From: "Björn Töpel" <bjorn@kernel.org>
To: Chen Guokai <chenguokai17@mails.ucas.ac.cn>,
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 <chenguokai17@mails.ucas.ac.cn>
Subject: Re: [PATCH v6 08/13] riscv/kprobe: Patch AUIPC/JALR pair to optimize kprobe
Date: Wed, 01 Feb 2023 14:31:07 +0100 [thread overview]
Message-ID: <87r0v9tsv8.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <20230127130541.1250865-9-chenguokai17@mails.ucas.ac.cn>
Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes:
> diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h
> index 9a7d7346001e..ee31539de65f 100644
> --- a/arch/riscv/include/asm/patch.h
> +++ b/arch/riscv/include/asm/patch.h
> @@ -8,5 +8,6 @@
>
> int patch_text_nosync(void *addr, const void *insns, size_t len);
> int patch_text(void *addr, u32 insn);
> +int patch_text_batch(void *addr, const void *insn, size_t size);
>
> #endif /* _ASM_RISCV_PATCH_H */
> diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
> index 765004b60513..ce324b6a6998 100644
> --- a/arch/riscv/kernel/patch.c
> +++ b/arch/riscv/kernel/patch.c
> @@ -15,7 +15,8 @@
>
> struct patch_insn {
> void *addr;
> - u32 insn;
> + const void *insn;
> + size_t size;
> atomic_t cpu_count;
> };
>
> @@ -106,8 +107,7 @@ static int patch_text_cb(void *data)
>
> if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {
> ret =
Nit: Please use the full width. No need for a NL here.
> - patch_text_nosync(patch->addr, &patch->insn,
> - GET_INSN_LENGTH(patch->insn));
> + patch_text_nosync(patch->addr, patch->insn, patch->size);
> atomic_inc(&patch->cpu_count);
> } else {
> while (atomic_read(&patch->cpu_count) <= num_online_cpus())
> @@ -123,7 +123,8 @@ int patch_text(void *addr, u32 insn)
> {
> struct patch_insn patch = {
> .addr = addr,
> - .insn = insn,
> + .insn = &insn,
> + .size = GET_INSN_LENGTH(insn),
> .cpu_count = ATOMIC_INIT(0),
> };
>
> @@ -131,3 +132,17 @@ int patch_text(void *addr, u32 insn)
> &patch, cpu_online_mask);
> }
> NOKPROBE_SYMBOL(patch_text);
> +
> +int patch_text_batch(void *addr, const void *insn, size_t size)
> +{
> + struct patch_insn patch = {
> + .addr = addr,
> + .insn = insn,
> + .size = size,
> + .cpu_count = ATOMIC_INIT(0),
> + };
> +
> + return stop_machine_cpuslocked(patch_text_cb, &patch, cpu_online_mask);
> +}
> +
> +NOKPROBE_SYMBOL(patch_text_batch);
> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c
> index a47f7d2bf3a6..c52d5bdc748c 100644
> --- a/arch/riscv/kernel/probes/opt.c
> +++ b/arch/riscv/kernel/probes/opt.c
> @@ -8,6 +8,7 @@
>
> #define pr_fmt(fmt) "optprobe: " fmt
>
> +#include <linux/types.h>
> #include <linux/kprobes.h>
> #include <asm/kprobes.h>
> #include <asm/patch.h>
> @@ -444,11 +445,19 @@ static bool can_optimize(unsigned long paddr, struct optimized_kprobe *op)
>
> int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
> {
> - return 0;
> + return optinsn->length;
> }
>
> int arch_check_optimized_kprobe(struct optimized_kprobe *op)
> {
> + unsigned long i;
> + struct kprobe *p;
> +
> + for (i = RVC_INSN_LEN; i < op->optinsn.length; i += RVC_INSN_LEN) {
> + p = get_kprobe(op->kp.addr + i);
> + if (p && !kprobe_disabled(p))
> + return -EEXIST;
> + }
> return 0;
> }
>
> @@ -509,23 +518,75 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
>
> void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
> {
> + if (op->optinsn.insn) {
> + free_optinsn_slot(op->optinsn.insn, 1);
> + op->optinsn.insn = NULL;
> + op->optinsn.length = 0;
> + }
> }
>
> void arch_optimize_kprobes(struct list_head *oplist)
> {
> + long offs;
> + kprobe_opcode_t insn[3];
> + struct optimized_kprobe *op, *tmp;
> +
> + list_for_each_entry_safe(op, tmp, oplist, list) {
> + WARN_ON(kprobe_disabled(&op->kp));
> +
> + /* Backup instructions which will be replaced by jump address */
> + memcpy(op->optinsn.copied_insn,
> + DETOUR_ADDR(op->optinsn.insn, DETOUR_INSN_OFFSET),
