200, Arnd Bergmann wrote: > On Wednesday 11 May 2016 11:04:38 Yury Norov wrote: > > On Wed, May 11, 2016 at 10:04:16AM +0800, Zhangjian (Bamvor) wrote: > > [...] > > > > > >>Ok, I will test the ltp syscall test. > > > >>With this changes, the issue I mentioned should be fixed. But we still > > > >>use mmap2 syscall for ILP32 application when we pass the offset instead > > > >>of page offset. Is it correct? > > > > > > > >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. > > > > > > > This is what generic unistd.h does. If you want to change it, you'd > > change each arch that uses generic unistd.h. > > Generic unistd.h has this: > > #ifdef __SYSCALL_COMPAT > #define __SC_COMP_3264(_nr, _32, _64, _comp) __SYSCALL(_nr, _comp) > #else > #define __SC_COMP_3264(_nr, _32, _64, _comp) __SC_3264(_nr, _32, _64) > #endif > > #define __NR3264_mmap 222 > __SC_3264(__NR3264_mmap, sys_mmap2, sys_mmap) > > > #if __BITS_PER_LONG == 64 && !defined(__SYSCALL_COMPAT) > #define __NR_mmap __NR3264_mmap > #else > #define __NR_mmap2 __NR3264_mmap > #endif > > So by default we get __NR_mmap2 and sys_mmap2 on 32-bit ABIs, but > __NR_mmap and sys_mmap on 64-bit ABIs, as it should be. > > The problem is that arch/arm64/kernel/sys_ilp32.c now overrides > this to use __NR_mmap2 with sys_mmap, so we have a mismatch. I think > we should either override both the implementation and the number, > or neither of them. I would vote for "neither of them" (so we use __NR_mmap2 and sys_mmap2) to keep it close to new 32-bit architectures, even though we would have some shifts by 12 in both glibc and kernel. -- Catalin -- 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
