From 67d43dfbb42d6575304daea67733c88fbf536a1c Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 17 Nov 2023 19:46:19 -0800 Subject: bpf: print spilled register state in stack slot Print the same register state representation when printing stack state, as we do for normal registers. Note that if stack slot contains subregister spill (1, 2, or 4 byte long), we'll still emit "m0?" mask for those bytes that are not part of spilled register. While means we can get something like fp-8=0000scalar() for a 4-byte spill with other 4 bytes still being STACK_ZERO. Some example before and after, taken from the log of pyperf_subprogs.bpf.o: 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx(off=0,imm=0) 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272= 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272=????scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) While at it, do a few other simple clean ups: - skip slot if it's not scratched before detecting whether it's valid; - move taking spilled_reg pointer outside of switch (only DYNPTR has to adjust that to get to the "main" slot); - don't recalculate types_buf second time for MISC/ZERO/default case. Acked-by: Eduard Zingerman Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231118034623.3320920-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/log.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) (limited to 'kernel/bpf/log.c') diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c index 05d737e2fab3..97a1641e848e 100644 --- a/kernel/bpf/log.c +++ b/kernel/bpf/log.c @@ -618,7 +618,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st bool print_all) { const struct bpf_reg_state *reg; - enum bpf_reg_type t; int i; if (state->frameno) @@ -637,32 +636,38 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { char types_buf[BPF_REG_SIZE + 1]; bool valid = false; + u8 slot_type; int j; + if (!print_all && !stack_slot_scratched(env, i)) + continue; + for (j = 0; j < BPF_REG_SIZE; j++) { - if (state->stack[i].slot_type[j] != STACK_INVALID) + slot_type = state->stack[i].slot_type[j]; + if (slot_type != STACK_INVALID) valid = true; - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; + types_buf[j] = slot_type_char[slot_type]; } types_buf[BPF_REG_SIZE] = 0; if (!valid) continue; - if (!print_all && !stack_slot_scratched(env, i)) - continue; + + reg = &state->stack[i].spilled_ptr; switch (state->stack[i].slot_type[BPF_REG_SIZE - 1]) { case STACK_SPILL: - reg = &state->stack[i].spilled_ptr; - t = reg->type; + /* print MISC/ZERO/INVALID slots above subreg spill */ + for (j = 0; j < BPF_REG_SIZE; j++) + if (state->stack[i].slot_type[j] == STACK_SPILL) + break; + types_buf[j] = '\0'; verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); - verbose(env, "=%s", t == SCALAR_VALUE ? "" : reg_type_str(env, t)); - if (t == SCALAR_VALUE && reg->precise) - verbose(env, "P"); - if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) - verbose(env, "%lld", reg->var_off.value + reg->off); + verbose(env, "=%s", types_buf); + print_reg_state(env, reg); break; case STACK_DYNPTR: + /* skip to main dynptr slot */ i += BPF_DYNPTR_NR_SLOTS - 1; reg = &state->stack[i].spilled_ptr; @@ -674,7 +679,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st break; case STACK_ITER: /* only main slot has ref_obj_id set; skip others */ - reg = &state->stack[i].spilled_ptr; if (!reg->ref_obj_id) continue; @@ -688,12 +692,6 @@ void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_st case STACK_MISC: case STACK_ZERO: default: - reg = &state->stack[i].spilled_ptr; - - for (j = 0; j < BPF_REG_SIZE; j++) - types_buf[j] = slot_type_char[state->stack[i].slot_type[j]]; - types_buf[BPF_REG_SIZE] = 0; - verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE); print_liveness(env, reg->live); verbose(env, "=%s", types_buf); -- cgit