From nobody Fri Apr 3 02:28:15 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8267FECAAD8 for ; Mon, 19 Sep 2022 03:17:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229949AbiISDRj (ORCPT ); Sun, 18 Sep 2022 23:17:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229888AbiISDQv (ORCPT ); Sun, 18 Sep 2022 23:16:51 -0400 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CF3A613CF3 for ; Sun, 18 Sep 2022 20:16:49 -0700 (PDT) Received: from localhost.localdomain (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8DxvmsQ3ydjUW4dAA--.34031S6; Mon, 19 Sep 2022 11:16:41 +0800 (CST) From: Qing Zhang To: Huacai Chen , Steven Rostedt , Ingo Molnar Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Jinyang He Subject: [PATCH v5 04/10] LoongArch/ftrace: Add dynamic function graph tracer support Date: Mon, 19 Sep 2022 11:16:26 +0800 Message-Id: <20220919031632.15374-5-zhangqing@loongson.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20220919031632.15374-1-zhangqing@loongson.cn> References: <20220919031632.15374-1-zhangqing@loongson.cn> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: AQAAf8DxvmsQ3ydjUW4dAA--.34031S6 X-Coremail-Antispam: 1UD129KBjvJXoWxGF4DAF1DKw4rGr1DWF45Jrb_yoWrKFyrpr y2y3ZxtrWjkFsakr9Igr4kXrW5A393W342qanrtryrCwsFqF13Aw1xA34qqFyaqw4UCryS vayrAr4jka1UXa7anT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBC14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26F4U JVW0owAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7V C0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j 6r4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY02Avz4vE14v_Gr 4l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWU JVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7V AKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVW8JVWxJwCI42 IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUneOJDUUUU X-CM-SenderInfo: x2kd0wptlqwqxorr0wxvrqhubq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Once the function_graph tracer is enabled, a filtered function has the following call sequence: 1) ftracer_caller =3D=3D> on/off by ftrace_make_call/ftrace_make_nop 2) ftrace_graph_caller 3) ftrace_graph_call =3D=3D> on/off by ftrace_en/disable_ftrace_graph_call= er 4) prepare_ftrace_return Considering the following DYNAMIC_FTRACE_WITH_REGS feature, it would be more extendable to have a ftrace_graph_caller function, instead of calling prepare_ftrace_return directly in ftrace_caller. Co-developed-by: Jinyang He Signed-off-by: Jinyang He Signed-off-by: Qing Zhang --- arch/loongarch/kernel/entry_dyn.S | 33 ++++++++++++++++++++++ arch/loongarch/kernel/ftrace_dyn.c | 45 ++++++++++++++++++++++++++++++ arch/loongarch/kernel/inst.c | 24 ++++++++++++++++ 3 files changed, 102 insertions(+) diff --git a/arch/loongarch/kernel/entry_dyn.S b/arch/loongarch/kernel/entr= y_dyn.S index 205925bc3822..0c12cc108e6f 100644 --- a/arch/loongarch/kernel/entry_dyn.S +++ b/arch/loongarch/kernel/entry_dyn.S @@ -62,6 +62,11 @@ SYM_CODE_START(ftrace_common) .globl ftrace_call ftrace_call: bl ftrace_stub +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + .globl ftrace_graph_call +ftrace_graph_call: + nop /* b ftrace_graph_caller */ +#endif /* * As we didn't use S series regs in this assmembly code and all calls * are C function which will save S series regs by themselves, there is @@ -84,6 +89,34 @@ ftrace_common_return: jr t0 SYM_CODE_END(ftrace_common) =20 +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +SYM_CODE_START(ftrace_graph_caller) + PTR_L a0, sp, PT_ERA + PTR_ADDI a0, a0, -8 /* arg0: self_addr */ + PTR_ADDI a1, sp, PT_R1 /* arg1: parent */ + bl prepare_ftrace_return + b ftrace_common_return +SYM_CODE_END(ftrace_graph_caller) + +SYM_CODE_START(return_to_handler) + /* save return value regs */ + PTR_ADDI sp, sp, -2 * SZREG + PTR_S a0, sp, 0 + PTR_S a1, sp, SZREG + + move a0, zero /* Has no check FP now. */ + bl ftrace_return_to_handler + move ra, a0 /* parent ra */ + + /* restore return value regs */ + PTR_L a0, sp, 0 + PTR_L a1, sp, SZREG + PTR_ADDI sp, sp, 2 * SZREG + + jr ra +SYM_CODE_END(return_to_handler) +#endif + SYM_FUNC_START(ftrace_stub) jr ra SYM_FUNC_END(ftrace_stub) diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftr= ace_dyn.c index 1f8955be8b64..3fe791b6783e 100644 --- a/arch/loongarch/kernel/ftrace_dyn.c +++ b/arch/loongarch/kernel/ftrace_dyn.c @@ -109,3 +109,48 @@ int __init ftrace_dyn_arch_init(void) { return 0; } + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +extern void ftrace_graph_call(void); + +void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent) +{ + unsigned long return_hooker =3D (unsigned long)&return_to_handler; + unsigned long old; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + old =3D *parent; + + if (!function_graph_enter(old, self_addr, 0, NULL)) + *parent =3D return_hooker; +} + +static int ftrace_modify_graph_caller(bool enable) +{ + unsigned long pc, func; + u32 branch, nop; + + pc =3D (unsigned long)&ftrace_graph_call; + func =3D (unsigned long)&ftrace_graph_caller; + + branch =3D larch_insn_gen_b(pc, func); + nop =3D larch_insn_gen_nop(); + + if (enable) + return ftrace_modify_code(pc, nop, branch, true); + else + return ftrace_modify_code(pc, branch, nop, true); +} + +int ftrace_enable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(true); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(false); +} +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c index d62cdf4a9ffb..2d2e942eb06a 100644 --- a/arch/loongarch/kernel/inst.c +++ b/arch/loongarch/kernel/inst.c @@ -55,6 +55,30 @@ u32 larch_insn_gen_nop(void) return INSN_NOP; } =20 +u32 larch_insn_gen_b(unsigned long pc, unsigned long dest) +{ + unsigned int immediate_l, immediate_h; + union loongarch_instruction insn; + long offset =3D dest - pc; + + if ((offset & 3) || offset < -SZ_128M || offset >=3D SZ_128M) { + pr_warn("The generated b instruction is out of range.\n"); + return INSN_BREAK; + } + + offset >>=3D 2; + + immediate_l =3D offset & 0xffff; + offset >>=3D 16; + immediate_h =3D offset & 0x3ff; + + insn.reg0i26_format.opcode =3D b_op; + insn.reg0i26_format.immediate_l =3D immediate_l; + insn.reg0i26_format.immediate_h =3D immediate_h; + + return insn.word; +} + u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest) { unsigned int immediate_l, immediate_h; --=20 2.36.1