From nobody Sat Oct 4 00:32:13 2025 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 425631DF749; Thu, 21 Aug 2025 14:43:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755787391; cv=none; b=jpInIfg0wyEQXwzfcWl7/qCsqu6tVu/2ZKf8vOb0+N8h56qtCF754mviFRxtvNn/2r+hV2f8zV9Pgp8jXk15mgJKcn8Wx5m7osblIt/2gUA03rFyxNIM4TY2oJmLcZMPhvkYaDjYXtRa5ZcI1u1gtsOBLzUgkt8KbP7bm6fKlqg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755787391; c=relaxed/simple; bh=lDPUFxvzjX9uelp51IbtN27pRFWfSQD14abwzw2Rr6o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eZgNtzOLLJFtnh4xibqK5i2KFrmcgKdSR05iE2nKJzQFNlsrd/+vzal/0GvqlJ+1nMBR1N7k5BUcAWbfMw3KqJurRR64jA1LkYKBsYI8pghWism/SHqLKGwfu2zSoATPyRekkmzgj4rp9SclZmojPJeq+w62J/mCmhkwB2IAD0A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [113.200.148.30]) by gateway (Coremail) with SMTP id _____8AxP_B6MKdoAXkBAA--.2872S3; Thu, 21 Aug 2025 22:43:06 +0800 (CST) Received: from linux.localdomain (unknown [113.200.148.30]) by front1 (Coremail) with SMTP id qMiowJBxzsF3MKdo0NpdAA--.294S3; Thu, 21 Aug 2025 22:43:04 +0800 (CST) From: Tiezhu Yang To: Huacai Chen , Hengqi Chen Cc: loongarch@lists.linux.dev, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 1/2] LoongArch: BPF: Add struct arguments support for trampoline Date: Thu, 21 Aug 2025 22:43:01 +0800 Message-ID: <20250821144302.14010-2-yangtiezhu@loongson.cn> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20250821144302.14010-1-yangtiezhu@loongson.cn> References: <20250821144302.14010-1-yangtiezhu@loongson.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowJBxzsF3MKdo0NpdAA--.294S3 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBj93XoW3GF4DGF4rJw4kKr45Ar4UZFc_yoW7tr1DpF 1qkr43CF4rJFW7Wa1DXr4UWFyYkFZ3A3ya9rWUG3ySyws8Xr98XF4rKFn0yFy5GrykAFyf urs0vryqkF1xJwcCm3ZEXasCq-sJn29KB7ZKAUJUUUUD529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUvEb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Jr0_Gr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_ GcCE3s1ln4kS14v26r126r1DM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2 x26I8E6xACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r126r1D McIj6I8E87Iv67AKxVW8JVWxJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr4 1lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_ Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17 CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0 I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I 8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73 UjIFyTuYvjxUcApnDUUUU Content-Type: text/plain; charset="utf-8" In the current BPF code, the struct argument size is at most 16 bytes, enforced by the verifier [1]. According to the Procedure Call Standard for LoongArch [2], struct argument size below 16 bytes are provided as part of the 8 argument registers, that is to say, the struct argument may be passed in a pair of registers if its size is more than 8 bytes and no more than 16 bytes. Extend the BPF trampoline JIT to support attachment to functions that take small structures (up to 16 bytes) as argument, save and restore a number of "argument registers" rather than a number of arguments. The initial aim is to pass the following related testcase: sudo ./test_progs -a tracing_struct/struct_args but there exist some other problems now, maybe it is related with the following failed testcase: sudo ./test_progs -t module_attach Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tr= ee/kernel/bpf/btf.c#n7383 [1] Link: https://github.com/loongson/la-abi-specs/blob/release/lapcs.adoc#stru= ctures [2] Signed-off-by: Tiezhu Yang --- arch/loongarch/net/bpf_jit.c | 55 ++++++++++++++++++++---------------- 1 file changed, 31 insertions(+), 24 deletions(-) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index