Re: [PATCH 3/3] mm: Care about shadow stack guard gap when getting an unmapped area
Deepak Gupta <[email protected]>
| Newsgroups | gmane.linux.ports.parisc,gmane.linux.ports.arm.kernel,gmane.linux.ports.alpha,gmane.linux.kernel,gmane.linux.kernel.arc,gmane.linux.ports.ppc64.devel,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 08:57:20PM +0100, Mark Brown wrote: >On Tue, Sep 03, 2024 at 03:41:49PM -0400, Liam R. Howlett wrote: >> * Mark Brown <[email protected]> [240902 15:09]: > >> > +static inline unsigned long stack_guard_placement(vm_flags_t vm_flags) >> > +{ >> > + if (vm_flags & VM_SHADOW_STACK) >> > + return PAGE_SIZE; > >> Is PAGE_SIZE is enough? > >It's what x86 currently uses so it'll be no worse off if it gets moved >to the generic code (there's a comment in the arch code explaing what's >needed there) and it's enough for arm64, we only do single record >pushes/pops or (optionally) writes to unconstrained addresses. It's enough for RISC-V too.