Re: [-mm][PATCH 0/6] (yet another) kprobes x86 code unification andboosters

From: Masami Hiramatsu
Date: Mon Dec 17 2007 - 14:25:36 EST


Hi,

Ingo Molnar wrote:
> * Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
>
>> Hello all,
>>
>> I developed a series of patches which unifies kprobes code on x86 and
>> introduces boosters on x86-64. These patches can be applied to
>> 2.6.24-rc4-mm1.
>>
>> The purpose of this patchset is unifying kprobes_[32|64].[c|h] to
>> kprobes.[c|h] for simplifying code maintenance.
>>
>> I know these patches are conflicting with Harvey's patch. We need to
>> solve that.
>
> your series fixes the 64-bit crash that i was seeing, so i've picked it
> up. Please work it out with Harvey which cleanups of him are not
> included yet.

Absolutely sure.
I compared my patch and Harvey's.
These directions are almost same.

Harvey, I have found some differences and I'd like to fix that with you.
I think following comments and style cleanups in your patch are good to me.

> @@ -156,7 +157,7 @@ twobyte_has_modrm[256 / sizeof(unsigned long)] = {
> #undef RF
>
> /* insert a jmp code */
> -static __always_inline void set_jmp_op(void *from, void *to)
> +static inline void set_jmp_op(void *from, void *to)
> {
> struct __arch_jmp_op {
> char op;
> @@ -170,7 +171,7 @@ static __always_inline void set_jmp_op(void *from, void *to)
> /*
> * returns non-zero if opcodes can be boosted.
> */
> -static __always_inline int can_boost(kprobe_opcode_t *opcodes)
> +static inline int can_boost(kprobe_opcode_t *opcodes)
> {
> kprobe_opcode_t opcode;
> kprobe_opcode_t *orig_opcodes = opcodes;


> @@ -734,7 +740,7 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
> regs->flags |= kcb->kprobe_saved_flags;
> trace_hardirqs_fixup_flags(regs->flags);
>
> - /*Restore back the original saved kprobes variables and continue. */
> + /* Restore the original saved kprobes variables and continue. */
> if (kcb->kprobe_status == KPROBE_REENTER) {
> restore_previous_kprobe(kcb);
> goto out;
> @@ -860,7 +866,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
> addr = (unsigned long)(kcb->jprobe_saved_sp);
>
> /*
> - * TBD: As Linus pointed out, gcc assumes that the callee
> + * As Linus pointed out, gcc assumes that the callee
> * owns the argument space and could overwrite it, e.g.
> * tailcall optimization. So, to be absolutely safe
> * we also save and restore enough stack bytes to cover

And also, if you can unify x86/mm/extable_*.c and introduce fixup_exception() to 64-bit,
it is very helpful to remove ifdefs from kprobe_fault_handler().

Thank you,

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx, masami.hiramatsu.pt@xxxxxxxxxxx

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