Messages in this thread | | | Subject | Re: [PATCH v13 05/10] arm64: Kprobes with single stepping support | From | David Long <> | Date | Mon, 13 Jun 2016 11:22:47 -0400 |
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On 06/13/2016 02:50 AM, Masami Hiramatsu wrote: > On Mon, 13 Jun 2016 00:10:29 -0400 > David Long <dave.long@linaro.org> wrote: > >>>> --- >>>> arch/arm64/Kconfig | 1 + >>>> arch/arm64/include/asm/debug-monitors.h | 5 + >>>> arch/arm64/include/asm/insn.h | 4 +- >>>> arch/arm64/include/asm/kprobes.h | 60 ++++ >>>> arch/arm64/include/asm/probes.h | 44 +++ >>>> arch/arm64/kernel/Makefile | 1 + >>>> arch/arm64/kernel/debug-monitors.c | 18 +- >>>> arch/arm64/kernel/kprobes-arm64.c | 144 +++++++++ >>>> arch/arm64/kernel/kprobes-arm64.h | 35 +++ >>>> arch/arm64/kernel/kprobes.c | 526 ++++++++++++++++++++++++++++++++ >>> >>> Not sure why kprobes.c and kprobes-arm64.c are splitted. >>> >>> >> >> This comes from the model of the arm32 kprobes code where handling of >> the low-level instruction simulation is implemented in separate files >> for 32-bit vs. thumb instructions. It should make a little more sense >> in the future when additional instruction simulation code will hopefully >> be added for those instructions we cannot currently single-step >> out-of-line. It also probably *could* be merged into one file. > > Hmm, at least the name of arch/arm64/kernel/kprobes-arm64.c is > meaningless. As we've done in x86, I think we can make it > arch/arm64/kernel/kprobes/decode-insn.{c,h} >
I've changed the name to kprobe-decode-insn.[hc], or do you feel strongly the three kprobes source files in arch/arm64/kernel need their own subdirectory?
> > [..] >>>> + >>>> +/* Return: >>>> + * INSN_REJECTED If instruction is one not allowed to kprobe, >>>> + * INSN_GOOD If instruction is supported and uses instruction slot, >>>> + * INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot. >>> >>> Is there any chance to return INSN_GOOD_NO_SLOT? >>> >> >> Ah, that gets used later when simulation support is added. I've removed >> this enum value from this commit and will add it to the later one. >> Please no one complain about using an enum instead of a bool, it will >> eventually have three possible values. > > OK :) > > [..] >>>> +enum kprobe_insn __kprobes >>>> +arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi) >>>> +{ >>>> + enum kprobe_insn decoded; >>>> + kprobe_opcode_t insn = le32_to_cpu(*addr); >>>> + kprobe_opcode_t *scan_start = addr - 1; >>>> + kprobe_opcode_t *scan_end = addr - MAX_ATOMIC_CONTEXT_SIZE; >>>> +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) >>>> + struct module *mod; >>>> +#endif >>>> + >>>> + if (addr >= (kprobe_opcode_t *)_text && >>>> + scan_end < (kprobe_opcode_t *)_text) >>>> + scan_end = (kprobe_opcode_t *)_text; >>>> +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) >>>> + else { >>>> + preempt_disable(); >>>> + mod = __module_address((unsigned long)addr); >>>> + if (mod && within_module_init((unsigned long)addr, mod) && >>>> + !within_module_init((unsigned long)scan_end, mod)) >>>> + scan_end = (kprobe_opcode_t *)mod->init_layout.base; >>>> + else if (mod && within_module_core((unsigned long)addr, mod) && >>>> + !within_module_core((unsigned long)scan_end, mod)) >>>> + scan_end = (kprobe_opcode_t *)mod->core_layout.base; >>> >>> What happen if mod == NULL? it should be return error, isn't it? >>> >> >> No, it should be fine. It just means it didn't have to do either of the >> extra checks to limit the end of the search through the code to the >> boundary of one of the corresponding module text sections. It means the >> instruction is in the regular kernel (non-module) text segment. > > Ah, I see. It is OK then. :) > > Thank you, > >
Thanks, -dl
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