Commit 1db747d7 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

bpf: omit default off=0 and imm=0 in register state log 



Simplify BPF verifier log further by omitting default (and frequently
irrelevant) off=0 and imm=0 parts for non-SCALAR_VALUE registers. As can
be seen from fixed tests, this is often a visual noise for PTR_TO_CTX
register and even for PTR_TO_PACKET registers.

Omitting default values follows the rest of register state logic: we
omit default values to keep verifier log succinct and to highlight
interesting state that deviates from default one. E.g., we do the same
for var_off, when it's unknown, which gives no additional information.

Acked-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231118034623.3320920-7-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0c95c9fd

kernel/bpf/log.c

+4 −6
Original line number Diff line number Diff line
@@ -602,15 +602,13 @@ static void print_reg_state(struct bpf_verifier_env *env, const struct bpf_reg_s 
			  reg->map_ptr->key_size,

			  reg->map_ptr->value_size);

	}

	if (t != SCALAR_VALUE)

	if (t != SCALAR_VALUE && reg->off)

		verbose_a("off=%d", reg->off);

	if (type_is_pkt_pointer(t))

		verbose_a("r=%d", reg->range);

	if (tnum_is_const(reg->var_off)) {

		/* Typically an immediate SCALAR_VALUE, but

		 * could be a pointer whose offset is too big

		 * for reg->off

		 */

		/* a pointer register with fixed offset */

		if (reg->var_off.value)

			verbose_a("imm=%llx", reg->var_off.value);

	} else {

		print_scalar_ranges(env, reg, &sep);

tools/testing/selftests/bpf/prog_tests/align.c

+21 −21
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{0, "R1", "ctx(off=0,imm=0)"},

			{0, "R1", "ctx()"},

			{0, "R10", "fp0"},

			{0, "R3_w", "2"},

			{1, "R3_w", "4"},
@@ -68,7 +68,7 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{0, "R1", "ctx(off=0,imm=0)"},

			{0, "R1", "ctx()"},

			{0, "R10", "fp0"},

			{0, "R3_w", "1"},

			{1, "R3_w", "2"},
@@ -97,7 +97,7 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{0, "R1", "ctx(off=0,imm=0)"},

			{0, "R1", "ctx()"},

			{0, "R10", "fp0"},

			{0, "R3_w", "4"},

			{1, "R3_w", "8"},
@@ -119,7 +119,7 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{0, "R1", "ctx(off=0,imm=0)"},

			{0, "R1", "ctx()"},

			{0, "R10", "fp0"},

			{0, "R3_w", "7"},

			{1, "R3_w", "7"},
@@ -162,13 +162,13 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{6, "R0_w", "pkt(off=8,r=8,imm=0)"},

			{6, "R0_w", "pkt(off=8,r=8)"},

			{6, "R3_w", "var_off=(0x0; 0xff)"},

			{7, "R3_w", "var_off=(0x0; 0x1fe)"},

			{8, "R3_w", "var_off=(0x0; 0x3fc)"},

			{9, "R3_w", "var_off=(0x0; 0x7f8)"},

			{10, "R3_w", "var_off=(0x0; 0xff0)"},

			{12, "R3_w", "pkt_end(off=0,imm=0)"},

			{12, "R3_w", "pkt_end()"},

			{17, "R4_w", "var_off=(0x0; 0xff)"},

			{18, "R4_w", "var_off=(0x0; 0x1fe0)"},

			{19, "R4_w", "var_off=(0x0; 0xff0)"},
@@ -235,11 +235,11 @@ static struct bpf_align_test tests[] = { 
		},

		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.matches = {

			{2, "R5_w", "pkt(off=0,r=0,imm=0)"},

			{4, "R5_w", "pkt(off=14,r=0,imm=0)"},

			{5, "R4_w", "pkt(off=14,r=0,imm=0)"},

			{9, "R2", "pkt(off=0,r=18,imm=0)"},

			{10, "R5", "pkt(off=14,r=18,imm=0)"},

			{2, "R5_w", "pkt(r=0)"},

			{4, "R5_w", "pkt(off=14,r=0)"},

			{5, "R4_w", "pkt(off=14,r=0)"},

			{9, "R2", "pkt(r=18)"},

			{10, "R5", "pkt(off=14,r=18)"},

			{10, "R4_w", "var_off=(0x0; 0xff)"},

			{13, "R4_w", "var_off=(0x0; 0xffff)"},

			{14, "R4_w", "var_off=(0x0; 0xffff)"},
@@ -299,7 +299,7 @@ static struct bpf_align_test tests[] = { 
			/* Calculated offset in R6 has unknown value, but known

			 * alignment of 4.

