bpf: Only print scratched registers and stack slots to verifier logs.

When printing verifier state for any log level, print full verifier
state only on function calls or on errors. Otherwise, only print the
registers and stack slots that were accessed.

Log size differences:

verif_scale_loop6 before: 234566564
verif_scale_loop6 after: 72143943
69% size reduction

kfree_skb before: 166406
kfree_skb after: 55386
69% size reduction

Before:

156: (61) r0 = *(u32 *)(r1 +0)
157: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=ctx(id=0,off=0,imm=0) R2_w=invP0 R10=fp0 fp-8_w=00000000 fp-16_w=00\
000000 fp-24_w=00000000 fp-32_w=00000000 fp-40_w=00000000 fp-48_w=00000000 fp-56_w=00000000 fp-64_w=00000000 fp-72_w=00000000 fp-80_w=00000\
000 fp-88_w=00000000 fp-96_w=00000000 fp-104_w=00000000 fp-112_w=00000000 fp-120_w=00000000 fp-128_w=00000000 fp-136_w=00000000 fp-144_w=00\
000000 fp-152_w=00000000 fp-160_w=00000000 fp-168_w=00000000 fp-176_w=00000000 fp-184_w=00000000 fp-192_w=00000000 fp-200_w=00000000 fp-208\
_w=00000000 fp-216_w=00000000 fp-224_w=00000000 fp-232_w=00000000 fp-240_w=00000000 fp-248_w=00000000 fp-256_w=00000000 fp-264_w=00000000 f\
p-272_w=00000000 fp-280_w=00000000 fp-288_w=00000000 fp-296_w=00000000 fp-304_w=00000000 fp-312_w=00000000 fp-320_w=00000000 fp-328_w=00000\
000 fp-336_w=00000000 fp-344_w=00000000 fp-352_w=00000000 fp-360_w=00000000 fp-368_w=00000000 fp-376_w=00000000 fp-384_w=00000000 fp-392_w=\
00000000 fp-400_w=00000000 fp-408_w=00000000 fp-416_w=00000000 fp-424_w=00000000 fp-432_w=00000000 fp-440_w=00000000 fp-448_w=00000000
; return skb->len;
157: (95) exit
Func#4 is safe for any args that match its prototype
Validating get_constant() func#5...
158: R1=invP(id=0) R10=fp0
; int get_constant(long val)
158: (bf) r0 = r1
159: R0_w=invP(id=1) R1=invP(id=1) R10=fp0
; return val - 122;
159: (04) w0 += -122
160: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=invP(id=1) R10=fp0
; return val - 122;
160: (95) exit
Func#5 is safe for any args that match its prototype
Validating get_skb_ifindex() func#6...
161: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0
; int get_skb_ifindex(int val, struct __sk_buff *skb, int var)
161: (bc) w0 = w3
162: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0

After:

156: (61) r0 = *(u32 *)(r1 +0)
157: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=ctx(id=0,off=0,imm=0)
; return skb->len;
157: (95) exit
Func#4 is safe for any args that match its prototype
Validating get_constant() func#5...
158: R1=invP(id=0) R10=fp0
; int get_constant(long val)
158: (bf) r0 = r1
159: R0_w=invP(id=1) R1=invP(id=1)
; return val - 122;
159: (04) w0 += -122
160: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff))
; return val - 122;
160: (95) exit
Func#5 is safe for any args that match its prototype
Validating get_skb_ifindex() func#6...
161: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0
; int get_skb_ifindex(int val, struct __sk_buff *skb, int var)
161: (bc) w0 = w3
162: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R3=invP(id=0)

Signed-off-by: Christy Lee <christylee@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211216213358.3374427-2-christylee@fb.com

