Hi,

On Sat, May 16, 2020 at 1:47 AM liwei (GF) [off-list ref] wrote:

quoted

quoted

-               kprobes_save_local_irqflag(kcb, regs);
+               kernel_prepare_single_step(&kcb->saved_irqflag, regs);

Is there some reason to have two functions?  It seems like every time
you call kernel_enable_single_step() you'd want to call
kernel_prepare_single_step().  ...and every time you call
kernel_disable_single_step() you'd want to call
kernel_cleanup_single_step().

Maybe you can just add the flags parameter to
kernel_enable_single_step() / kernel_disable_single_step() and put the
code in there?

As kernel_enable_single_step() / kernel_disable_single_step() are also called in
breakpoint_handler() and watchpoint_handler(), i am not sure it's a right thing
to put the daif flag prepare/cleanup into them, especially we don't have a context
to save the flags.

I think you misunderstood what I was suggesting.  Maybe better with
examples?  I was suggesting doing this:

kcb->saved_irqflag = kernel_enable_single_step(regs);
...
kernel_disable_single_step(kcb->saved_irqflag, regs);

To me that seems better than what you have now:

kcb->saved_irqflag = kernel_prepare_single_step(regs);
kernel_enable_single_step(regs);
...
kernel_cleanup_single_step(kcb->saved_irqflag, regs);
kernel_disable_single_step();

...or am I confused?

-Doug

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