Merge: livepatch: backport v6.17 updates to rhel-10.2

CKI KWF Bot · CKI KWF Bot · commit 5861304247c0 · 2025-11-20T11:13:14.000Z
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/1571 JIRA: https://issues.redhat.com/browse/RHEL-114915 Depends: !1424 - selftests: livepatch: test if ftrace can trace a livepatched function (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] - selftests: livepatch: add new ftrace helpers functions (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] - samples/livepatch: add module descriptions (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] - selftest/livepatch: Only run test-kprobe with CONFIG_KPROBES_ON_FTRACE (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] - docs: livepatch: move text out of code block (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] - livepatch: Add comment to clarify klp_add_nops() (Rado Vrbovsky) [[RHEL-114915](https://issues.redhat.com/browse/RHEL-114915)] Signed-off-by: Rado Vrbovsky <rvrbovsk@redhat.com> Approved-by: Joe Lawrence <joe.lawrence@redhat.com> Approved-by: Yannick Cote <ycote@redhat.com> Approved-by: Josh Poimboeuf <jpoimboe@redhat.com> Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com> Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>
diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst
@@ -217,16 +217,19 @@ livepatch relocation section refer to their respective symbols with their symbol
 indices, and the original symbol indices (and thus the symtab ordering) must be
 preserved in order for apply_relocate_add() to find the right symbol.
 
-For example, take this particular rela from a livepatch module:::
+For example, take this particular rela from a livepatch module::
 
   Relocation section '.klp.rela.btrfs.text.btrfs_feature_attr_show' at offset 0x2ba0 contains 4 entries:
       Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
   000000000000001f  0000005e00000002 R_X86_64_PC32          0000000000000000 .klp.sym.vmlinux.printk,0 - 4
 
-  This rela refers to the symbol '.klp.sym.vmlinux.printk,0', and the symbol index is encoded
-  in 'Info'. Here its symbol index is 0x5e, which is 94 in decimal, which refers to the
-  symbol index 94.
-  And in this patch module's corresponding symbol table, symbol index 94 refers to that very symbol:
+This rela refers to the symbol '.klp.sym.vmlinux.printk,0', and the symbol
+index is encoded in 'Info'. Here its symbol index is 0x5e, which is 94 in
+decimal, which refers to the symbol index 94.
+
+And in this patch module's corresponding symbol table, symbol index 94 refers
+to that very symbol::
+
   [ snip ]
   94: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT OS [0xff20] .klp.sym.vmlinux.printk,0
   [ snip ]
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
@@ -601,9 +601,12 @@ static int klp_add_object_nops(struct klp_patch *patch,
 }
 
 /*
- * Add 'nop' functions which simply return to the caller to run
- * the original function. The 'nop' functions are added to a
- * patch to facilitate a 'replace' mode.
+ * Add 'nop' functions which simply return to the caller to run the
+ * original function.
+ *
+ * They are added only when the atomic replace mode is used and only for
+ * functions which are currently livepatched but are no longer included
+ * in the new livepatch.
  */
 static int klp_add_nops(struct klp_patch *patch)
 {
diff --git a/samples/livepatch/livepatch-callbacks-busymod.c b/samples/livepatch/livepatch-callbacks-busymod.c
@@ -56,4 +56,5 @@ static void livepatch_callbacks_mod_exit(void)
 
 module_init(livepatch_callbacks_mod_init);
 module_exit(livepatch_callbacks_mod_exit);
+MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks, support module");
 MODULE_LICENSE("GPL");
diff --git a/samples/livepatch/livepatch-callbacks-demo.c b/samples/livepatch/livepatch-callbacks-demo.c
@@ -192,5 +192,6 @@ static void livepatch_callbacks_demo_exit(void)
 
 module_init(livepatch_callbacks_demo_init);
 module_exit(livepatch_callbacks_demo_exit);
+MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks");
 MODULE_LICENSE("GPL");
 MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-callbacks-mod.c b/samples/livepatch/livepatch-callbacks-mod.c
@@ -38,4 +38,5 @@ static void livepatch_callbacks_mod_exit(void)
 
 module_init(livepatch_callbacks_mod_init);
 module_exit(livepatch_callbacks_mod_exit);
+MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks, support module");
 MODULE_LICENSE("GPL");
diff --git a/samples/livepatch/livepatch-sample.c b/samples/livepatch/livepatch-sample.c
@@ -66,5 +66,6 @@ static void livepatch_exit(void)
 
 module_init(livepatch_init);
 module_exit(livepatch_exit);
+MODULE_DESCRIPTION("Kernel Live Patching Sample Module");
 MODULE_LICENSE("GPL");
 MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
@@ -168,5 +168,6 @@ static void livepatch_shadow_fix1_exit(void)
 
