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 think what happened is that you chose to override sys_mmap because sys_mmap2 sometimes takes an off_t argument, however the kernel just treats it as 'unsigned long', with a range of 44 bits for the offset. Using sys_mmap with a __kernel_loff_t argument gives us 64-bit range, but if we do that, I think it should be __NR_mmap. 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
