When the stack protector is enabled, compiler would generate code to
check stack overflow with a special value called 'stack carary' at
runtime. On x86_64, GCC hard-codes the stack canary as %gs:40.
While there's a definition of fixed_percpu_data in asm/processor.h,
it seems that the header is not included everywhere and many places
it cannot find the type info. As it's in the well-known location (at
%gs:40), let's add a pseudo stack canary type to handle it specially.
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/annotate-data.c | 7 +++++++
tools/perf/util/annotate-data.h | 1 +
tools/perf/util/annotate.c | 17 +++++++++++++++++
3 files changed, 25 insertions(+)
diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 677dc01432d3..68d7d207e2f7 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -37,6 +37,13 @@ struct annotated_data_type stackop_type = {
},
};
+struct annotated_data_type canary_type = {
+ .self = {
+ .type_name = (char *)"(stack canary)",
+ .children = LIST_HEAD_INIT(canary_type.self.children),
+ },
+};
+
/* Data type collection debug statistics */
struct annotated_data_stat ann_data_stat;
diff --git a/tools/perf/util/annotate-data.h b/tools/perf/util/annotate-data.h
index 0bfef29fa52c..e293980eb11b 100644
--- a/tools/perf/util/annotate-data.h
+++ b/tools/perf/util/annotate-data.h
@@ -77,6 +77,7 @@ struct annotated_data_type {
extern struct annotated_data_type unknown_type;
extern struct annotated_data_type stackop_type;
+extern struct annotated_data_type canary_type;
/**
* struct data_loc_info - Data location information
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 414ae45b7c06..f343f90612d0 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -3720,6 +3720,17 @@ static bool is_stack_operation(struct arch *arch, struct disasm_line *dl)
return false;
}
+static bool is_stack_canary(struct arch *arch, struct annotated_op_loc *loc)
+{
+ /* On x86_64, %gs:40 is used for stack canary */
+ if (arch__is(arch, "x86")) {
+ if (loc->segment == INSN_SEG_X86_GS && loc->offset == 40)
+ return true;
+ }
+
+ return false;
+}
+
u64 annotate_calc_pcrel(struct map_symbol *ms, u64 ip, int offset,
struct disasm_line *dl)
{
@@ -3889,6 +3900,12 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he)
}
mem_type = find_data_type(&dloc);
+
+ if (mem_type == NULL && is_stack_canary(arch, op_loc)) {
+ mem_type = &canary_type;
+ dloc.type_offset = 0;
+ }
+
if (mem_type)
istat->good++;
else
--
2.42.0.655.g421f12c284-goog
|