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SubjectRe: [PATCH v5] arm64: kprobe: Enable OPTPROBE for arm64
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On 2022/1/3 17:03, Jianhua Liu wrote:
> On Thu, Dec 16, 2021 at 8:26 PM Jianhua Liu <jianhua.ljh@gmail.com> wrote:
>>
>> On Thu, Dec 16, 2021 at 7:18 PM liuqi (BA) <liuqi115@huawei.com> wrote:
>>>
>>>
>>>
>>> On 2021/12/14 23:55, Jianhua Liu wrote:
>>>> On Tue, Dec 14, 2021 at 8:27 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>>>>>
>>>>> On Mon, 13 Dec 2021 18:38:52 +0000
>>>>> Will Deacon <will@kernel.org> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> [+Janet Liu]
>>>>>>
>>>>>> On Tue, Dec 07, 2021 at 08:40:02PM +0800, Qi Liu wrote:
>>>>>>> This patch introduce optprobe for ARM64. In optprobe, probed
>>>>>>> instruction is replaced by a branch instruction to trampoline.
>>>>>>>
>>>>>>> Performance of optprobe on Hip08 platform is test using kprobe
>>>>>>> example module[1] to analyze the latency of a kernel function,
>>>>>>> and here is the result:
>>>>>>>
>>>>>>> common kprobe:
>>>>>>> [280709.846380] do_empty returned 0 and took 1530 ns to execute
>>>>>>> [280709.852057] do_empty returned 0 and took 550 ns to execute
>>>>>>> [280709.857631] do_empty returned 0 and took 440 ns to execute
>>>>>>> [280709.863215] do_empty returned 0 and took 380 ns to execute
>>>>>>> [280709.868787] do_empty returned 0 and took 360 ns to execute
>>>>>>> [280709.874362] do_empty returned 0 and took 340 ns to execute
>>>>>>> [280709.879936] do_empty returned 0 and took 320 ns to execute
>>>>>>> [280709.885505] do_empty returned 0 and took 300 ns to execute
>>>>>>> [280709.891075] do_empty returned 0 and took 280 ns to execute
>>>>>>> [280709.896646] do_empty returned 0 and took 290 ns to execute
>>>>>>>
>>>>>>> optprobe:
>>>>>>> [ 2965.964572] do_empty returned 0 and took 90 ns to execute
>>>>>>> [ 2965.969952] do_empty returned 0 and took 80 ns to execute
>>>>>>> [ 2965.975332] do_empty returned 0 and took 70 ns to execute
>>>>>>> [ 2965.980714] do_empty returned 0 and took 60 ns to execute
>>>>>>> [ 2965.986128] do_empty returned 0 and took 80 ns to execute
>>>>>>> [ 2965.991507] do_empty returned 0 and took 70 ns to execute
>>>>>>> [ 2965.996884] do_empty returned 0 and took 70 ns to execute
>>>>>>> [ 2966.002262] do_empty returned 0 and took 80 ns to execute
>>>>>>> [ 2966.007642] do_empty returned 0 and took 70 ns to execute
>>>>>>> [ 2966.013020] do_empty returned 0 and took 70 ns to execute
>>>>>>> [ 2966.018400] do_empty returned 0 and took 70 ns to execute
>>>>>>>
>>>>>>> As the result shows, optprobe can greatly reduce the latency. Big
>>>>>>> latency of common kprobe will significantly impact the real result
>>>>>>> while doing performance analysis or debugging performance issues
>>>>>>> in lab, so optprobe is useful in this scenario.
>>>>>>>
>>>>>>> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
>>>>>>> Signed-off-by: Qi Liu <liuqi115@huawei.com>
>>>>>>>
>>>>>>> Note:
>>>>>>> As branch instruction in Arm64 has a 128M range limitation, optprobe
>>>>>>> could only used when offset between probe point and trampoline
>>>>>>> is less than 128M, otherwise kernel will choose common kprobe
>>>>>>> automaticly.
>>>>>>>
>>>>>>> Limitation caused by branch isn't unique to Arm64, but also to
>>>>>>> x86/arm/powerpc.
