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[Qemu-devel] Re: linux-user issues
From: |
malc |
Subject: |
[Qemu-devel] Re: linux-user issues |
Date: |
Sat, 13 Mar 2010 05:06:31 +0300 (MSK) |
User-agent: |
Alpine 2.00 (LNX 1167 2008-08-23) |
On Sat, 13 Mar 2010, Paul Brook wrote:
> > a) elfload.c:859
> >
> > #define TARGET_ELF_PAGESTART(_v) ((_v) & ~(unsigned
> > long)(TARGET_ELF_EXEC_PAGESIZE-1))
> >
> > This means that for 64bit guest on a 32bit host the _v's value is
> > silently reduced to 32bit, the cast should be abi_ulong.
> >
> > b) mmap.c:428
> >
> > real_start = start & qemu_host_page_mask;
> >
> > Same thing basically qemu_host_page_mask is unsigned long and so
> > the upper bits are sliently cleared. Again qemu_host_page_mask
> > should probably be abi_ulong.
> >
> > The above two make elf binary with one of the segments above 4G load
> > and run on 32bit guest only to fail well into execution and without
> > any indication that it shouldn't have been allowed to run in the first
> > place.
>
> I'd be amazed if these are the only two issues, and expect 64-bit guests on
> 32-bit hosts to be generally unsafe.
These are the two issues i've been bitten by while trying to solve
x86_64's far jumps, if you are okay with code silently misbehaving
fine by me.
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