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Date: Tue, 6 Feb 2024 14:04:30 -0800 Message-Id: <20240206220441.38311-6-alexei.starovoitov@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) In-Reply-To: <20240206220441.38311-1-alexei.starovoitov@gmail.com> References: <20240206220441.38311-1-alexei.starovoitov@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Alexei Starovoitov LLVM generates rX = bpf_cast_kern/_user(rY, address_space) instructions when pointers in non-zero address space are used by the bpf program. Signed-off-by: Alexei Starovoitov --- include/uapi/linux/bpf.h | 5 +++++ kernel/bpf/disasm.c | 11 +++++++++++ tools/include/uapi/linux/bpf.h | 5 +++++ 3 files changed, 21 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f6648851eae6..3de1581379d4 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1313,6 +1313,11 @@ enum { */ #define BPF_PSEUDO_KFUNC_CALL 2 +enum bpf_arena_cast_kinds { + BPF_ARENA_CAST_KERN = 1, + BPF_ARENA_CAST_USER = 2, +}; + /* flags for BPF_MAP_UPDATE_ELEM command */ enum { BPF_ANY = 0, /* create new element or update existing */ diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c index 49940c26a227..37d9b37b34f7 100644 --- a/kernel/bpf/disasm.c +++ b/kernel/bpf/disasm.c @@ -166,6 +166,12 @@ static bool is_movsx(const struct bpf_insn *insn) (insn->off == 8 || insn->off == 16 || insn->off == 32); } +static bool is_arena_cast(const struct bpf_insn *insn) +{ + return insn->code == (BPF_ALU64 | BPF_MOV | BPF_X) && + (insn->off == BPF_ARENA_CAST_KERN || insn->off == BPF_ARENA_CAST_USER); +} + void print_bpf_insn(const struct bpf_insn_cbs *cbs, const struct bpf_insn *insn, bool allow_ptr_leaks) @@ -184,6 +190,11 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs, insn->code, class == BPF_ALU ? 'w' : 'r', insn->dst_reg, class == BPF_ALU ? 'w' : 'r', insn->dst_reg); + } else if (is_arena_cast(insn)) { + verbose(cbs->private_data, "(%02x) r%d = cast_%s(r%d, %d)\n", + insn->code, insn->dst_reg, + insn->off == BPF_ARENA_CAST_KERN ? "kern" : "user", + insn->src_reg, insn->imm); } else if (BPF_SRC(insn->code) == BPF_X) { verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n", insn->code, class == BPF_ALU ? 'w' : 'r', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index f6648851eae6..3de1581379d4 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1313,6 +1313,11 @@ enum { */ #define BPF_PSEUDO_KFUNC_CALL 2 +enum bpf_arena_cast_kinds { + BPF_ARENA_CAST_KERN = 1, + BPF_ARENA_CAST_USER = 2, +}; + /* flags for BPF_MAP_UPDATE_ELEM command */ enum { BPF_ANY = 0, /* create new element or update existing */