From: Adrian Hunter <adrian.hunter@intel.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Leo Yan <leo.yan@linaro.org>, Jiri Olsa <jolsa@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH V8 03/15] kprobes: Add symbols for kprobe insn pages
Date: Thu, 28 May 2020 11:00:58 +0300 [thread overview]
Message-ID: <20200528080058.20230-1-adrian.hunter@intel.com> (raw)
In-Reply-To: <20200527174345.GB706478@hirez.programming.kicks-ass.net>
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 /proc/kallsyms.
Note: kprobe insn pages are not used if ftrace is configured. To see the
effect of this patch, the kernel must be configured with:
# CONFIG_FUNCTION_TRACER is not set
CONFIG_KPROBES=y
and for optimised kprobes:
CONFIG_OPTPROBES=y
Example on x86:
# perf probe __schedule
Added new event:
probe:__schedule (on __schedule)
# cat /proc/kallsyms | grep '\[__builtin__kprobes\]'
ffffffffc00d4000 t kprobe_insn_page [__builtin__kprobes]
ffffffffc00d6000 t kprobe_optinsn_page [__builtin__kprobes]
Note: This patch adds "__builtin__kprobes" as a module name in
/proc/kallsyms for symbols for pages allocated for kprobes' purposes, even
though "__builtin__kprobes" is not a module.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
Changes in V8:
Move kprobe_cache_get_kallsym() under __ARCH_WANT_KPROBES_INSN_SLOT
include/linux/kprobes.h | 15 ++++++++++++++
kernel/kallsyms.c | 37 +++++++++++++++++++++++++++++----
kernel/kprobes.c | 45 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 93 insertions(+), 4 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 04bdaf01112c..39878bc9bcb0 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -242,6 +242,7 @@ struct kprobe_insn_cache {
struct mutex mutex;
void *(*alloc)(void); /* allocate insn page */
void (*free)(void *); /* free insn page */
+ const char *sym; /* symbol for insn pages */
struct list_head pages; /* list of kprobe_insn_page */
size_t insn_size; /* size of instruction slot */
int nr_garbage;
@@ -272,6 +273,10 @@ static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
{ \
return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \
}
+#define KPROBE_INSN_PAGE_SYM "kprobe_insn_page"
+#define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page"
+int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
+ unsigned long *value, char *type, char *sym);
#else /* __ARCH_WANT_KPROBES_INSN_SLOT */
#define DEFINE_INSN_CACHE_OPS(__name) \
static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
@@ -373,6 +378,11 @@ void dump_kprobe(struct kprobe *kp);
void *alloc_insn_page(void);
void free_insn_page(void *page);
+int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
+ char *sym);
+
+int arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
+ char *type, char *sym);
#else /* !CONFIG_KPROBES: */
static inline int kprobes_built_in(void)
@@ -435,6 +445,11 @@ static inline bool within_kprobe_blacklist(unsigned long addr)
{
return true;
}
+static inline int kprobe_get_kallsym(unsigned int symnum, unsigned long *value,
+ char *type, char *sym)
+{
+ return -ERANGE;
+}
#endif /* CONFIG_KPROBES */
static inline int disable_kretprobe(struct kretprobe *rp)
{
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 16c8c605f4b0..c6cc293c0e67 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -24,6 +24,7 @@
#include <linux/slab.h>
#include <linux/filter.h>
#include <linux/ftrace.h>
+#include <linux/kprobes.h>
#include <linux/compiler.h>
/*
@@ -437,6 +438,7 @@ struct kallsym_iter {
loff_t pos_arch_end;
loff_t pos_mod_end;
loff_t pos_ftrace_mod_end;
+ loff_t pos_bpf_end;
unsigned long value;
unsigned int nameoff; /* If iterating in core kernel symbols. */
char type;
@@ -496,11 +498,33 @@ static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
static int get_ksymbol_bpf(struct kallsym_iter *iter)
{
+ int ret;
+
strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
iter->exported = 0;
- return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
- &iter->value, &iter->type,
- iter->name) < 0 ? 0 : 1;
+ ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
+ &iter->value, &iter->type,
+ iter->name);
+ if (ret < 0) {
+ iter->pos_bpf_end = iter->pos;
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * This uses "__builtin__kprobes" as a module name for symbols for pages
+ * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
+ * module.
