Re: svn commit: r360233 - in head: contrib/jemalloc . . . : This partially breaks a 2-socket 32-bit powerpc (old PowerMac G4) based on head -r360311
Mark Millard via freebsd-ppc <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.ppc,gmane.os.freebsd.current,gmane.os.freebsd.devel.hackers,gmane.os.freebsd.current.scm |
|---|---|
| Message-ID | <[email protected]> |
On 2020-May-13, at 08:56, Justin Hibbits <[email protected]> wrote: > Hi Mark, Hello Justin. > On Wed, 13 May 2020 01:43:23 -0700 > Mark Millard <[email protected]> wrote: > >> [I'm adding a reference to an old arm64/aarch64 bug that had >> pages turning to zero, in case this 32-bit powerpc issue is >> somewhat analogous.] >> >>> . . . > ... >> . . . >> >> (Note: dsl-only.net closed down, so the E-mail >> address reference is no longer valid.) >> >> Author: kib >> Date: Mon Apr 10 15:32:26 2017 >> New Revision: 316679 >> URL: >> https://svnweb.freebsd.org/changeset/base/316679 >> >> >> Log: >> Do not lose dirty bits for removing PROT_WRITE on arm64. >> >> Arm64 pmap interprets accessed writable ptes as modified, since >> ARMv8.0 does not track Dirty Bit Modifier in hardware. If writable >> bit is removed, page must be marked as dirty for MI VM. >> >> This change is most important for COW, where fork caused losing >> content of the dirty pages which were not yet scanned by pagedaemon. >> >> Reviewed by: alc, andrew >> Reported and tested by: Mark Millard <markmi at dsl-only.net> >> PR: 217138, 217239 >> Sponsored by: The FreeBSD Foundation >> MFC after: 2 weeks >> >> Modified: >> head/sys/arm64/arm64/pmap.c >> >> Modified: head/sys/arm64/arm64/pmap.c >> ============================================================================== >> --- head/sys/arm64/arm64/pmap.c Mon Apr 10 12:35:58 >> 2017 (r316678) +++ head/sys/arm64/arm64/pmap.c Mon Apr >> 10 15:32:26 2017 (r316679) @@ -2481,6 +2481,11 @@ >> pmap_protect(pmap_t pmap, vm_offset_t sv sva += L3_SIZE) { >> l3 = pmap_load(l3p); >> if (pmap_l3_valid(l3)) { >> + if ((l3 & ATTR_SW_MANAGED) && >> + pmap_page_dirty(l3)) { >> + >> vm_page_dirty(PHYS_TO_VM_PAGE(l3 & >> + ~ATTR_MASK)); >> + } >> pmap_set(l3p, ATTR_AP(ATTR_AP_RO)); >> PTE_SYNC(l3p); >> /* XXX: Use pmap_invalidate_range */ >> >> . . . >> > > Thanks for this reference. I took a quick look at the 3 pmap > implementations we have (haven't check the new radix pmap yet), and it > looks like only mmu_oea.c (32-bit AIM pmap, for G3 and G4) is missing > vm_page_dirty() calls in its pmap_protect() implementation, analogous > to the change you posted right above. Given this, I think it's safe to > say that this missing piece is necessary. We'll work on a fix for > this; looking at moea64_protect(), there may be additional work needed > to support this as well, so it may take a few days. Ping? Any clue when the above might happen? I've been avoiding the old PowerMacs and leaving them at head -r360311 , pending an update that would avoid the kernel zeroing pages that it should not zero. But I've seen that you were busy with more modern contexts this last about a month. And, clearly, my own context has left pending (for much longer) other more involved activities (compared to just periodically updating to more recent FreeBSD vintages). === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar) _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-ppc To unsubscribe, send any mail to "[email protected]"