* [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information
@ 2018-05-02 20:17 Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 1/3] bpf: unify main prog and subprog Jiong Wang
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Jiong Wang @ 2018-05-02 20:17 UTC (permalink / raw)
To: alexei.starovoitov, borkmann
Cc: john.fastabend, ecree, netdev, oss-drivers, Jiong Wang
This patch set clean up some code logic related with managing subprog
information.
Part of the set are inspried by Edwin's code in his RFC:
"bpf/verifier: subprog/func_call simplifications"
but with clearer separation so it could be easier to review.
- Path 1 unifies main prog and subprogs. All of them are registered in
env->subprog_starts.
- After patch 1, it is clear that subprog_starts and subprog_stack_depth
could be merged as both of them now have main and subprog unified.
Patch 2 therefore does the merge, all subprog information are centred
at bpf_subprog_info.
- Patch 3 goes further to introduce a new fake "exit" subprog which
serves as an ending marker to the subprog list. We could then turn the
following code snippets across verifier:
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
subprog_end = env->subprog_info[cur_subprog + 1].start;
into:
subprog_end = env->subprog_info[cur_subprog + 1].start;
There is no functional change by this patch set.
No bpf selftest (both non-jit and jit) regression found after this set.
v2:
- fixed adjust_subprog_starts to also update fake "exit" subprog start.
- for John's suggestion on renaming subprog to prog, I could work on
a follow-up patch if it is recognized as worth the change.
Jiong Wang (3):
bpf: unify main prog and subprog
bpf: centre subprog information fields
bpf: add faked "ending" subprog
include/linux/bpf_verifier.h | 9 ++--
kernel/bpf/verifier.c | 121 ++++++++++++++++++++++---------------------
2 files changed, 67 insertions(+), 63 deletions(-)
--
2.7.4
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 bpf-next 1/3] bpf: unify main prog and subprog
2018-05-02 20:17 [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Jiong Wang
@ 2018-05-02 20:17 ` Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 2/3] bpf: centre subprog information fields Jiong Wang
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Jiong Wang @ 2018-05-02 20:17 UTC (permalink / raw)
To: alexei.starovoitov, borkmann
Cc: john.fastabend, ecree, netdev, oss-drivers, Jiong Wang
Currently, verifier treat main prog and subprog differently. All subprogs
detected are kept in env->subprog_starts while main prog is not kept there.
Instead, main prog is implicitly defined as the prog start at 0.
There is actually no difference between main prog and subprog, it is better
to unify them, and register all progs detected into env->subprog_starts.
This could also help simplifying some code logic.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
---
include/linux/bpf_verifier.h | 2 +-
kernel/bpf/verifier.c | 57 ++++++++++++++++++++++++--------------------
2 files changed, 32 insertions(+), 27 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 7e61c39..f655b92 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -191,7 +191,7 @@ struct bpf_verifier_env {
bool seen_direct_write;
struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
struct bpf_verifier_log log;
- u32 subprog_starts[BPF_MAX_SUBPROGS];
+ u32 subprog_starts[BPF_MAX_SUBPROGS + 1];
/* computes the stack depth of each bpf function */
u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1];
u32 subprog_cnt;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index eb1a596..16ec977 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -765,7 +765,7 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
ret = find_subprog(env, off);
if (ret >= 0)
return 0;
- if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
+ if (env->subprog_cnt > BPF_MAX_SUBPROGS) {
verbose(env, "too many subprograms\n");
return -E2BIG;
}
