diff mbox series

[13/15] perf tools: Synthesize bpf_trampoline/dispatcher ksymbol event

Message ID 20200312195610.346362-14-jolsa@kernel.org
State Awaiting Upstream
Delegated to: BPF Maintainers
Headers show
Series bpf: Add trampoline and dispatcher to /proc/kallsyms | expand

Commit Message

Jiri Olsa March 12, 2020, 7:56 p.m. UTC
Synthesize bpf images (trampolines/dispatchers) on start,
as ksymbol events from /proc/kallsyms. Having this perf
can recognize samples from those images and perf report
and top shows them correctly.

The rest of the ksymbol handling is already in place from
for the bpf programs monitoring, so only the initial state
was needed.

perf report output:

  # Overhead  Command     Shared Object                  Symbol

    12.37%  test_progs  [kernel.vmlinux]                 [k] entry_SYSCALL_64
    11.80%  test_progs  [kernel.vmlinux]                 [k] syscall_return_via_sysret
     9.63%  test_progs  bpf_prog_bcf7977d3b93787c_prog2  [k] bpf_prog_bcf7977d3b93787c_prog2
     6.90%  test_progs  bpf_trampoline_24456             [k] bpf_trampoline_24456
     6.36%  test_progs  [kernel.vmlinux]                 [k] memcpy_erms

Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/util/bpf-event.c | 92 +++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

Comments

Arnaldo April 6, 2020, 12:54 p.m. UTC | #1
Em Thu, Mar 12, 2020 at 08:56:08PM +0100, Jiri Olsa escreveu:
> +static int
> +process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
> +{
> +	struct machine *machine = data->machine;
> +	union perf_event *event = data->event;
> +	struct perf_record_ksymbol *ksymbol;
> +
> +	ksymbol = &event->ksymbol;
> +
> +	*ksymbol = (struct perf_record_ksymbol) {
> +		.header = {
> +			.type = PERF_RECORD_KSYMBOL,
> +			.size = offsetof(struct perf_record_ksymbol, name),
> +		},
> +		.addr      = addr,
> +		.len       = page_size,
> +		.ksym_type = PERF_RECORD_KSYMBOL_TYPE_BPF,
> +		.flags     = 0,
> +	};
> +
> +	strncpy(ksymbol->name, name, KSYM_NAME_LEN);
> +	ksymbol->header.size += PERF_ALIGN(strlen(name) + 1, sizeof(u64));
> +	memset((void *) event + event->header.size, 0, machine->id_hdr_size);
> +	event->header.size += machine->id_hdr_size;
> +
> +	return perf_tool__process_synth_event(data->tool, event, machine,
> +					      data->process);

This explodes in fedora 32 and rawhide and in openmandriva:cooker:

  GEN      /tmp/build/perf/python/perf.so
  CC       /tmp/build/perf/util/bpf-event.o
In file included from /usr/include/string.h:495,
                 from /git/perf/tools/lib/bpf/libbpf_common.h:12,
                 from /git/perf/tools/lib/bpf/bpf.h:31,
                 from util/bpf-event.c:4:
In function ‘strncpy’,
    inlined from ‘process_bpf_image’ at util/bpf-event.c:323:2,
    inlined from ‘kallsyms_process_symbol’ at util/bpf-event.c:358:9:
/usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 256 equals destination size [-Werror=stringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
mv: cannot stat '/tmp/build/perf/util/.bpf-event.o.tmp': No such file or directory
make[4]: *** [/git/perf/tools/build/Makefile.build:97: /tmp/build/perf/util/bpf-event.o] Error 1
make[3]: *** [/git/perf/tools/build/Makefile.build:139: util] Error 2
make[2]: *** [Makefile.perf:617: /tmp/build/perf/perf-in.o] Error 2
make[1]: *** [Makefile.perf:225: sub-make] Error 2
make: *** [Makefile:70: all] Error 2
make: Leaving directory '/git/perf/tools/perf'
[perfbuilder@fc58e82bfba4 ~]$

So I patched it a bit, please ack:


diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index 3728db98981e..0cd41a862952 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -306,6 +306,7 @@ process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
 	struct machine *machine = data->machine;
 	union perf_event *event = data->event;
 	struct perf_record_ksymbol *ksymbol;
+	int len;
 
 	ksymbol = &event->ksymbol;
 
@@ -320,8 +321,8 @@ process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
 		.flags     = 0,
 	};
 