>>>>>>>
>>>>>>> In fact, Module PLT has been tried to get rid of limiation, but
>>>>>>> destination of PLT must be a fixed value, and we need to modify
>>>>>>> the destination (as each optprobe has its own trampoline).
>>>>>>>
>>>>>>> As discussed with Masami[2], we can start with core-kernel point
>>>>>>> (within 128M) as the first step, like other architectures.
>>>>>>>
>>>>>>> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/samples/kprobes/kretprobe_example.c
>>>>>>> [2] https://lore.kernel.org/lkml/20211201105001.5164f98ba783e7207df1229c@kernel.org/
>>>>>>> ---
>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>> arch/arm64/include/asm/kprobes.h | 21 ++
>>>>>>> arch/arm64/kernel/probes/Makefile | 2 +
>>>>>>> arch/arm64/kernel/probes/opt_arm64.c | 199 ++++++++++++++++++
>>>>>>> .../arm64/kernel/probes/optprobe_trampoline.S | 97 +++++++++
>>>>>>> include/linux/kprobes.h | 2 +
>>>>>>> kernel/kprobes.c | 22 ++
>>>>>>> 7 files changed, 344 insertions(+)
>>>>>>> create mode 100644 arch/arm64/kernel/probes/opt_arm64.c
>>>>>>> create mode 100644 arch/arm64/kernel/probes/optprobe_trampoline.S
>>>>>>
>>>>>> I've not looked at these changes in detail, but it looks like there is an
>>>>>> independent patch from Janet Liu trying to do the same thing:
>>>>>>
>>>>>> https://lore.kernel.org/r/1635858706-27320-1-git-send-email-jianhua.ljh@gmail.com
>>>>>>
>>>>>
>>>>> Thanks for noticing. I missed it.
>>>>>
>>>>>> The patch here from Qi Liu looks like it's a bit further along, but it
>>>>>> would be good for Janet to at least test it out and confirm that it works
>>>>>> for them.
>>>>>
>>>>> Yeah, it's now v5.
>>>>> But it seems Janet's one also has good points. I would like Janet's sharing
>>>>> save_all_base_regs macro and the comment about the branch instruction.
>>>>>
>>>>>>
>>>>>> Cheers,
>>>>>>
>>>>>> Will
>>>>>>
>>>>>> [Kept diff inline for Janet]
>>>>>
>>>>> Janet, please feel free to review and test it. It is important that you confirm
>>>>> this can work with your envionment too.
>>>>> I will review your KPROBE_ON_FTRACE patch.
>>>>>
>>>> I have tested these patch on UNISOC s9863a platform before sending.
>>>>
>>>> The test case from:
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/samples/kprobes/
>>>>
>>>> And I do the following change for kprobe_example.c before testing:
>>>> 1. delete function handler_post,
>>>> kprobe_init does "kp.post_handler = handler_post; --->
>>>> p.post_handler = NULL;"
>>>> 2. handler_pre calls dump_stack.
>>>>
>>>
>>> Hi Jianhua,
>>>
>>> Could you kindly review this patch and test it on your UNISOC s9863a
>>> platform? Let's work together to make arm64 optprobe work : )
>>>
>>> Thanks,
>>> Qi
>>
>> OK, I will review. I have left UNISOC, I get some help from old
>> colleage to do the test.
>> Only on weekend, he can do it. So the time will be longer a little.
>>
>> Thanks
>> Jianhua
>>
>>
> Hi Qi,
> I have tested your patch on UNISOC s9863a.
> Test case "kprobe_example & kretprobe_example" is OK.
>
Hi Jianhua,

Thanks for your test.

> Two point:
> 1. backtrace is not perfect.
> optprobe_common does not saved frame pointer,
> backtrace lacks two calls.
Got it, I'll check optprobe_common to see the lost frame pointer, thanks.
