From: Pu Lehui <pulehui@huaweicloud.com> To: bpf@vger.kernel.org, linux-riscv@lists.infradead.org, netdev@vger.kernel.org Cc: "Björn Töpel" <bjorn@kernel.org>, "Alexei Starovoitov" <ast@kernel.org>, "Daniel Borkmann" <daniel@iogearbox.net>, "Andrii Nakryiko" <andrii@kernel.org>, "Martin KaFai Lau" <martin.lau@linux.dev>, "Eduard Zingerman" <eddyz87@gmail.com>, "Song Liu" <song@kernel.org>, "Yonghong Song" <yhs@fb.com>, "John Fastabend" <john.fastabend@gmail.com>, "KP Singh" <kpsingh@kernel.org>, "Stanislav Fomichev" <sdf@google.com>, "Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>, "Palmer Dabbelt" <palmer@dabbelt.com>, "Luke Nelson" <luke.r.nels@gmail.com>, "Pu Lehui" <pulehui@huawei.com>, "Pu Lehui" <pulehui@huaweicloud.com> Subject: [PATCH bpf] riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi Date: Sun, 24 Mar 2024 10:33:06 +0000 [thread overview] Message-ID: <20240324103306.2202954-1-pulehui@huaweicloud.com> (raw) From: Pu Lehui <pulehui@huawei.com> We encountered a failing case when running selftest in no_alu32 mode: The failure case is `kfunc_call/kfunc_call_test4` and its source code is like bellow: ``` long bpf_kfunc_call_test4(signed char a, short b, int c, long d) __ksym; int kfunc_call_test4(struct __sk_buff *skb) { ... tmp = bpf_kfunc_call_test4(-3, -30, -200, -1000); ... } ``` And its corresponding asm code is: ``` 0: r1 = -3 1: r2 = -30 2: r3 = 0xffffff38 # opcode: 18 03 00 00 38 ff ff ff 00 00 00 00 00 00 00 00 4: r4 = -1000 5: call bpf_kfunc_call_test4 ``` insn 2 is parsed to ld_imm64 insn to emit 0x00000000ffffff38 imm, and converted to int type and then send to bpf_kfunc_call_test4. But since it is zero-extended in the bpf calling convention, riscv jit will directly treat it as an unsigned 32-bit int value, and then fails with the message "actual 4294966063 != expected -1234". The reason is the incompatibility between bpf and riscv abi, that is, bpf will do zero-extension on uint, but riscv64 requires sign-extension on int or uint. We can solve this problem by sign extending the 32-bit parameters in kfunc. The issue is related to [0], and thanks to Yonghong and Alexei. Link: https://github.com/llvm/llvm-project/pull/84874 [0] Fixes: d40c3847b485 ("riscv, bpf: Add kfunc support for RV64") Signed-off-by: Pu Lehui <pulehui@huawei.com> --- arch/riscv/net/bpf_jit_comp64.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 869e4282a2c4..e3fc39370f7d 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1454,6 +1454,22 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, if (ret < 0) return ret; + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + const struct btf_func_model *fm; + int idx; + + fm = bpf_jit_find_kfunc_model(ctx->prog, insn); + if (!fm) + return -EINVAL; + + for (idx = 0; idx < fm->nr_args; idx++) { + u8 reg = bpf_to_rv_reg(BPF_REG_1 + idx, ctx); + + if (fm->arg_size[idx] == sizeof(int)) + emit_sextw(reg, reg, ctx); + } + } + ret = emit_call(addr, fixed_addr, ctx); if (ret) return ret; -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: Pu Lehui <pulehui@huaweicloud.com> To: bpf@vger.kernel.org, linux-riscv@lists.infradead.org, netdev@vger.kernel.org Cc: "Björn Töpel" <bjorn@kernel.org>, "Alexei Starovoitov" <ast@kernel.org>, "Daniel Borkmann" <daniel@iogearbox.net>, "Andrii Nakryiko" <andrii@kernel.org>, "Martin KaFai Lau" <martin.lau@linux.dev>, "Eduard