Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] arm64: Enable CONFIG_COMPAT also for 64k page size | Date | Wed, 11 Mar 2015 13:47:36 +0100 |
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On Wednesday 11 March 2015 06:24:16 Alexander Graf wrote: > So after recompiling all of the distribution with newer binutils we now > have an openSUSE Factory tree that has 64k aligned 32bit binaries. > > Unfortunately however, the 32bit glibc has a bogus mmap() implementation > that hard codes 4k page size. > > With the patch below applied to glibc, I can successfully run 32bit user > space on Seattle with 64k PAGE_SIZE though. So I guess we'll need to fix > up glibc next. > > Do you know of anyone who's fluent enough in 32bit ARM assembly to > convert the hard coded assumptions in there to instead use a variable > that takes the actual host page size into account?
I believe this is a kernel bug, and the kernel API for 32-bit emulation should always take the pgoff argument in 4KB units instead of PAGE_SIZE units, see the implementation of sys_mmap2 in arch/powerpc/kernel/sys_ppc32.c.
All user space programs that call mmap2 still need to make sure that their arguments are PAGE_SIZE aligned, but the libc need not care about this here.
Arnd
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