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(unknown [219.141.235.82]) by APP-03 (Coremail) with SMTP id rQCowABXCVmKPV5jkxYmBw--.33365S11; Sun, 30 Oct 2022 17:02:18 +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 7/8] riscv/kprobe: Prepare detour buffer for optimized kprobe Date: Sun, 30 Oct 2022 17:01:40 +0800 Message-Id: <20221030090141.2550837-8-chenguokai17@mails.ucas.ac.cn> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221030090141.2550837-1-chenguokai17@mails.ucas.ac.cn> References: <20221030090141.2550837-1-chenguokai17@mails.ucas.ac.cn> MIME-Version: 1.0 X-CM-TRANSID: rQCowABXCVmKPV5jkxYmBw--.33365S11 X-Coremail-Antispam: 1UD129KBjvJXoW3Gr1fWw45Xw4DJrW5uFWxZwb_yoWDJF4fpa 95CwnxXF4UZFn7Cry7t3Z5Jr4Sqws5Jws7Grs7GFW5Jan3KrW5Xan2g345Xr15G390gry7 ua45JryUuF9xXrJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQF14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26F4UJVW0owA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE 3s1lnxkEFVAIw20F6cxK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2 IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r4j6F4U McvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I64 8v4I1lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc2xSY4AK67AK6r4fMxAIw28IcxkI7VAKI48J MxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwV AFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv2 0xvE14v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWxJVW8Jr1lIxAIcVCF04k26c xKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAF wI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUzv3nUUUUU= X-Originating-IP: [219.141.235.82] X-CM-SenderInfo: xfkh0w5xrntxyrx6ztxlovh3xfdvhtffof0/1tbiCgUPE2NeGqorXQABsp X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, 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?1748103941997302063?= X-GMAIL-MSGID: =?utf-8?q?1748103941997302063?= From: Liao Chang This patch introduces code to prepare instruction slot for optimized kprobe. The instruction slot for regular kprobe just records two instructions, first one is the original instruction replaced by EBREAK, the second one is EBREAK for single-step. While instruction slot for optimized kprobe is larger, beside execute instruction out-of-line, it also contains a standalone stackframe for calling kprobe handler. All optimized instruction slots consis of 5 major parts, which copied from the assembly code template in opt_trampoline.S. SAVE REGS CALL optimized_callback RESTORE REGS EXECUTE INSNS OUT-OF-LINE RETURN BACK Although most instructions in each slot are same, these slots still have a bit difference in their payload, it is caused by three parts: - 'CALL optimized_callback', the relative offset for 'call' instruction is different for each kprobe. - 'EXECUTE INSN OUT-OF-LINE', no doubt. - 'RETURN BACK', the chosen free register is reused here as the destination register of jumping back. So we also need customize the slot payload for each optimized kprobe. Co-developed-by: Chen Guokai Signed-off-by: Chen Guokai Signed-off-by: Liao Chang --- arch/riscv/include/asm/kprobes.h | 16 +++ arch/riscv/kernel/probes/opt.c | 75 +++++++++++++ arch/riscv/kernel/probes/opt_trampoline.S | 125 ++++++++++++++++++++++ 3 files changed, 216 insertions(+) diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h index 22b73a2fd1fd..a9ef864f7225 100644 --- a/arch/riscv/include/asm/kprobes.h +++ b/arch/riscv/include/asm/kprobes.h @@ -48,10 +48,26 @@ void __kprobes *trampoline_probe_handler(struct pt_regs *regs); /* optinsn template addresses */ extern __visible kprobe_opcode_t optprobe_template_entry[]; extern __visible