linux-kernel - [PATCH 25/41] perf dso: Add BPF DSO read and size hooks

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Date:   Wed, 29 May 2019 10:35:49 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Song Liu <songliubraving@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 25/41] perf dso: Add BPF DSO read and size hooks

From: Jiri Olsa <jolsa@...nel.org>

Add BPF related code into DSO reading paths to return size (bpf_size)
and read the BPF code (bpf_read).

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
Acked-by: Song Liu <songliubraving@...com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stanislav Fomichev <sdf@...gle.com>
Link: http://lkml.kernel.org/r/20190508132010.14512-5-jolsa@kernel.org
[ Use uintptr_t when casting from u64 to u8 pointers ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/dso.c | 49 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 1e6a045adb8c..1fb18292c2d3 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -9,6 +9,8 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
+#include <bpf/libbpf.h>
+#include "bpf-event.h"
 #include "compress.h"
 #include "namespaces.h"
 #include "path.h"
@@ -706,6 +708,44 @@ bool dso__data_status_seen(struct dso *dso, enum dso_data_status_seen by)
 	return false;
 }
 
+static ssize_t bpf_read(struct dso *dso, u64 offset, char *data)
+{
+	struct bpf_prog_info_node *node;
+	ssize_t size = DSO__DATA_CACHE_SIZE;
+	u64 len;
+	u8 *buf;
+
+	node = perf_env__find_bpf_prog_info(dso->bpf_prog.env, dso->bpf_prog.id);
+	if (!node || !node->info_linear) {
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		return -1;
+	}
+
+	len = node->info_linear->info.jited_prog_len;
+	buf = (u8 *)(uintptr_t)node->info_linear->info.jited_prog_insns;
+
+	if (offset >= len)
+		return -1;
+
+	size = (ssize_t)min(len - offset, (u64)size);
+	memcpy(data, buf + offset, size);
+	return size;
+}
+
+static int bpf_size(struct dso *dso)
+{
+	struct bpf_prog_info_node *node;
+
+	node = perf_env__find_bpf_prog_info(dso->bpf_prog.env, dso->bpf_prog.id);
+	if (!node || !node->info_linear) {
+		dso->data.status = DSO_DATA_STATUS_ERROR;
+		return -1;
+	}
+
+	dso->data.file_size = node->info_linear->info.jited_prog_len;
+	return 0;
+}
+
 static void
 dso_cache__free(struct dso *dso)
 {
@@ -832,7 +872,11 @@ dso_cache__read(struct dso *dso, struct machine *machine,
 	if (!cache)
 		return -ENOMEM;
 
-	ret = file_read(dso, machine, cache_offset, cache->data);
+	if (dso->binary_type == DSO_BINARY_TYPE__BPF_PROG_INFO)
+		ret = bpf_read(dso, cache_offset, cache->data);
+	else
+		ret = file_read(dso, machine, cache_offset, cache->data);
+
 	if (ret > 0) {
 		cache->offset = cache_offset;
 		cache->size   = ret;
@@ -941,6 +985,9 @@ int dso__data_file_size(struct dso *dso, struct machine *machine)
 	if (dso->data.status == DSO_DATA_STATUS_ERROR)
 		return -1;
 
+	if (dso->binary_type == DSO_BINARY_TYPE__BPF_PROG_INFO)
+		return bpf_size(dso);
+
 	return file_size(dso, machine);
 }
 
-- 
2.20.1