Re: [PATCH 3/3] mm: Care about shadow stack guard gap when getting an unmapped area
Mark Brown <[email protected]>
| Newsgroups | gmane.linux.ports.ppc.embedded,gmane.linux.ports.arm.kernel,gmane.linux.ports.alpha,gmane.linux.kernel,gmane.linux.kernel.arc,gmane.linux.ports.parisc,gmane.linux.ports.sh.devel,gmane.linux.ports.sparc,gmane.linux.kernel.mm |
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| Message-ID | <[email protected]> |
On Tue, Sep 03, 2024 at 06:49:46PM +0100, Lorenzo Stoakes wrote: > On Mon, Sep 02, 2024 at 08:08:15PM GMT, Mark Brown wrote: > > On x86 there is a custom arch_get_unmapped_area() which was updated by the > > above commit to cover this case by specifying a start_gap for allocations > > with VM_SHADOW_STACK. Both arm64 and RISC-V have equivalent features and > > use the generic implementation of arch_get_unmapped_area() so let's make > > the equivalent change there so they also don't get shadow stack pages > > placed without guard pages. > Don't you need to unwind that change in x86 now you're doing it in generic code? No, x86 had a preexisting custom implementation for some other reason (hence the "updated by the above commit" part above) - the shadow stack support would most likely have been added in the core in the first place were it not for that.
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