> + op->optinsn.length);
> +
> + /*
> + * After patching, it should be:
> + * auipc free_register, %hi(detour_buffer)
> + * jalr free_register, free_register, %lo(detour_buffer)
> + * where free_register will eventually save the return address
> + */
> + offs = (unsigned long)op->optinsn.insn -
> + (unsigned long)op->kp.addr;
> + insn[0] = rv_auipc(op->optinsn.rd, (offs + (1 << 11)) >> 12);
> + insn[1] = rv_jalr(op->optinsn.rd, op->optinsn.rd, offs & 0xFFF);
> + /* For 3 RVC + 1 RVI scenario, fill C.NOP for padding */
> + if (op->optinsn.length > 2 * RVI_INSN_LEN)
> + insn[2] = rvc_addi(0, 0);
> +
> + patch_text_batch(op->kp.addr, insn, op->optinsn.length);
> + if (memcmp(op->kp.addr, insn, op->optinsn.length))
> + continue;
> +
> + list_del_init(&op->list);
> + }
> }
>
> void arch_unoptimize_kprobes(struct list_head *oplist,
> struct list_head *done_list)
> {
> + struct optimized_kprobe *op, *tmp;
> +
> + list_for_each_entry_safe(op, tmp, oplist, list) {
> + arch_unoptimize_kprobe(op);
> + list_move(&op->list, done_list);
> + }
> }
>
> void arch_unoptimize_kprobe(struct optimized_kprobe *op)
> {
> + kprobe_opcode_t buf[MAX_COPIED_INSN];
> +
> + memcpy(buf, op->optinsn.copied_insn, op->optinsn.length);
> + if (GET_INSN_LENGTH(op->kp.opcode) == RVI_INSN_LEN)
> + *(u32 *)buf = __BUG_INSN_32;
> + else
> + *(u16 *)buf = __BUG_INSN_16;
> + patch_text_batch(op->kp.addr, buf, op->optinsn.length);
> }
>
> int arch_within_optimized_kprobe(struct optimized_kprobe *op,
> kprobe_opcode_t *addr)
> {
> - return 0;
> + return (op->kp.addr <= addr &&
> + op->kp.addr + op->optinsn.length > addr);
Nit: Use the whole 100 char line width, please.
With or w/o the nits fixed:
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Björn
next prev parent reply other threads:[~2023-02-01 13:32 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 13:05 [PATCH v6 00/13] Add OPTPROBES feature on RISCV Chen Guokai
2023-01-27 13:05 ` [PATCH v6 01/13] riscv/kprobe: Prepare the skeleton to implement RISCV OPTPROBES Chen Guokai
2023-01-27 13:05 ` [PATCH v6 02/13] riscv/kprobe: Allocate detour buffer from module region Chen Guokai
2023-01-27 13:05 ` [PATCH v6 03/13] riscv/kprobe: Add skeleton for preparing optimized kprobe Chen Guokai
2023-01-27 13:05 ` [PATCH v6 04/13] riscv/kprobe: Add common RVI and RVC instruction decoder code Chen Guokai
2023-02-01 13:29 ` Björn Töpel
2023-02-02 10:16 ` Conor Dooley
2023-01-27 13:05 ` [PATCH v6 05/13] riscv/kprobe: Introduce free register(s) searching algorithm Chen Guokai
2023-01-27 13:05 ` [PATCH v6 06/13] riscv/kprobe: Add code to check if kprobe can be optimized Chen Guokai
2023-02-01 13:30 ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 07/13] riscv/kprobe: Prepare detour buffer for optimized kprobe Chen Guokai
2023-02-01 13:30 ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 08/13] riscv/kprobe: Patch AUIPC/JALR pair to optimize kprobe Chen Guokai
2023-02-01 13:31 ` Björn Töpel [this message]
2023-01-27 13:05 ` [PATCH v6 09/13] riscv/kprobe: Search free registers from unused caller-saved ones Chen Guokai
2023-02-01 13:31 ` Björn Töpel
2023-02-02 9:08 ` Conor Dooley
2023-01-27 13:05 ` [PATCH v6 10/13] riscv/kprobe: Add instruction boundary check for RVI/RVC hybrid kernel Chen Guokai
2023-01-27 13:05 ` [PATCH v6 11/13] riscv/kprobe: Fix instruction simulation of JALR Chen Guokai
2023-01-31 12:51 ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 12/13] riscv/kprobe: Move exception related symbols to .kprobe_blacklist Chen Guokai
2023-02-01 13:30 ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 13/13] selftest/kprobes: Add testcase for kprobe SYM[+offs] Chen Guokai
2023-01-30 12:31 ` [PATCH v6 00/13] Add OPTPROBES feature on RISCV Björn Töpel
2023-01-30 14:38 ` Xim
2023-04-26 18:01 ` Palmer Dabbelt
2023-02-01 13:29 ` Björn Töpel
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