> such as for dup_mm: lack copy_process-->dup_mm
> dup_mm backtrace from your patch:
> [ 832.387066] CPU: 0 PID: 296 Comm: sh Not tainted 5.16.0-rc5+ #8
> [ 832.387078] Hardware name: Spreadtrum SP9863A-1H10 Board (DT)
> [ 832.387083] Call trace:
> [ 832.387086] dump_backtrace+0x0/0x1e0
> [ 832.387103] show_stack+0x24/0x30
> [ 832.387112] dump_stack_lvl+0x68/0x84
> [ 832.387123] dump_stack+0x18/0x34
> [ 832.387131] handler_pre+0x40/0x50 [kprobe_example]
> [ 832.387143] opt_pre_handler+0x84/0xc0
> [ 832.387154] optprobe_optimized_callback+0xec/0x164
> [ 832.387164] optprobe_common+0x70/0xc4
> [ 832.387173] kernel_clone+0x98/0x440
> [ 832.387182] __do_sys_clone+0x54/0x80
> [ 832.387191] __arm64_sys_clone+0x2c/0x40
> [ 832.387199] invoke_syscall+0x50/0x120
> [ 832.387208] el0_svc_common.constprop.0+0x4c/0xf4
> [ 832.387217] do_el0_svc+0x30/0x9c
> [ 832.387225] el0_svc+0x20/0x60
> [ 832.387235] el0t_64_sync_handler+0xe8/0xf0
> [ 832.387242] el0t_64_sync+0x1a0/0x1a4
>
>
> dup_mm backtrace from other:
> [ 173.352294] CPU: 6 PID: 309 Comm: sh Not tainted 5.16.0-rc5+ #19
> [ 173.352301] Hardware name: Spreadtrum SP9863A-1H10 Board (DT)
> [ 173.352304] Call trace:
> [ 173.352307] dump_backtrace+0x0/0x1d4
> [ 173.352319] show_stack+0x18/0x24
> [ 173.352326] dump_stack_lvl+0x68/0x84
> [ 173.352333] dump_stack+0x18/0x34
> [ 173.352338] handler_pre+0x38/0x48 [kprobe_example]
> [ 173.352347] opt_pre_handler+0x74/0xb0
> [ 173.352354] optimized_callback+0x108/0x130
> [ 173.352361] optinsn_slot+0x258/0x1000
> [ 173.352366] dup_mm+0x4/0x4b0
> [ 173.352373] copy_process+0x1284/0x1360
> [ 173.352378] kernel_clone+0x5c/0x3c0
> [ 173.352384] __do_sys_clone+0x54/0x80
> [ 173.352390] __arm64_sys_clone+0x24/0x30
> [ 173.352396] invoke_syscall+0x48/0x114
> [ 173.352402] el0_svc_common.constprop.0+0x44/0xec
> [ 173.352408] do_el0_svc+0x24/0x90
> [ 173.352413] el0_svc+0x20/0x60
> [ 173.352420] el0t_64_sync_handler+0xe8/0xf0
> [ 173.352427] el0t_64_sync+0x1a0/0x1a4
>
> 2. The reserve memory "OPT_SLOT_SIZE - PAGE_SIZE" is waste.
> kernel/kprobe.c used only one PAGE_SIZE slot memory.
>
Got it, will fix this. By the way, could I add your test-by tag in next
version?

Thanks,
Qi
> Thanks
> Jianhua
>
>>> Thanks for the review.
