From: Michael Ellerman Date: Wed, 25 Oct 2023 01:24:52 +0000 (+1100) Subject: powerpc: Make cpu_spec __ro_after_init X-Git-Tag: v6.8-rc1~202^2~67 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=98eb30fe4c69a9b602f29e406317c49b5580352a;p=thirdparty%2Fkernel%2Flinux.git powerpc: Make cpu_spec __ro_after_init 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 Link: https://msgid.link/20231025012452.1985680-1-mpe@ellerman.id.au --- diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index e97a0fd0ae905..6f6801da9dc1e 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -20,9 +20,9 @@ #include #include -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 */