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SubjectRe: [BUGFIX PATCH] kprobes/x86: Remove IRQ disabling from jprobe handlers
On Tue, 3 Oct 2017 11:33:44 +0200
Ingo Molnar <mingo@kernel.org> wrote:

>
> * Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > Jprobe actually doesn't need to disable IRQs while calling
> > handlers, because Documentation/kprobes.txt says:
> >
> > -----
> > Probe handlers are run with preemption disabled. Depending on the
> > architecture and optimization state, handlers may also run with
> > interrupts disabled (e.g., kretprobe handlers and optimized kprobe
> > handlers run without interrupt disabled on x86/x86-64).
> > -----
> >
> > So let's remove IRQ disabling from jprobes too.
> >
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> > arch/x86/kernel/kprobes/core.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> > index b48e0efd668e..bd36f3c33cd0 100644
> > --- a/arch/x86/kernel/kprobes/core.c
> > +++ b/arch/x86/kernel/kprobes/core.c
> > @@ -1099,8 +1099,6 @@ int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
> > * raw stack chunk with redzones:
> > */
> > __memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, MIN_STACK_SIZE(addr));
> > - regs->flags &= ~X86_EFLAGS_IF;
> > - trace_hardirqs_off();
> > regs->ip = (unsigned long)(jp->entry);
> >
> > /*
>
> Could you please also do a patch that disables jprobes permanently, in preparation
> of eventually removing them later?

Would you mean introducing CONFIG_JPROBE_API and cut APIs out,
or just adding "__deprecated" for each API?

Thank you,

>
> Thanks,
>
> Ingo


--
Masami Hiramatsu <mhiramat@kernel.org>

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