[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <e827138f9d8800e3db158831bca88d1ea8b559af.camel@intel.com>
Date: Mon, 31 Jul 2023 23:19:34 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "broonie@...nel.org" <broonie@...nel.org>
CC: "corbet@....net" <corbet@....net>,
"ardb@...nel.org" <ardb@...nel.org>,
"keescook@...omium.org" <keescook@...omium.org>,
"shuah@...nel.org" <shuah@...nel.org>,
"Szabolcs.Nagy@....com" <Szabolcs.Nagy@....com>,
"maz@...nel.org" <maz@...nel.org>,
"james.morse@....com" <james.morse@....com>,
"debug@...osinc.com" <debug@...osinc.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"catalin.marinas@....com" <catalin.marinas@....com>,
"hjl.tools@...il.com" <hjl.tools@...il.com>,
"paul.walmsley@...ive.com" <paul.walmsley@...ive.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
"oleg@...hat.com" <oleg@...hat.com>,
"arnd@...db.de" <arnd@...db.de>,
"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
"will@...nel.org" <will@...nel.org>,
"suzuki.poulose@....com" <suzuki.poulose@....com>,
"kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
"oliver.upton@...ux.dev" <oliver.upton@...ux.dev>,
"linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
"palmer@...belt.com" <palmer@...belt.com>
Subject: Re: [PATCH v3 21/36] arm64/mm: Implement map_shadow_stack()
On Mon, 2023-07-31 at 18:06 +0100, Mark Brown wrote:
> > Someday when the x86 side is finally upstream I have a manpage for
> > map_shadow_stack. Any differences on the arm side would need to be
> > documented, but I'm not sure why there should be any differences.
> > Like,
> > why not use the same flags? Or have a new flag for token+end marker
> > that x86 can use as well?
>
> Ah, it wasn't clear to me that this was a question rather than just
> open decisions about the eventual manpage. Looking again I think
> what
> you're asking about is that I see that at some point in development I
> lost the SHADOW_STACK_SET_TOKEN flag which x86 has. I suspect that
> was
> a rebasing issue as it wasn't a deliberate decision, there's no
> reason
> we couldn't have that. Other than that and the fact that we add both
> a
> stack swap token and a top of stack marker I'm not aware of any
> differences.
The thing I was trying to get at was, we have this shared syscall that
means create shadow stack memory and prepopulate it like this flag
says. On x86 we optionally support SHADOW_STACK_SET_TOKEN which means
put a token right at the end of size. So maybe arm should have a
different flag value that includes putting the marker and then the
token, and x86 could match it someday if we get markers too.
It could be a different flag, like SHADOW_STACK_SET_TOKEN_MARKER, or it
could be SHADOW_STACK_SET_MARKER, and callers could pass
(SHADOW_STACK_SET_TOKEN | SHADOW_STACK_SET_MARKER) to get what you have
implemented here. What do you think?
Powered by blists - more mailing lists