>>>>
>>>>> Thank you,
>>>>>
>>>>>>
>>>>>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>>>>>>> index c4207cf9bb17..6b68ec498e67 100644
>>>>>>> --- a/arch/arm64/Kconfig
>>>>>>> +++ b/arch/arm64/Kconfig
>>>>>>> @@ -200,6 +200,7 @@ config ARM64
>>>>>>> select HAVE_STACKPROTECTOR
>>>>>>> select HAVE_SYSCALL_TRACEPOINTS
>>>>>>> select HAVE_KPROBES
>>>>>>> + select HAVE_OPTPROBES
>>>>>>> select HAVE_KRETPROBES
>>>>>>> select HAVE_GENERIC_VDSO
>>>>>>> select IOMMU_DMA if IOMMU_SUPPORT
>>>>>>> diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h
>>>>>>> index 05cd82eeca13..3838e4317877 100644
>>>>>>> --- a/arch/arm64/include/asm/kprobes.h
>>>>>>> +++ b/arch/arm64/include/asm/kprobes.h
>>>>>>> @@ -39,6 +39,27 @@ void arch_remove_kprobe(struct kprobe *);
>>>>>>> int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
>>>>>>> int kprobe_exceptions_notify(struct notifier_block *self,
>>>>>>> unsigned long val, void *data);
>>>>>>> +
>>>>>>> +struct arch_optimized_insn {
>>>>>>> + kprobe_opcode_t orig_insn[1];
>>>>>>> + kprobe_opcode_t *trampoline;
>>>>>>> +};
>>>>>>> +
>>>>>>> +#define MAX_OPTIMIZED_LENGTH sizeof(kprobe_opcode_t)
>>>>>>> +#define MAX_OPTINSN_SIZE \
>>>>>>> + ((unsigned long)optprobe_template_restore_end - (unsigned long)optprobe_template_entry)
>>>>>>> +
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_entry[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_val[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_common[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_end[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_restore_begin[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_restore_orig_insn[];
>>>>>>> +extern __visible kprobe_opcode_t optprobe_template_restore_end[];
>>>>>>> +extern __visible kprobe_opcode_t optinsn_slot[];
>>>>>>> +
>>>>>>> +void optprobe_common(void);
>>>>>>> +
>>>>>>> void __kretprobe_trampoline(void);
>>>>>>> void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
>>>>>>>
>>>>>>> diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile
>>>>>>> index 8e4be92e25b1..07105fd3261d 100644
>>>>>>> --- a/arch/arm64/kernel/probes/Makefile
>>>>>>> +++ b/arch/arm64/kernel/probes/Makefile
>>>>>>> @@ -4,3 +4,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \
>>>>>>> simulate-insn.o
>>>>>>> obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \
>>>>>>> simulate-insn.o
>>>>>>> +obj-$(CONFIG_OPTPROBES) += opt_arm64.o \
>>>>>>> + optprobe_trampoline.o
>>>>>>> diff --git a/arch/arm64/kernel/probes/opt_arm64.c b/arch/arm64/kernel/probes/opt_arm64.c
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..1bad5cddcdf2
>>>>>>> --- /dev/null
>>>>>>> +++ b/arch/arm64/kernel/probes/opt_arm64.c
>>>>>>> @@ -0,0 +1,199 @@
>>>>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>>>>> +/*
>>>>>>> + * Code for Kernel probes Jump optimization.
>>>>>>> + *
>>>>>>> + * Copyright (C) 2021 Hisilicon Limited
>>>>>>> + */
>>>>>>> +
>>>>>>> +#include <linux/jump_label.h>
>>>>>>> +#include <linux/kprobes.h>
>>>>>>> +
>>>>>>> +#include <asm/cacheflush.h>
>>>>>>> +#include <asm/compiler.h>
>>>>>>> +#include <asm/insn.h>
>>>>>>> +#include <asm/kprobes.h>
