Date: Sat, 4 Aug 2018 08:56:58 -0500 From: Kyle Evans <kevans@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-current Current <freebsd-current@freebsd.org>, Eitan Adler <eadler@freebsd.org> Subject: Re: panic: mutex pmap not owned at ... efirt_machdep.c:255 Message-ID: <CACNAnaFUto6gSaDx3vrgnSykRfBhV_Mgx4OLaXJgENvgqjgSHg@mail.gmail.com> In-Reply-To: <20180804131352.GL6049@kib.kiev.ua> References: <CAF6rxg=4OnHEJa1OnJerMeEKD66nZg3j-H-XZ-9YAA1TE_NoDQ@mail.gmail.com> <CACNAnaFv9Gj%2BM2Gb8FbwY5q56dnTR6OgjZ5qth9gjr8LreHeow@mail.gmail.com> <20180804083720.GJ6049@kib.kiev.ua> <CACNAnaGZJxm=_oM_f0xinUe2NZ=tZn3w%2BnLTE62_r9EAm0UuTA@mail.gmail.com> <20180804131352.GL6049@kib.kiev.ua>
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On Sat, Aug 4, 2018 at 8:13 AM, Konstantin Belousov <kostikbel@gmail.com> wrote: > On Sat, Aug 04, 2018 at 08:05:24AM -0500, Kyle Evans wrote: >> On Sat, Aug 4, 2018 at 3:37 AM, Konstantin Belousov <kostikbel@gmail.com> wrote: >> > On Fri, Aug 03, 2018 at 11:27:02PM -0500, Kyle Evans wrote: >> >> >> >> This seems odd- pmap lock is acquired at [1], then asserted shortly >> >> later at [2]... I avoid some of this stuff as well as I can, but is it >> >> actually possible for PCPU_GET(...) acquired curpmap to not match >> >> curthread->td_proc->p_vmspace->vm_pmap in this context? >> >> >> >> [1] https://svnweb.freebsd.org/base/head/sys/dev/efidev/efirt.c?view=markup#l260 >> >> [2] https://svnweb.freebsd.org/base/head/sys/amd64/amd64/efirt_machdep.c?view=markup#l254 >> > There could be that curpcpu not yet synced with proc0 pmap. It could be >> > fixed. >> > >> > But it is not clear to me why efi_arch_enter() is called there. I see >> > the check for GetTime belonging to the range described by a map descriptor. >> > I do not see why do you need an enter into the EFI context for comparing >> > integers. >> >> This probably could have been documented better, but efi_runtime >> pointer may (always?) point into runtime service memory that isn't >> valid/available at that point, so we get a fault and panic when >> dereferencing it to grab rt_gettime address. We ran into this wall >> when adding the check originally. > Wouldn't it be enough to access it by translating physical address into > DMAP ? Ah, sure, sure. [1] is proper form, yeah? [1] https://people.freebsd.org/~kevans/efi-dmap.diff
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