kprobes: Add perf ksymbol events for kprobe insn pages

Symbols are needed for tools to describe instruction addresses. Pages
allocated for kprobe's purposes need symbols to be created for them.
Add such symbols to be visible via perf ksymbol events.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20200512121922.8997-5-adrian.hunter@intel.com

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index e5bee6c17b86818b0e058545f61340cf91f385e9..e1a4179144a136fd5126fdb688c5d2431e71ef23 100644 (file)
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1049,6 +1049,11 @@ enum perf_event_type {
 enum perf_record_ksymbol_type {
        PERF_RECORD_KSYMBOL_TYPE_UNKNOWN        = 0,
        PERF_RECORD_KSYMBOL_TYPE_BPF            = 1,
+       /*
+        * Out of line code such as kprobe-replaced instructions or optimized
+        * kprobes.
+        */
+       PERF_RECORD_KSYMBOL_TYPE_OOL            = 2,
        PERF_RECORD_KSYMBOL_TYPE_MAX            /* non-ABI */
 };
 

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 058c0be3464beea117c6c5d2722cb569dcb94d44..2b58740ca0f356cab59f681dd210cb9d7b0431ca 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -35,6 +35,7 @@
 #include <linux/ftrace.h>
 #include <linux/cpu.h>
 #include <linux/jump_label.h>
+#include <linux/perf_event.h>
 
 #include <asm/sections.h>
 #include <asm/cacheflush.h>
@@ -184,6 +185,10 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
        kip->cache = c;
        list_add_rcu(&kip->list, &c->pages);
        slot = kip->insns;
+
+       /* Record the perf ksymbol register event after adding the page */
+       perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns,
+                          PAGE_SIZE, false, c->sym);
 out:
        mutex_unlock(&c->mutex);
        return slot;
@@ -202,6 +207,13 @@ static int collect_one_slot(struct kprobe_insn_page *kip, int idx)
                 * next time somebody inserts a probe.
                 */
                if (!list_is_singular(&kip->list)) {
+                       /*
+                        * Record perf ksymbol unregister event before removing
+                        * the page.
+                        */
+                       perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
+                                          (unsigned long)kip->insns, PAGE_SIZE, true,
+                                          kip->cache->sym);
                        list_del_rcu(&kip->list);
                        synchronize_rcu();
                        kip->cache->free(kip->insns);