@@ -781,6 +781,11 @@ static int check_subprogs(struct bpf_verifier_env *env)
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
+ /* Add entry function. */
+ ret = add_subprog(env, 0);
+ if (ret < 0)
+ return ret;
+
/* determine subprog starts. The end is one before the next starts */
for (i = 0; i < insn_cnt; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
@@ -806,10 +811,10 @@ static int check_subprogs(struct bpf_verifier_env *env)
/* now check that all jumps are within the same subprog */
subprog_start = 0;
- if (env->subprog_cnt == cur_subprog)
+ if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
- subprog_end = env->subprog_starts[cur_subprog++];
+ subprog_end = env->subprog_starts[cur_subprog + 1];
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
@@ -833,11 +838,13 @@ static int check_subprogs(struct bpf_verifier_env *env)
verbose(env, "last insn is not an exit or jmp\n");
return -EINVAL;
}
+ cur_subprog++;
subprog_start = subprog_end;
- if (env->subprog_cnt == cur_subprog)
+ if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
- subprog_end = env->subprog_starts[cur_subprog++];
+ subprog_end =
+ env->subprog_starts[cur_subprog + 1];
}
}
return 0;
@@ -1505,10 +1512,10 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
return -EACCES;
}
continue_func:
- if (env->subprog_cnt == subprog)
+ if (env->subprog_cnt == subprog + 1)
subprog_end = insn_cnt;
else
- subprog_end = env->subprog_starts[subprog];
+ subprog_end = env->subprog_starts[subprog + 1];
for (; i < subprog_end; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
continue;
@@ -1526,7 +1533,6 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
i);
return -EFAULT;
}
- subprog++;
frame++;
if (frame >= MAX_CALL_FRAMES) {
WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
@@ -1558,7 +1564,6 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env,
start);
return -EFAULT;
}
- subprog++;
return env->subprog_stack_depth[subprog];
}
#endif
@@ -2087,7 +2092,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_FUNC_tail_call:
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
goto error;
- if (env->subprog_cnt) {
+ if (env->subprog_cnt > 1) {
verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
return -EINVAL;
}
@@ -2259,7 +2264,7 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
/* remember the callsite, it will be used by bpf_exit */
*insn_idx /* callsite */,
state->curframe + 1 /* frameno within this callchain */,
- subprog + 1 /* subprog number within this prog */);
+ subprog /* subprog number within this prog */);
/* copy r1 - r5 args that callee can access */
for (i = BPF_REG_1; i <= BPF_REG_5; i++)
@@ -3818,7 +3823,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
return -EINVAL;
}
- if (env->subprog_cnt) {
+ if (env->subprog_cnt > 1) {
/* when program has LD_ABS insn JITs and interpreter assume
* that r1 == ctx == skb which is not the case for callees
* that can have arbitrary arguments. It's problematic
@@ -4849,11 +4854,11 @@ static int do_check(struct bpf_verifier_env *env)
verbose(env, "processed %d insns (limit %d), stack depth ",
insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);
- for (i = 0; i < env->subprog_cnt + 1; i++) {
+ for (i = 0; i < env->subprog_cnt; i++) {
u32 depth = env->subprog_stack_depth[i];
verbose(env, "%d", depth);
- if (i + 1 < env->subprog_cnt + 1)
+ if (i + 1 < env->subprog_cnt)
verbose(env, "+");
}
verbose(env, "\n");
@@ -5230,7 +5235,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
void *old_bpf_func;
int err = -ENOMEM;
- if (env->subprog_cnt == 0)
+ if (env->subprog_cnt <= 1)
return 0;
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
@@ -5246,7 +5251,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
/* temporarily remember subprog id inside insn instead of
* aux_data, since next loop will split up all insns into funcs
*/
- insn->off = subprog + 1;
+ insn->off = subprog;
/* remember original imm in case JIT fails and fallback
* to interpreter will be needed
*/
