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Stephen reported that a static key warning splat appears during early boot on systems that credit randomness from device trees that contain an "rng-seed" property, because because setup_machine_fdt() is called before jump_label_init() during setup_arch(): 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 A trivial fix went in to address this on arm64,73e2d827a5("arm64: Initialize jump labels before setup_machine_fdt()"). I wrote patches as well for arm32 and risc-v. But still patches are needed on xtensa, powerpc, arc, and mips. So that's 7 platforms where things aren't quite right. This sort of points to larger issues that might need a larger solution. Instead, this commit just defers setting the static branch until later in the boot process. random_init() is called after jump_label_init() has been called, and so is always a safe place from which to adjust the static branch. Fixes:f5bda35fba("random: use static branch for crng_ready()") Reported-by: Stephen Boyd <swboyd@chromium.org> Reported-by: Phil Elwell <phil@raspberrypi.com> Tested-by: Phil Elwell <phil@raspberrypi.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.