a87f51f5b708..2bdc0e535468 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1340,21 +1340,21 @@ int bpf_arch_text_invalidate(void *dst, size_t len) return ret; } =20 -static void store_args(struct jit_ctx *ctx, int nargs, int args_off) +static void store_args(struct jit_ctx *ctx, int nregs, int args_off) { int i; =20 - for (i =3D 0; i < nargs; i++) { + for (i =3D 0; i < nregs; i++) { emit_insn(ctx, std, LOONGARCH_GPR_A0 + i, LOONGARCH_GPR_FP, -args_off); args_off -=3D 8; } } =20 -static void restore_args(struct jit_ctx *ctx, int nargs, int args_off) +static void restore_args(struct jit_ctx *ctx, int nregs, int args_off) { int i; =20 - for (i =3D 0; i < nargs; i++) { + for (i =3D 0; i < nregs; i++) { emit_insn(ctx, ldd, LOONGARCH_GPR_A0 + i, LOONGARCH_GPR_FP, -args_off); args_off -=3D 8; } @@ -1477,8 +1477,8 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i void *func_addr, u32 flags) { int i, ret, save_ret; - int stack_size =3D 0, nargs =3D 0; - int retval_off, args_off, nargs_off, ip_off, run_ctx_off, sreg_off, tcc_p= tr_off; + int stack_size =3D 0, nregs =3D m->nr_args; + int retval_off, args_off, nregs_off, ip_off, run_ctx_off, sreg_off, tcc_p= tr_off; bool is_struct_ops =3D flags & BPF_TRAMP_F_INDIRECT; void *orig_call =3D func_addr; struct bpf_tramp_links *fentry =3D &tlinks[BPF_TRAMP_FENTRY]; @@ -1498,11 +1498,11 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i * * FP - retval_off [ return value ] BPF_TRAMP_F_CALL_ORIG or * BPF_TRAMP_F_RET_FENTRY_RET - * [ argN ] + * [ arg regN ] * [ ... ] - * FP - args_off [ arg1 ] + * FP - args_off [ arg reg1 ] * - * FP - nargs_off [ regs count ] + * FP - nregs_off [ arg regs count ] * * FP - ip_off [ traced func ] BPF_TRAMP_F_IP_ARG * @@ -1513,15 +1513,23 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i * FP - tcc_ptr_off [ tail_call_cnt_ptr ] */ =20 - if (m->nr_args > LOONGARCH_MAX_REG_ARGS) - return -ENOTSUPP; - - /* don't support struct argument */ + /* extra regiters for struct arguments */ for (i =3D 0; i < m->nr_args; i++) { - if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) - return -ENOTSUPP; + if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) { + /* + * The struct argument size is at most 16 bytes, + * enforced by the verifier. The struct argument + * may be passed in a pair of registers if its + * size is more than 8 bytes and no more than 16 + * bytes. + */ + nregs +=3D round_up(m->arg_size[i], 8) / 8 - 1; + } } =20 + if (nregs > LOONGARCH_MAX_REG_ARGS) + return -ENOTSUPP; + if (flags & (BPF_TRAMP_F_ORIG_STACK | BPF_TRAMP_F_SHARE_IPMODIFY)) return -ENOTSUPP; =20 @@ -1538,13 +1546,12 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i } =20 /* Room of trampoline frame to store args */ - nargs =3D m->nr_args; - stack_size +=3D nargs * 8; + stack_size +=3D nregs * 8; args_off =3D stack_size; =20 /* Room of trampoline frame to store args number */ stack_size +=3D 8; - nargs_off =3D stack_size; + nregs_off =3D stack_size; =20 /* Room of trampoline frame to store ip address */ if (flags & BPF_TRAMP_F_IP_ARG) { @@ -1607,11 +1614,11 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -ip_off); } =20 - /* store nargs number */ - move_imm(ctx, LOONGARCH_GPR_T1, nargs, false); - emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -nargs_off); + /* store arg regs count */ + move_imm(ctx, LOONGARCH_GPR_T1, nregs, false); + emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -nregs_off); =20 - store_args(ctx, nargs, args_off); + store_args(ctx, nregs, args_off); =20 /* To traced function */ /* Ftrace jump skips 2 NOP instructions */ @@ -1643,7 +1650,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i } =20 if (flags & BPF_TRAMP_F_CALL_ORIG) { - restore_args(ctx, m->nr_args, args_off); + restore_args(ctx, nregs, args_off); =20 