Date: Tue, 18 Jan 2022 14:58:04 -0500 From: Mark Johnston <markj@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 706f4a81a812 - main - exec: Introduce the PROC_PS_STRINGS() macro Message-ID: <YecbzOqrCZA2uLLM@nuc> In-Reply-To: <4e0db863-71fd-faa3-41f1-3cb05d539def@FreeBSD.org> References: <202201172113.20HLD7v9006931@gitrepo.freebsd.org> <4e0db863-71fd-faa3-41f1-3cb05d539def@FreeBSD.org>
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On Tue, Jan 18, 2022 at 07:31:47AM -0800, John Baldwin wrote: > On 1/17/22 1:13 PM, Mark Johnston wrote: > > The branch main has been updated by markj: > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=706f4a81a81250a326ea25914e7effe1768f1a37 > > > > commit 706f4a81a81250a326ea25914e7effe1768f1a37 > > Author: Mark Johnston <markj@FreeBSD.org> > > AuthorDate: 2022-01-17 16:42:28 +0000 > > Commit: Mark Johnston <markj@FreeBSD.org> > > CommitDate: 2022-01-17 21:11:54 +0000 > > > > exec: Introduce the PROC_PS_STRINGS() macro > > > > Rather than fetching the ps_strings address directly from a process' > > sysentvec, use this macro. With stack address randomization the > > ps_strings address is no longer fixed. > > > > Reviewed by: kib > > MFC after: 2 weeks > > Sponsored by: The FreeBSD Foundation > > Differential Revision: https://reviews.freebsd.org/D33704 > > FWIW, in CheriBSD we have a 'p_psstrings' member in struct proc that is a pointer > to the ps_strings structure in user space that is set by the ABI during exec. I did the exact same thing in an earlier version of the patch. It ended up being more useful to keep the stacktop address, and to derive the ps_strings address from that. I would like to MFC this as well, and that'll be easier without having modified the layout of struct proc. > CHERI removes the need for ASLR, but due to alignment requirements of capabilities > the stack is not a fixed location as its address can vary based on the size. Is it possible to use PROC_PS_STRINGS() there?
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