bpf: maintain bitmasks across all active frames in __mark_chain_precision

Teach __mark_chain_precision logic to maintain register/stack masks
across all active frames when going from child state to parent state.
Currently this should be mostly no-op, as precision backtracking usually
bails out when encountering subprog entry/exit.

It's not very apparent from the diff due to increased indentation, but
the logic remains the same, except everything is done on specific `fr`
frame index. Calls to bt_clear_reg() and bt_clear_slot() are replaced
with frame-specific bt_clear_frame_reg() and bt_clear_frame_slot(),
where frame index is passed explicitly, instead of using current frame
number.

We also adjust logging to emit affected frame number. And we also add
better logging of human-readable register and stack slot masks, similar
to previous patch.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/tools/testing/selftests/bpf/verifier/precise.c b/tools/testing/selftests/bpf/verifier/precise.c
index a22fabd404ed..77ea018582c5 100644
--- a/tools/testing/selftests/bpf/verifier/precise.c
+++ b/tools/testing/selftests/bpf/verifier/precise.c
@@ -44,7 +44,7 @@
 	mark_precise: frame0: regs=r2 stack= before 23\
 	mark_precise: frame0: regs=r2 stack= before 22\
 	mark_precise: frame0: regs=r2 stack= before 20\
-	parent didn't have regs=4 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r2 stack=:\
 	mark_precise: frame0: last_idx 19 first_idx 10\
 	mark_precise: frame0: regs=r2 stack= before 19\
 	mark_precise: frame0: regs=r9 stack= before 18\
@@ -55,7 +55,7 @@
 	mark_precise: frame0: regs=r9 stack= before 12\
 	mark_precise: frame0: regs=r9 stack= before 11\
 	mark_precise: frame0: regs=r9 stack= before 10\
-	parent already had regs=0 stack=0 marks:",
+	mark_precise: frame0: parent state regs= stack=:",
 },
 {
 	"precise: test 2",
@@ -104,15 +104,15 @@
 	mark_precise: frame0: regs=r2 stack= before 24\
 	mark_precise: frame0: regs=r2 stack= before 23\
 	mark_precise: frame0: regs=r2 stack= before 22\
-	parent didn't have regs=4 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r2 stack=:\
 	mark_precise: frame0: last_idx 20 first_idx 20\
 	mark_precise: frame0: regs=r2 stack= before 20\
-	parent didn't have regs=4 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r2 stack=:\
 	mark_precise: frame0: last_idx 19 first_idx 17\
 	mark_precise: frame0: regs=r2 stack= before 19\
 	mark_precise: frame0: regs=r9 stack= before 18\
 	mark_precise: frame0: regs=r8,r9 stack= before 17\
-	parent already had regs=0 stack=0 marks:",
+	mark_precise: frame0: parent state regs= stack=:",
 },
 {
 	"precise: cross frame pruning",
@@ -153,14 +153,14 @@
 	.prog_type = BPF_PROG_TYPE_XDP,
 	.flags = BPF_F_TEST_STATE_FREQ,
 	.errstr = "mark_precise: frame0: last_idx 5 first_idx 5\
-	parent didn't have regs=10 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r4 stack=:\
 	mark_precise: frame0: last_idx 4 first_idx 2\
 	mark_precise: frame0: regs=r4 stack= before 4\
 	mark_precise: frame0: regs=r4 stack= before 3\
 	mark_precise: frame0: regs= stack=-8 before 2\
 	mark_precise: frame0: falling back to forcing all scalars precise\
 	mark_precise: frame0: last_idx 5 first_idx 5\
-	parent didn't have regs=1 stack=0 marks:",
+	mark_precise: frame0: parent state regs=r0 stack=:",
 	.result = VERBOSE_ACCEPT,
 	.retval = -1,
 },
@@ -179,7 +179,7 @@
 	.prog_type = BPF_PROG_TYPE_XDP,
 	.flags = BPF_F_TEST_STATE_FREQ,
 	.errstr = "mark_precise: frame0: last_idx 6 first_idx 6\
-	parent didn't have regs=10 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r4 stack=:\
 	mark_precise: frame0: last_idx 5 first_idx 3\
 	mark_precise: frame0: regs=r4 stack= before 5\
 	mark_precise: frame0: regs=r4 stack= before 4\
@@ -188,7 +188,7 @@
 	force_precise: frame0: forcing r0 to be precise\
 	force_precise: frame0: forcing r0 to be precise\
 	mark_precise: frame0: last_idx 6 first_idx 6\
-	parent didn't have regs=1 stack=0 marks:\
+	mark_precise: frame0: parent state regs=r0 stack=:\
 	mark_precise: frame0: last_idx 5 first_idx 3\
 	mark_precise: frame0: regs=r0 stack= before 5",
 	.result = VERBOSE_ACCEPT,