On Mon, Apr 25, 2011 at 10:59:52PM +0100, Peter Maydell wrote: > On 25 April 2011 22:09, Aurelien Jarno <aurel...@aurel32.net> wrote: > > On Thu, Apr 21, 2011 at 05:01:48PM +0100, Peter Maydell wrote: > > >> + tb_flush(env); > > > > If you flush all tbs, you also have to ensure that on the translate.c > > side, this is the last instruction of the tb. Otherwise, the rest of the > > TB will be executed with the wrong access rights. > > This is OK, because we can't get here unless we're in privileged > mode (PMUSERENR is never writable in user mode), and changing > PMUSERENR doesn't affect the access rights for privileged mode. > And a switch into user mode will be a change of TB anyway. > > (Compare the handling of the TEECR, which also doesn't need to change > TB after a tb_flush(), for the same reasons.)
Ok, fine then. > > Instead of having this complex test for all cp15 access, but only for > > catching a few access to performance registers, wouldn't it make more > > sense to have this test and an exception triggering directly in > > helper.c? > > That was what my first design did, but in discussions on IRC > with Paul Brook he basically said that you can't generate an > exception in the helper routine, you have to either generate > runtime code to do the test or throw away the TBs. Unfortunately > I forget the exact rationale, so I've cc'd Paul to remind me :-) This is something strange, plenty of targets are raising exceptions from helpers without any problem. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net http://www.aurel32.net
