bpf: support proper non-jit func info
Subsystems (6)
cover bpf: support proper non-jit func info
Commit 838e96904ff3 ("bpf: Introduce bpf_func_info") added bpf func info support. The userspace is able to get better ksym's for bpf programs with jit, and is able to print out func prototypes.
For a program containing func-to-func calls, the existing implementation returns user specified number of function calls and BTF types if jit is enabled. If the jit is not enabled, it only returns the type for the main function.
This is undesirable. Interpreter may still be used and we should keep feature identical regardless of whether jit is enabled or not.
This patch fixed this discrepancy.
The following example shows bpftool output for the bpf program in selftests test_btf_haskv.o when jit is disabled:
$ bpftool prog dump xlated id 1490
int _dummy_tracepoint(struct dummy_tracepoint_args * arg):
0: (85) call pc+2#__bpf_prog_run_args32
1: (b7) r0 = 0
2: (95) exit
int test_long_fname_1(struct dummy_tracepoint_args * arg):
3: (85) call pc+1#__bpf_prog_run_args32
4: (95) exit
int test_long_fname_2(struct dummy_tracepoint_args * arg):
5: (b7) r2 = 0
6: (63) *(u32 *)(r10 -4) = r2
7: (79) r1 = *(u64 *)(r1 +8)
8: (15) if r1 == 0x0 goto pc+9
9: (bf) r2 = r10
10: (07) r2 += -4
11: (18) r1 = map[id:1173]
13: (85) call bpf_map_lookup_elem#77088
14: (15) if r0 == 0x0 goto pc+3
15: (61) r1 = *(u32 *)(r0 +4)
16: (07) r1 += 1
17: (63) *(u32 *)(r0 +4) = r1
18: (95) exit
$ bpftool prog dump jited id 1490
no instructions returnedYonghong Song (2):
bpf: btf: support proper non-jit func info tools/bpf: change selftest test_btf for both jit and non-jit
include/linux/bpf.h | 6 ++- include/linux/bpf_verifier.h | 1 - kernel/bpf/core.c | 3 +- kernel/bpf/syscall.c | 33 ++++------------ kernel/bpf/verifier.c | 55 ++++++++++++++++++-------- tools/testing/selftests/bpf/test_btf.c | 33 ++-------------- 6 files changed, 55 insertions(+), 76 deletions(-)
Signature · 1 line
2.17.1
PATCH 1/2 bpf: btf: support proper non-jit func info
Commit 838e96904ff3 ("bpf: Introduce bpf_func_info") added bpf func info support. The userspace is able to get better ksym's for bpf programs with jit, and is able to print out func prototypes.
For a program containing func-to-func calls, the existing implementation returns user specified number of function calls and BTF types if jit is enabled. If the jit is not enabled, it only returns the type for the main function.
This is undesirable. Interpreter may still be used and we should keep feature identical regardless of whether jit is enabled or not.
This patch fixed this discrepancy.
--- include/linux/bpf.h | 6 ++-- include/linux/bpf_verifier.h | 1 - kernel/bpf/core.c | 3 +- kernel/bpf/syscall.c | 33 ++++++---------------- kernel/bpf/verifier.c | 55 +++++++++++++++++++++++++----------- 5 files changed, 52 insertions(+), 46 deletions(-)
include/linux/bpf.h +4 -2
@@ -299,7 +299,8 @@ struct bpf_prog_aux {u32 max_pkt_offset;u32 stack_depth;u32 id; -u32 func_cnt; +u32 func_cnt;/* used by non-func prog as the number of func progs */ +u32 func_idx;/* 0 for non-func prog, the index in func array for func prog */ bool offload_requested;struct bpf_prog **func;void *jit_data;/* JIT specific data. arch dependent */
@@ -317,7 +318,8 @@ struct bpf_prog_aux {#endif struct bpf_prog_offload *offload;struct btf *btf; -u32 type_id;/* type id for this prog/func */ +struct bpf_func_info *func_info; +u32 func_info_cnt;union {struct work_struct work;struct rcu_head rcu;
include/linux/bpf_verifier.h +0 -1