>>>>>>> +#include <asm/patching.h>
>>>>>>> +
>>>>>>> +#define OPTPROBE_BATCH_SIZE 64
>>>>>>> +#define GET_LO_VAL(val) FIELD_GET(GENMASK(31, 0), val)
>>>>>>> +#define GET_HI_VAL(val) FIELD_GET(GENMASK(63, 32), val)
>>>>>>> +
>>>>>>> +#define TMPL_VAL_IDX \
>>>>>>> + (optprobe_template_val - optprobe_template_entry)
>>>>>>> +#define TMPL_CALL_COMMON \
>>>>>>> + (optprobe_template_common - optprobe_template_entry)
>>>>>>> +#define TMPL_RESTORE_ORIGN_INSN \
>>>>>>> + (optprobe_template_restore_orig_insn - optprobe_template_entry)
>>>>>>> +#define TMPL_RESTORE_END \
>>>>>>> + (optprobe_template_restore_end - optprobe_template_entry)
>>>>>>> +#define TMPL_END_IDX \
>>>>>>> + (optprobe_template_end - optprobe_template_entry)
>>>>>>> +
>>>>>>> +static bool insn_page_in_use;
>>>>>>> +
>>>>>>> +void *alloc_optinsn_page(void)
>>>>>>> +{
>>>>>>> + if (insn_page_in_use)
>>>>>>> + return NULL;
>>>>>>> + insn_page_in_use = true;
>>>>>>> + return &optinsn_slot;
>>>>>>> +}
>>>>>>> +
>>>>>>> +void free_optinsn_page(void *page)
>>>>>>> +{
>>>>>>> + insn_page_in_use = false;
>>>>>>> +}
>>>>>>> +
>>>>>>> +int arch_check_optimized_kprobe(struct optimized_kprobe *op)
>>>>>>> +{
>>>>>>> + return 0;
>>>>>>> +}
>>>>>>> +
>>>>>>> +int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
>>>>>>> +{
>>>>>>> + return optinsn->trampoline != NULL;
>>>>>>> +}
>>>>>>> +
>>>>>>> +int arch_within_optimized_kprobe(struct optimized_kprobe *op, kprobe_opcode_t *addr)
>>>>>>> +{
>>>>>>> + return op->kp.addr == addr;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static void optprobe_set_pc_value(struct optimized_kprobe *op, struct pt_regs *regs)
>>>>>>> +{
>>>>>>> + regs->pc = (unsigned long)op->kp.addr;
>>>>>>> +}
>>>>>>> +
>>>>>>> +static int optprobe_check_branch_limit(unsigned long pc, unsigned long addr)
>>>>>>> +{
>>>>>>> + long offset;
>>>>>>> +
>>>>>>> + if ((pc & 0x3) || (addr & 0x3))
>>>>>>> + return -ERANGE;
>>>>>>> +
>>>>>>> + offset = (long)addr - (long)pc;
>>>>>>> + if (offset < -SZ_128M || offset >= SZ_128M)
>>>>>>> + return -ERANGE;
>>>>>>> +
>>>>>>> + return 0;
>>>>>>> +}
>>>>>>> +
>>>>>>> +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig)
>>>>>>> +{
>>>>>>> + kprobe_opcode_t *code, *buf;
>>>>>>> + u32 insn;
>>>>>>> + int ret = -ENOMEM;
>>>>>>> + int i;
>>>>>>> +
>>>>>>> + buf = kcalloc(MAX_OPTINSN_SIZE, sizeof(kprobe_opcode_t), GFP_KERNEL);
>>>>>>> + if (!buf)
>>>>>>> + return ret;
>>>>>>> +
>>>>>>> + code = get_optinsn_slot();
>>>>>>> + if (!code)
>>>>>>> + goto out;
>>>>>>> +
>>>>>>> + if (optprobe_check_branch_limit((unsigned long)code, (unsigned long)orig->addr + 8)) {
>>>>>>> + ret = -ERANGE;
>>>>>>> + goto error;
>>>>>>> + }
>>>>>>> +
>>>>>>> + op->set_pc = optprobe_set_pc_value;
>>>>>>> + memcpy(buf, optprobe_template_entry, MAX_OPTINSN_SIZE * sizeof(kprobe_opcode_t));
>>>>>>> +
>>>>>>> + insn = aarch64_insn_gen_branch_imm((unsigned long)&code[TMPL_CALL_COMMON],
>>>>>>> + (unsigned long)&optprobe_common,
>>>>>>> + AARCH64_INSN_BRANCH_LINK);
>>>>>>> + buf[TMPL_CALL_COMMON] = insn;
>>>>>>> +
>>>>>>> + insn = aarch64_insn_gen_branch_imm((unsigned long)&code[TMPL_RESTORE_END],
>>>>>>> + (unsigned long)op->kp.addr + 4,
