The cpu_spec is a struct holding various information about the CPU the kernel is executing on. It's populated early in boot and must not change after that.
In particular the cpu_features and mmu_features hold the set of discovered CPU/MMU features and are used to set static keys for each feature, and do binary patching of assembly. So any change to the cpu_features/mmu_features later in boot will not be reflected in the state of the static keys or patched code. There is already logic to check that cpu_features/mmu_features don't change, see check_features() in feature-fixups.c. But as another layer of protection the entire cpu_spec should be read only after init, annotate it as such. Signed-off-by: Michael Ellerman <m...@ellerman.id.au> --- arch/powerpc/kernel/cputable.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index e97a0fd0ae90..c6678c91401b 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -20,9 +20,9 @@ #include <asm/setup.h> #include <asm/cpu_setup.h> -static struct cpu_spec the_cpu_spec __read_mostly; +static struct cpu_spec the_cpu_spec __ro_after_init; -struct cpu_spec* cur_cpu_spec __read_mostly = NULL; +struct cpu_spec* cur_cpu_spec __ro_after_init = NULL; EXPORT_SYMBOL(cur_cpu_spec); /* The platform string corresponding to the real PVR */ -- 2.41.0
