[bpf-next,07/15] bpf: Add the get_reg_width function

Message ID	20231220214013.3327288-8-maxtram95@gmail.com
State	Superseded
Headers	show Received: from mail-lj1-f170.google.com (mail-lj1-f170.google.com [209.85.208.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 661BD4A9BF; Wed, 20 Dec 2023 21:40:41 +0000 (UTC) From: Maxim Mikityanskiy <maxtram95@gmail.com> To: Eduard Zingerman <eddyz87@gmail.com>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com>, Martin KaFai Lau <martin.lau@linux.dev>, Song Liu <song@kernel.org>, Yonghong Song <yonghong.song@linux.dev>, KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>, "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Jesper Dangaard Brouer <hawk@kernel.org>, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, Maxim Mikityanskiy <maxim@isovalent.com> Subject: [PATCH bpf-next 07/15] bpf: Add the get_reg_width function Date: Wed, 20 Dec 2023 23:40:05 +0200 Message-ID: <20231220214013.3327288-8-maxtram95@gmail.com> In-Reply-To: <20231220214013.3327288-1-maxtram95@gmail.com> References: <20231220214013.3327288-1-maxtram95@gmail.com> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	Improvements for tracking scalars in the BPF verifier \| expand [bpf-next,00/15] Improvements for tracking scalars in the BPF verifier [bpf-next,01/15] selftests/bpf: Fix the u64_offset_to_skb_data test [bpf-next,02/15] bpf: make infinite loop detection in is_state_visited() exact [bpf-next,03/15] selftests/bpf: check if imprecise stack spills confuse infinite loop detection [bpf-next,04/15] bpf: Make bpf_for_each_spilled_reg consider narrow spills [bpf-next,05/15] selftests/bpf: Add a test case for 32-bit spill tracking [bpf-next,06/15] bpf: Add the assign_scalar_id_before_mov function [bpf-next,07/15] bpf: Add the get_reg_width function [bpf-next,08/15] bpf: Assign ID to scalars on spill [bpf-next,09/15] selftests/bpf: Test assigning ID to scalars on spill [bpf-next,10/15] bpf: Track spilled unbounded scalars [bpf-next,11/15] selftests/bpf: Test tracking spilled unbounded scalars [bpf-next,12/15] bpf: Preserve boundaries and track scalars on narrowing fill [bpf-next,13/15] selftests/bpf: Add test cases for narrowing fill [bpf-next,14/15] bpf: Optimize state pruning for spilled scalars [bpf-next,15/15] selftests/bpf: states pruning checks for scalar vs STACK_{MISC,ZERO}

Message ID

20231220214013.3327288-8-maxtram95@gmail.com

State

Superseded

Headers

From: Maxim Mikityanskiy <maxtram95@gmail.com>
To: Eduard Zingerman <eddyz87@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>,
	Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Mykola Lysenko <mykolal@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	netdev@vger.kernel.org,
	Maxim Mikityanskiy <maxim@isovalent.com>
Subject: [PATCH bpf-next 07/15] bpf: Add the get_reg_width function
Date: Wed, 20 Dec 2023 23:40:05 +0200
Message-ID: <20231220214013.3327288-8-maxtram95@gmail.com>
In-Reply-To: <20231220214013.3327288-1-maxtram95@gmail.com>
References: <20231220214013.3327288-1-maxtram95@gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Series

Improvements for tracking scalars in the BPF verifier | expand

Commit Message

Maxim Mikityanskiy Dec. 20, 2023, 9:40 p.m. UTC

From: Maxim Mikityanskiy <maxim@isovalent.com>

Put calculation of the register value width into a dedicated function.
This function will also be used in a following commit.

Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
---
 kernel/bpf/verifier.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a703e3adedd3..b757fdbbbdd2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4448,6 +4448,11 @@  static bool is_bpf_st_mem(struct bpf_insn *insn)
 	return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
 }
 
+static int get_reg_width(struct bpf_reg_state *reg)
+{
+	return fls64(reg->umax_value);
+}
+
 /* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
  * stack boundary and alignment are checked in check_mem_access()
  */
@@ -4500,7 +4505,7 @@  static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
 	if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && env->bpf_capable) {
 		save_register_state(env, state, spi, reg, size);
 		/* Break the relation on a narrowing spill. */
-		if (fls64(reg->umax_value) > BITS_PER_BYTE * size)
+		if (get_reg_width(reg) > BITS_PER_BYTE * size)
 			state->stack[spi].spilled_ptr.id = 0;
 	} else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
 		   insn->imm != 0 && env->bpf_capable) {
@@ -13940,7 +13945,7 @@  static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 					return -EACCES;
 				} else if (src_reg->type == SCALAR_VALUE) {
 					if (insn->off == 0) {
-						bool is_src_reg_u32 = src_reg->umax_value <= U32_MAX;
+						bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;
 
 						if (is_src_reg_u32)
 							assign_scalar_id_before_mov(env, src_reg);

[bpf-next,07/15] bpf: Add the get_reg_width function

Commit Message

Patch