@@ -204,7 +204,6 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)struct bpf_subprog_info {u32 start;/* insn idx of function entry point */ u16 stack_depth;/* max. stack depth used by this function */ -u32 type_id;/* btf type_id for this subprog */ };/* single container for all structs
kernel/bpf/core.c +2 -1
@@ -411,7 +411,8 @@ static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)/* prog->aux->name will be ignored if full btf name is available */ if (prog->aux->btf) { - type =btf_type_by_id (prog->aux->btf, prog->aux->type_id); + type =btf_type_by_id (prog->aux->btf, + prog->aux->func_info[prog->aux->func_idx].type_id); func_name =btf_name_by_offset (prog->aux->btf, type->name_off);snprintf (sym, (size_t )(end - sym),"_%s" , func_name);return ;
kernel/bpf/syscall.c +8 -25
@@ -1214,6 +1214,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)bpf_prog_free_id (prog, do_idr_lock);bpf_prog_kallsyms_del_all (prog);btf_put (prog->aux->btf); +kvfree (prog->aux->func_info);call_rcu (&prog->aux->rcu, __bpf_prog_put_rcu); }
@@ -2219,46 +2220,28 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, }if (prog->aux->btf) { +u32 krec_size =sizeof (struct bpf_func_info );u32 ucnt, urec_size; info.btf_id =btf_id (prog->aux->btf); ucnt = info.func_info_cnt; - info.func_info_cnt = prog->aux->func_cnt ? :1 ; + info.func_info_cnt = prog->aux->func_info_cnt; urec_size = info.func_info_rec_size; - info.func_info_rec_size =sizeof (struct bpf_func_info ); + info.func_info_rec_size = krec_size;if (ucnt) {/* expect passed-in urec_size is what the kernel expects */ if (urec_size != info.func_info_rec_size)return -EINVAL ;if (bpf_dump_raw_ok ()) { -struct bpf_func_info kern_finfo;char __user *user_finfo; -u32 i, insn_offset; user_finfo =u64_to_user_ptr (info.func_info); -if (prog->aux->func_cnt) { - ucnt =min_t (u32, info.func_info_cnt, ucnt); - insn_offset =0 ; -for (i =0 ; i < ucnt; i++) { - kern_finfo.insn_offset = insn_offset; - kern_finfo.type_id = prog->aux->func[i]->aux->type_id; -if (copy_to_user (user_finfo, &kern_finfo, -sizeof (kern_finfo))) -return -EFAULT ; - -/* func[i]->len holds the prog len */ - insn_offset += prog->aux->func[i]->len; - user_finfo += urec_size; - } - }else { - kern_finfo.insn_offset =0 ; - kern_finfo.type_id = prog->aux->type_id; -if (copy_to_user (user_finfo, &kern_finfo, -sizeof (kern_finfo))) -return -EFAULT ; - } + ucnt =min_t (u32, info.func_info_cnt, ucnt); +if (copy_to_user (user_finfo, prog->aux->func_info, + krec_size * ucnt)) +return -EFAULT ; }else { info.func_info_cnt =0 ; }
kernel/bpf/verifier.c +38 -17
131 lines not on this page · raw message
Signature · 1 line
2.17.1
Re: [PATCH bpf-next 1/2] bpf: btf: support proper non-jit func info
Quoted 10 lines · Yonghong Song
Commit
838e96904ff3("bpf: Introducebpf_func_info") added bpf func info support. The userspace is able to get better ksym's for bpf programs with jit, and is able to print out func prototypes.For a program containing func-to-func calls, the existing implementation returns user specified number of function calls and BTF types if jit is enabled. If the jit is not enabled, it only returns the type for the main function.
Quoted 4 lines
This is undesirable. Interpreter may still be used and we should keep feature identical regardless of whether jit is enabled or not.
This patch fixed this discrepancy.
PATCH 2/2 tools/bpf: change selftest test_btf for both jit and non-jit
In reply to Yonghong SongThe selftest test_btf is changed to test both jit and non-jit. The test result should be the same regardless of whether jit is enabled or not.
