linux-kernel - [PATCH v1 3/6] perf dwarf-aux: Better type matching for stack variables

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250725202809.1230085-4-zecheng@google.com>
Date: Fri, 25 Jul 2025 20:28:06 +0000
From: Zecheng Li <zecheng@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>, Masami Hiramatsu <mhiramat@...nel.org>
Cc: Zecheng Li <zli94@...u.edu>, Xu Liu <xliuprof@...gle.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Zecheng Li <zecheng@...gle.com>
Subject: [PATCH v1 3/6] perf dwarf-aux: Better type matching for stack variables

Utilizes the previous is_breg_access_indirect function to determine if
the stack location stores the variable itself or the struct it points
to.

If the DWARF expression shows DW_OP_stack_value without DW_OP_deref, it
indicates the variable value is the reg + offset itself, and the stack
location it points to is the dereferenced type.

Signed-off-by: Zecheng Li <zecheng@...gle.com>
---
 tools/perf/util/dwarf-aux.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 814c96ea509f..4039dbd2b8c0 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1635,6 +1635,14 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg)
 	if (die_get_real_type(die_mem, &type_die) == NULL)
 		return DIE_FIND_CB_SIBLING;
 
+	if ((ops->atom == DW_OP_fbreg || ops->atom == DW_OP_breg7) &&
+	    dwarf_tag(&type_die) == DW_TAG_pointer_type &&
+	    is_breg_access_indirect(ops, nops)) {
+		/* Get the target type of the pointer */
+		if (die_get_real_type(&type_die, &type_die) == NULL)
+			return DIE_FIND_CB_SIBLING;
+	}
+
 	vt = malloc(sizeof(*vt));
 	if (vt == NULL)
 		return DIE_FIND_CB_END;
-- 
2.50.1.470.g6ba607880d-goog