linux-kernel - [PATCH 1/2] perf auxtrace: Fix address filter entire kernel size

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Date:   Mon,  3 Apr 2023 18:48:30 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: [PATCH 1/2] perf auxtrace: Fix address filter entire kernel size

kallsyms is not completely in address order.

In find_entire_kern_cb(), calculate the kernel end from the maximum
address not the last symbol.

Example:

 Before:

    $ sudo cat /proc/kallsyms | grep ' [twTw] ' | tail -1
    ffffffffc00b8bd0 t bpf_prog_6deef7357e7b4530    [bpf]
    $ sudo cat /proc/kallsyms | grep ' [twTw] ' | sort | tail -1
    ffffffffc15e0cc0 t iwl_mvm_exit [iwlmvm]
    $ perf.d093603a05aa record -v --kcore -e intel_pt// --filter 'filter *' -- uname |& grep filter
    Address filter: filter 0xffffffff93200000/0x2ceba000

 After:

    $ perf.8fb0f7a01f8e record -v --kcore -e intel_pt// --filter 'filter *' -- uname |& grep filter
    Address filter: filter 0xffffffff93200000/0x2e3e2000

Fixes: 1b36c03e3569 ("perf record: Add support for using symbols in address filters")
Cc: stable@...r.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/auxtrace.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 498ff7f24463..b2a5e5397bad 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -2449,6 +2449,7 @@ static int find_entire_kern_cb(void *arg, const char *name __maybe_unused,
 			       char type, u64 start)
 {
 	struct sym_args *args = arg;
+	u64 size;
 
 	if (!kallsyms__is_function(type))
 		return 0;
@@ -2458,7 +2459,9 @@ static int find_entire_kern_cb(void *arg, const char *name __maybe_unused,
 		args->start = start;
 	}
 	/* Don't know exactly where the kernel ends, so we add a page */
-	args->size = round_up(start, page_size) + page_size - args->start;
+	size = round_up(start, page_size) + page_size - args->start;
+	if (size > args->size)
+		args->size = size;
 
 	return 0;
 }
-- 
2.34.1