Re: [Qemu-devel] [PATCH] linux-user sysinfo support & do_sigreturn fix for i386-user

[Fabrice Bellard <fabrice@bellard.org>]

François Guimond wrote:

> First is the fix to signal handling.  When I paid attention to strace's 
> changes in sigprocmask, I realize that masks entering linux-user's 
> signal processing handler would be wrong leaving the handler.  Upon 
> further investigation I noticed that the mask was getting written in the 
> sig frame using __put_user but getting restored by simple assignment, so 
> in this case it would result in the wrong value as qemu-i386 was running 
> on a PowerPC with a different endianess than a x86.   Looking around in 
> the code I saw the 'generic' do_sigreturn used __get_user properly to 
> retrieve it, so I copied over that bit of code into the x86 
> do_sigreturn, and it fixed the deadlock problem I was experiencing 
> (which was caused by wrong sigprocmask).  Here's the related patch:

The code was buggy, but your patch is still not correct. I tried to make 
a correction. Try it !

> The next problem I was running into was the sysinfo not implemented 
> syscall.  The problem would just run in a loop waiting to get a decent 
> result from it, so I had to implement (so far tested by me and two 
> others, all running PowerMac G3s with qemu-i386 as the target).

OK. A small note: it is better now to use __get_user() and __put_user() 
to access to the target memory.

Fabrice.