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(unknown [219.141.235.82]) by APP-01 (Coremail) with SMTP id qwCowADX3Eg9zNNjDyF3Ag--.52827S7; Fri, 27 Jan 2023 21:06:09 +0800 (CST) From: Chen Guokai To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, rostedt@goodmis.org, mingo@redhat.com, sfr@canb.auug.org.au Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, liaochang1@huawei.com, Chen Guokai Subject: [PATCH v6 03/13] riscv/kprobe: Add skeleton for preparing optimized kprobe Date: Fri, 27 Jan 2023 21:05:31 +0800 Message-Id: <20230127130541.1250865-4-chenguokai17@mails.ucas.ac.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230127130541.1250865-1-chenguokai17@mails.ucas.ac.cn> References: <20230127130541.1250865-1-chenguokai17@mails.ucas.ac.cn> MIME-Version: 1.0 X-CM-TRANSID: qwCowADX3Eg9zNNjDyF3Ag--.52827S7 X-Coremail-Antispam: 1UD129KBjvJXoWxuFyUWr4fGw18ZFy8ur1Dtrb_yoWrXryrpF s3Cw45trWDJa93urWfZwsYvrySyFsYqr47CrW7J345Zr17Jr90va97tr1YqF9xGrWF9rW3 JFsYyry5uFW3ZFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQj14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JrWl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1l84 ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AKxVW8Jr0_Cr1U M2vYz4IE04k24VAvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64 kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm 72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYx C7M4IIrI8v6xkF7I0E8cxan2IY04v7MxkIecxEwVAFwVW5GwCF04k20xvY0x0EwIxGrwCF x2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14 v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY 67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2 IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_ Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JU3DG5UUUUU= X-Originating-IP: [219.141.235.82] X-CM-SenderInfo: xfkh0w5xrntxyrx6ztxlovh3xfdvhtffof0/1tbiCggEE2PTtMIZxAAAsO X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_MSPIKE_H2, SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756181509476691088?= X-GMAIL-MSGID: =?utf-8?q?1756181509476691088?= From: Liao Chang The skeleton for preparing optprobe is consist of three major parts: - Check if kprobe satisfies the requirements of optimization. - Search two registers to form AUIPC/JALR instructions. - Prepare detour buffer for optimized kprobe. To avoid introducing too much code in single patch just add some dummy implementaion for compilation. Signed-off-by: Liao Chang Co-developed-by: Chen Guokai Signed-off-by: Chen Guokai --- arch/riscv/kernel/probes/opt.c | 98 +++++++++++++++++++++++++++++++++- 1 file changed, 97 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c index 56c8a227c857..c03cdb1512a6 100644 --- a/arch/riscv/kernel/probes/opt.c +++ b/arch/riscv/kernel/probes/opt.c @@ -10,6 +10,53 @@ #include #include +#include + +static int in_auipc_jalr_range(long val) +{ +#ifdef CONFIG_ARCH_RV32I + return 1; +#else + /* + * Note that the set of address offsets that can be formed + * by pairing LUI with LD, AUIPC with JALR, etc. RV64I is + * [−2^31−2^11, 2^31−2^11−1]. + */ + return ((-(1L << 31) - (1L << 11)) <= val) && + (val < ((1L << 31) - (1L << 11))); +#endif +} + +/* + * Copy optprobe assembly code template into detour buffer and modify some + * instructions for each kprobe. + */ +static void prepare_detour_buffer(kprobe_opcode_t *code, kprobe_opcode_t *slot, + int rd, struct optimized_kprobe *op, + kprobe_opcode_t opcode) +{ +} + +/* + * In RISC-V ISA, AUIPC/JALR clobber one register to form target address, + * inspired by register renaming in OoO processor, this involves search + * backward that is not previously used as a source register and is used + * as a destination register before any branch or jump instruction. + */ +static void find_free_registers(struct kprobe *kp, struct optimized_kprobe *op, + int *rd, int *ra) +{ +} + +/* + * The kprobe based on breakpoint just requires the instrumented instruction + * supports execute out-of-line or simulation, besides that, optimized kprobe + * requires no near instruction jump to any instruction replaced by AUIPC/JALR. + */ +static bool can_optimize(unsigned long paddr, struct optimized_kprobe *op) +{ + return false; +} int arch_prepared_optinsn(struct arch_optimized_insn *optinsn) { @@ -24,7 +71,56 @@ int arch_check_optimized_kprobe(struct optimized_kprobe *op) int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig) { - return 0; + long rel; + int rd = 0, ra = 0, ret; + kprobe_opcode_t *code = NULL, *slot = NULL; + + if (!can_optimize((unsigned long)orig->addr, op)) + return -EILSEQ; + + code = kzalloc(MAX_OPTINSN_SIZE, GFP_KERNEL); + slot = get_optinsn_slot(); + if (!code || !slot) { + ret = -ENOMEM; + goto on_error; + } + + /* Check if the detour buffer is in the 32-bit pc-relative range. */ + rel = (unsigned long)slot - (unsigned long)orig->addr; + if (!in_auipc_jalr_range(rel)) { + ret = -ERANGE; + goto on_error; + } + + /* + * Search two free registers, rd is used to form AUIPC/JALR jumping + * to detour buffer, ra is used to form JR jumping back from detour + * buffer. + */ + find_free_registers(orig, op, &rd, &ra); + if (rd == 0 || ra == 0) { + ret = -EILSEQ; + goto on_error; + } + + op->optinsn.rd = rd; + prepare_detour_buffer(code, slot, ra, op, orig->opcode); + + ret = patch_text_nosync((void *)slot, code, MAX_OPTINSN_SIZE); + if (!ret) { + op->optinsn.insn = slot; + kfree(code); + return 0; + } + +on_error: + if (slot) { + free_optinsn_slot(slot, 0); + op->optinsn.insn = NULL; + op->optinsn.length = 0; + } + kfree(code); + return ret; } void arch_remove_optimized_kprobe(struct optimized_kprobe *op)