>>>>>>> + AARCH64_INSN_BRANCH_NOLINK);
>>>>>>> + buf[TMPL_RESTORE_END] = insn;
>>>>>>> +
>>>>>>> + buf[TMPL_VAL_IDX] = cpu_to_le32(GET_LO_VAL((unsigned long)op));
>>>>>>> + buf[TMPL_VAL_IDX + 1] = cpu_to_le32(GET_HI_VAL((unsigned long)op));
>>>>>>> + buf[TMPL_RESTORE_ORIGN_INSN] = orig->opcode;
>>>>>>> +
>>>>>>> + /* Setup template */
>>>>>>> + for (i = 0; i < MAX_OPTINSN_SIZE; i++)
>>>>>>> + aarch64_insn_patch_text_nosync(code + i, buf[i]);
>>>>>>> +
>>>>>>> + flush_icache_range((unsigned long)code, (unsigned long)(&code[TMPL_VAL_IDX]));
>>>>>>> + /* Set op->optinsn.trampoline means prepared. */
>>>>>>> + op->optinsn.trampoline = code;
>>>>>>> +
>>>>>>> +out:
>>>>>>> + kfree(buf);
>>>>>>> + return ret;
>>>>>>> +
>>>>>>> +error:
>>>>>>> + free_optinsn_slot(code, 0);
>>>>>>> + goto out;
>>>>>>> +}
>>>>>>> +
>>>>>>> +void arch_optimize_kprobes(struct list_head *oplist)
>>>>>>> +{
>>>>>>> + struct optimized_kprobe *op, *tmp;
>>>>>>> + kprobe_opcode_t insns[OPTPROBE_BATCH_SIZE];
>>>>>>> + void *addrs[OPTPROBE_BATCH_SIZE];
>>>>>>> + int i = 0;
>>>>>>> +
>>>>>>> + 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.orig_insn, op->kp.addr, AARCH64_INSN_SIZE);
>>>>>>> +
>>>>>>> + addrs[i] = (void *)op->kp.addr;
>>>>>>> + insns[i] = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr,
>>>>>>> + (unsigned long)op->optinsn.trampoline,
>>>>>>> + AARCH64_INSN_BRANCH_NOLINK);
>>>>>>> +
>>>>>>> + list_del_init(&op->list);
>>>>>>> + if (++i == OPTPROBE_BATCH_SIZE)
>>>>>>> + break;
>>>>>>> + }
>>>>>>> +
>>>>>>> + aarch64_insn_patch_text(addrs, insns, i);
>>>>>>> +}
>>>>>>> +
>>>>>>> +void arch_unoptimize_kprobe(struct optimized_kprobe *op)
>>>>>>> +{
>>>>>>> + arch_arm_kprobe(&op->kp);
>>>>>>> +}
>>>>>>> +
>>>>>>> +/*
>>>>>>> + * Recover original instructions and breakpoints from relative jumps.
>>>>>>> + * Caller must call with locking kprobe_mutex.
>>>>>>> + */
>>>>>>> +void arch_unoptimize_kprobes(struct list_head *oplist,
>>>>>>> + struct list_head *done_list)
>>>>>>> +{
>>>>>>> + struct optimized_kprobe *op, *tmp;
>>>>>>> + kprobe_opcode_t insns[OPTPROBE_BATCH_SIZE];
>>>>>>> + void *addrs[OPTPROBE_BATCH_SIZE];
>>>>>>> + int i = 0;
>>>>>>> +
>>>>>>> + list_for_each_entry_safe(op, tmp, oplist, list) {
>>>>>>> + addrs[i] = (void *)op->kp.addr;
>>>>>>> + insns[i] = BRK64_OPCODE_KPROBES;
>>>>>>> + list_move(&op->list, done_list);
>>>>>>> +
>>>>>>> + if (++i == OPTPROBE_BATCH_SIZE)
>>>>>>> + break;
>>>>>>> + }
>>>>>>> +
>>>>>>> + aarch64_insn_patch_text(addrs, insns, i);
>>>>>>> +}
>>>>>>> +
>>>>>>> +void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
>>>>>>> +{
>>>>>>> + if (op->optinsn.trampoline) {
>>>>>>> + free_optinsn_slot(op->optinsn.trampoline, 1);
>>>>>>> + op->optinsn.trampoline = NULL;
>>>>>>> + }
>>>>>>> +}
>>>>>>> diff --git a/arch/arm64/kernel/probes/optprobe_trampoline.S b/arch/arm64/kernel/probes/optprobe_trampoline.S
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..1376daeae844
>>>>>>> --- /dev/null
>>>>>>> +++ b/arch/arm64/kernel/probes/optprobe_trampoline.S
>>>>>>> @@ -0,0 +1,97 @@
>>>>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>>>>> +/*
>>>>>>> + * trampoline entry and return code for optprobes.
