Date: Wed, 30 Dec 2020 16:53:25 -0600 From: "Brandon Bergren" <bdragon@FreeBSD.org> To: "Piotr Kubaj" <pkubaj@FreeBSD.org>, src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: =?UTF-8?Q?Re:_git:_76ff03aef741_-_main_-_powerpc:_Fix_copyin/copyout_rac?= =?UTF-8?Q?e_condition?= Message-ID: <050b7622-0766-42b9-a7a3-420f586e39ea@www.fastmail.com> In-Reply-To: <202012302245.0BUMjrpm032399@gitrepo.freebsd.org> References: <202012302245.0BUMjrpm032399@gitrepo.freebsd.org>
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Note: This commit series is stuff salvaged from jhibbits' local tree. Apologies for the malformed commit messages, Piotr and I were discussing them in IRC earlier and I was under the mistaken assumption that they would get reworded before the push. On Wed, Dec 30, 2020, at 4:45 PM, Piotr Kubaj wrote: > The branch main has been updated by pkubaj (ports committer): > > URL: > https://cgit.FreeBSD.org/src/commit/?id=76ff03aef7411e601673dfc997bd6d691bd9a14e > > commit 76ff03aef7411e601673dfc997bd6d691bd9a14e > Author: Justin Hibbits <chmeeedalf@gmail.com> > AuthorDate: 2020-12-08 22:49:25 +0000 > Commit: Piotr Kubaj <pkubaj@FreeBSD.org> > CommitDate: 2020-12-30 22:45:44 +0000 > > powerpc: Fix copyin/copyout race condition > > It's possible for a context switch, and CPU migration, to occur between > fetching the PCPU context and extracting the pc_curpcb. This can cause > the fault handler to be installed for the wrong thread, leading to a > panic in copyin()/copyout(). Since curthread is already in %r13, just > use that directly, as GPRs are migrated, so there is no migration race > risk. -- Brandon Bergren bdragon@FreeBSD.org
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