path: root/Makefile
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authorKees Cook <>2021-04-01 16:23:46 -0700
committerThomas Gleixner <>2021-04-08 14:12:19 +0200
commit70918779aec9bd01d16f4e6e800ffe423d196021 (patch)
tree55ba55366efd83242e4ddfe44dcc6f48fe8d78d8 /Makefile
parent68ef8735d253f3d840082b78f996bf2d89ee6e5f (diff)
arm64: entry: Enable random_kstack_offset support
Allow for a randomized stack offset on a per-syscall basis, with roughly 5 bits of entropy. (And include AAPCS rationale AAPCS thanks to Mark Rutland.) In order to avoid unconditional stack canaries on syscall entry (due to the use of alloca()), also disable stack protector to avoid triggering needless checks and slowing down the entry path. As there is no general way to control stack protector coverage with a function attribute[1], this must be disabled at the compilation unit level. This isn't a problem here, though, since stack protector was not triggered before: examining the resulting syscall.o, there are no changes in canary coverage (none before, none now). [1] a working __attribute__((no_stack_protector)) has been added to GCC and Clang but has not been released in any version yet:;h=346b302d09c1e6db56d9fe69048acb32fbb97845 Signed-off-by: Kees Cook <> Signed-off-by: Thomas Gleixner <> Acked-by: Will Deacon <> Link:
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