>>>>>>> + */
>>>>>>> +
>>>>>>> +#include <linux/linkage.h>
>>>>>>> +#include <asm/asm-offsets.h>
>>>>>>> +#include <asm/assembler.h>
>>>>>>> +
>>>>>>> +#define OPT_SLOT_SIZE 65536
>>>>>>> +
>>>>>>> + .global optinsn_slot
>>>>>>> +optinsn_slot:
>>>>>>> + .space OPT_SLOT_SIZE
>>>>>>> +
>>>>>>> +SYM_CODE_START(optprobe_common)
>>>>>>> + stp x2, x3, [sp, #S_X2]
>>>>>>> + stp x4, x5, [sp, #S_X4]
>>>>>>> + stp x6, x7, [sp, #S_X6]
>>>>>>> + stp x8, x9, [sp, #S_X8]
>>>>>>> + stp x10, x11, [sp, #S_X10]
>>>>>>> + stp x12, x13, [sp, #S_X12]
>>>>>>> + stp x14, x15, [sp, #S_X14]
>>>>>>> + stp x16, x17, [sp, #S_X16]
>>>>>>> + stp x18, x19, [sp, #S_X18]
>>>>>>> + stp x20, x21, [sp, #S_X20]
>>>>>>> + stp x22, x23, [sp, #S_X22]
>>>>>>> + stp x24, x25, [sp, #S_X24]
>>>>>>> + stp x26, x27, [sp, #S_X26]
>>>>>>> + stp x28, x29, [sp, #S_X28]
>>>>>>> + add x2, sp, #PT_REGS_SIZE
>>>>>>> + str x2, [sp, #S_SP]
>>>>>>> + /* Construct a useful saved PSTATE */
>>>>>>> + mrs x2, nzcv
>>>>>>> + mrs x3, daif
>>>>>>> + orr x2, x2, x3
>>>>>>> + mrs x3, CurrentEL
>>>>>>> + orr x2, x2, x3
>>>>>>> + mrs x3, SPSel
>>>>>>> + orr x2, x2, x3
>>>>>>> + stp xzr, x2, [sp, #S_PC]
>>>>>>> +
>>>>>>> + /* set the pt_regs address to x1 */
>>>>>>> + mov x1, sp
>>>>>>> + /* store lr of optprobe_common temporary */
>>>>>>> + sub sp, sp, #0x10
>>>>>>> + str lr, [sp, #0x8]
>>>>>>> +
>>>>>>> + bl optprobe_optimized_callback
>>>>>>> +
>>>>>>> + ldr lr, [sp, #0x8]
>>>>>>> + add sp, sp, #0x10
>>>>>>> + ldr x0, [sp, #S_PSTATE]
>>>>>>> + and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
>>>>>>> + msr nzcv, x0
>>>>>>> + ldp x0, x1, [sp, #S_X0]
>>>>>>> + ldp x2, x3, [sp, #S_X2]
>>>>>>> + ldp x4, x5, [sp, #S_X4]
>>>>>>> + ldp x6, x7, [sp, #S_X6]
>>>>>>> + ldp x8, x9, [sp, #S_X8]
>>>>>>> + ldp x10, x11, [sp, #S_X10]
>>>>>>> + ldp x12, x13, [sp, #S_X12]
>>>>>>> + ldp x14, x15, [sp, #S_X14]
>>>>>>> + ldp x16, x17, [sp, #S_X16]
>>>>>>> + ldp x18, x19, [sp, #S_X18]
>>>>>>> + ldp x20, x21, [sp, #S_X20]
>>>>>>> + ldp x22, x23, [sp, #S_X22]
>>>>>>> + ldp x24, x25, [sp, #S_X24]
>>>>>>> + ldp x26, x27, [sp, #S_X26]
>>>>>>> + ldp x28, x29, [sp, #S_X28]
>>>>>>> + ret
>>>>>>> +SYM_CODE_END(optprobe_common)
>>>>>>> +
>>>>>>> + .global optprobe_template_entry
>>>>>>> +optprobe_template_entry:
>>>>>>> + sub sp, sp, #PT_REGS_SIZE
>>>>>>> + str lr, [sp, #S_LR]
>>>>>>> + stp x0, x1, [sp, #S_X0]
>>>>>>> + /* Get parameters to optimized_callback() */
>>>>>>> + ldr x0, 1f
>>>>>>> + .global optprobe_template_common
>>>>>>> +optprobe_template_common:
>>>>>>> + nop
>>>>>>> + ldr lr, [sp, #S_LR]
>>>>>>> + add sp, sp, #PT_REGS_SIZE
