From 321993a874f571a94b5a596f1132f798c663b56e Mon Sep 17 00:00:00 2001 From: Hengqi Chen Date: Wed, 31 Dec 2025 15:19:20 +0800 Subject: [PATCH] LoongArch: BPF: Sign extend kfunc call arguments commit 3f5a238f24d7b75f9efe324d3539ad388f58536e upstream. The kfunc calls are native calls so they should follow LoongArch calling conventions. Sign extend its arguments properly to avoid kernel panic. This is done by adding a new emit_abi_ext() helper. The emit_abi_ext() helper performs extension in place meaning a value already store in the target register (Note: this is different from the existing sign_extend() helper and thus we can't reuse it). Cc: stable@vger.kernel.org Fixes: 5dc615520c4d ("LoongArch: Add BPF JIT support") Signed-off-by: Hengqi Chen Signed-off-by: Huacai Chen Signed-off-by: Greg Kroah-Hartman --- arch/loongarch/net/bpf_jit.c | 16 ++++++++++++++++ arch/loongarch/net/bpf_jit.h | 26 ++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 9d9948e549de..4be8515197ce 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -952,6 +952,22 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext emit_insn(ctx, ldd, REG_TCC, LOONGARCH_GPR_SP, tcc_ptr_off); } + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { + const struct btf_func_model *m; + int i; + + m = bpf_jit_find_kfunc_model(ctx->prog, insn); + if (!m) + return -EINVAL; + + for (i = 0; i < m->nr_args; i++) { + u8 reg = regmap[BPF_REG_1 + i]; + bool sign = m->arg_flags[i] & BTF_FMODEL_SIGNED_ARG; + + emit_abi_ext(ctx, reg, m->arg_size[i], sign); + } + } + move_addr(ctx, t1, func_addr); emit_insn(ctx, jirl, LOONGARCH_GPR_RA, t1, 0); diff --git a/arch/loongarch/net/bpf_jit.h b/arch/loongarch/net/bpf_jit.h index 5697158fd164..75b6330030a9 100644 --- a/arch/loongarch/net/bpf_jit.h +++ b/arch/loongarch/net/bpf_jit.h @@ -88,6 +88,32 @@ static inline void emit_sext_32(struct jit_ctx *ctx, enum loongarch_gpr reg, boo emit_insn(ctx, addiw, reg, reg, 0); } +/* Emit proper extension according to ABI requirements. + * Note that it requires a value of size `size` already resides in register `reg`. + */ +static inline void emit_abi_ext(struct jit_ctx *ctx, int reg, u8 size, bool sign) +{ + /* ABI requires unsigned char/short to be zero-extended */ + if (!sign && (size == 1 || size == 2)) + return; + + switch (size) { + case 1: + emit_insn(ctx, extwb, reg, reg); + break; + case 2: + emit_insn(ctx, extwh, reg, reg); + break; + case 4: + emit_insn(ctx, addiw, reg, reg, 0); + break; + case 8: + break; + default: + pr_warn("bpf_jit: invalid size %d for extension\n", size); + } +} + static inline void move_addr(struct jit_ctx *ctx, enum loongarch_gpr rd, u64 addr) { u64 imm_11_0, imm_31_12, imm_51_32, imm_63_52;