Hi Ard,
On 6/3/22, Ard Biesheuvel ardb@kernel.org wrote:
On Thu, 2 Jun 2022 at 23:22, Jason A. Donenfeld Jason@zx2c4.com wrote:
Stephen reported that a static key warning splat appears during early boot on arm64 systems that credit randomness from device trees that contain an "rng-seed" property, because setup_machine_fdt() is called before jump_label_init() during setup_arch(), which was fixed by 73e2d827a501 ("arm64: Initialize jump labels before setup_machine_fdt()").
Upon cursory inspection, the same basic issue appears to apply to arm32 as well. In this case, we reorder setup_arch() to do things in the same order as is now the case on arm64.
Reported-by: Stephen Boyd swboyd@chromium.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Ard Biesheuvel ardb@kernel.org Cc: stable@vger.kernel.org Fixes: f5bda35fba61 ("random: use static branch for crng_ready()")
Wouldn't it be better to defer the static_branch_enable(&crng_is_ready) call to later in the boot (e.g., using an initcall()), rather than going around 'fixing' fragile, working early boot code across multiple architectures?
Yes, maybe. It's just more book keeping that's potentially unnecessary, which would be nice to avoid. I wrote a patch for this before, but it wasn't beautiful. And Catalin got a pretty easy arm64 patch queued up sufficiently fast that I figured this was better.
Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com
arch/arm/kernel/setup.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 1e8a50a97edf..ef40d9f5d5a7 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -1097,10 +1097,15 @@ void __init setup_arch(char **cmdline_p) const struct machine_desc *mdesc = NULL; void *atags_vaddr = NULL;
setup_initial_init_mm(_text, _etext, _edata, _end);setup_processor();early_fixmap_init();early_ioremap_init();jump_label_init();Is it really necessary to reorder all these calls? What does jump_label_init() actually need?
I'm not quite sure, but it matched how arm64 does things now. Was hoping somebody with deep arm32 knowledge (e.g. you or rmk) would be able to eyeball that to confirm.
Jason