1 files changed, 15 insertions, 15 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/align.c b/tools/testing/selftests/bpf/prog_tests/align.c
index 837f67c6bfda..aeb2080a67f7 100644
--- a/tools/testing/selftests/bpf/prog_tests/align.c
+++ b/tools/testing/selftests/bpf/prog_tests/align.c
@@ -39,8 +39,8 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{1, "R1=ctx(id=0,off=0,imm=0)"},
-			{1, "R10=fp0"},
+			{0, "R1=ctx(id=0,off=0,imm=0)"},
+			{0, "R10=fp0"},
 			{1, "R3_w=inv2"},
 			{2, "R3_w=inv4"},
 			{3, "R3_w=inv8"},
@@ -67,8 +67,8 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{1, "R1=ctx(id=0,off=0,imm=0)"},
-			{1, "R10=fp0"},
+			{0, "R1=ctx(id=0,off=0,imm=0)"},
+			{0, "R10=fp0"},
 			{1, "R3_w=inv1"},
 			{2, "R3_w=inv2"},
 			{3, "R3_w=inv4"},
@@ -96,8 +96,8 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{1, "R1=ctx(id=0,off=0,imm=0)"},
-			{1, "R10=fp0"},
+			{0, "R1=ctx(id=0,off=0,imm=0)"},
+			{0, "R10=fp0"},
 			{1, "R3_w=inv4"},
 			{2, "R3_w=inv8"},
 			{3, "R3_w=inv10"},
@@ -118,8 +118,8 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{1, "R1=ctx(id=0,off=0,imm=0)"},
-			{1, "R10=fp0"},
+			{0, "R1=ctx(id=0,off=0,imm=0)"},
+			{0, "R10=fp0"},
 			{1, "R3_w=inv7"},
 			{2, "R3_w=inv7"},
 			{3, "R3_w=inv14"},
@@ -161,13 +161,13 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{7, "R0_w=pkt(id=0,off=8,r=8,imm=0)"},
+			{6, "R0_w=pkt(id=0,off=8,r=8,imm=0)"},
 			{7, "R3_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff))"},
 			{8, "R3_w=inv(id=0,umax_value=510,var_off=(0x0; 0x1fe))"},
 			{9, "R3_w=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
 			{10, "R3_w=inv(id=0,umax_value=2040,var_off=(0x0; 0x7f8))"},
 			{11, "R3_w=inv(id=0,umax_value=4080,var_off=(0x0; 0xff0))"},
-			{18, "R3=pkt_end(id=0,off=0,imm=0)"},
+			{13, "R3_w=pkt_end(id=0,off=0,imm=0)"},
 			{18, "R4_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff))"},
 			{19, "R4_w=inv(id=0,umax_value=8160,var_off=(0x0; 0x1fe0))"},
 			{20, "R4_w=inv(id=0,umax_value=4080,var_off=(0x0; 0xff0))"},
@@ -234,10 +234,10 @@ static struct bpf_align_test tests[] = {
 		},
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.matches = {
-			{4, "R5_w=pkt(id=0,off=0,r=0,imm=0)"},
+			{3, "R5_w=pkt(id=0,off=0,r=0,imm=0)"},
 			{5, "R5_w=pkt(id=0,off=14,r=0,imm=0)"},
 			{6, "R4_w=pkt(id=0,off=14,r=0,imm=0)"},
-			{10, "R2=pkt(id=0,off=0,r=18,imm=0)"},
+			{9, "R2=pkt(id=0,off=0,r=18,imm=0)"},
 			{10, "R5=pkt(id=0,off=14,r=18,imm=0)"},
 			{10, "R4_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff))"},
 			{14, "R4_w=inv(id=0,umax_value=65535,var_off=(0x0; 0xffff))"},
@@ -296,7 +296,7 @@ static struct bpf_align_test tests[] = {
 			/* Calculated offset in R6 has unknown value, but known
 			 * alignment of 4.
 			 */
-			{8, "R2_w=pkt(id=0,off=0,r=8,imm=0)"},
+			{6, "R2_w=pkt(id=0,off=0,r=8,imm=0)"},
 			{8, "R6_w=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
 			/* Offset is added to packet pointer R5, resulting in
 			 * known fixed offset, and variable offset from R6.
@@ -386,7 +386,7 @@ static struct bpf_align_test tests[] = {
 			/* Calculated offset in R6 has unknown value, but known
 			 * alignment of 4.
 			 */
-			{8, "R2_w=pkt(id=0,off=0,r=8,imm=0)"},
+			{6, "R2_w=pkt(id=0,off=0,r=8,imm=0)"},
 			{8, "R6_w=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
 			/* Adding 14 makes R6 be (4n+2) */
 			{9, "R6_w=inv(id=0,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
@@ -458,7 +458,7 @@ static struct bpf_align_test tests[] = {
 			/* Checked s>=0 */
 			{9, "R5=inv(id=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc)"},
 			/* packet pointer + nonnegative (4n+2) */
-			{11, "R6_w=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc)"},
+			{12, "R6_w=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc)"},
 			{13, "R4_w=pkt(id=1,off=4,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc)"},
 			/* NET_IP_ALIGN + (4n+2) == (4n), alignment is fine.
 			 * We checked the bounds, but it might have been able