On Fri, Jul 17, 2020 at 12:20:43AM -0700, ira.weiny@intel.com wrote:
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f362ce0d5ac0..d69250a7c1bf 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -42,6 +42,7 @@ #include <asm/spec-ctrl.h> #include <asm/io_bitmap.h> #include <asm/proto.h> +#include <asm/pkeys_internal.h> #include "process.h" @@ -184,6 +185,36 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, return ret; } +/*
- NOTE: We wrap pks_init_task() and pks_sched_in() with
- CONFIG_ARCH_HAS_SUPERVISOR_PKEYS because using IS_ENABLED() fails
- due to the lack of task_struct->saved_pkrs in this configuration.
- Furthermore, we place them here because of the complexity introduced by
- header conflicts introduced to get the task_struct definition in the pkeys
- headers.
- */
I don't see anything much useful in that comment.
+#ifdef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS +DECLARE_PER_CPU(u32, pkrs_cache); +static inline void pks_init_task(struct task_struct *tsk) +{
- /* New tasks get the most restrictive PKRS value */
- tsk->thread.saved_pkrs = INIT_PKRS_VALUE;
+} +static inline void pks_sched_in(void) +{
- u64 current_pkrs = current->thread.saved_pkrs;
- /* Only update the MSR when current's pkrs is different from the MSR. */
- if (this_cpu_read(pkrs_cache) == current_pkrs)
return;- write_pkrs(current_pkrs);
Should we write that like:
/* * PKRS is only temporarily changed during specific code paths. * Only a preemption during these windows away from the default * value would require updating the MSR. */ if (unlikely(this_cpu_read(pkrs_cache) != current_pkrs)) write_pkrs(current_pkrs);
?
+} +#else +static inline void pks_init_task(struct task_struct *tsk) { } +static inline void pks_sched_in(void) { } +#endif