Merge tag 'probes-v7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes updates from Masami Hiramatsu:
 "Asynchronous optprobe optimizer and cleanups:

   - Make optprobe optimizer multi-generational and asynchronous

     Rework the optimizer as a state machine to avoid calling
     time-consuming synchronize_rcu_tasks() while holding kprobe_mutex,
     text_mutex, and cpus_read_lock(). Uses call_rcu_tasks() and a fixed
     ring of generation slots instead, so locks are only held during the
     brief instruction- patching window

   - Use DEFINE_DEBUGFS_ATTRIBUTE for the kprobes enabled knob

     Replace a hand-rolled debugfs read/write pair (dating from 2007)
     with the proper DEFINE_DEBUGFS_ATTRIBUTE macro, removing dead code
     and the stale XXX comment

  Code quality and documentation cleanups:

   - Add const qualifier to new_argv allocation type in trace_probe.c,
     preparing for the type-aware kmalloc_obj allocator conversion

   - Clarify btf_find_struct_member() container parameter

     Rename the misleading @member_type parameter to @container_type and
     add proper kernel-doc documentation for all parameters and return
     values

  Boot tracing test framework and testcases:

   - Add a generic boot tracing test framework under
     tools/testing/selftests/ftrace/boottime/

     The test runner builds a minimal initramfs with busybox, boots
     QEMU, and runs tracefs checker scripts, supporting bootconfig,
     kernel command-line options, and multi-boot crash/reboot scenarios

   - Add boot-time tracing testcases

     Verify dynamic kprobe, synthetic events, eprobe, fprobe, tprobe,
     and trace instance creation via bootconfig

   - Add kernel cmdline tracing testcases

     Verify ftrace, trace_event, trace_buf_size, trace_options,
     trace_clock, and trace_instance kernel parameters

   - Add persistent ring buffer testcases:

     Verify memory reservation via reserve_mem= and trace data retention
     across guest crash/reboot, as well as backup instance creation and
     boot log preservation

   - Change non-unique test symbol from name_show to init_once in
     kprobe_non_uniq_symbol.tc for more reliable cross-architecture
     testing"

* tag 'probes-v7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace/selftests: Change non-unique test symbol to init_once
  tracing/probes: Clarify btf_find_struct_member() container parameter and add kernel-doc
  kprobes: Make optprobe optimizer multi-generational and asynchronous
  tracing/probes: Add const to new_argv allocation type
  kprobes: use DEFINE_DEBUGFS_ATTRIBUTE for the enabled knob
  selftests/ftrace: Add persistent ring buffer testcases
  selftests/ftrace: Add kernel cmdline tracing testcases
  selftests/ftrace: Add boot-time tracing testcases
  selftests/ftrace: Add generic boot tracing test framework

3 files changed, 30 insertions, 15 deletions

diff --git a/kernel/trace/trace_btf.c b/kernel/trace/trace_btf.c
index adefd3969b1b..f0e0c04d58d9 100644
--- a/kernel/trace/trace_btf.c
+++ b/kernel/trace/trace_btf.c
@@ -63,19 +63,33 @@ struct btf_anon_stack {
 	u32 offset;
 };
 
-/*
- * Find a member of data structure/union by name and return it.
- * Return NULL if not found, or ERR_PTR(-EINVAL) if parameter is invalid.
- * If the member is a member of an anonymous union/structure, the bit offset
- * of that anonymous union/structure is stored into @anon_offset.
- * If @member_type is non-NULL, the actual containing structure/union type
- * of the found member is stored into @member_type.
+/**
+ * btf_find_struct_member() - Find a member of data structure/union by name
+ * @btf: Pointer to BTF object.
+ * @type: Pointer to the struct/union BTF type to search within.
+ * @member_name: Name of the member to find.
+ * @anon_offset: Pointer to store bit offset of enclosing anonymous union/struct.
+ * @container_type: Pointer to store the actual containing struct/union type.
+ *
+ * Find a member of data structure/union by name, traversing into anonymous
+ * unions and structures if necessary.
+ *
+ * If the member is inside an anonymous union/structure, the bit offset
+ * of that anonymous union/structure from @type is stored into @anon_offset.
+ * If @container_type is non-NULL, the actual struct/union BTF type that
+ * directly contains the found member is stored into @container_type.
+ *
+ * Return:
+ * * Pointer to &struct btf_member on success.
+ * * %NULL if the member was not found.
+ * * %ERR_PTR(-EINVAL) if @type is not a struct/union.
+ * * %ERR_PTR(-ENOMEM) if memory allocation failed.
  */
 const struct btf_member *btf_find_struct_member(struct btf *btf,
 						const struct btf_type *type,
 						const char *member_name,
 						u32 *anon_offset,
-						const struct btf_type **member_type)
+						const struct btf_type **container_type)
 {
 	struct btf_anon_stack *anon_stack;
 	const struct btf_member *member;
@@ -107,8 +121,8 @@ retry:
 			if (name && !strcmp(member_name, name)) {
 				if (anon_offset)
 					*anon_offset = cur_offset;
-				if (member_type)
-					*member_type = type;
+				if (container_type)
+					*container_type = type;
 				goto out;
 			}
 		}
diff --git a/kernel/trace/trace_btf.h b/kernel/trace/trace_btf.h
index 20cbc3d4ae0e..b3d408e6a7f6 100644
--- a/kernel/trace/trace_btf.h
+++ b/kernel/trace/trace_btf.h
@@ -18,7 +18,8 @@ const struct btf_member *btf_find_struct_member(struct btf *btf,
 						const struct btf_type *type,
 						const char *member_name,
 						u32 *anon_offset,
-						const struct btf_type **member_type);
+						const struct btf_type **container_type);
+
 #ifdef CONFIG_DEBUG_INFO_BTF
 void btf_trim_retval(unsigned long func, unsigned long *retval, bool *print_retval,
 		     int *fmt, bool hex);
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 88518c5322a5..a880a90642d7 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -625,7 +625,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty
 {
 	const struct btf_type *type = *ptype;
 	const struct btf_member *field;
-	const struct btf_type *mtype;
+	const struct btf_type *container_type;
 	struct btf *btf = ctx_btf(ctx);
 	char *fieldname = *pfieldname;
 	int bitoffs = 0;
@@ -641,7 +641,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty
 
 		anon_offs = 0;
 		field = btf_find_struct_member(btf, type, fieldname,
-						&anon_offs, &mtype);
+						&anon_offs, &container_type);
 		if (IS_ERR(field)) {
 			trace_probe_log_err(ctx->offset, BAD_BTF_TID);
 			return PTR_ERR(field);
@@ -654,7 +654,7 @@ static int get_bitoffset_of_field(char **pfieldname, const struct btf_type **pty
 		bitoffs += anon_offs;
 
 		/* Accumulate the bit-offsets of the dot-connected fields */
-		if (btf_type_kflag(mtype)) {
+		if (btf_type_kflag(container_type)) {
 			bitoffs += BTF_MEMBER_BIT_OFFSET(field->offset);
 			ctx->last_bitsize = BTF_MEMBER_BITFIELD_SIZE(field->offset);
 		} else {
@@ -2315,7 +2315,7 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
 	else
 		*new_argc = argc;
 
-	new_argv = kcalloc(*new_argc, sizeof(char *), GFP_KERNEL);
+	new_argv = kcalloc(*new_argc, sizeof(*new_argv), GFP_KERNEL);
 	if (!new_argv)
 		return ERR_PTR(-ENOMEM);