+ */
+static int get_ksymbol_kprobe(struct kallsym_iter *iter)
+{
+ strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
+ iter->exported = 0;
+ return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
+ &iter->value, &iter->type,
+ iter->name) < 0 ? 0 : 1;
}
/* Returns space to next name. */
@@ -527,6 +551,7 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
iter->pos_arch_end = 0;
iter->pos_mod_end = 0;
iter->pos_ftrace_mod_end = 0;
+ iter->pos_bpf_end = 0;
}
}
@@ -551,7 +576,11 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
get_ksymbol_ftrace_mod(iter))
return 1;
- return get_ksymbol_bpf(iter);
+ if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
+ get_ksymbol_bpf(iter))
+ return 1;
+
+ return get_ksymbol_kprobe(iter);
}
/* Returns false if pos at or past end of file. */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 2625c241ac00..c2a7330e406e 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -118,6 +118,7 @@ struct kprobe_insn_cache kprobe_insn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
.alloc = alloc_insn_page,
.free = free_insn_page,
+ .sym = KPROBE_INSN_PAGE_SYM,
.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
.insn_size = MAX_INSN_SIZE,
.nr_garbage = 0,
@@ -290,12 +291,34 @@ bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
return ret;
}
+int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
+ unsigned long *value, char *type, char *sym)
+{
+ struct kprobe_insn_page *kip;
+ int ret = -ERANGE;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(kip, &c->pages, list) {
+ if ((*symnum)--)
+ continue;
+ strlcpy(sym, c->sym, KSYM_NAME_LEN);
+ *type = 't';
+ *value = (unsigned long)kip->insns;
+ ret = 0;
+ break;
+ }
+ rcu_read_unlock();
+
+ return ret;
+}
+
#ifdef CONFIG_OPTPROBES
/* For optimized_kprobe buffer */
struct kprobe_insn_cache kprobe_optinsn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
.alloc = alloc_insn_page,
.free = free_insn_page,
+ .sym = KPROBE_OPTINSN_PAGE_SYM,
.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
/* .insn_size is initialized later */
.nr_garbage = 0,
@@ -2179,6 +2202,28 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
return 0;
}
+int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
+ char *type, char *sym)
+{
+ return -ERANGE;
+}
+
+int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
+ char *sym)
+{
+#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
+ if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym))
+ return 0;
+#ifdef CONFIG_OPTPROBES
+ if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym))
+ return 0;
+#endif
+#endif
+ if (!arch_kprobe_get_kallsym(&symnum, value, type, sym))
+ return 0;
+ return -ERANGE;
+}
+
int __init __weak arch_populate_kprobe_blacklist(void)
{
return 0;
--
2.17.1
next prev parent reply other threads:[~2020-05-28 8:01 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 12:19 [PATCH V7 00/15] perf/x86: Add perf text poke events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 01/15] perf: Add perf text poke event Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 02/15] perf/x86: Add support for perf text poke event for text_poke_bp_batch() callers Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 03/15] kprobes: Add symbols for kprobe insn pages Adrian Hunter
2020-05-27 17:43 ` Peter Zijlstra
2020-05-28 0:31 ` Masami Hiramatsu
2020-05-28 8:00 ` Adrian Hunter
2020-05-28 8:00 ` Adrian Hunter [this message]
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-28 0:25 ` [PATCH V7 03/15] " Masami Hiramatsu
2020-05-12 12:19 ` [PATCH V7 04/15] kprobes: Add perf ksymbol events " Adrian Hunter
2020-05-27 16:17 ` Peter Zijlstra
2020-05-27 17:20 ` Peter Zijlstra
2020-05-28 7:58 ` Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 05/15] perf/x86: Add perf text poke events for kprobes Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 06/15] ftrace: Add symbols for ftrace trampolines Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 07/15] ftrace: Add perf ksymbol events " Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 08/15] ftrace: Add perf text poke " Adrian Hunter
2020-06-16 12:21 ` [tip: perf/core] " tip-bot2 for Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 09/15] perf kcore_copy: Fix module map when there are no modules loaded Adrian Hunter
2020-05-27 15:44 ` Arnaldo Carvalho de Melo
2020-05-12 12:19 ` [PATCH V7 10/15] perf evlist: Disable 'immediate' events last Adrian Hunter
2020-05-27 15:44 ` Arnaldo Carvalho de Melo
2020-05-12 12:19 ` [PATCH V7 11/15] perf tools: Add support for PERF_RECORD_TEXT_POKE Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 12/15] perf tools: Add support for PERF_RECORD_KSYMBOL_TYPE_OOL Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 13/15] perf intel-pt: Add support for text poke events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 14/15] perf script: Add option --show-text-poke-events Adrian Hunter
2020-05-12 12:19 ` [PATCH V7 15/15] perf script: Show text poke address symbol Adrian Hunter
2020-05-20 1:38 ` Arnaldo Carvalho de Melo
2020-07-10 11:34 ` Arnaldo Carvalho de Melo
2020-07-10 11:38 ` Adrian Hunter
2020-05-17 13:16 ` [PATCH V7 00/15] perf/x86: Add perf text poke events Adrian Hunter
2020-05-20 1:40 ` Arnaldo Carvalho de Melo
2020-05-20 15:56 ` Peter Zijlstra
2020-05-27 15:47 ` Arnaldo Carvalho de Melo
2020-05-27 15:54 ` Peter Zijlstra
2020-07-08 11:55 ` Adrian Hunter
2020-07-08 12:34 ` Arnaldo Carvalho de Melo
2020-07-10 11:43 ` Arnaldo Carvalho de Melo
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