| Message ID | 20230827152821.2001129-1-yonghong.song@linux.dev (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 974da9f3ee66c982cf89c8537e0ec36649a7ad5e |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: Add support for local percpu kptr | expand |
diff --git a/tools/testing/selftests/bpf/progs/percpu_alloc_array.c b/tools/testing/selftests/bpf/progs/percpu_alloc_array.c index 3bd7d47870a9..bbc45346e006 100644 --- a/tools/testing/selftests/bpf/progs/percpu_alloc_array.c +++ b/tools/testing/selftests/bpf/progs/percpu_alloc_array.c @@ -146,10 +146,6 @@ int BPF_PROG(test_array_map_10) /* race condition */ bpf_percpu_obj_drop(p1); } - - p = e->pc; - if (!p) - goto out; } v = bpf_this_cpu_ptr(p);
For the second argument of bpf_kptr_xchg(), if the reg type contains MEM_ALLOC and MEM_PERCPU, which means a percpu allocation, after bpf_kptr_xchg(), the argument is marked as MEM_RCU and MEM_PERCPU if in rcu critical section. This way, re-reading from the map value is not needed. Remove it from the percpu_alloc_array.c selftest. Without previous kernel change, the test will fail like below: 0: R1=ctx(off=0,imm=0) R10=fp0 ; int BPF_PROG(test_array_map_10, int a) 0: (b4) w1 = 0 ; R1_w=0 ; int i, index = 0; 1: (63) *(u32 *)(r10 -4) = r1 ; R1_w=0 R10=fp0 fp-8=0000???? 2: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 ; 3: (07) r2 += -4 ; R2_w=fp-4 ; e = bpf_map_lookup_elem(&array, &index); 4: (18) r1 = 0xffff88810e771800 ; R1_w=map_ptr(off=0,ks=4,vs=16,imm=0) 6: (85) call bpf_map_lookup_elem#1 ; R0_w=map_value_or_null(id=1,off=0,ks=4,vs=16,imm=0) 7: (bf) r6 = r0 ; R0_w=map_value_or_null(id=1,off=0,ks=4,vs=16,imm=0) R6_w=map_value_or_null(id=1,off=0,ks=4,vs=16,imm=0) ; if (!e) 8: (15) if r6 == 0x0 goto pc+81 ; R6_w=map_value(off=0,ks=4,vs=16,imm=0) ; bpf_rcu_read_lock(); 9: (85) call bpf_rcu_read_lock#87892 ; ; p = e->pc; 10: (bf) r7 = r6 ; R6=map_value(off=0,ks=4,vs=16,imm=0) R7_w=map_value(off=0,ks=4,vs=16,imm=0) 11: (07) r7 += 8 ; R7_w=map_value(off=8,ks=4,vs=16,imm=0) 12: (79) r6 = *(u64 *)(r6 +8) ; R6_w=percpu_rcu_ptr_or_null_val_t(id=2,off=0,imm=0) ; if (!p) { 13: (55) if r6 != 0x0 goto pc+13 ; R6_w=0 ; p = bpf_percpu_obj_new(struct val_t); 14: (18) r1 = 0x12 ; R1_w=18 16: (b7) r2 = 0 ; R2_w=0 17: (85) call bpf_percpu_obj_new_impl#87883 ; R0_w=percpu_ptr_or_null_val_t(id=4,ref_obj_id=4,off=0,imm=0) refs=4 18: (bf) r6 = r0 ; R0=percpu_ptr_or_null_val_t(id=4,ref_obj_id=4,off=0,imm=0) R6=percpu_ptr_or_null_val_t(id=4,ref_obj_id=4,off=0,imm=0) refs=4 ; if (!p) 19: (15) if r6 == 0x0 goto pc+69 ; R6=percpu_ptr_val_t(ref_obj_id=4,off=0,imm=0) refs=4 ; p1 = bpf_kptr_xchg(&e->pc, p); 20: (bf) r1 = r7 ; R1_w=map_value(off=8,ks=4,vs=16,imm=0) R7=map_value(off=8,ks=4,vs=16,imm=0) refs=4 21: (bf) r2 = r6 ; R2_w=percpu_ptr_val_t(ref_obj_id=4,off=0,imm=0) R6=percpu_ptr_val_t(ref_obj_id=4,off=0,imm=0) refs=4 22: (85) call bpf_kptr_xchg#194 ; R0_w=percpu_ptr_or_null_val_t(id=6,ref_obj_id=6,off=0,imm=0) refs=6 ; if (p1) { 23: (15) if r0 == 0x0 goto pc+3 ; R0_w=percpu_ptr_val_t(ref_obj_id=6,off=0,imm=0) refs=6 ; bpf_percpu_obj_drop(p1); 24: (bf) r1 = r0 ; R0_w=percpu_ptr_val_t(ref_obj_id=6,off=0,imm=0) R1_w=percpu_ptr_val_t(ref_obj_id=6,off=0,imm=0) refs=6 25: (b7) r2 = 0 ; R2_w=0 refs=6 26: (85) call bpf_percpu_obj_drop_impl#87882 ; ; v = bpf_this_cpu_ptr(p); 27: (bf) r1 = r6 ; R1_w=scalar(id=7) R6=scalar(id=7) 28: (85) call bpf_this_cpu_ptr#154 R1 type=scalar expected=percpu_ptr_, percpu_rcu_ptr_, percpu_trusted_ptr_ The R1 which gets its value from R6 is a scalar. But before insn 22, R6 is R6=percpu_ptr_val_t(ref_obj_id=4,off=0,imm=0) Its type is changed to a scalar at insn 22 without previous patch. Signed-off-by: Yonghong Song <yonghong.song@linux.dev> --- tools/testing/selftests/bpf/progs/percpu_alloc_array.c | 4 ---- 1 file changed, 4 deletions(-)