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Mon, 14 Sep 2026 19:29:12 -0700 (PDT) From: Nicholas Dudar To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de Cc: martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev, bpf@vger.kernel.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, visitorckw@gmail.com Subject: [PATCH bpf-next v2 1/2] bpf, parisc: Add support for BPF_SDIV and BPF_SMOD in the parisc64 JIT Date: Mon, 14 Sep 2026 22:29:04 -0400 Message-ID: <20260915022905.1535566-2-main.kalliope@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260915022905.1535566-1-main.kalliope@gmail.com> References: <20260915022905.1535566-1-main.kalliope@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit emit_call_libgcc_ll() zero-extends the ALU32 operands and calls the unsigned hppa_div64()/hppa_div64_rem() helpers regardless of the BPF instruction's signedness, so the parisc64 JIT does not implement signed BPF_SDIV and BPF_SMOD (off == 1). Signed ALU32 and ALU64 div/mod get an unsigned quotient and remainder rather than the verifier's and the interpreter's signed result for negative operands. Add hppa_sdiv64()/hppa_sdiv64_rem() wrapping div64_s64(), thread is_signed = (insn->off == 1) through the div/mod emit sites, and on the signed path sign-extend the ALU32 operands (and the immediate divisor) instead of zero-extending them before calling the signed helpers. bpf_do_misc_fixups() rewrites the zero-divisor and INT_MIN/-1 cases out of the instruction stream before the JIT runs. Acked-by: Helge Deller Tested-by: Helge Deller Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Nicholas Dudar --- arch/parisc/net/bpf_jit.h | 2 ++ arch/parisc/net/bpf_jit_comp64.c | 35 ++++++++++++++++++++++++-------- arch/parisc/net/bpf_jit_core.c | 14 +++++++++++++ 3 files changed, 42 insertions(+), 9 deletions(-) diff --git a/arch/parisc/net/bpf_jit.h b/arch/parisc/net/bpf_jit.h index 8b8896959f044..074115c93c909 100644 --- a/arch/parisc/net/bpf_jit.h +++ b/arch/parisc/net/bpf_jit.h @@ -467,6 +467,8 @@ static inline u32 hppa_t21_insn(u8 opcode, u8 r2, u8 r1, u8 ext8, u8 t) u64 hppa_div64(u64 div, u64 divisor); u64 hppa_div64_rem(u64 div, u64 divisor); +u64 hppa_sdiv64(u64 div, u64 divisor); +u64 hppa_sdiv64_rem(u64 div, u64 divisor); /* Helper functions that emit HPPA instructions when possible. */ diff --git a/arch/parisc/net/bpf_jit_comp64.c b/arch/parisc/net/bpf_jit_comp64.c index 54b0d5e25e024..c326fa737ec8c 100644 --- a/arch/parisc/net/bpf_jit_comp64.c +++ b/arch/parisc/net/bpf_jit_comp64.c @@ -502,14 +502,19 @@ static void emit_call(u64 addr, bool fixed, struct hppa_jit_context *ctx) emit_hppa_copy(HPPA_REG_RET0, regmap[BPF_REG_0], ctx); } -static void emit_call_libgcc_ll(void *func, const s8 arg0, - const s8 arg1, u8 opcode, struct hppa_jit_context *ctx) +static void emit_call_libgcc_ll(void *func, const s8 arg0, const s8 arg1, + u8 opcode, bool is_signed, struct hppa_jit_context *ctx) { u64 func_addr; if (BPF_CLASS(opcode) == BPF_ALU) { - emit_hppa64_zext32(arg0, HPPA_REG_ARG0, ctx); - emit_hppa64_zext32(arg1, HPPA_REG_ARG1, ctx); + if (is_signed) { + emit_hppa64_sext32(arg0, HPPA_REG_ARG0, ctx); + emit_hppa64_sext32(arg1, HPPA_REG_ARG1, ctx); + } else { + emit_hppa64_zext32(arg0, HPPA_REG_ARG0, ctx); + emit_hppa64_zext32(arg1, HPPA_REG_ARG1, ctx); + } } else { emit_hppa_copy(arg0, HPPA_REG_ARG0, ctx); emit_hppa_copy(arg1, HPPA_REG_ARG1, ctx); @@ -600,6 +605,8 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct hppa_jit_context *ctx, u8 rd = -1, rs = -1, code = insn->code; s16 off = insn->off; s32 imm = insn->imm; + bool is_signed; + void *func; init_regs(&rd, &rs, insn, ctx); @@ -656,29 +663,39 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct hppa_jit_context *ctx, fallthrough; case BPF_ALU | BPF_MUL | BPF_X: case BPF_ALU64 | BPF_MUL | BPF_X: - emit_call_libgcc_ll(__muldi3, rd, rs, code, ctx); + emit_call_libgcc_ll(__muldi3, rd, rs, code, false, ctx); if (!is64 && !aux->verifier_zext) emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_DIV | BPF_K: case BPF_ALU64 | BPF_DIV | BPF_K: - emit_imm(HPPA_REG_T1, is64 ? (s64)(s32)imm : (u32)imm, HPPA_REG_T2, ctx); + is_signed = (off == 1); + emit_imm(HPPA_REG_T1, + is64 || is_signed ? (s64)(s32)imm : (u32)imm, + HPPA_REG_T2, ctx); rs = HPPA_REG_T1; fallthrough; case BPF_ALU | BPF_DIV | BPF_X: case BPF_ALU64 | BPF_DIV | BPF_X: - emit_call_libgcc_ll(&hppa_div64, rd, rs, code, ctx); + is_signed = (off == 1); + func = is_signed ? &hppa_sdiv64 : &hppa_div64; + emit_call_libgcc_ll(func, rd, rs, code, is_signed, ctx); if (!is64 && !aux->verifier_zext) emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_MOD | BPF_K: case BPF_ALU64 | BPF_MOD | BPF_K: - emit_imm(HPPA_REG_T1, is64 ? (s64)(s32)imm : (u32)imm, HPPA_REG_T2, ctx); + is_signed = (off == 1); + emit_imm(HPPA_REG_T1, + is64 || is_signed ? (s64)(s32)imm : (u32)imm, + HPPA_REG_T2, ctx); rs = HPPA_REG_T1; fallthrough; case BPF_ALU | BPF_MOD | BPF_X: case BPF_ALU64 | BPF_MOD | BPF_X: - emit_call_libgcc_ll(&hppa_div64_rem, rd, rs, code, ctx); + is_signed = (off == 1); + func = is_signed ? &hppa_sdiv64_rem : &hppa_div64_rem; + emit_call_libgcc_ll(func, rd, rs, code, is_signed, ctx); if (!is64 && !aux->verifier_zext) emit_zext_32(rd, ctx); break; diff --git a/arch/parisc/net/bpf_jit_core.c b/arch/parisc/net/bpf_jit_core.c index 172770132440d..a2f93202a2ef9 100644 --- a/arch/parisc/net/bpf_jit_core.c +++ b/arch/parisc/net/bpf_jit_core.c @@ -190,3 +190,17 @@ u64 hppa_div64_rem(u64 div, u64 divisor) div64_u64_rem(div, divisor, &rem); return rem; } + +u64 hppa_sdiv64(u64 div, u64 divisor) +{ + s64 sdiv = div64_s64((s64)div, (s64)divisor); + + return (u64)sdiv; +} + +u64 hppa_sdiv64_rem(u64 div, u64 divisor) +{ + s64 sdiv = div64_s64((s64)div, (s64)divisor); + + return (u64)((s64)div - sdiv * (s64)divisor); +}