Date: Wed, 7 Nov 2018 14:23:23 -0800 From: Mark Millard <marklmi@yahoo.com> To: John Baldwin <jhb@freebsd.org>, svn-src-head@freebsd.org Subject: Re: svn commit: r340231 - head/sys/kern Message-ID: <F4A4E491-0792-409B-BFF9-C7BE8C8B7B87@yahoo.com>
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John Baldwin jhb at FreeBSD.org wrote on Wed Nov 7 21:36:02 UTC 2018 : > On 11/7/18 1:01 PM, Ed Schouten wrote: > > Op wo 7 nov. 2018 om 19:32 schreef John Baldwin <jhb at = freebsd.org>: > >> Modified: head/sys/kern/imgact_elf.c > >> = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D > >> --- head/sys/kern/imgact_elf.c Wed Nov 7 18:29:54 2018 = (r340230) > >> +++ head/sys/kern/imgact_elf.c Wed Nov 7 18:32:02 2018 = (r340231) > >> @@ -120,7 +120,8 @@ SYSCTL_INT(_debug, OID_AUTO, = __elfN(legacy_coredump), > >> > >> int __elfN(nxstack) =3D > >> #if defined(__amd64__) || defined(__powerpc64__) /* both 64 and 32 = bit */ || \ > >> - (defined(__arm__) && __ARM_ARCH >=3D 7) || = defined(__aarch64__) > >> + (defined(__arm__) && __ARM_ARCH >=3D 7) || = defined(__aarch64__) || \ > >> + defined(__riscv) > >> 1; > >> #else > >> 0; > >=20 > > Are we getting to the point that it might make sense to invert this > > logic, i.e., just list the architectures that require executable > > stacks? >=20 > It's not clear. The remaining set is i386 (should be able to use = nxstack > when using PAE and PG_NX is supported), MIPS (no X permission in = PTEs), > 32-bit powerpc (no X permissions in PTEs AFAICT), and sparc64 (no X > permissions in PTEs AFAICT). For architectures without X ptes, = removing > VM_PROT_EXECUTE from the stack permissions is a no-op and would be > harmless, so we could perhaps just default this to always on at this > point? FreeBSD for 32-bit powerpc can also run on powerpc64 hardware, something I commonly do with 32-bit powerpc FreeBSD. So I'm not sure if some of the powerpc64 context sometimes applies for such use or not. May be the mode of use is as-if it was limited like 32-bit powerpc hardware for what you propose? I do not now if i386 or mips have the same sort of question relative to use on 64-bit capable hardware. =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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