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authorLinus Torvalds <torvalds@linux-foundation.org>2025-03-27 19:26:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2025-03-27 19:26:10 -0700
commitdcf9f31c62b3d31c033ee5bce522855c3d7f56b1 (patch)
tree213e4ba3dcb9a6d0943036d1f37b800946b45e59
parent96050814a3f667eb28dabb78e7b3a7b06e5243e9 (diff)
parentd11f0d172a3c2ea9cbe9b07abd47d5b767600ad9 (diff)
downloadlivepatching-master.tar.gz
Merge tag 'livepatching-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatchingHEADmaster
Pull livepatching updates from Petr Mladek: - Add a selftest for tracing of a livepatched function - Skip a selftest when kprobes are not using ftrace - Some documentation clean up * tag 'livepatching-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: selftests: livepatch: test if ftrace can trace a livepatched function selftests: livepatch: add new ftrace helpers functions selftest/livepatch: Only run test-kprobe with CONFIG_KPROBES_ON_FTRACE docs: livepatch: move text out of code block livepatch: Add comment to clarify klp_add_nops()
Diffstat
-rw-r--r--Documentation/livepatch/module-elf-format.rst13
-rw-r--r--kernel/livepatch/core.c9
-rw-r--r--tools/testing/selftests/livepatch/functions.sh49
-rwxr-xr-xtools/testing/selftests/livepatch/test-ftrace.sh34
-rwxr-xr-xtools/testing/selftests/livepatch/test-kprobe.sh2
5 files changed, 99 insertions, 8 deletions
diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst
index a03ed02ec57e21..5d48778d4dfc2b 100644
--- 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
index 0cd39954d5a10f..4a0fb7978d0dfe 100644
--- 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/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 15601402dee656..46991a029f7c64 100644
--- 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 ($function) did not appear in the trace"
+ fi
+ done
+
+ cleanup_tracing
+}
diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index fe14f248913acb..094176f1a46aee 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -61,4 +61,38 @@ livepatch: '$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
index 115065156016a2..b67dfad03d97f7 100755
--- 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
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-05-18 07:43:54 +0000