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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-12-03 10:50:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-12-03 10:50:14 -0800 |
| commit | a2aeaeabbc9a1fbfb22d23539ae315cf52f09a0a (patch) | |
| tree | 4a9954a44ad3a676c3ecb4fcb7a49c5e5f08b022 /Documentation | |
| parent | f66062c7491b0f861ba1ee9c767c860fd615b2c3 (diff) | |
| parent | 35b6b28e69985eafb20b3b2c7bd6eca452b56b53 (diff) | |
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon:
"Three arm64 fixes for -rc4.
One of them is just a trivial documentation fix, whereas the other two
address a warning in the kexec code and a crash in ftrace on systems
implementing BTI.
The latter patch has a couple of ugly ifdefs which Mark plans to clean
up separately, but as-is the patch is straightforward for backporting
to stable kernels.
Summary:
- Add missing BTI landing instructions to the ftrace*_caller
trampolines
- Fix kexec() WARN when DEBUG_VIRTUAL is enabled
- Fix PAC documentation by removing stale references to compiler
flags"
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: ftrace: add missing BTIs
arm64: kexec: use __pa_symbol(empty_zero_page)
arm64: update PAC description for kernel
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/arm64/pointer-authentication.rst | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/Documentation/arm64/pointer-authentication.rst b/Documentation/arm64/pointer-authentication.rst index f127666ea3a8..e5dad2e40aa8 100644 --- a/Documentation/arm64/pointer-authentication.rst +++ b/Documentation/arm64/pointer-authentication.rst @@ -53,11 +53,10 @@ The number of bits that the PAC occupies in a pointer is 55 minus the virtual address size configured by the kernel. For example, with a virtual address size of 48, the PAC is 7 bits wide. -Recent versions of GCC can compile code with APIAKey-based return -address protection when passed the -msign-return-address option. This -uses instructions in the HINT space (unless -march=armv8.3-a or higher -is also passed), and such code can run on systems without the pointer -authentication extension. +When ARM64_PTR_AUTH_KERNEL is selected, the kernel will be compiled +with HINT space pointer authentication instructions protecting +function returns. Kernels built with this option will work on hardware +with or without pointer authentication support. In addition to exec(), keys can also be reinitialized to random values using the PR_PAC_RESET_KEYS prctl. A bitmask of PR_PAC_APIAKEY, |