RE: [PATCH v11 8/9] arm64: Add kernel return probes support (kretprobes)

[平松雅巳 / HIRAMATU，MASAMI]

Hi,

>From: Sandeepa Prabhu <sandeepa.s.prabhu@xxxxxxxxx>
>
>The pre-handler of this special 'trampoline' kprobe executes the return
>probe handler functions and restores original return address in ELR_EL1.
>This way the saved pt_regs still hold the original register context to be
>carried back to the probed kernel function.

This patch seems not well separated.

>diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c
>index bd3f233..13d3333 100644
>--- a/arch/arm64/kernel/kprobes.c
>+++ b/arch/arm64/kernel/kprobes.c

[snip]

>+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
>+				      struct pt_regs *regs)
>+{
>+	ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
>+
>+	/* replace return addr (x30) with trampoline */
>+	regs->regs[30] = (long)&kretprobe_trampoline;

So, where is the kretprobe_trampoline? It seems that function is
defined in other patch.

>+}
>+
>+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
>+{
>+	return 0;
> }

And what this function is for??

Thank you,

>
> int __init arch_init_kprobes(void)
>--
>2.5.0
>
>
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