From nobody Tue Sep 29 02:35:32 2026 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2A3832E88A4; Thu, 13 Aug 2026 04:53:16 +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=1786596800; cv=none; b=AE9oZaav3VI3xl+999BzCh/WsbG9fBzSdtD1vUmaTENPxo5s0AbDV/hnzenZz3JhAZamvn2c84nGG5IMQeylmmtkPMwRKTVcuzmHQPmW5Ll1IzIUJasPBq66aSfCUubjKWX87jnhhRhkpHfjsAqzqDphxD8bqx6zcy5L7mX9jfE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786596800; c=relaxed/simple; bh=/WeQs4kp94i9NU69HhPn78X79uzPNVFGzKZwcMv6Ntk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Xwhht8jN9/8A4UZxlLC8hJDbx7lcbzlMrBK2K0ao8R2O5k+JkeRF6IBtqgzjivYFN10c4dTaTFnX6akA59A+s7g1qo4Y9voROGA45BM56hqhipR1ogQq9Kpm1F41x9JFts62Dzbkee+PQQRkXuyI034Jn74jDhTq5ccQz7fLXso= 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 [123.138.236.242]) by gateway (Coremail) with SMTP id _____8BxbdK1TX1qAMwAAA--.2512S3; Thu, 13 Aug 2026 12:53:09 +0800 (CST) Received: from linux.localdomain (unknown [123.138.236.242]) by front1 (Coremail) with SMTP id qMiowJCxPs+0TX1qpf0CAA--.20229S2; Thu, 13 Aug 2026 12:53:09 +0800 (CST) From: Tiezhu Yang To: Huacai Chen , Hengqi Chen Cc: loongarch@lists.linux.dev, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, George Guo Subject: [PATCH v1] LoongArch: BPF: Implement arch_bpf_stack_walk() Date: Thu, 13 Aug 2026 12:53:06 +0800 Message-ID: <20260813045306.21571-1-yangtiezhu@loongson.cn> X-Mailer: git-send-email 2.42.0 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: qMiowJCxPs+0TX1qpf0CAA--.20229S2 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBj93XoWxJFWxKF43KFW3WryxWr4rJFc_yoW5GF1xpr s0kanxKrZ0g34xXry3tw4UZrZ8Xr4kCr47KFW3CFyrCF9rX3Wxur9YkayqqFn8ArykJa1I qrZ0kF9Ika95AagCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUU90b4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Jr0_Gr1l84ACjcxK6I8E87Iv67AKxVWxJVW8Jr1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6r4UJVWxJr1ln4kS14v26r1Y6r17M2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12 xvs2x26I8E6xACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y 6r17McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64 vIr41l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_ Jrv_JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1V AY17CE14v26r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAI cVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42 IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVj vjDU0xZFpf9x07jepB-UUUUU= Content-Type: text/plain; charset="utf-8" From: George Guo Implement arch_bpf_stack_walk() on top of the ORC unwinder within the LoongArch BPF JIT backend to provide generic BPF stack walking capabilities. This function is required by advanced BPF features, including timed may_goto timeout tracing and BPF exceptions. It will be invoked in the BPF core subsystem unwinding paths: bpf_prog_find_from_stack(), bpf_stream_stage_dump_stack(), and bpf_throw(). Co-developed-by: Tiezhu Yang Signed-off-by: Tiezhu Yang Signed-off-by: George Guo --- This is an independent feature, so split it from https://lore.kernel.org/loongarch/20260702022322.51033-6-dongtai.guo@linux.= dev/ Based on the latest loongarch-next, tested on Loongson-3A6000. arch/loongarch/net/bpf_jit.c | 38 ++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 7533917c6d47..78c20df2a2f3 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -2402,6 +2402,44 @@ bool bpf_jit_supports_subprog_tailcalls(void) return true; } =20 +#if defined(CONFIG_UNWINDER_ORC) +#include + +static noinline void walk_bpf_stackframe(bool (*consume_fn)(void *cookie, = u64 ip, u64 sp, u64 bp), + void *cookie, unsigned long fp) +{ + struct pt_regs dummyregs; + struct pt_regs *regs =3D &dummyregs; + struct unwind_state state; + unsigned long addr; + + regs->regs[3] =3D (unsigned long)__builtin_frame_address(0); + regs->csr_era =3D (unsigned long)__builtin_return_address(0); + regs->regs[1] =3D 0; + regs->regs[22] =3D fp; + + for (unwind_start(&state, current, regs); + !unwind_done(&state); unwind_next_frame(&state)) { + addr =3D unwind_get_return_address(&state); + if (!addr || !consume_fn(cookie, (u64)addr, (u64)state.sp, (u64)state.fp= )) + break; + } +} + +void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, = u64 bp), void *cookie) +{ + unsigned long fp; + + /* + * Capture the live frame pointer ($r22) at the very front-line before + * any kernel C code clobbers it. This must be a thin wrapper with no + * large stack locals to prevent the compiler from reusing $r22 early. + */ + asm volatile("move %0, $r22" : "=3Dr"(fp)); + walk_bpf_stackframe(consume_fn, cookie, fp); +} +#endif /* CONFIG_UNWINDER_ORC */ + bool bpf_jit_supports_timed_may_goto(void) { return true; --=20 2.42.0