 module_init(livepatch_shadow_fix1_init);
 module_exit(livepatch_shadow_fix1_exit);
+MODULE_DESCRIPTION("Live patching demo for shadow variables");
 MODULE_LICENSE("GPL");
 MODULE_INFO(livepatch, "Y");
diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c
@@ -128,5 +128,6 @@ static void livepatch_shadow_fix2_exit(void)
 
 module_init(livepatch_shadow_fix2_init);
 module_exit(livepatch_shadow_fix2_exit);
+MODULE_DESCRIPTION("Live patching demo for shadow variables");
 MODULE_LICENSE("GPL");
 MODULE_INFO(livepatch, "Y");
diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
@@ -10,6 +10,7 @@ SYSFS_KERNEL_DIR="/sys/kernel"
 SYSFS_KLP_DIR="$SYSFS_KERNEL_DIR/livepatch"
 SYSFS_DEBUG_DIR="$SYSFS_KERNEL_DIR/debug"
 SYSFS_KPROBES_DIR="$SYSFS_DEBUG_DIR/kprobes"
+SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing"
 
 # Kselftest framework requirement - SKIP code is 4
 ksft_skip=4
@@ -62,6 +63,9 @@ function push_config() {
 			awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
 	FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
 	KPROBE_ENABLED=$(cat "$SYSFS_KPROBES_DIR/enabled")
+	TRACING_ON=$(cat "$SYSFS_TRACING_DIR/tracing_on")
+	CURRENT_TRACER=$(cat "$SYSFS_TRACING_DIR/current_tracer")
+	FTRACE_FILTER=$(cat "$SYSFS_TRACING_DIR/set_ftrace_filter")
 }
 
 function pop_config() {
@@ -74,6 +78,17 @@ function pop_config() {
 	if [[ -n "$KPROBE_ENABLED" ]]; then
 		echo "$KPROBE_ENABLED" > "$SYSFS_KPROBES_DIR/enabled"
 	fi
+	if [[ -n "$TRACING_ON" ]]; then
+		echo "$TRACING_ON" > "$SYSFS_TRACING_DIR/tracing_on"
+	fi
+	if [[ -n "$CURRENT_TRACER" ]]; then
+		echo "$CURRENT_TRACER" > "$SYSFS_TRACING_DIR/current_tracer"
+	fi
+	if [[ -n "$FTRACE_FILTER" ]]; then
+		echo "$FTRACE_FILTER" \
+			| sed -e "/#### all functions enabled ####/d" \
+			> "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	fi
 }
 
 function set_dynamic_debug() {
@@ -352,3 +367,37 @@ function check_sysfs_value() {
 		die "Unexpected value in $path: $expected_value vs. $value"
 	fi
 }
+
+# cleanup_tracing() - stop and clean up function tracing
+function cleanup_tracing() {
+	echo 0 > "$SYSFS_TRACING_DIR/tracing_on"
+	echo "" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	echo "nop" > "$SYSFS_TRACING_DIR/current_tracer"
+	echo "" > "$SYSFS_TRACING_DIR/trace"
+}
+
+# trace_function(function) - start tracing of a function
+#	function - to be traced function
+function trace_function() {
+	local function="$1"; shift
+
+	cleanup_tracing
+
+	echo "function" > "$SYSFS_TRACING_DIR/current_tracer"
+	echo "$function" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	echo 1 > "$SYSFS_TRACING_DIR/tracing_on"
+}
+
+# check_traced_functions(functions...) - check whether each function appeared in the trace log
+#	functions - list of functions to be checked
+function check_traced_functions() {
+	local function
+
+	for function in "$@"; do
+		if ! grep -Fwq "$function" "$SYSFS_TRACING_DIR/trace" ; then
+			die "Function ($function) did not appear in the trace"
+		fi
+	done
+
+	cleanup_tracing
+}
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -61,4 +61,38 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH"
 
 
+# - verify livepatch can load
+# - check if traces have a patched function
+# - reset trace and unload livepatch
+
+start_test "trace livepatched function and check that the live patch remains in effect"
+
+FUNCTION_NAME="livepatch_cmdline_proc_show"
+
+load_lp $MOD_LIVEPATCH
+trace_function "$FUNCTION_NAME"
+
+if [[ "$(cat /proc/cmdline)" == "$MOD_LIVEPATCH: this has been live patched" ]] ; then
+	log "livepatch: ok"
+fi
+
+check_traced_functions "$FUNCTION_NAME"
+
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+livepatch: ok
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH"
+
 exit 0
diff --git a/tools/testing/selftests/livepatch/test-kprobe.sh b/tools/testing/selftests/livepatch/test-kprobe.sh
@@ -5,6 +5,8 @@
 
 . $(dirname $0)/functions.sh
 
+grep -q kprobe_ftrace_ops /proc/kallsyms || skip "test-kprobe requires CONFIG_KPROBES_ON_FTRACE"
+
 MOD_LIVEPATCH=test_klp_livepatch
 MOD_KPROBE=test_klp_kprobe
 