			 */

			{6, "R2_w", "pkt(off=0,r=8,imm=0)"},

			{6, "R2_w", "pkt(r=8)"},

			{7, "R6_w", "var_off=(0x0; 0x3fc)"},

			/* Offset is added to packet pointer R5, resulting in

			 * known fixed offset, and variable offset from R6.
@@ -337,7 +337,7 @@ static struct bpf_align_test tests[] = { 
			/* Constant offset is added to R5 packet pointer,

			 * resulting in reg->off value of 14.

			 */

			{26, "R5_w", "pkt(off=14,r=8,"},

			{26, "R5_w", "pkt(off=14,r=8)"},

			/* Variable offset is added to R5, resulting in a

			 * variable offset of (4n). See comment for insn #18

			 * for R4 = R5 trick.
@@ -397,7 +397,7 @@ static struct bpf_align_test tests[] = { 
			/* Calculated offset in R6 has unknown value, but known

			 * alignment of 4.

			 */

			{6, "R2_w", "pkt(off=0,r=8,imm=0)"},

			{6, "R2_w", "pkt(r=8)"},

			{7, "R6_w", "var_off=(0x0; 0x3fc)"},

			/* Adding 14 makes R6 be (4n+2) */

			{8, "R6_w", "var_off=(0x2; 0x7fc)"},
@@ -459,7 +459,7 @@ static struct bpf_align_test tests[] = { 
		.prog_type = BPF_PROG_TYPE_SCHED_CLS,

		.result = REJECT,

		.matches = {

			{3, "R5_w", "pkt_end(off=0,imm=0)"},

			{3, "R5_w", "pkt_end()"},

			/* (ptr - ptr) << 2 == unknown, (4n) */

			{5, "R5_w", "var_off=(0x0; 0xfffffffffffffffc)"},

			/* (4n) + 14 == (4n+2).  We blow our bounds, because
@@ -513,7 +513,7 @@ static struct bpf_align_test tests[] = { 
			/* Calculated offset in R6 has unknown value, but known

			 * alignment of 4.

			 */

			{6, "R2_w", "pkt(off=0,r=8,imm=0)"},

			{6, "R2_w", "pkt(r=8)"},

			{8, "R6_w", "var_off=(0x0; 0x3fc)"},

			/* Adding 14 makes R6 be (4n+2) */

			{9, "R6_w", "var_off=(0x2; 0x7fc)"},
@@ -566,7 +566,7 @@ static struct bpf_align_test tests[] = { 
			/* Calculated offset in R6 has unknown value, but known

			 * alignment of 4.

			 */

			{6, "R2_w", "pkt(off=0,r=8,imm=0)"},

			{6, "R2_w", "pkt(r=8)"},

			{9, "R6_w", "var_off=(0x0; 0x3c)"},

			/* Adding 14 makes R6 be (4n+2) */

			{10, "R6_w", "var_off=(0x2; 0x7c)"},
@@ -659,14 +659,14 @@ static int do_test_single(struct bpf_align_test *test) 
			/* Check the next line as well in case the previous line

			 * did not have a corresponding bpf insn. Example:

			 * func#0 @0

			 * 0: R1=ctx(off=0,imm=0) R10=fp0

			 * 0: R1=ctx() R10=fp0

			 * 0: (b7) r3 = 2                 ; R3_w=2

			 *

			 * Sometimes it's actually two lines below, e.g. when

			 * searching for "6: R3_w=scalar(umax=255,var_off=(0x0; 0xff))":

