docs: cgroup-v2: fix misc.events key format descriptiongrafted

In misc cgroup, misc.events does not output a simple "max" key. Instead,
each registered misc resource outputs a separate key suffixed with ".max"
(i.e., "<res>.max").
Update the documentation to clarify that the entry key is "<res>.max".

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Cheng Lingfei <chenglingfei@foxmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/Documentation/userspace-api/ELF.rst b/Documentation/userspace-api/ELF.rst
new file mode 100644
index 000000000..ac8aeacd4
--- /dev/null
+++ b/Documentation/userspace-api/ELF.rst
@@ -0,0 +1,34 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================
+Linux-specific ELF idiosyncrasies
+=================================
+
+Definitions
+===========
+
+"First" program header is the one with the smallest offset in the file:
+e_phoff.
+
+"Last" program header is the one with the biggest offset in the file:
+e_phoff + (e_phnum - 1) * sizeof(Elf_Phdr).
+
+PT_INTERP
+=========
+
+First PT_INTERP program header is used to locate the filename of ELF
+interpreter. Other PT_INTERP headers are ignored (since Linux 2.4.11).
+
+PT_GNU_STACK
+============
+
+Last PT_GNU_STACK program header defines userspace stack executability
+(since Linux 2.6.6). Other PT_GNU_STACK headers are ignored.
+
+PT_GNU_PROPERTY
+===============
+
+ELF interpreter's last PT_GNU_PROPERTY program header is used (since
+Linux 5.8). If interpreter doesn't have one, then the last PT_GNU_PROPERTY
+program header of an executable is used. Other PT_GNU_PROPERTY headers
+are ignored.