From: ???? / HIRAMATU?MASAMI [mailto:masami.hiramatsu.pt at hitachi.com]

Hi,

quoted

From: Sandeepa Prabhu <redacted>

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.

quoted

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]

quoted

+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.

quoted

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

And what this function is for??

Ah, sorry, this was my fault. Yes, this function is required.
But this implementation also means there is an asm-based trampoline
function which should be included in this patch.

David, could you tell me the repository which I can get the latest
version of this series? I'd like to see the whole code of kprobes/arm64.

Thank you,