			 *   from 4 to 6: R0_w=pkt(off=8,r=8,imm=0) R1=ctx(off=0,imm=0) R2_w=pkt(off=0,r=8,imm=0) R3_w=pkt_end(off=0,imm=0) R10=fp0

			 *   6: R0_w=pkt(off=8,r=8,imm=0) R1=ctx(off=0,imm=0) R2_w=pkt(off=0,r=8,imm=0) R3_w=pkt_end(off=0,imm=0) R10=fp0

			 *   6: (71) r3 = *(u8 *)(r2 +0)           ; R2_w=pkt(off=0,r=8,imm=0) R3_w=scalar(umax=255,var_off=(0x0; 0xff))

			 *   from 4 to 6: R0_w=pkt(off=8,r=8) R1=ctx() R2_w=pkt(r=8) R3_w=pkt_end() R10=fp0

			 *   6: R0_w=pkt(off=8,r=8) R1=ctx() R2_w=pkt(r=8) R3_w=pkt_end() R10=fp0

			 *   6: (71) r3 = *(u8 *)(r2 +0)           ; R2_w=pkt(r=8) R3_w=scalar(umax=255,var_off=(0x0; 0xff))

			 */

			while (!(p = strstr(line_ptr, m.reg)) || !strstr(p, m.match)) {

				cur_line = -1;

tools/testing/selftests/bpf/prog_tests/log_buf.c

+2 −2
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ static void obj_load_log_buf(void) 
	ASSERT_OK_PTR(strstr(libbpf_log_buf, "prog 'bad_prog': BPF program load failed"),

		      "libbpf_log_not_empty");

	ASSERT_OK_PTR(strstr(obj_log_buf, "DATASEC license"), "obj_log_not_empty");

	ASSERT_OK_PTR(strstr(good_log_buf, "0: R1=ctx(off=0,imm=0) R10=fp0"),

	ASSERT_OK_PTR(strstr(good_log_buf, "0: R1=ctx() R10=fp0"),

		      "good_log_verbose");

	ASSERT_OK_PTR(strstr(bad_log_buf, "invalid access to map value, value_size=16 off=16000 size=4"),

		      "bad_log_not_empty");
@@ -175,7 +175,7 @@ static void bpf_prog_load_log_buf(void) 
	opts.log_level = 2;

	fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "good_prog", "GPL",

			   good_prog_insns, good_prog_insn_cnt, &opts);

	ASSERT_OK_PTR(strstr(log_buf, "0: R1=ctx(off=0,imm=0) R10=fp0"), "good_log_2");

	ASSERT_OK_PTR(strstr(log_buf, "0: R1=ctx() R10=fp0"), "good_log_2");

	ASSERT_GE(fd, 0, "good_fd2");

	if (fd >= 0)

		close(fd);

tools/testing/selftests/bpf/prog_tests/spin_lock.c

+7 −7
Original line number Diff line number Diff line
@@ -13,22 +13,22 @@ static struct { 
	const char *err_msg;

} spin_lock_fail_tests[] = {

	{ "lock_id_kptr_preserve",

	  "5: (bf) r1 = r0                       ; R0_w=ptr_foo(id=2,ref_obj_id=2,off=0,imm=0) "

	  "R1_w=ptr_foo(id=2,ref_obj_id=2,off=0,imm=0) refs=2\n6: (85) call bpf_this_cpu_ptr#154\n"

	  "5: (bf) r1 = r0                       ; R0_w=ptr_foo(id=2,ref_obj_id=2) "

	  "R1_w=ptr_foo(id=2,ref_obj_id=2) refs=2\n6: (85) call bpf_this_cpu_ptr#154\n"

	  "R1 type=ptr_ expected=percpu_ptr_" },

	{ "lock_id_global_zero",

	  "; R1_w=map_value(map=.data.A,ks=4,vs=4,off=0,imm=0)\n2: (85) call bpf_this_cpu_ptr#154\n"

	  "; R1_w=map_value(map=.data.A,ks=4,vs=4)\n2: (85) call bpf_this_cpu_ptr#154\n"

