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authorMark Brown <broonie@kernel.org>2022-01-27 22:03:23 +0300
committerWill Deacon <will@kernel.org>2022-02-15 19:00:09 +0300
commit4c022f57ad954e1ad6f838bd3b7d54e459745eeb (patch)
tree267a25c32e8746c79a67dbe82b83a7ecb3b1075f /Documentation/arm64
parentb8ac4ee08d48d4bb46669a2deef10454313e1a00 (diff)
downloadlinux-4c022f57ad954e1ad6f838bd3b7d54e459745eeb.tar.xz
arm64/mte: Clarify mode reported by PR_GET_TAGGED_ADDR_CTRL
With the current wording readers might infer that PR_GET_TAGGED_ADDR_CTRL will report the mode currently active in the thread however this is not the actual behaviour, instead all modes currently selected by the process will be reported with the mode used depending on the combination of the requested modes and the default set for the current CPU. This has been the case since 433c38f40f6a81 ("arm64: mte: change ASYNC and SYNC TCF settings into bitfields"), before that we did not allow more than one mode to be requested simultaneously. Update the documentation to more clearly reflect current behaviour. Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220127190324.660405-1-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'Documentation/arm64')
-rw-r--r--Documentation/arm64/memory-tagging-extension.rst5
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/arm64/memory-tagging-extension.rst b/Documentation/arm64/memory-tagging-extension.rst
index 7b99c8f428eb..a0ab2f65b235 100644
--- a/Documentation/arm64/memory-tagging-extension.rst
+++ b/Documentation/arm64/memory-tagging-extension.rst
@@ -91,8 +91,9 @@ mode is specified, the program will run in that mode. If multiple
modes are specified, the mode is selected as described in the "Per-CPU
preferred tag checking modes" section below.
-The current tag check fault mode can be read using the
-``prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)`` system call.
+The current tag check fault configuration can be read using the
+``prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)`` system call. If
+multiple modes were requested then all will be reported.
Tag checking can also be disabled for a user thread by setting the
``PSTATE.TCO`` bit with ``MSR TCO, #1``.