[PATCH bpf-next v2 3/6] docs/procfs: Document KALLSYMS_QUERY ioctl on /proc/kallsyms

[Samuel Wu <wusamuel@google.com>]

Document the existence of the KALLSYMS_QUERY ioctl() in the section
describing the /proc/kallsyms file. Refer the user to the UAPI header
for low-level details of this programmatic interface. Add a "kallsyms"
row to the /proc file table.

Signed-off-by: Samuel Wu <wusamuel@google.com>
---
 Documentation/filesystems/proc.rst | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index c102b62023cd..a0e2fe14a01a 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -761,6 +761,7 @@ files are there, and which are missing.
  ioports      I/O port usage
  irq 	      Masks for irq to cpu affinity			(2.4)(smp?)
  isapnp       ISA PnP (Plug&Play) Info				(2.4)
+ kallsyms     Kernel symbol table with dynamic queries (see text)
  kcore        Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
  kmsg         Kernel messages
  ksyms        Kernel symbol table
@@ -1368,6 +1369,20 @@ Provides counts of softirq handlers serviced since boot time, for each CPU.
     HRTIMER:         0          0          0          0
 	RCU:      1678       1769       2178       2250
 
+
+kallsyms
+~~~~~~~~
+
+The /proc/kallsyms file lists all symbols in vmlinux and loaded modules.
+
+In addition to sequential text reading, /proc/kallsyms provides an ioctl()-based
+API (`KALLSYMS_QUERY`) for querying specific symbols and addresses. This
+interface is binary and is meant for efficient extraction of data without
+parsing the entire text file. `struct kallsyms_query`, defined in the
+linux/fs.h UAPI header, serves as the input/output argument to the
+`KALLSYMS_QUERY` ioctl() command. See comments in the linux/fs.h UAPI header
+for details on query semantics, supported flags, and return values.
+
 1.3 Networking info in /proc/net
 --------------------------------
 
-- 
2.56.0.257.gf7497c7d27-goog