[ Upstream commit 90d77b30a6 ]
Starting with commit bdb249fce9 ("ARM: integrator: read counter using
syscon/regmap"), intcp_init_early calls syscon_regmap_lookup_by_compatible
which in turn calls of_syscon_register. This function allocates memory.
Since the memory management code has not been initialized at that time,
the call always fails. It either returns -ENOMEM or crashes as follows.
Unable to handle kernel NULL pointer dereference at virtual address 0000000c when read
[0000000c] *pgd=00000000
Internal error: Oops: 5 [#1] ARM
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.15.0-rc5-00026-g5fcc9bf84ee5 #1 PREEMPT
Hardware name: ARM Integrator/CP (Device Tree)
PC is at __kmalloc_cache_noprof+0xec/0x39c
LR is at __kmalloc_cache_noprof+0x34/0x39c
...
Call trace:
__kmalloc_cache_noprof from of_syscon_register+0x7c/0x310
of_syscon_register from device_node_get_regmap+0xa4/0xb0
device_node_get_regmap from intcp_init_early+0xc/0x40
intcp_init_early from start_kernel+0x60/0x688
start_kernel from 0x0
The crash is seen due to a dereferenced pointer which is not supposed to be
NULL but is NULL if the memory management subsystem has not been
initialized. The crash is not seen with all versions of gcc. Some versions
such as gcc 9.x apparently do not dereference the pointer, presumably if
tracing is disabled. The problem has been reproduced with gcc 10.x, 11.x,
and 13.x. Either case, if the crash is not seen, the call to
syscon_regmap_lookup_by_compatible returns -ENOMEM, and
sched_clock_register is never called.
Fix the problem by moving the early initialization code into the standard
machine initialization code.
Fixes: bdb249fce9 ("ARM: integrator: read counter using syscon/regmap")
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/20250518164118.3859567-1-linux@roeck-us.net
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20260505-integrator-fixes-v1-1-56ab9aac59db@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
812103fb6d