Re: [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2024-09-10 07:22:01
Also in:
live-patching
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2024-09-10 07:22:01
Also in:
live-patching
"Ryan B. Sullivan" [off-list ref] writes:
Hello all, Just wanted to ping and see if there was any further feedback or questions regarding the patch?
Hi Ryan, I'd really like a selftest that triggers the sibling call behaviour. As I said upthread I tried writing one but failed. Which you later explained is because the cross-module sibling call is not generated by the compiler but rather by the code being objcopy'ed (or similar). I think it should be possible to trick the compiler into letting us do a cross-module sibling call by doing it in an inline asm block. Obviously that's non-standard, but I think it might work well enough for a test? We have an example of calling a function within an inline asm block in call_do_irq(). I'll try to find time to get that done, but I can't promise when. cheers