--- tools/testing/selftests/bpf/test_btf.c | 33 +++----------------------- 1 file changed, 3 insertions(+), 30 deletions(-)
tools/testing/selftests/bpf/test_btf.c +3 -30
@@ -29,7 +29,6 @@static uint32_t pass_cnt;static uint32_t error_cnt;static uint32_t skip_cnt; -static bool jit_enabled; #define CHECK(condition, format...) ({ \ int __ret = !!(condition); \
@@ -65,24 +64,6 @@ static int __base_pr(const char *format, ...)return err; } -static bool is_jit_enabled (void ) -{ -const char *jit_sysctl ="/proc/sys/net/core/bpf_jit_enable" ; -bool enabled = false; -int sysctl_fd; - - sysctl_fd =open (jit_sysctl,0 ,O_RDONLY ); -if (sysctl_fd !=-1 ) { -char tmpc; - -if (read (sysctl_fd, &tmpc,sizeof (tmpc)) ==1 ) - enabled = (tmpc !='0' ); -close (sysctl_fd); - } - -return enabled; -} -#define BTF_INFO_ENC (kind, root, vlen) \ ((!!(root) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
@@ -2547,8 +2528,8 @@ static int do_test_file(unsigned int test_num) test->btf_kv_notfound)) goto done; -if (!jit_enabled || !has_btf_ext) - goto skip_jit; +if (!has_btf_ext) + goto skip;/* get necessary program info */ info_len =sizeof (struct bpf_prog_info );
@@ -2636,7 +2617,7 @@ static int do_test_file(unsigned int test_num) finfo = (void *)finfo + rec_size; } -skip_jit: +skip:fprintf (stderr,"OK" ); done:
@@ -3270,12 +3251,6 @@ static int do_test_func_type(int test_num) err =-1 ; goto done; } -if (!jit_enabled) { - skip_cnt++; -fprintf (stderr,"SKIPPED, please enable sysctl bpf_jit_enable\n" ); - err =0 ; - goto done; - }/* get necessary lens */ info_len =sizeof (struct bpf_prog_info );
@@ -3452,8 +3427,6 @@ int main(int argc, char **argv)if (args.always_log)libbpf_set_print (__base_pr, __base_pr, __base_pr); - jit_enabled =is_jit_enabled (); -if (args.raw_test) err |=test_raw ();
Signature · 1 line
2.17.1
Re: [PATCH bpf-next 2/2] tools/bpf: change selftest test_btf for both jit and non-jit
Quoted 3 lines · Yonghong Song
The selftest
test_btfis changed to test both jit and non-jit. The test result should be the same regardless of whether jit is enabled or not.
Alexei Starovoitov
AppliedQuoted 34 lines · Yonghong Song
Commit
838e96904ff3("bpf: Introducebpf_func_info") added bpf func info support. The userspace is able to get better ksym's for bpf programs with jit, and is able to print out func prototypes.For a program containing func-to-func calls, the existing implementation returns user specified number of function calls and BTF types if jit is enabled. If the jit is not enabled, it only returns the type for the main function.
This is undesirable. Interpreter may still be used and we should keep feature identical regardless of whether jit is enabled or not.
This patch fixed this discrepancy.The following example shows bpftool output for the bpf program in selftests test_btf_haskv.o when jit is disabled:
$ bpftool prog dump xlated id 1490 int _dummy_tracepoint(struct dummy_tracepoint_args * arg): 0: (85) call pc+2#__bpf_prog_run_args32 1: (b7) r0 = 0 2: (95) exit int test_long_fname_1(struct dummy_tracepoint_args * arg): 3: (85) call pc+1#__bpf_prog_run_args32 4: (95) exit int test_long_fname_2(struct dummy_tracepoint_args * arg): 5: (b7) r2 = 0 6: (63) *(u32 *)(r10 -4) = r2 7: (79) r1 = *(u64 *)(r1 +8) 8: (15) if r1 == 0x0 goto pc+9 9: (bf) r2 = r10 10: (07) r2 += -4 11: (18) r1 = map[id:1173]
Quoted 8 lines
13: (85) call bpf_map_lookup_elem#77088
14: (15) if r0 == 0x0 goto pc+3
15: (61) r1 = *(u32 *)(r0 +4)
16: (07) r1 += 1
17: (63) *(u32 *)(r0 +4) = r1
18: (95) exit
$ bpftool prog dump jited id 1490
no instructions returnedApplied to bpf-next. Thanks