Date: Tue, 10 Oct 2023 09:53:15 GMT From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: d09a64e15d8f - main - arm64: Enable kernel branch protection Message-ID: <202310100953.39A9rFWk036835@gitrepo.freebsd.org>
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The branch main has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=d09a64e15d8fad6588b9aad62979f20afa8441df commit d09a64e15d8fad6588b9aad62979f20afa8441df Author: Andrew Turner <andrew@FreeBSD.org> AuthorDate: 2023-10-02 15:55:31 +0000 Commit: Andrew Turner <andrew@FreeBSD.org> CommitDate: 2023-10-10 09:52:16 +0000 arm64: Enable kernel branch protection Add the build flags to enable branch protection on arm64. This enable the use of PAC and BTI in the kernel. For PAC we already install the kernel keys when entering the kernel from userspace so this will start using these to sign the stack. For BTI we need to mark the kernel page tables with a new guarded page field. As this will require all code that could be reached through a function pointer with an appropriate branch target instruction we are enabling this before setting the field. As the pointer authentication support shouldn't be reached via a function pointer it is safe to not enable the use of BTI there. Reviewed by: markj Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D42079 --- sys/conf/kern.mk | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk index b508bc81b5f0..72b7387d3959 100644 --- a/sys/conf/kern.mk +++ b/sys/conf/kern.mk @@ -140,6 +140,8 @@ INLINE_LIMIT?= 8000 CFLAGS += -mgeneral-regs-only # Reserve x18 for pcpu data CFLAGS += -ffixed-x18 +# Build with BTI+PAC +CFLAGS += -mbranch-protection=standard INLINE_LIMIT?= 8000 .endif
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