On Thu 2020-05-28 09:48:48, Yannick Cote wrote:
This change makes the test feel more familiar with narrowing to a typical usage by operating on a number of identical structure instances and populating the same two new shadow variables symmetrically while keeping the same testing and verification criteria for the extra variables.
@@ -157,122 +165,96 @@ struct test_object { static int test_klp_shadow_vars_init(void) {
- struct test_object obj1, obj2, obj3;
- char nfield1, nfield2, *pnfield1, *pnfield2, **sv1, **sv2;
- int nfield3, nfield4, *pnfield3, *pnfield4, **sv3, **sv4;
- struct test_object objs[NUM_OBJS];
- char nfields1[NUM_OBJS], *pnfields1[NUM_OBJS], **sv1[NUM_OBJS];
- char *pndup[NUM_OBJS];
- int nfields2[NUM_OBJS], *pnfields2[NUM_OBJS], **sv2[NUM_OBJS]; void **sv;
- /* pass 1: init & alloc a char+int pair of svars for each objs */
- for (i = 0; i < NUM_OBJS; i++) {
pnfields1[i] = &nfields1[i];pnfields2[i] = &nfields2[i];ptr_id(pnfields1[i]);ptr_id(pnfields2[i]);/* alloc a few svars with different <obj> and <id>. */sv1[i] = shadow_alloc(&objs[i], SV_ID1, sizeof(pnfields1[i]),GFP_KERNEL, shadow_ctor, &pnfields1[i]);if (!sv1[i])return -ENOMEM;
Please, put empty line here to delimit ID1 ID2 handling a bit.
Also I have got a bit more predictable PTR IDs when I moved pnfields2 initialization here:
pnfields2[i] = &nfields2[i]; ptr_id(pnfields2[i]);
sv2[i] = shadow_alloc(&objs[i], SV_ID2, sizeof(pnfields2[i]),GFP_KERNEL, shadow_ctor, &pnfields2[i]);if (!sv2[i])return -ENOMEM;- }
It looks like:
test_klp_shadow_vars: klp_shadow_alloc(obj=PTR1, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR4, ctor_data=PTR2 = PTR3 test_klp_shadow_vars: shadow_ctor: PTR6 -> PTR5 test_klp_shadow_vars: klp_shadow_alloc(obj=PTR1, id=0x1235, size=8, gfp_flags=GFP_KERNEL), ctor=PTR4, ctor_data=PTR5 = PTR6 test_klp_shadow_vars: shadow_ctor: PTR8 -> PTR7 test_klp_shadow_vars: klp_shadow_alloc(obj=PTR9, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR4, ctor_data=PTR7 = PTR8 test_klp_shadow_vars: shadow_ctor: PTR11 -> PTR10
instead of
test_klp_shadow_vars: klp_shadow_alloc(obj=PTR1, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR2 = PTR4 test_klp_shadow_vars: shadow_ctor: PTR6 -> PTR3 test_klp_shadow_vars: klp_shadow_alloc(obj=PTR1, id=0x1235, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR3 = PTR6 test_klp_shadow_vars: shadow_ctor: PTR9 -> PTR7 test_klp_shadow_vars: klp_shadow_alloc(obj=PTR10, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR7 = PTR9 test_klp_shadow_vars: shadow_ctor: PTR11 -> PTR8
By other words, the PTR IDs are incrementing by the same offset for both SV_ID1 and SV_ID2. It looks better even later in the log.
- /* pass 3: verify that 'get_of_alloc' returns already allocated svars */
- for (i = 0; i < NUM_OBJS; i++) {
sv = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pndup[i]),GFP_KERNEL, shadow_ctor, &pndup[i]);
First, the test failed on my system. I have got:
# --- expected # +++ result # @@ -27,20 +27,20 @@ test_klp_shadow_vars: klp_shadow_get(obj # test_klp_shadow_vars: got expected PTR16 -> PTR13 result # test_klp_shadow_vars: klp_shadow_get_or_alloc(obj=PTR1, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR17 = PTR4 # test_klp_shadow_vars: got expected PTR4 -> PTR2 result # -test_klp_shadow_vars: klp_shadow_get_or_alloc(obj=PTR10, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR18 = PTR9 # +test_klp_shadow_vars: klp_shadow_get_or_alloc(obj=PTR10, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR0 = PTR9 # test_klp_shadow_vars: got expected PTR9 -> PTR7 result # -test_klp_shadow_vars: klp_shadow_get_or_alloc(obj=PTR15, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR19 = PTR14 # +test_klp_shadow_vars: klp_shadow_get_or_alloc(obj=PTR15, id=0x1234, size=8, gfp_flags=GFP_KERNEL), ctor=PTR5, ctor_data=PTR0 = PTR14
In my build, it uses PTR0 for ctor_data. But it takes a new pointer in your case.
It is because pndup[i] was not initialized. Note that it is the value (data) that is stored in the shadow variable.
The solution is to initialize pndup[i] here:
pndup[i] = &nfields1[i]; ptr_id(pndup[i]);
2nd problem, klp_shadow_get_or_alloc() is always called for already allocated values now. It would be great to test that they can be created when they are not available.
A solution might be to allocate half of the variables by shadow_alloc() and the other half with shadow_get_or_alloc(). I would do this in the first cycle, using:
if (i % 2) { sv1[i] = shadow_alloc(&objs[i], SV_ID1, sizeof(pnfields1[i]), GFP_KERNEL, shadow_ctor, &pnfields1[i]); } else { sv1[i] = shadow_get_or_alloc(&objs[i], SV_ID1, sizeof(pnfields1[i]), GFP_KERNEL, shadow_ctor, &pnfields1[i]); }
Otherwise, it is a nice clean up.
Best Regards, Petr