kprobe_opcode_t optprobe_template_end[]; +extern __visible kprobe_opcode_t optprobe_template_save[]; +extern __visible kprobe_opcode_t optprobe_template_call[]; +extern __visible kprobe_opcode_t optprobe_template_insn[]; +extern __visible kprobe_opcode_t optprobe_template_return[]; #define MAX_OPTINSN_SIZE \ ((unsigned long)optprobe_template_end - \ (unsigned long)optprobe_template_entry) +#define DETOUR_SAVE_OFFSET \ + ((unsigned long)optprobe_template_save - \ + (unsigned long)optprobe_template_entry) +#define DETOUR_CALL_OFFSET \ + ((unsigned long)optprobe_template_call - \ + (unsigned long)optprobe_template_entry) +#define DETOUR_INSN_OFFSET \ + ((unsigned long)optprobe_template_insn - \ + (unsigned long)optprobe_template_entry) +#define DETOUR_RETURN_OFFSET \ + ((unsigned long)optprobe_template_return - \ + (unsigned long)optprobe_template_entry) /* * For RVI and RVC hybird encoding kernel, althought long jump just needs diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c index 876bec539554..77248ed7d4e8 100644 --- a/arch/riscv/kernel/probes/opt.c +++ b/arch/riscv/kernel/probes/opt.c @@ -11,9 +11,37 @@ #include #include #include +#include #include "simulate-insn.h" #include "decode-insn.h" +#include "../../net/bpf_jit.h" + +static void +optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) +{ + unsigned long flags; + struct kprobe_ctlblk *kcb; + + /* Save skipped registers */ + regs->epc = (unsigned long)op->kp.addr; + regs->orig_a0 = ~0UL; + + local_irq_save(flags); + kcb = get_kprobe_ctlblk(); + + if (kprobe_running()) { + kprobes_inc_nmissed_count(&op->kp); + } else { + __this_cpu_write(current_kprobe, &op->kp); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + opt_pre_handler(&op->kp, regs); + __this_cpu_write(current_kprobe, NULL); + } + local_irq_restore(flags); +} + +NOKPROBE_SYMBOL(optimized_callback) static inline int in_auipc_jalr_range(long val) { @@ -30,6 +58,11 @@ static inline int in_auipc_jalr_range(long val) #endif } +#define DETOUR_ADDR(code, offs) \ + ((void *)((unsigned long)(code) + (offs))) +#define DETOUR_INSN(code, offs) \ + (*(kprobe_opcode_t *)((unsigned long)(code) + (offs))) + /* * Copy optprobe assembly code template into detour buffer and modify some * instructions for each kprobe. @@ -38,6 +71,49 @@ static void prepare_detour_buffer(kprobe_opcode_t *code, kprobe_opcode_t *slot, int rd, struct optimized_kprobe *op, kprobe_opcode_t opcode) { + long offs; + unsigned long data; + + memcpy(code, optprobe_template_entry, MAX_OPTINSN_SIZE); + + /* Step1: record optimized_kprobe pointer into detour buffer */ + memcpy(DETOUR_ADDR(code, DETOUR_SAVE_OFFSET), &op, sizeof(op)); + + /* + * Step2 + * auipc ra, 0 --> aupic ra, HI20.{optimized_callback - pc} + * jalr ra, 0(ra) --> jalr ra, LO12.{optimized_callback - pc}(ra) + */ + offs = (unsigned long)&optimized_callback - + (unsigned long)DETOUR_ADDR(slot, DETOUR_CALL_OFFSET); + DETOUR_INSN(code, DETOUR_CALL_OFFSET) = + rv_auipc(1, (offs + (1 << 11)) >> 12); + DETOUR_INSN(code, DETOUR_CALL_OFFSET + 0x4) = + rv_jalr(1, 1, offs & 0xFFF); + + /* Step3: copy replaced instructions into detour buffer */ + memcpy(DETOUR_ADDR(code, DETOUR_INSN_OFFSET), op->kp.addr, + op->optinsn.length); + memcpy(DETOUR_ADDR(code, DETOUR_INSN_OFFSET), &opcode, + GET_INSN_LENGTH(opcode)); + + /* Step4: record return address of long jump into detour buffer */ + data = (unsigned long)op->kp.addr + op->optinsn.length; + memcpy(DETOUR_ADDR(code, DETOUR_RETURN_OFFSET), &data, sizeof(data)); + + /* + * Step5 + * auipc ra, 0 --> auipc rd, 0 + * ld/w ra, -4(ra) --> ld/w rd, -8(rd) + * jalr x0, 0(ra) --> jalr