@@ -5255,16 +5260,16 @@ static int jit_subprogs(struct bpf_verifier_env *env)
insn->imm = 1;
}
- func = kzalloc(sizeof(prog) * (env->subprog_cnt + 1), GFP_KERNEL);
+ func = kzalloc(sizeof(prog) * env->subprog_cnt, GFP_KERNEL);
if (!func)
return -ENOMEM;
- for (i = 0; i <= env->subprog_cnt; i++) {
+ for (i = 0; i < env->subprog_cnt; i++) {
subprog_start = subprog_end;
- if (env->subprog_cnt == i)
+ if (env->subprog_cnt == i + 1)
subprog_end = prog->len;
else
- subprog_end = env->subprog_starts[i];
+ subprog_end = env->subprog_starts[i + 1];
len = subprog_end - subprog_start;
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
@@ -5294,7 +5299,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
* now populate all bpf_calls with correct addresses and
* run last pass of JIT
*/
- for (i = 0; i <= env->subprog_cnt; i++) {
+ for (i = 0; i < env->subprog_cnt; i++) {
insn = func[i]->insnsi;
for (j = 0; j < func[i]->len; j++, insn++) {
if (insn->code != (BPF_JMP | BPF_CALL) ||
@@ -5307,7 +5312,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
__bpf_call_base;
}
}
- for (i = 0; i <= env->subprog_cnt; i++) {
+ for (i = 0; i < env->subprog_cnt; i++) {
old_bpf_func = func[i]->bpf_func;
tmp = bpf_int_jit_compile(func[i]);
if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
@@ -5321,7 +5326,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
/* finally lock prog and jit images for all functions and
* populate kallsysm
*/
- for (i = 0; i <= env->subprog_cnt; i++) {
+ for (i = 0; i < env->subprog_cnt; i++) {
bpf_prog_lock_ro(func[i]);
bpf_prog_kallsyms_add(func[i]);
}
@@ -5338,7 +5343,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
continue;
insn->off = env->insn_aux_data[i].call_imm;
subprog = find_subprog(env, i + insn->off + 1);
- addr = (unsigned long)func[subprog + 1]->bpf_func;
+ addr = (unsigned long)func[subprog]->bpf_func;
addr &= PAGE_MASK;
insn->imm = (u64 (*)(u64, u64, u64, u64, u64))
addr - __bpf_call_base;
@@ -5347,10 +5352,10 @@ static int jit_subprogs(struct bpf_verifier_env *env)
prog->jited = 1;
prog->bpf_func = func[0]->bpf_func;
prog->aux->func = func;
- prog->aux->func_cnt = env->subprog_cnt + 1;
+ prog->aux->func_cnt = env->subprog_cnt;
return 0;
out_free:
- for (i = 0; i <= env->subprog_cnt; i++)
+ for (i = 0; i < env->subprog_cnt; i++)
if (func[i])
bpf_jit_free(func[i]);
kfree(func);
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 bpf-next 2/3] bpf: centre subprog information fields
2018-05-02 20:17 [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 1/3] bpf: unify main prog and subprog Jiong Wang
@ 2018-05-02 20:17 ` Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 3/3] bpf: add faked "ending" subprog Jiong Wang
2018-05-04 19:20 ` [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: Jiong Wang @ 2018-05-02 20:17 UTC (permalink / raw)
To: alexei.starovoitov, borkmann
Cc: john.fastabend, ecree, netdev, oss-drivers, Jiong Wang
It is better to centre all subprog information fields into one structure.
This structure could later serve as function node in call graph.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
---
include/linux/bpf_verifier.h | 9 ++++---
kernel/bpf/verifier.c | 62 +++++++++++++++++++++++---------------------
2 files changed, 38 insertions(+), 33 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index f655b92..8f70dc1 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -173,6 +173,11 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
#define BPF_MAX_SUBPROGS 256
+struct bpf_subprog_info {
+ u32 start; /* insn idx of function entry point */
+ u16 stack_depth; /* max. stack depth used by this function */
+};
+
/* single container for all structs
* one verifier_env per bpf_check() call
*/
@@ -191,9 +196,7 @@ struct bpf_verifier_env {
bool seen_direct_write;
struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
struct bpf_verifier_log log;
- u32 subprog_starts[BPF_MAX_SUBPROGS + 1];
- /* computes the stack depth of each bpf function */
- u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1];
+ struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
u32 subprog_cnt;
};
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 16ec977..9764b9b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -738,18 +738,19 @@ enum reg_arg_type {
static int cmp_subprogs(const void *a, const void *b)
{
- return *(int *)a - *(int *)b;
+ return ((struct bpf_subprog_info *)a)->start -
+ ((struct bpf_subprog_info *)b)->start;
}
static int find_subprog(struct bpf_verifier_env *env, int off)
{
- u32 *p;
+ struct bpf_subprog_info *p;
- p = bsearch(&off, env->subprog_starts, env->subprog_cnt,
- sizeof(env->subprog_starts[0]), cmp_subprogs);
+ p = bsearch(&off, env->subprog_info, env->subprog_cnt,
+ sizeof(env->subprog_info[0]), cmp_subprogs);
if (!p)
return -ENOENT;
- return p - env->subprog_starts;
+ return p - env->subprog_info;
}
@@ -769,15 +770,16 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
verbose(env, "too many subprograms\n");
return -E2BIG;
}
- env->subprog_starts[env->subprog_cnt++] = off;
- sort(env->subprog_starts, env->subprog_cnt,
- sizeof(env->subprog_starts[0]), cmp_subprogs, NULL);
+ env->subprog_info[env->subprog_cnt++].start = off;
+ sort(env->subprog_info, env->subprog_cnt,
+ sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
return 0;
}
static int check_subprogs(struct bpf_verifier_env *env)
{
int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
+ struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
@@ -807,14 +809,14 @@ static int check_subprogs(struct bpf_verifier_env *env)
if (env->log.level > 1)
for (i = 0; i < env->subprog_cnt; i++)
- verbose(env, "func#%d @%d\n", i, env->subprog_starts[i]);
+ verbose(env, "func#%d @%d\n", i, subprog[i].start);
/* now check that all jumps are within the same subprog */
subprog_start = 0;
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
- subprog_end = env->subprog_starts[cur_subprog + 1];
+ subprog_end = subprog[cur_subprog + 1].start;
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
@@ -843,8 +845,7 @@ static int check_subprogs(struct bpf_verifier_env *env)
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
- subprog_end =
- env->subprog_starts[cur_subprog + 1];
+ subprog_end = subprog[cur_subprog + 1].start;
}
}
return 0;
@@ -1477,13 +1478,13 @@ static int update_stack_depth(struct bpf_verifier_env *env,
const struct bpf_func_state *func,
int off)
{
- u16 stack = env->subprog_stack_depth[func->subprogno];
+ u16 stack = env->subprog_info[func->subprogno].stack_depth;
if (stack >= -off)
return 0;
/* update known max for given subprogram */
- env->subprog_stack_depth[func->subprogno] = -off;
+ env->subprog_info[func->subprogno].stack_depth = -off;
return 0;
}
@@ -1495,7 +1496,8 @@ static int update_stack_depth(struct bpf_verifier_env *env,
*/
static int check_max_stack_depth(struct bpf_verifier_env *env)
{
- int depth = 0, frame = 0, subprog = 0, i = 0, subprog_end;
+ int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
+ struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
int ret_insn[MAX_CALL_FRAMES];
@@ -1505,17 +1507,17 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
/* round up to 32-bytes, since this is granularity
* of interpreter stack size
*/
- depth += round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
+ depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
if (depth > MAX_BPF_STACK) {
verbose(env, "combined stack size of %d calls is %d. Too large\n",
frame + 1, depth);
return -EACCES;
}
continue_func:
- if (env->subprog_cnt == subprog + 1)
+ if (env->subprog_cnt == idx + 1)
subprog_end = insn_cnt;
else
- subprog_end = env->subprog_starts[subprog + 1];
+ subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
continue;
@@ -1523,12 +1525,12 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
continue;
/* remember insn and function to return to */
ret_insn[frame] = i + 1;
- ret_prog[frame] = subprog;
+ ret_prog[frame] = idx;
/* find the callee */
i = i + insn[i].imm + 1;
