| Message ID | 20231025012452.1985680-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 98eb30fe4c69a9b602f29e406317c49b5580352a |
| Headers | show |
| Series | powerpc: Make cpu_spec __ro_after_init | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 6 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 23 jobs. |
On Wed, 25 Oct 2023 12:24:52 +1100, Michael Ellerman wrote: > 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. > > [...] Applied to powerpc/next. [1/1] powerpc: Make cpu_spec __ro_after_init https://git.kernel.org/powerpc/c/98eb30fe4c69a9b602f29e406317c49b5580352a cheers
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 */
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 <mpe@ellerman.id.au> --- arch/powerpc/kernel/cputable.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)