	  "R1 type=map_value expected=percpu_ptr_" },

	{ "lock_id_mapval_preserve",

	  "[0-9]\\+: (bf) r1 = r0                       ;"

	  " R0_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)"

	  " R1_w=map_value(id=1,map=array_map,ks=4,vs=8,off=0,imm=0)\n"

	  " R0_w=map_value(id=1,map=array_map,ks=4,vs=8)"

	  " R1_w=map_value(id=1,map=array_map,ks=4,vs=8)\n"

	  "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n"

	  "R1 type=map_value expected=percpu_ptr_" },

	{ "lock_id_innermapval_preserve",

	  "[0-9]\\+: (bf) r1 = r0                      ;"

	  " R0=map_value(id=2,ks=4,vs=8,off=0,imm=0)"

	  " R1_w=map_value(id=2,ks=4,vs=8,off=0,imm=0)\n"

	  " R0=map_value(id=2,ks=4,vs=8)"

	  " R1_w=map_value(id=2,ks=4,vs=8)\n"

	  "[0-9]\\+: (85) call bpf_this_cpu_ptr#154\n"

	  "R1 type=map_value expected=percpu_ptr_" },

	{ "lock_id_mismatch_kptr_kptr", "bpf_spin_unlock of different lock" },

tools/testing/selftests/bpf/progs/exceptions_assert.c

+5 −5
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ check_assert(s64, ge, neg, INT_MIN); 


SEC("?tc")

__log_level(2) __failure

__msg(": R0=0 R1=ctx(off=0,imm=0) R2=scalar(smin=smin32=-2147483646,smax=smax32=2147483645) R10=fp0")

__msg(": R0=0 R1=ctx() R2=scalar(smin=smin32=-2147483646,smax=smax32=2147483645) R10=fp0")

int check_assert_range_s64(struct __sk_buff *ctx)

{

	struct bpf_sock *sk = ctx->sk;
@@ -75,7 +75,7 @@ int check_assert_range_s64(struct __sk_buff *ctx) 


SEC("?tc")

__log_level(2) __failure

__msg(": R1=ctx(off=0,imm=0) R2=scalar(smin=umin=smin32=umin32=4096,smax=umax=smax32=umax32=8192,var_off=(0x0; 0x3fff))")

__msg(": R1=ctx() R2=scalar(smin=umin=smin32=umin32=4096,smax=umax=smax32=umax32=8192,var_off=(0x0; 0x3fff))")

int check_assert_range_u64(struct __sk_buff *ctx)

{

	u64 num = ctx->len;
@@ -86,7 +86,7 @@ int check_assert_range_u64(struct __sk_buff *ctx) 


SEC("?tc")

__log_level(2) __failure

__msg(": R0=0 R1=ctx(off=0,imm=0) R2=4096 R10=fp0")

__msg(": R0=0 R1=ctx() R2=4096 R10=fp0")

int check_assert_single_range_s64(struct __sk_buff *ctx)

{

	struct bpf_sock *sk = ctx->sk;
@@ -103,7 +103,7 @@ int check_assert_single_range_s64(struct __sk_buff *ctx) 


SEC("?tc")

__log_level(2) __failure

__msg(": R1=ctx(off=0,imm=0) R2=4096 R10=fp0")

__msg(": R1=ctx() R2=4096 R10=fp0")

int check_assert_single_range_u64(struct __sk_buff *ctx)

{

	u64 num = ctx->len;
@@ -114,7 +114,7 @@ int check_assert_single_range_u64(struct __sk_buff *ctx) 


SEC("?tc")

__log_level(2) __failure

__msg(": R1=pkt(off=64,r=64,imm=0) R2=pkt_end(off=0,imm=0) R6=pkt(off=0,r=64,imm=0) R10=fp0")

__msg(": R1=pkt(off=64,r=64) R2=pkt_end() R6=pkt(r=64) R10=fp0")

int check_assert_generic(struct __sk_buff *ctx)

{

	u8 *data_end = (void *)(long)ctx->data_end;