Messages in this thread | | | Date | Tue, 7 Jun 2022 16:51:24 +0100 | Subject | Re: [PATCH v2] ARM: initialize jump labels before setup_machine_fdt() | From | Phil Elwell <> |
| |
On 07/06/2022 16:44, Jason A. Donenfeld wrote: > Hi Phil, > > On Tue, Jun 07, 2022 at 04:35:32PM +0100, Phil Elwell wrote: >> Jason, >> >> On 07/06/2022 16:14, Jason A. Donenfeld wrote: >>> Hey again, >>> >>> On Tue, Jun 07, 2022 at 10:15:27AM +0100, Phil Elwell wrote: >>>> On 07/06/2022 09:43, Jason A. Donenfeld wrote: >>>>> Hi Phil, >>>>> >>>>> On Tue, Jun 7, 2022 at 10:29 AM Phil Elwell <phil@raspberrypi.com> wrote: >>>>>> >>>>>> This patch is fatal for me in the downstream Raspberry Pi kernel - it locks up >>>>>> on boot even before the earlycon output is available. Hacking jump_label_init to >>>>>> skip the jump_entry for "crng_is_ready" allows it to boot, but is likely to have >>>>>> consequences further down the line. >>>>> >>>>> Also, reading this a few times, I'm not 100% sure I understand what >>>>> you did to hack around this and why that works. Think you could paste >>>>> your hackpatch just out of interest to the discussion (but obviously >>>>> not to be applied)? >>>> >>>> This is the minimal version of my workaround patch that at least allows the >>>> board to boot. Bear in mind that it was written with no previous knowledge of >>>> jump labels and was arrived at by iteratively bisecting the list of jump_labels >>>> until the first dangerous one was found, then later working out that there was >>>> only one. >>> >>> Looks like this patch fails due to CONFIG_STRICT_KERNEL_RWX. >>> Investigating deeper now, but that for starters seems to be the >>> differentiating factor between my prior test rig and one that reproduces >>> the error. I assume your raspi also sets CONFIG_STRICT_KERNEL_RWX. >> >> Yes, it does, as does multi_v7_defconfig. > > Oh good. Adjusting my CI now to have that. > > Having tickled arch/arm/ a little bit now, this is looking sort of > complicated. So I think I might be leaning toward giving up and just > rolling with <https://git.zx2c4.com/linux-rng/commit/?id=78f79dda>. > > Unless of course somebody has some ARM chops and can think of a quick > easy fix.
I've not looked at the performance implications (if any), but in terms of when the RNG initilialization completes and the lack of a WARN I'm happy with that patch, a.k.a. [1].
Phil
[1] https://lore.kernel.org/lkml/20220607100210.683136-1-Jason@zx2c4.com/
| |