Zingerman" <eddyz87@gmail.com>, "Song Liu" <song@kernel.org>, "Yonghong Song" <yhs@fb.com>, "John Fastabend" <john.fastabend@gmail.com>, "KP Singh" <kpsingh@kernel.org>, "Stanislav Fomichev" <sdf@google.com>, "Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>, "Palmer Dabbelt" <palmer@dabbelt.com>, "Luke Nelson" <luke.r.nels@gmail.com>, "Pu Lehui" <pulehui@huawei.com>, "Pu Lehui" <pulehui@huaweicloud.com> Subject: [PATCH bpf] riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi Date: Sun, 24 Mar 2024 10:33:06 +0000 [thread overview] Message-ID: <20240324103306.2202954-1-pulehui@huaweicloud.com> (raw) From: Pu Lehui <pulehui@huawei.com> We encountered a failing case when running selftest in no_alu32 mode: The failure case is `kfunc_call/kfunc_call_test4` and its source code is like bellow: ``` long bpf_kfunc_call_test4(signed char a, short b, int c, long d) __ksym; int kfunc_call_test4(struct __sk_buff *skb) { ... tmp = bpf_kfunc_call_test4(-3, -30, -200, -1000); ... } ``` And its corresponding asm code is: ``` 0: r1 = -3 1: r2 = -30 2: r3 = 0xffffff38 # opcode: 18 03 00 00 38 ff ff ff 00 00 00 00 00 00 00 00 4: r4 = -1000 5: call bpf_kfunc_call_test4 ``` insn 2 is parsed to ld_imm64 insn to emit 0x00000000ffffff38 imm, and converted to int type and then send to bpf_kfunc_call_test4. But since it is zero-extended in the bpf calling convention, riscv jit will directly treat it as an unsigned 32-bit int value, and then fails with the message "actual 4294966063 != expected -1234". The reason is the incompatibility between bpf and riscv abi, that is, bpf will do zero-extension on uint, but riscv64 requires sign-extension on int or uint. We can solve this problem by sign extending the 32-bit parameters in kfunc. The issue is related to [0], and thanks to Yonghong and Alexei. Link: https://github.com/llvm/llvm-project/pull/84874 [0] Fixes: d40c3847b485 ("riscv, bpf: Add kfunc support for RV64") Signed-off-by: Pu Lehui <pulehui@huawei.com> --- arch/riscv/net/bpf_jit_comp64.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 869e4282a2c4..e3fc39370f7d 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1454,6 +1454,22 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, if (ret < 0) return ret; + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + const struct btf_func_model *fm; + int idx; + + fm = bpf_jit_find_kfunc_model(ctx->prog, insn); + if (!fm) + return -EINVAL; + + for (idx = 0; idx < fm->nr_args; idx++) { + u8 reg = bpf_to_rv_reg(BPF_REG_1 + idx, ctx); + + if (fm->arg_size[idx] == sizeof(int)) + emit_sextw(reg, reg, ctx); + } + } + ret = emit_call(addr, fixed_addr, ctx); if (ret) return ret; -- 2.34.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next reply other threads:[~2024-03-24 10:32 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-24 10:33 Pu Lehui [this message] 2024-03-24 10:33 ` [PATCH bpf] riscv, bpf: Fix kfunc parameters incompatibility between bpf and riscv abi Pu Lehui 2024-03-24 18:26 ` Puranjay Mohan 2024-03-24 18:26 ` Puranjay Mohan 2024-03-24 18:40 ` Alexei Starovoitov 2024-03-24 18:40 ` Alexei Starovoitov 2024-03-25 15:27 ` Pu Lehui 2024-03-25 15:27 ` Pu Lehui 2024-03-25 18:34 ` Alexei Starovoitov 2024-03-25 18:34 ` Alexei Starovoitov 2024-03-26 1:32 ` Pu Lehui 2024-03-26 1:32 ` Pu Lehui
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