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) emit_insn(ctx, ldd, REG_TCC, LOONGARCH_GPR_FP, -tcc_ptr_off); @@ -1680,7 +1687,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i } =20 if (flags & BPF_TRAMP_F_RESTORE_REGS) - restore_args(ctx, m->nr_args, args_off); + restore_args(ctx, nregs, args_off); =20 if (save_ret) { emit_insn(ctx, ldd, LOONGARCH_GPR_A0, LOONGARCH_GPR_FP, -retval_off); --=20 2.42.0 From nobody Sat Oct 4 00:32:13 2025 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 637F3215175; Thu, 21 Aug 2025 14:43:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755787392; cv=none; b=hDmUR0VVlNLjAgKil5tsluDib/AsJvILzFhRohAEIpLb1FnGTWFfm7qWyatkRRS4YM9tyYYiOAywp48favCukWOy7Ew0yWe2zPpN+5eWk7HPMqCKrYD9XFo+VJ5Gq9QqOMHUu7KlxGxfSts3VNvtBs3H33VZ+nxIb9QKaGl6He0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755787392; c=relaxed/simple; bh=nqN0eKRTGHrfWvACIIjuTnOAdlvzHw7y/Yc2sXNZMY8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EBRemhbBmVPNGmF5cE/VhPfQH28TyUokXr2LR4vWPdUm7lZWrNr2KhlUm7BIHapuA2dXQAKMVlE4WtG0VG5QWkDuAcr6TaQ6VVCnzlnJj5eDryfJAOCTsJcU6nBtNrEI3HK2jN4k6NSLuW3w2Wbl3S4FUN7eHyXj8vANPMqwd8c= ARC-Authentication-Results: i=1; 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charset="utf-8" Currently, LoongArch bpf trampoline supports up to 8 function arguments. According to the statistics from commit 473e3150e30a ("bpf, x86: allow function arguments up to 12 for TRACING"), there are over 200 functions accept 9 to 12 arguments, so add 12 arguments support for trampoline. The initial aim is to pass the following related testcases: sudo ./test_progs -a tracing_struct/struct_many_args sudo ./test_progs -a fentry_test/fentry_many_args sudo ./test_progs -a fexit_test/fexit_many_args but there exist some other problems now, maybe it is related with the following failed testcase: sudo ./test_progs -t module_attach Signed-off-by: Tiezhu Yang --- arch/loongarch/net/bpf_jit.c | 79 +++++++++++++++++++++++++----------- 1 file changed, 55 insertions(+), 24 deletions(-) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 2bdc0e535468..805fa6dba2d8 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1340,26 +1340,48 @@ int bpf_arch_text_invalidate(void *dst, size_t len) return ret; } =20 -static void store_args(struct jit_ctx *ctx, int nregs, int args_off) +static void store_args(struct jit_ctx *ctx, int nr_arg_slots, int args_off) { int i; =20 - for (i =3D 0; i < nregs; i++) { - emit_insn(ctx, std, LOONGARCH_GPR_A0 + i, LOONGARCH_GPR_FP, -args_off); + for (i =3D 0; i < nr_arg_slots; i++) { + if (i < LOONGARCH_MAX_REG_ARGS) { + emit_insn(ctx, std, LOONGARCH_GPR_A0 + i, LOONGARCH_GPR_FP, -args_off); + } else { + /* skip slots for T0 and FP of traced function */ + emit_insn(ctx, ldd, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, + 16 + (i - LOONGARCH_MAX_REG_ARGS) * 8); + emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -args_off); + } args_off -=3D 8; } } =20 -static void restore_args(struct jit_ctx *ctx, int nregs, int args_off) +static void restore_args(struct jit_ctx *ctx, int nr_reg_args, int args_of= f) { int i; =20 - for (i =3D 0; i < nregs; i++) { + for (i =3D 0; i < nr_reg_args; i++) { emit_insn(ctx, ldd, LOONGARCH_GPR_A0 + i, LOONGARCH_GPR_FP, -args_off); args_off -=3D 8; } } =20 +static void restore_stk_args(struct jit_ctx *ctx, int nr_stk_args, + int args_off, int stk_arg_off) +{ + int i; + + for (i =3D 0; i < nr_stk_args; i++) { + emit_insn(ctx, ldd, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, + -(args_off - LOONGARCH_MAX_REG_ARGS * 8)); + emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, + -stk_arg_off); + args_off -=3D 8; + stk_arg_off -=3D 8; + } +} + static int invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l, const struct btf_func_model *m, int args_off, int retval_off, int run_ctx_off, bool save_ret) @@ -1477,7 +1499,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i void *func_addr, u32 flags) { int i, ret, save_ret; - int stack_size =3D 0, nregs =3D m->nr_args; + int stack_size =3D 0, nr_arg_slots =3D 0, stk_arg_off; int retval_off, args_off, nregs_off, ip_off, run_ctx_off, sreg_off, tcc_p= tr_off; bool is_struct_ops =3D flags & BPF_TRAMP_F_INDIRECT; void *orig_call =3D func_addr; @@ -1511,25 +1533,27 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i * FP - sreg_off [ callee saved reg ] * * FP - tcc_ptr_off [ tail_call_cnt_ptr ] + * + * [ stack_argN ] + * [ ... ] + * FP - stk_arg_off [ stack_arg1 ] BPF_TRAMP_F_CALL_ORIG */ =20 + if (m->nr_args > MAX_BPF_FUNC_ARGS) + return -ENOTSUPP; + /* extra regiters for struct arguments */ for (i =3D 0; i < m->nr_args; i++) { - if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) { - /* - * The struct argument size is at most 16 bytes, - * enforced by the verifier. The struct argument - * may be passed in a pair of registers if its - * size is more than 8 bytes and no more than 16 - * bytes. - */ - nregs +=3D round_up(m->arg_size[i], 8) / 8 - 1; - } + /* + * The struct argument size is at most 16 bytes, + * enforced by the verifier. The struct argument + * may be passed in a pair of registers if its + * size is more than 8 bytes and no more than 16 + * bytes. + */ + nr_arg_slots +=3D round_up(m->arg_size[i], 8) / 8; } =20 - if (nregs > LOONGARCH_MAX_REG_ARGS) - return -ENOTSUPP; - if (flags & (BPF_TRAMP_F_ORIG_STACK | BPF_TRAMP_F_SHARE_IPMODIFY)) return -ENOTSUPP; =20 @@ -1546,7 +1570,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i } =20 /* Room of trampoline frame to store args */ - stack_size +=3D nregs * 8; + stack_size +=3D nr_arg_slots * 8; args_off =3D stack_size; =20 /* Room of trampoline frame to store args number */ @@ -1572,8 +1596,14 @@ static int __arch_prepare_bpf_trampoline(struct jit_= ctx *ctx, struct bpf_tramp_i tcc_ptr_off =3D stack_size; } =20 + if ((flags & BPF_TRAMP_F_CALL_ORIG) && (nr_arg_slots - LOONGARCH_MAX_REG_= ARGS > 0)) + stack_size +=3D (nr_arg_slots - LOONGARCH_MAX_REG_ARGS) * 8; + stack_size =3D round_up(stack_size, 16); =20 + /* Room for args on stack must be at the top of stack */ + stk_arg_off =3D stack_size; + if (is_struct_ops) { /* * For the trampoline called directly, just handle @@ -1615,10 +1645,10 @@ static int __arch_prepare_bpf_trampoline(struct jit= _ctx *ctx, struct bpf_tramp_i } =20 /* store arg regs count */ - move_imm(ctx, LOONGARCH_GPR_T1, nregs, false); + move_imm(ctx, LOONGARCH_GPR_T1, nr_arg_slots, false); emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -nregs_off); =20 - store_args(ctx, nregs, args_off); + store_args(ctx, nr_arg_slots, args_off); =20 /* To traced function */ /* Ftrace jump skips 2 NOP instructions */ @@ -1650,7 +1680,8 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i } =20 if (flags & BPF_TRAMP_F_CALL_ORIG) { - restore_args(ctx, nregs, args_off); + restore_args(ctx, min_t(int, nr_arg_slots, LOONGARCH_MAX_REG_ARGS), args= _off); + restore_stk_args(ctx, nr_arg_slots - LOONGARCH_MAX_REG_ARGS, args_off, s= tk_arg_off); =20 if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) emit_insn(ctx, ldd, REG_TCC, LOONGARCH_GPR_FP, -tcc_ptr_off); @@ -1687,7 +1718,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_c= tx *ctx, struct bpf_tramp_i } =20 if (flags & BPF_TRAMP_F_RESTORE_REGS) - restore_args(ctx, nregs, args_off); + restore_args(ctx, min_t(int, nr_arg_slots, LOONGARCH_MAX_REG_ARGS), args= _off); =20 if (save_ret) { emit_insn(ctx, ldd, LOONGARCH_GPR_A0, LOONGARCH_GPR_FP, -retval_off); --=20 2.42.0