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authorStephen Kitt <steve@sk2.org>2020-05-15 23:24:44 +0200
committerJonathan Corbet <corbet@lwn.net>2020-05-25 18:59:59 -0600
commit997c798e1444ad02e8af8b18c869fff5c61867da (patch)
treec59a8893adf9e6484c714e8faa9aa22407e64a5e
parent4eb9241127a0b5ac3aaaf1b246728009527ebc86 (diff)
downloadlinux-997c798e1444ad02e8af8b18c869fff5c61867da.tar.bz2
docs: sysctl/kernel: document unaligned controls
This documents ignore-unaligned-usertrap, unaligned-dump-stack, and unaligned-trap, based on arch/arc/kernel/unaligned.c, arch/ia64/kernel/unaligned.c, and arch/parisc/kernel/unaligned.c. While we're at it, integrate unaligned-memory-access.txt into the docs tree. Signed-off-by: Stephen Kitt <steve@sk2.org> Link: https://lore.kernel.org/r/20200515212443.5012-1-steve@sk2.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
-rw-r--r--Documentation/admin-guide/sysctl/kernel.rst51
-rw-r--r--Documentation/process/index.rst1
-rw-r--r--Documentation/process/unaligned-memory-access.rst (renamed from Documentation/unaligned-memory-access.txt)0
3 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 6b313b6d42d5..4752d9a79235 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -402,6 +402,25 @@ Controls whether the panic kmsg data should be reported to Hyper-V.
= =========================================================
+ignore-unaligned-usertrap
+=========================
+
+On architectures where unaligned accesses cause traps, and where this
+feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN``;
+currently, ``arc`` and ``ia64``), controls whether all unaligned traps
+are logged.
+
+= =============================================================
+0 Log all unaligned accesses.
+1 Only warn the first time a process traps. This is the default
+ setting.
+= =============================================================
+
+See also `unaligned-trap`_ and `unaligned-dump-stack`_. On ``ia64``,
+this allows system administrators to override the
+``IA64_THREAD_UAC_NOPRINT`` ``prctl`` and avoid logs being flooded.
+
+
kexec_load_disabled
===================
@@ -1261,6 +1280,38 @@ See :doc:`/admin-guide/kernel-parameters` and
:doc:`/trace/boottime-trace`.
+.. _unaligned-dump-stack:
+
+unaligned-dump-stack (ia64)
+===========================
+
+When logging unaligned accesses, controls whether the stack is
+dumped.
+
+= ===================================================
+0 Do not dump the stack. This is the default setting.
+1 Dump the stack.
+= ===================================================
+
+See also `ignore-unaligned-usertrap`_.
+
+
+unaligned-trap
+==============
+
+On architectures where unaligned accesses cause traps, and where this
+feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW``; currently,
+``arc`` and ``parisc``), controls whether unaligned traps are caught
+and emulated (instead of failing).
+
+= ========================================================
+0 Do not emulate unaligned accesses.
+1 Emulate unaligned accesses. This is the default setting.
+= ========================================================
+
+See also `ignore-unaligned-usertrap`_.
+
+
unknown_nmi_panic
=================
diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst
index 6399d92f0b21..f07c9250c3ac 100644
--- a/Documentation/process/index.rst
+++ b/Documentation/process/index.rst
@@ -61,6 +61,7 @@ lack of a better place.
botching-up-ioctls
clang-format
../riscv/patch-acceptance
+ unaligned-memory-access
.. only:: subproject and html
diff --git a/Documentation/unaligned-memory-access.txt b/Documentation/process/unaligned-memory-access.rst
index 1ee82419d8aa..1ee82419d8aa 100644
--- a/Documentation/unaligned-memory-access.txt
+++ b/Documentation/process/unaligned-memory-access.rst