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 | 46 +++++++++++++++++++++++++++++++++
tools/perf/util/annotate-data.h | 1 +
tools/perf/util/annotate.c | 25 ++++++++++++++++++
3 files changed, 72 insertions(+)
diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index bd10a576cfbf..633fe125fcd8 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -30,6 +30,7 @@ enum type_state_kind {
TSR_KIND_PERCPU_BASE,
TSR_KIND_CONST,
TSR_KIND_POINTER,
+ TSR_KIND_CANARY,
};
#define pr_debug_dtp(fmt, ...) \
@@ -62,6 +63,9 @@ static void pr_debug_type_name(Dwarf_Die *die, enum type_state_kind kind)
pr_info(" pointer");
/* it also prints the type info */
break;
+ case TSR_KIND_CANARY:
+ pr_info(" stack canary\n");
+ return;
case TSR_KIND_TYPE:
default:
break;
@@ -676,6 +680,15 @@ static void update_insn_state_x86(struct type_state *state,
*/
var_addr = src->offset;
+ if (var_addr == 40) {
+ tsr->kind = TSR_KIND_CANARY;
+ tsr->ok = true;
+
+ pr_debug_dtp("mov [%x] stack canary -> reg%d\n",
+ insn_offset, dst->reg1);
+ return;
+ }
+
if (!get_global_var_type(cu_die, dloc, ip, var_addr,
&offset, &type_die) ||
!die_get_member_type(&type_die, offset, &type_die)) {
@@ -991,6 +1004,16 @@ static void delete_var_types(struct die_var_type *var_types)
}
}
+/* should match to is_stack_canary() in util/annotate.c */
+static void setup_stack_canary(struct data_loc_info *dloc)
+{
+ if (arch__is(dloc->arch, "x86")) {
+ dloc->op->segment = INSN_SEG_X86_GS;
+ dloc->op->imm = true;
+ dloc->op->offset = 40;
+ }
+}
+
/* It's at the target address, check if it has a matching type */
static bool check_matching_type(struct type_state *state,
struct data_loc_info *dloc, int reg,
@@ -1038,6 +1061,11 @@ static bool check_matching_type(struct type_state *state,
if (stack == NULL)
return false;
+ if (stack->kind == TSR_KIND_CANARY) {
+ setup_stack_canary(dloc);
+ return false;
+ }
+
*type_die = stack->type;
/* Update the type offset from the start of slot */
dloc->type_offset -= stack->offset;
@@ -1062,6 +1090,11 @@ static bool check_matching_type(struct type_state *state,
if (stack == NULL)
return false;
+ if (stack->kind == TSR_KIND_CANARY) {
+ setup_stack_canary(dloc);
+ return false;
+ }
+
*type_die = stack->type;
/* Update the type offset from the start of slot */
dloc->type_offset -= fboff + stack->offset;
@@ -1102,6 +1135,19 @@ static bool check_matching_type(struct type_state *state,
return true;
}
+ if (state->regs[reg].ok && state->regs[reg].kind == TSR_KIND_CANARY) {
+ pr_debug_dtp(" stack canary\n");
+
+ /*
+ * This is a saved value of the stack canary which will be handled
+ * in the outer logic when it returns failure here. Pretend it's
+ * from the stack canary directly.
+ */
+ setup_stack_canary(dloc);
+
+ return false;
+ }
+
if (map__dso(dloc->ms->map)->kernel && arch__is(dloc->arch, "x86")) {
u64 addr;
int offset;
diff --git a/tools/perf/util/annotate-data.h b/tools/perf/util/annotate-data.h
index ae0f87aed804..1b5a152163b5 100644
--- a/tools/perf/util/annotate-data.h
+++ b/tools/perf/util/annotate-data.h
@@ -73,6 +73,7 @@ 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 e4121acb4f88..64e54ff1aa1d 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -118,6 +118,13 @@ 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),
+ },
+};
+
static int arch__grow_instructions(struct arch *arch)
{
struct ins *new_instructions;
@@ -3803,6 +3810,18 @@ 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->imm &&
+ loc->offset == 40)
+ return true;
+ }
+
+ return false;
+}
+
u64 annotate_calc_pcrel(struct map_symbol *ms, u64 ip, int offset,
struct disasm_line *dl)
{
@@ -3929,6 +3948,12 @@ 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
--
2.44.0.291.gc1ea87d7ee-goog
|