- subprog = find_subprog(env, i);
- if (subprog < 0) {
+ idx = find_subprog(env, i);
+ if (idx < 0) {
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
i);
return -EFAULT;
@@ -1545,10 +1547,10 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
*/
if (frame == 0)
return 0;
- depth -= round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
+ depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
frame--;
i = ret_insn[frame];
- subprog = ret_prog[frame];
+ idx = ret_prog[frame];
goto continue_func;
}
@@ -1564,7 +1566,7 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env,
start);
return -EFAULT;
}
- return env->subprog_stack_depth[subprog];
+ return env->subprog_info[subprog].stack_depth;
}
#endif
@@ -4855,14 +4857,14 @@ static int do_check(struct bpf_verifier_env *env)
verbose(env, "processed %d insns (limit %d), stack depth ",
insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);
for (i = 0; i < env->subprog_cnt; i++) {
- u32 depth = env->subprog_stack_depth[i];
+ u32 depth = env->subprog_info[i].stack_depth;
verbose(env, "%d", depth);
if (i + 1 < env->subprog_cnt)
verbose(env, "+");
}
verbose(env, "\n");
- env->prog->aux->stack_depth = env->subprog_stack_depth[0];
+ env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
return 0;
}
@@ -5069,9 +5071,9 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len
if (len == 1)
return;
for (i = 0; i < env->subprog_cnt; i++) {
- if (env->subprog_starts[i] < off)
+ if (env->subprog_info[i].start < off)
continue;
- env->subprog_starts[i] += len - 1;
+ env->subprog_info[i].start += len - 1;
}
}
@@ -5269,7 +5271,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
if (env->subprog_cnt == i + 1)
subprog_end = prog->len;
else
- subprog_end = env->subprog_starts[i + 1];
+ subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
@@ -5286,7 +5288,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
* Long term would need debug info to populate names
*/
func[i]->aux->name[0] = 'F';
- func[i]->aux->stack_depth = env->subprog_stack_depth[i];
+ func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
func[i]->jit_requested = 1;
func[i] = bpf_int_jit_compile(func[i]);
if (!func[i]->jited) {
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 bpf-next 3/3] bpf: add faked "ending" subprog
2018-05-02 20:17 [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 1/3] bpf: unify main prog and subprog Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 2/3] bpf: centre subprog information fields Jiong Wang
@ 2018-05-02 20:17 ` Jiong Wang
2018-05-04 19:20 ` [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: Jiong Wang @ 2018-05-02 20:17 UTC (permalink / raw)
To: alexei.starovoitov, borkmann
Cc: john.fastabend, ecree, netdev, oss-drivers, Jiong Wang
There are quite a few code snippet like the following in verifier:
subprog_start = 0;
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
subprog_end = env->subprog_info[cur_subprog + 1].start;
The reason is there is no marker in subprog_info array to tell the end of
it.
We could resolve this issue by introducing a faked "ending" subprog.
The special "ending" subprog is with "insn_cnt" as start offset, so it is
serving as the end mark whenever we iterate over all subprogs.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
---
kernel/bpf/verifier.c | 34 ++++++++++++++--------------------
1 file changed, 14 insertions(+), 20 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9764b9b..65a6e2e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -766,7 +766,7 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
ret = find_subprog(env, off);
if (ret >= 0)
return 0;
- if (env->subprog_cnt > BPF_MAX_SUBPROGS) {
+ if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
verbose(env, "too many subprograms\n");
return -E2BIG;
}
@@ -807,16 +807,18 @@ static int check_subprogs(struct bpf_verifier_env *env)
return ret;
}
+ /* Add a fake 'exit' subprog which could simplify subprog iteration
+ * logic. 'subprog_cnt' should not be increased.
