[PATCH v2 01/10] perf dwarf-aux: Use signed variable types in match_var_offset

[Zecheng Li <zecheng@google.com>]

match_var_offset compares address offsets to determine if an access
falls within a variable's bounds. The offsets involved for those
relative to base registers from DW_OP_breg can be negative.

The current implementation uses unsigned types (u64) for these offsets,
which rejects almost all negative values.

Change the signature of match_var_offset to use signed types (s64). This
ensures correct behavior when addr_offset or addr_type are negative.

Signed-off-by: Zecheng Li <zecheng@google.com>
---
 tools/perf/util/dwarf-aux.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 559c953ca172..920054425578 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1388,18 +1388,19 @@ struct find_var_data {
 #define DWARF_OP_DIRECT_REGS  32
 
 static bool match_var_offset(Dwarf_Die *die_mem, struct find_var_data *data,
-			     u64 addr_offset, u64 addr_type, bool is_pointer)
+			     s64 addr_offset, s64 addr_type, bool is_pointer)
 {
 	Dwarf_Die type_die;
 	Dwarf_Word size;
+	s64 offset = addr_offset - addr_type;
 
-	if (addr_offset == addr_type) {
+	if (offset == 0) {
 		/* Update offset relative to the start of the variable */
 		data->offset = 0;
 		return true;
 	}
 
-	if (addr_offset < addr_type)
+	if (offset < 0)
 		return false;
 
 	if (die_get_real_type(die_mem, &type_die) == NULL)
@@ -1414,11 +1415,11 @@ static bool match_var_offset(Dwarf_Die *die_mem, struct find_var_data *data,
 	if (dwarf_aggregate_size(&type_die, &size) < 0)
 		return false;
 
-	if (addr_offset >= addr_type + size)
+	if ((u64)offset >= size)
 		return false;
 
 	/* Update offset relative to the start of the variable */
-	data->offset = addr_offset - addr_type;
+	data->offset = offset;
 	return true;
 }
 
-- 
2.51.0.261.g7ce5a0a67e-goog