-	strncpy(ksymbol->name, name, KSYM_NAME_LEN);
-	ksymbol->header.size += PERF_ALIGN(strlen(name) + 1, sizeof(u64));
+	len = scnprintf(ksymbol->name, KSYM_NAME_LEN, "%s", name);
+	ksymbol->header.size += PERF_ALIGN(len + 1, sizeof(u64));
 	memset((void *) event + event->header.size, 0, machine->id_hdr_size);
 	event->header.size += machine->id_hdr_size;
Jiri Olsa April 6, 2020, 1 p.m. UTC | #2
On Mon, Apr 06, 2020 at 09:54:12AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Thu, Mar 12, 2020 at 08:56:08PM +0100, Jiri Olsa escreveu:
> > +static int
> > +process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
> > +{
> > +	struct machine *machine = data->machine;
> > +	union perf_event *event = data->event;
> > +	struct perf_record_ksymbol *ksymbol;
> > +
> > +	ksymbol = &event->ksymbol;
> > +
> > +	*ksymbol = (struct perf_record_ksymbol) {
> > +		.header = {
> > +			.type = PERF_RECORD_KSYMBOL,
> > +			.size = offsetof(struct perf_record_ksymbol, name),
> > +		},
> > +		.addr      = addr,
> > +		.len       = page_size,
> > +		.ksym_type = PERF_RECORD_KSYMBOL_TYPE_BPF,
> > +		.flags     = 0,
> > +	};
> > +
> > +	strncpy(ksymbol->name, name, KSYM_NAME_LEN);
> > +	ksymbol->header.size += PERF_ALIGN(strlen(name) + 1, sizeof(u64));
> > +	memset((void *) event + event->header.size, 0, machine->id_hdr_size);
> > +	event->header.size += machine->id_hdr_size;
> > +
> > +	return perf_tool__process_synth_event(data->tool, event, machine,
> > +					      data->process);
> 
> This explodes in fedora 32 and rawhide and in openmandriva:cooker:
> 
>   GEN      /tmp/build/perf/python/perf.so
>   CC       /tmp/build/perf/util/bpf-event.o
> In file included from /usr/include/string.h:495,
>                  from /git/perf/tools/lib/bpf/libbpf_common.h:12,
>                  from /git/perf/tools/lib/bpf/bpf.h:31,
>                  from util/bpf-event.c:4:
> In function ‘strncpy’,
>     inlined from ‘process_bpf_image’ at util/bpf-event.c:323:2,
>     inlined from ‘kallsyms_process_symbol’ at util/bpf-event.c:358:9:
> /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 256 equals destination size [-Werror=stringop-truncation]
>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
>       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> mv: cannot stat '/tmp/build/perf/util/.bpf-event.o.tmp': No such file or directory
> make[4]: *** [/git/perf/tools/build/Makefile.build:97: /tmp/build/perf/util/bpf-event.o] Error 1
> make[3]: *** [/git/perf/tools/build/Makefile.build:139: util] Error 2
> make[2]: *** [Makefile.perf:617: /tmp/build/perf/perf-in.o] Error 2
> make[1]: *** [Makefile.perf:225: sub-make] Error 2
> make: *** [Makefile:70: all] Error 2
> make: Leaving directory '/git/perf/tools/perf'
> [perfbuilder@fc58e82bfba4 ~]$
> 
> So I patched it a bit, please ack:

perfect, thanks

Acked-by: Jiri Olsa <jolsa@redhat.com>

jirka

> 
> 
> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> index 3728db98981e..0cd41a862952 100644
> --- a/tools/perf/util/bpf-event.c
> +++ b/tools/perf/util/bpf-event.c
> @@ -306,6 +306,7 @@ process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
>  	struct machine *machine = data->machine;
>  	union perf_event *event = data->event;
>  	struct perf_record_ksymbol *ksymbol;
> +	int len;
>  
>  	ksymbol = &event->ksymbol;
>  
> @@ -320,8 +321,8 @@ process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
>  		.flags     = 0,
>  	};
>  
> -	strncpy(ksymbol->name, name, KSYM_NAME_LEN);
> -	ksymbol->header.size += PERF_ALIGN(strlen(name) + 1, sizeof(u64));
> +	len = scnprintf(ksymbol->name, KSYM_NAME_LEN, "%s", name);
> +	ksymbol->header.size += PERF_ALIGN(len + 1, sizeof(u64));
>  	memset((void *) event + event->header.size, 0, machine->id_hdr_size);
>  	event->header.size += machine->id_hdr_size;
>  
>
diff mbox series