+ */
+ subprog[env->subprog_cnt].start = insn_cnt;
+
if (env->log.level > 1)
for (i = 0; i < env->subprog_cnt; i++)
verbose(env, "func#%d @%d\n", i, subprog[i].start);
/* now check that all jumps are within the same subprog */
- subprog_start = 0;
- if (env->subprog_cnt == cur_subprog + 1)
- subprog_end = insn_cnt;
- else
- subprog_end = subprog[cur_subprog + 1].start;
+ subprog_start = subprog[cur_subprog].start;
+ subprog_end = subprog[cur_subprog + 1].start;
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
@@ -840,11 +842,9 @@ static int check_subprogs(struct bpf_verifier_env *env)
verbose(env, "last insn is not an exit or jmp\n");
return -EINVAL;
}
- cur_subprog++;
subprog_start = subprog_end;
- if (env->subprog_cnt == cur_subprog + 1)
- subprog_end = insn_cnt;
- else
+ cur_subprog++;
+ if (cur_subprog < env->subprog_cnt)
subprog_end = subprog[cur_subprog + 1].start;
}
}
@@ -1499,7 +1499,6 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
int ret_insn[MAX_CALL_FRAMES];
int ret_prog[MAX_CALL_FRAMES];
@@ -1514,10 +1513,7 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
return -EACCES;
}
continue_func:
- if (env->subprog_cnt == idx + 1)
- subprog_end = insn_cnt;
- else
- subprog_end = subprog[idx + 1].start;
+ subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
continue;
@@ -5070,7 +5066,8 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len
if (len == 1)
return;
- for (i = 0; i < env->subprog_cnt; i++) {
+ /* NOTE: fake 'exit' subprog should be updated as well. */
+ for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start < off)
continue;
env->subprog_info[i].start += len - 1;
@@ -5268,10 +5265,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
for (i = 0; i < env->subprog_cnt; i++) {
subprog_start = subprog_end;
- if (env->subprog_cnt == i + 1)
- subprog_end = prog->len;
- else
- subprog_end = env->subprog_info[i + 1].start;
+ subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information
2018-05-02 20:17 [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Jiong Wang
` (2 preceding siblings ...)
2018-05-02 20:17 ` [PATCH v2 bpf-next 3/3] bpf: add faked "ending" subprog Jiong Wang
@ 2018-05-04 19:20 ` Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: Daniel Borkmann @ 2018-05-04 19:20 UTC (permalink / raw)
To: Jiong Wang, alexei.starovoitov, borkmann
Cc: john.fastabend, ecree, netdev, oss-drivers
On 05/02/2018 10:17 PM, Jiong Wang wrote:
> This patch set clean up some code logic related with managing subprog
> information.
>
> Part of the set are inspried by Edwin's code in his RFC:
>
> "bpf/verifier: subprog/func_call simplifications"
>
> but with clearer separation so it could be easier to review.
>
> - Path 1 unifies main prog and subprogs. All of them are registered in
> env->subprog_starts.
>
> - After patch 1, it is clear that subprog_starts and subprog_stack_depth
> could be merged as both of them now have main and subprog unified.
> Patch 2 therefore does the merge, all subprog information are centred
> at bpf_subprog_info.
>
> - Patch 3 goes further to introduce a new fake "exit" subprog which
> serves as an ending marker to the subprog list. We could then turn the
> following code snippets across verifier:
>
> if (env->subprog_cnt == cur_subprog + 1)
> subprog_end = insn_cnt;
> else
> subprog_end = env->subprog_info[cur_subprog + 1].start;
>
> into:
> subprog_end = env->subprog_info[cur_subprog + 1].start;
>
> There is no functional change by this patch set.
> No bpf selftest (both non-jit and jit) regression found after this set.
>
> v2:
> - fixed adjust_subprog_starts to also update fake "exit" subprog start.
> - for John's suggestion on renaming subprog to prog, I could work on
> a follow-up patch if it is recognized as worth the change.
>
> Jiong Wang (3):
> bpf: unify main prog and subprog
> bpf: centre subprog information fields
> bpf: add faked "ending" subprog
>
> include/linux/bpf_verifier.h | 9 ++--
> kernel/bpf/verifier.c | 121 ++++++++++++++++++++++---------------------
> 2 files changed, 67 insertions(+), 63 deletions(-)
>
LGTM, applied to bpf-next, thanks Jiong!
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2018-05-02 20:17 [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Jiong Wang
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2018-05-02 20:17 ` [PATCH v2 bpf-next 2/3] bpf: centre subprog information fields Jiong Wang
2018-05-02 20:17 ` [PATCH v2 bpf-next 3/3] bpf: add faked "ending" subprog Jiong Wang
2018-05-04 19:20 ` [PATCH v2 bpf-next 0/3] bpf: cleanups on managing subprog information Daniel Borkmann
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