Messages in this thread | | | Date | Thu, 3 Nov 2022 09:23:47 +0800 | Subject | Re: [PATCH 1/8] riscv/kprobe: Prepare the skeleton to implement RISCV OPTPROBES feature | From | "liaochang (A)" <> |
| |
在 2022/11/2 7:30, Conor Dooley 写道: > On Tue, Nov 01, 2022 at 07:07:44PM +0800, liaochang (A) wrote: >> Hi,Conor, >> >> 在 2022/11/1 3:42, Conor Dooley 写道: >>> Hey Chen Guokai, >>> >>> On Sun, Oct 30, 2022 at 05:01:34PM +0800, Chen Guokai wrote: >>>> From: Liao Chang <liaochang1@huawei.com> >>>> >>>> Prepare skeleton to implement optimized kprobe on RISCV, it consists >>>> of Makfile, Kconfig and some architecture specific files: kprobe.h and >>>> opt.c opt.c includes some macro, type definition and functions required >>>> by kprobe framework, opt_trampoline.S provides a piece of assembly code >>>> template used to construct the detour buffer as the target of long jump >>>> instruction(s) for each optimzed kprobe. >>>> >>>> Since the jump range of PC-relative instruction JAL is +/-1M, that is >>>> too small to reach the detour buffer, hence the foudamental idea to >>>> address OPTPROBES on RISCV is to replace 'EBREAK' with 'AUIPC+JALR'. which >>>> means it needs to clobber one more instruction beside the kprobe >>>> instruction, furthermore, RISCV supports hybird RVI and RVC in single >>>> kernel binary, so in theory a pair of 'AUIPC/JALR' is about to clobber >>>> 10 bytes(3 RVC and 1 RVI, 2 bytes is padding for alignment) at worst >>>> case. The second hardsome problem is looking for one integer register as >>>> the destination of 'AUIPC/JALR' without any side-effect. >>>> >>>> More solution details will be introduced in the coming commits. >>> >>> nit: you can drop this reference to future commits. >>> >>>> >>>> Co-developed-by: Chen Guokai <chenguokai17@mails.ucas.ac.cn> >>>> Signed-off-by: Chen Guokai <chenguokai17@mails.ucas.ac.cn> >>>> Signed-off-by: Liao Chang <liaochang1@huawei.com> >>> >>> FYI, your signoff should come last since you're sending the patches, so >>> this would become: >>> >>>> Signed-off-by: Liao Chang <liaochang1@huawei.com> >>>> Co-developed-by: Chen Guokai <chenguokai17@mails.ucas.ac.cn> >>>> Signed-off-by: Chen Guokai <chenguokai17@mails.ucas.ac.cn> >>> >>> I noticed on some of the other patches that your SoB is missing there, >>> for example patch 2. >> >> Yes, i have sent patch 2 to mailing list long time ago, got some feedback from >> Palmer Debbelt. Because that patch is designed for riscv optprobe, so i bring it >> to this patchset. > > Not sure if you understood the point I was making - you need to have a > Signed-off-by: Chen Guokai <chenguokai17@mails.ucas.ac.cn> > at the end of every patch that Chen sends. Patch 2 does not have one. > For the other patches, the order should be you, followed by Chen since > they are the one that sent the patch to the list this time. > > See: > https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by > Or: > Documentation/translations/zh_CN/process/submitting-patches.rst > > In the zh_CN document, the relevant section is: > 何时使用Acked-by:,CC:,和Co-Developed by:
Thanks for your explanation, it is very clear and helpful, i will make SoB correct.
Thanks. > > Hope that helps, > Conor. > >>>> --- >>>> arch/riscv/Kconfig | 1 + >>>> arch/riscv/include/asm/kprobes.h | 32 ++++++++++++++ >>>> arch/riscv/kernel/probes/Makefile | 1 + >>>> arch/riscv/kernel/probes/opt.c | 51 +++++++++++++++++++++++ >>>> arch/riscv/kernel/probes/opt_trampoline.S | 12 ++++++ >>>> 5 files changed, 97 insertions(+) >>>> create mode 100644 arch/riscv/kernel/probes/opt.c >>>> create mode 100644 arch/riscv/kernel/probes/opt_trampoline.S >>>> >>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >>>> index 6b48a3ae9843..ca29306c93e2 100644 >>>> --- a/arch/riscv/Kconfig >>>> +++ b/arch/riscv/Kconfig >>>> @@ -99,6 +99,7 @@ config RISCV >>>> select HAVE_KPROBES if !XIP_KERNEL >>>> select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL >>>> select HAVE_KRETPROBES if !XIP_KERNEL >>>> + select HAVE_OPTPROBES if !XIP_KERNEL >>>> select HAVE_MOVE_PMD >>>> select HAVE_MOVE_PUD >>>> select HAVE_PCI >>>> diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h >>>> index 217ef89f22b9..22b73a2fd1fd 100644 >>>> --- a/arch/riscv/include/asm/kprobes.h >>>> +++ b/arch/riscv/include/asm/kprobes.h >>>> @@ -43,5 +43,37 @@ bool kprobe_single_step_handler(struct pt_regs *regs); >>>> void __kretprobe_trampoline(void); >>>> void __kprobes *trampoline_probe_handler(struct pt_regs *regs); >>>> >>>> +#ifdef CONFIG_OPTPROBES >>>> + >>>> +/* optinsn template addresses */ >>>> +extern __visible kprobe_opcode_t optprobe_template_entry[]; >>>> +extern __visible kprobe_opcode_t optprobe_template_end[]; >>>> + >>>> +#define MAX_OPTINSN_SIZE \ >>>> + ((unsigned long)optprobe_template_end - \ >>>> + (unsigned long)optprobe_template_entry) >>>> + >>>> +/* >>>> + * For RVI and RVC hybird encoding kernel, althought long jump just needs >>>> + * 2 RVI instructions(AUIPC+JALR), optimized instructions is 10 bytes long >>>> + * at most to ensure no RVI would be truncated actually, so it means four >>>> + * combinations: >>>> + * - 2 RVI >>>> + * - 4 RVC >>>> + * - 2 RVC + 1 RVI >>>> + * - 3 RVC + 1 RVI (truncated, need padding) >>>> + */ >>>> +#define MAX_COPIED_INSN 4 >>>> +#define MAX_OPTIMIZED_LENGTH 10 >>>> + >>>> +struct arch_optimized_insn { >>>> + kprobe_opcode_t copied_insn[MAX_COPIED_INSN]; >>>> + /* detour code buffer */ >>>> + kprobe_opcode_t *insn; >>>> + unsigned long length; >>>> + int rd; >>>> +}; >>>> + >>>> +#endif /* CONFIG_OPTPROBES */ >>>> #endif /* CONFIG_KPROBES */ >>>> #endif /* _ASM_RISCV_KPROBES_H */ >>>> diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile >>>> index 7f0840dcc31b..6255b4600875 100644 >>>> --- a/arch/riscv/kernel/probes/Makefile >>>> +++ b/arch/riscv/kernel/probes/Makefile >>>> @@ -3,4 +3,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o >>>> obj-$(CONFIG_KPROBES) += kprobes_trampoline.o >>>> obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o >>>> obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o simulate-insn.o >>>> +obj-$(CONFIG_OPTPROBES) += opt.o opt_trampoline.o >>>> CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE) >>>> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c >>>> new file mode 100644 >>>> index 000000000000..56c8a227c857 >>>> --- /dev/null >>>> +++ b/arch/riscv/kernel/probes/opt.c >>>> @@ -0,0 +1,51 @@ >>>> +// SPDX-License-Identifier: GPL-2.0-or-later >>>> +/* >>>> + * Kernel Probes Jump Optimization (Optprobes) >>>> + * >>>> + * Copyright (C) Guokai Chen, 2022 >>>> + * Author: Guokai Chen chenguokai17@mails.ucas.ac.cn >>>> + */ >>>> + >>>> +#define pr_fmt(fmt) "optprobe: " fmt >>>> + >>>> +#include <linux/kprobes.h> >>>> +#include <asm/kprobes.h> >>>> + >>>> +int arch_prepared_optinsn(struct arch_optimized_insn *optinsn) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +int arch_check_optimized_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, >>>> + struct kprobe *orig) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +void arch_remove_optimized_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> +} >>>> + >>>> +void arch_optimize_kprobes(struct list_head *oplist) >>>> +{ >>>> +} >>>> + >>>> +void arch_unoptimize_kprobes(struct list_head *oplist, >>>> + struct list_head *done_list) >>>> +{ >>>> +} >>>> + >>>> +void arch_unoptimize_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> +} >>>> + >>>> +int arch_within_optimized_kprobe(struct optimized_kprobe *op, >>>> + kprobe_opcode_t *addr) >>>> +{ >>>> + return 0; >>>> +} >>>> diff --git a/arch/riscv/kernel/probes/opt_trampoline.S b/arch/riscv/kernel/probes/opt_trampoline.S >>>> new file mode 100644 >>>> index 000000000000..16160c4367ff >>>> --- /dev/null >>>> +++ b/arch/riscv/kernel/probes/opt_trampoline.S >>>> @@ -0,0 +1,12 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>>> +/* >>>> + * Copyright (C) 2022 Guokai Chen >>>> + */ >>>> + >>>> +#include <linux/linkage.h> >>>> + >>>> +#incldue <asm/csr.h> >>>> +#include <asm/asm-offsets.h> >>>> + >>>> +SYM_ENTRY(optprobe_template_entry, SYM_L_GLOBAL, SYM_A_NONE) >>>> +SYM_ENTRY(optprobe_template_end, SYM_L_GLOBAL, SYM_A_NONE) >>>> -- >>>> 2.25.1 >>>> >>>> >>>> _______________________________________________ >>>> linux-riscv mailing list >>>> linux-riscv@lists.infradead.org >>>> http://lists.infradead.org/mailman/listinfo/linux-riscv >>> . >> >> -- >> BR, >> Liao, Chang > .
-- BR, Liao, Chang
| |