On Wed, May 08, 2019 at 05:39:07PM +0200, Peter Zijlstra wrote:
On Wed, May 08, 2019 at 07:42:48AM -0500, Josh Poimboeuf wrote:
On Wed, May 08, 2019 at 02:04:16PM +0200, Peter Zijlstra wrote:
Do the x86_64 variants also want some ORC annotation?
Maybe so. Though it looks like regs->ip isn't saved. The saved registers might need to be tweaked. I'll need to look into it.
What all these sites do (and maybe we should look at unifying them somehow) is turn a CALL frame (aka RET-IP) into an exception frame (aka pt_regs).
So regs->ip will be the return address (which is fixed up to be the CALL address in the handler).
But from what I can tell, trampoline_handler() hard-codes regs->ip to point to kretprobe_trampoline(), and the original return address is placed in regs->sp.
Masami, is there a reason why regs->ip doesn't have the original return address and regs->sp doesn't have the original SP? I think that would help the unwinder understand things.