x0, 0(rd) + */ + DETOUR_INSN(code, DETOUR_RETURN_OFFSET + 0x8) = rv_auipc(rd, 0); +#if __riscv_xlen == 32 + DETOUR_INSN(code, DETOUR_RETURN_OFFSET + 0xC) = rv_lw(rd, -8, rd); +#else + DETOUR_INSN(code, DETOUR_RETURN_OFFSET + 0xC) = rv_ld(rd, -8, rd); +#endif + DETOUR_INSN(code, DETOUR_RETURN_OFFSET + 0x10) = rv_jalr(0, rd, 0); } /* Registers the first usage of which is the destination of instruction */ diff --git a/arch/riscv/kernel/probes/opt_trampoline.S b/arch/riscv/kernel/probes/opt_trampoline.S index 16160c4367ff..75e34e373cf2 100644 --- a/arch/riscv/kernel/probes/opt_trampoline.S +++ b/arch/riscv/kernel/probes/opt_trampoline.S @@ -1,12 +1,137 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* * Copyright (C) 2022 Guokai Chen + * Copyright (C) 2022 Liao, Chang */ #include +#include #incldue #include SYM_ENTRY(optprobe_template_entry, SYM_L_GLOBAL, SYM_A_NONE) + addi sp, sp, -(PT_SIZE_ON_STACK) + REG_S x1, PT_RA(sp) + REG_S x2, PT_SP(sp) + REG_S x3, PT_GP(sp) + REG_S x4, PT_TP(sp) + REG_S x5, PT_T0(sp) + REG_S x6, PT_T1(sp) + REG_S x7, PT_T2(sp) + REG_S x8, PT_S0(sp) + REG_S x9, PT_S1(sp) + REG_S x10, PT_A0(sp) + REG_S x11, PT_A1(sp) + REG_S x12, PT_A2(sp) + REG_S x13, PT_A3(sp) + REG_S x14, PT_A4(sp) + REG_S x15, PT_A5(sp) + REG_S x16, PT_A6(sp) + REG_S x17, PT_A7(sp) + REG_S x18, PT_S2(sp) + REG_S x19, PT_S3(sp) + REG_S x20, PT_S4(sp) + REG_S x21, PT_S5(sp) + REG_S x22, PT_S6(sp) + REG_S x23, PT_S7(sp) + REG_S x24, PT_S8(sp) + REG_S x25, PT_S9(sp) + REG_S x26, PT_S10(sp) + REG_S x27, PT_S11(sp) + REG_S x28, PT_T3(sp) + REG_S x29, PT_T4(sp) + REG_S x30, PT_T5(sp) + REG_S x31, PT_T6(sp) + /* Update fp is friendly for stacktrace */ + addi s0, sp, (PT_SIZE_ON_STACK) + j 1f + +SYM_ENTRY(optprobe_template_save, SYM_L_GLOBAL, SYM_A_NONE) + /* + * Step1: + * Filled with the pointer to optimized_kprobe data + */ + .dword 0 +1: + /* Load optimize_kprobe pointer from .dword below */ + auipc a0, 0 + REG_L a0, -8(a0) + add a1, sp, x0 + +SYM_ENTRY(optprobe_template_call, SYM_L_GLOBAL, SYM_A_NONE) + /* + * Step2: + * of AUIPC/JALR are modified to the offset to optimized_callback + * jump target is loaded from above .dword. + */ + auipc ra, 0 + jalr ra, 0(ra) + + REG_L x1, PT_RA(sp) + REG_L x3, PT_GP(sp) + REG_L x4, PT_TP(sp) + REG_L x5, PT_T0(sp) + REG_L x6, PT_T1(sp) + REG_L x7, PT_T2(sp) + REG_L x8, PT_S0(sp) + REG_L x9, PT_S1(sp) + REG_L x10, PT_A0(sp) + REG_L x11, PT_A1(sp) + REG_L x12, PT_A2(sp) + REG_L x13, PT_A3(sp) + REG_L x14, PT_A4(sp) + REG_L x15, PT_A5(sp) + REG_L x16, PT_A6(sp) + REG_L x17, PT_A7(sp) + REG_L x18, PT_S2(sp) + REG_L x19, PT_S3(sp) + REG_L x20, PT_S4(sp) + REG_L x21, PT_S5(sp) + REG_L x22, PT_S6(sp) + REG_L x23, PT_S7(sp) + REG_L x24, PT_S8(sp) + REG_L x25, PT_S9(sp) + REG_L x26, PT_S10(sp) + REG_L x27, PT_S11(sp) + REG_L x28, PT_T3(sp) + REG_L x29, PT_T4(sp) + REG_L x30, PT_T5(sp) + REG_L x31, PT_T6(sp) + REG_L x2, PT_SP(sp) + addi sp, sp, (PT_SIZE_ON_STACK) + +SYM_ENTRY(optprobe_template_insn, SYM_L_GLOBAL, SYM_A_NONE) + /* + * Step3: + * NOPS will be replaced by the probed instruction, at worst case 3 RVC + * and 1 RVI instructions is about to execute out of line. + */ + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + j 2f + +SYM_ENTRY(optprobe_template_return, SYM_L_GLOBAL, SYM_A_NONE) + /* + * Step4: + * Filled with the return address of long jump(AUIPC/JALR) + */ + .dword 0 +2: + /* + * Step5: + * The of AUIPC/LD/JALR will be replaced for each kprobe, + * used to read return address saved in .dword above. + */ + auipc ra, 0 + REG_L ra, -8(ra) + jalr x0, 0(ra) SYM_ENTRY(optprobe_template_end, SYM_L_GLOBAL, SYM_A_NONE)