>>>>>>> + .global optprobe_template_restore_orig_insn
>>>>>>> +optprobe_template_restore_orig_insn:
>>>>>>> + nop
>>>>>>> + .global optprobe_template_restore_end
>>>>>>> +optprobe_template_restore_end:
>>>>>>> + nop
>>>>>>> + .global optprobe_template_val
>>>>>>> +optprobe_template_val:
>>>>>>> + 1: .long 0
>>>>>>> + .long 0
>>>>>>> + .global optprobe_template_end
>>>>>>> +optprobe_template_end:
>>>>>>> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
>>>>>>> index 8c8f7a4d93af..7be680155df7 100644
>>>>>>> --- a/include/linux/kprobes.h
>>>>>>> +++ b/include/linux/kprobes.h
>>>>>>> @@ -329,6 +329,7 @@ struct optimized_kprobe {
>>>>>>> struct kprobe kp;
>>>>>>> struct list_head list; /* list for optimizing queue */
>>>>>>> struct arch_optimized_insn optinsn;
>>>>>>> + void (*set_pc)(struct optimized_kprobe *op, struct pt_regs *regs);
>>>>>>> };
>>>>>>>
>>>>>>> /* Architecture dependent functions for direct jump optimization */
>>>>>>> @@ -345,6 +346,7 @@ extern int arch_within_optimized_kprobe(struct optimized_kprobe *op,
>>>>>>> kprobe_opcode_t *addr);
>>>>>>>
>>>>>>> extern void opt_pre_handler(struct kprobe *p, struct pt_regs *regs);
>>>>>>> +extern void optprobe_optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs);
>>>>>>>
>>>>>>> DEFINE_INSN_CACHE_OPS(optinsn);
>>>>>>>
>>>>>>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>>>>>>> index 21eccc961bba..d799e562a39a 100644
>>>>>>> --- a/kernel/kprobes.c
>>>>>>> +++ b/kernel/kprobes.c
>>>>>>> @@ -430,6 +430,28 @@ void opt_pre_handler(struct kprobe *p, struct pt_regs *regs)
>>>>>>> }
>>>>>>> NOKPROBE_SYMBOL(opt_pre_handler);
>>>>>>>
>>>>>>> +void optprobe_optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
>>>>>>> +{
>>>>>>> + if (kprobe_disabled(&op->kp))
>>>>>>> + return;
>>>>>>> +
>>>>>>> + preempt_disable();
>>>>>>> +
>>>>>>> + if (kprobe_running()) {
>>>>>>> + kprobes_inc_nmissed_count(&op->kp);
>>>>>>> + } else {
>>>>>>> + op->set_pc(op, regs);
>>>>>>> + __this_cpu_write(current_kprobe, &op->kp);
>>>>>>> + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
>>>>>>> + opt_pre_handler(&op->kp, regs);
>>>>>>> + __this_cpu_write(current_kprobe, NULL);
>>>>>>> + }
>>>>>>> +
>>>>>>> + preempt_enable();
>>>>>>> +}
>>>>>>> +NOKPROBE_SYMBOL(optprobe_optimized_callback)
>>>>>>> +
>>>>>>> +
>>>>>>> /* Free optimized instructions and optimized_kprobe */
>>>>>>> static void free_aggr_kprobe(struct kprobe *p)
>>>>>>> {
>>>>>>> --
>>>>>>> 2.33.0
>>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Masami Hiramatsu <mhiramat@kernel.org>
>>>> .
>>>>
> .
>

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