path: root/Documentation/arm64
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authorKuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>2021-12-01 11:40:10 +0800
committerWill Deacon <will@kernel.org>2021-12-02 10:13:35 +0000
commitce39d473d1edd6914e1eed097deb0c0612baa8f6 (patch)
tree7769dfb833bd3b1e2e94f45991bb749bf0104104 /Documentation/arm64
parentarm64: uaccess: avoid blocking within critical sections (diff)
arm64: update PAC description for kernel
Remove the paragraph which has nothing to do with the kernel and add PAC description related to kernel. Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com> Link: https://lore.kernel.org/r/20211201034014.20048-1-Kuan-Ying.Lee@mediatek.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Documentation/arm64')
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,