The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 60e5b2886b92afa9e7af56bba7f5fa5f057e1e97 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Jason@zx2c4.com Date: Tue, 7 Jun 2022 17:28:06 +0200 Subject: [PATCH] random: do not use jump labels before they are initialized
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, 73e2d827a501 ("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: f5bda35fba61 ("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
diff --git a/drivers/char/random.c b/drivers/char/random.c index 60d701a2516b..0b78b9c4acf5 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -650,7 +650,8 @@ static void __cold _credit_init_bits(size_t bits)
if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */ - execute_in_process_context(crng_set_ready, &set_ready); + if (static_key_initialized) + execute_in_process_context(crng_set_ready, &set_ready); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); pr_notice("crng init done\n"); @@ -798,6 +799,14 @@ int __init random_init(const char *command_line) _mix_pool_bytes(command_line, strlen(command_line)); add_latent_entropy();
+ /* + * If we were initialized by the bootloader before jump labels are + * initialized, then we should enable the static branch here, where + * it's guaranteed that jump labels have been initialized. + */ + if (!static_branch_likely(&crng_is_ready) && crng_init >= CRNG_READY) + crng_set_ready(NULL); + if (crng_ready()) crng_reseed(); else if (trust_cpu)