Il 21/04/2014 18:08, Peter Maydell ha scritto:
Thinking more about this, we'd be wrong already for bigendian if these were wrong. The bit about the linux-user/main.c strex/ldrex still stands, though, because those use get_user*/put_user* which use the TARGET_BIGENDIAN specified endianness.
Ok.
The commpage code may also need updating to correctly handle the effects of being called with the wrong endianness (though we can probably get away with declaring that to be lunacy and not well defined...)
Yeah, I think this is lunacy. :)
If we take an exception while the E bit is set we'll now incorrectly start executing the exception handler in big-endian mode. Minimally, we need to force "always little endian". Ideally, we would implement SCTLR.EE correctly.
I'll look into SCTLR.
Also worth checking: in linux-user mode, if the guest executes SETEND and then takes a signal, what does the Linux ABI say should be the value of CPSR.E on entry to the signal handler, and do we get it right?
No, my patch does not even try. Thanks for pointing out. The kernel sets CPSR.E for armeb and clears it otherwise.
Paolo
[Tangentially: we really need a vdso for aarch64, at which point we might as well do the aarch32 commpage with one too. IIRC RTH had some patches for x86-64 vdso which I should fish out of the archives...] thanks -- PMM
