Date: Sat, 4 Aug 2018 16:13:52 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Kyle Evans <kevans@freebsd.org> Cc: freebsd-current Current <freebsd-current@freebsd.org> Subject: Re: panic: mutex pmap not owned at ... efirt_machdep.c:255 Message-ID: <20180804131352.GL6049@kib.kiev.ua> In-Reply-To: <CACNAnaGZJxm=_oM_f0xinUe2NZ=tZn3w%2BnLTE62_r9EAm0UuTA@mail.gmail.com> 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>
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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 ?
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