[PATCH 1/9] perf dwarf-aux: Check allowed location expressions when collecting variables

[Namhyung Kim]

It missed to call check_allowed_ops() in __die_collect_vars_cb() so it
can take variables with complex location expression incorrectly.

For example, I found some variable has this expression.

    015d8df8 ffffffff81aacfb3 (base address)
    015d8e01 v000000000000004 v000000000000000 views at 015d8df2 for:
             ffffffff81aacfb3 ffffffff81aacfd2 (DW_OP_fbreg: -176; DW_OP_deref;
						DW_OP_plus_uconst: 332; DW_OP_deref_size: 4;
						DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64;
						DW_OP_minus; DW_OP_stack_value)
    015d8e14 v000000000000000 v000000000000000 views at 015d8df4 for:
             ffffffff81aacfd2 ffffffff81aacfd7 (DW_OP_reg3 (rbx))
    015d8e19 v000000000000000 v000000000000000 views at 015d8df6 for:
             ffffffff81aacfd7 ffffffff81aad020 (DW_OP_fbreg: -176; DW_OP_deref;
						DW_OP_plus_uconst: 332; DW_OP_deref_size: 4;
						DW_OP_lit1; DW_OP_shra; DW_OP_const1u: 64;
						DW_OP_minus; DW_OP_stack_value)
    015d8e2c <End of list>

It looks like '((int *)(-176(%rbp) + 332) >> 1) - 64' but the current
code thought it's just -176(%rbp) and processed the variable incorrectly.
It should reject such a complex expression if check_allowed_ops()
doesn't like it. :)

Fixes: 932dcc2c39ae ("perf dwarf-aux: Add die_collect_vars()")
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/dwarf-aux.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 5e080d7e22c2..beb632153a74 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -1598,6 +1598,9 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg)
 	if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
 		return DIE_FIND_CB_SIBLING;
 
+	if (!check_allowed_ops(ops, nops))
+		return DIE_FIND_CB_SIBLING;
+
 	if (die_get_real_type(die_mem, &type_die) == NULL)
 		return DIE_FIND_CB_SIBLING;
 
-- 
2.46.0.184.g6999bdac58-goog