Re: [PATCH] arm64: Initialize jump labels before setup_machine_fdt()
From: Jason A. Donenfeld
Date: Thu Jun 02 2022 - 02:50:31 EST
Hi Stephen,
On 6/2/22, Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
> A static key warning splat appears during early boot on arm64 systems
> that credit randomness from devicetrees that contain an "rng-seed"
> property. This is because setup_machine_fdt() is called before
> jump_label_init() during setup_arch(). Let's swap the order of these two
> calls so that jump labels are initialized before the devicetree is
> unflattened and the rng seed is credited.
>
> static_key_enable_cpuslocked(): static key '0xffffffe51c6fcfc0' used before
> call to jump_label_init()
> WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166
> static_key_enable_cpuslocked+0xb0/0xb8
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0+ #224
> 44b43e377bfc84bc99bb5ab885ff694984ee09ff
> pstate: 600001c9 (nZCv dAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : static_key_enable_cpuslocked+0xb0/0xb8
> lr : static_key_enable_cpuslocked+0xb0/0xb8
> sp : ffffffe51c393cf0
> x29: ffffffe51c393cf0 x28: 000000008185054c x27: 00000000f1042f10
> x26: 0000000000000000 x25: 00000000f10302b2 x24: 0000002513200000
> x23: 0000002513200000 x22: ffffffe51c1c9000 x21: fffffffdfdc00000
> x20: ffffffe51c2f0831 x19: ffffffe51c6fcfc0 x18: 00000000ffff1020
> x17: 00000000e1e2ac90 x16: 00000000000000e0 x15: ffffffe51b710708
> x14: 0000000000000066 x13: 0000000000000018 x12: 0000000000000000
> x11: 0000000000000000 x10: 00000000ffffffff x9 : 0000000000000000
> x8 : 0000000000000000 x7 : 61632065726f6665 x6 : 6220646573752027
> x5 : ffffffe51c641d25 x4 : ffffffe51c13142c x3 : ffff0a00ffffff05
> x2 : 40000000ffffe003 x1 : 00000000000001c0 x0 : 0000000000000065
> Call trace:
> static_key_enable_cpuslocked+0xb0/0xb8
> static_key_enable+0x2c/0x40
> crng_set_ready+0x24/0x30
> execute_in_process_context+0x80/0x90
> _credit_init_bits+0x100/0x154
> add_bootloader_randomness+0x64/0x78
> early_init_dt_scan_chosen+0x140/0x184
> early_init_dt_scan_nodes+0x28/0x4c
> early_init_dt_scan+0x40/0x44
> setup_machine_fdt+0x7c/0x120
> setup_arch+0x74/0x1d8
> start_kernel+0x84/0x44c
> __primary_switched+0xc0/0xc8
> ---[ end trace 0000000000000000 ]---
> random: crng init done
> Machine model: Google Lazor (rev1 - 2) with LTE
>
> Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> Cc: Douglas Anderson <dianders@xxxxxxxxxxxx>
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Jason A. Donenfeld <Jason@xxxxxxxxx>
> Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
> Fixes: f5bda35fba61 ("random: use static branch for crng_ready()")
> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Thanks for fixing this.
Reviewed-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
In looking at the matter more in depth, it looks like riscv does
things in the right order, but arm32 still does not. AFAICT, it uses
the logic in init/main.c, in which jump_label_init() is called before
setup_arch()->setup_machine_fdt(). Want to submit a patch for arm32?
Jason