Patch

diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index a3207d900339..3728db98981e 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -6,6 +6,9 @@ 
 #include <bpf/libbpf.h>
 #include <linux/btf.h>
 #include <linux/err.h>
+#include <linux/string.h>
+#include <internal/lib.h>
+#include <symbol/kallsyms.h>
 #include "bpf-event.h"
 #include "debug.h"
 #include "dso.h"
@@ -290,11 +293,81 @@  static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
 	return err ? -1 : 0;
 }
 
+struct kallsyms_parse {
+	union perf_event	*event;
+	perf_event__handler_t	 process;
+	struct machine		*machine;
+	struct perf_tool	*tool;
+};
+
+static int
+process_bpf_image(char *name, u64 addr, struct kallsyms_parse *data)
+{
+	struct machine *machine = data->machine;
+	union perf_event *event = data->event;
+	struct perf_record_ksymbol *ksymbol;
+
+	ksymbol = &event->ksymbol;
+
+	*ksymbol = (struct perf_record_ksymbol) {
+		.header = {
+			.type = PERF_RECORD_KSYMBOL,
+			.size = offsetof(struct perf_record_ksymbol, name),
+		},
+		.addr      = addr,
+		.len       = page_size,
+		.ksym_type = PERF_RECORD_KSYMBOL_TYPE_BPF,
+		.flags     = 0,
+	};
+
+	strncpy(ksymbol->name, name, KSYM_NAME_LEN);
+	ksymbol->header.size += PERF_ALIGN(strlen(name) + 1, sizeof(u64));
+	memset((void *) event + event->header.size, 0, machine->id_hdr_size);
+	event->header.size += machine->id_hdr_size;
+
+	return perf_tool__process_synth_event(data->tool, event, machine,
+					      data->process);
+}
+
+static int
+kallsyms_process_symbol(void *data, const char *_name,
+			char type __maybe_unused, u64 start)
+{
+	char disp[KSYM_NAME_LEN];
+	char *module, *name;
+	unsigned long id;
+	int err = 0;
+
+	module = strchr(_name, '\t');
+	if (!module)
+		return 0;
+
+	/* We are going after [bpf] module ... */
+	if (strcmp(module + 1, "[bpf]"))
+		return 0;
+
+	name = memdup(_name, (module - _name) + 1);
+	if (!name)
+		return -ENOMEM;
+
+	name[module - _name] = 0;
+
+	/* .. and only for trampolines and dispatchers */
+	if ((sscanf(name, "bpf_trampoline_%lu", &id) == 1) ||
+	    (sscanf(name, "bpf_dispatcher_%s", disp) == 1))
+		err = process_bpf_image(name, start, data);
+
+	free(name);
+	return err;
+}
+
 int perf_event__synthesize_bpf_events(struct perf_session *session,
 				      perf_event__handler_t process,
 				      struct machine *machine,
 				      struct record_opts *opts)
 {
+	const char *kallsyms_filename = "/proc/kallsyms";
+	struct kallsyms_parse arg;
 	union perf_event *event;
 	__u32 id = 0;
 	int err;
@@ -303,6 +376,8 @@  int perf_event__synthesize_bpf_events(struct perf_session *session,
 	event = malloc(sizeof(event->bpf) + KSYM_NAME_LEN + machine->id_hdr_size);
 	if (!event)
 		return -1;
+
+	/* Synthesize all the bpf programs in system. */
 	while (true) {
 		err = bpf_prog_get_next_id(id, &id);
 		if (err) {
@@ -335,6 +410,23 @@  int perf_event__synthesize_bpf_events(struct perf_session *session,
 			break;
 		}
 	}
+
+	/* Synthesize all the bpf images - trampolines/dispatchers. */
+	if (symbol_conf.kallsyms_name != NULL)
+		kallsyms_filename = symbol_conf.kallsyms_name;
+
+	arg = (struct kallsyms_parse) {
+		.event   = event,
+		.process = process,
+		.machine = machine,
+		.tool    = session->tool,
+	};
+
+	if (kallsyms__parse(kallsyms_filename, &arg, kallsyms_process_symbol)) {
+		pr_err("%s: failed to synthesize bpf images: %s\n",
+		       __func__, strerror(errno));
+	}
+
 	free(event);
 	return err;
 }