On Tue, Jun 20, 2017 at 10:22:10PM -0700, Andy Lutomirski wrote:
> - * The x86 doesn't have a mmu context, but
> - * we put the segment information here.
> + * x86 has arch-specific MMU state beyond what lives in mm_struct.
> */
> typedef struct {
> + /*
> + * ctx_id uniquely identifies this mm_struct. A ctx_id will never
> + * be reused, and zero is not a valid ctx_id.
> + */
> + u64 ctx_id;
> +
> + /*
> + * Any code that needs to do any sort of TLB flushing for this
> + * mm will first make its changes to the page tables, then
> + * increment tlb_gen, then flush. This lets the low-level
> + * flushing code keep track of what needs flushing.
> + *
> + * This is not used on Xen PV.
> + */
> + atomic64_t tlb_gen;
> +
> #ifdef CONFIG_MODIFY_LDT_SYSCALL
> struct ldt_struct *ldt;
> #endif
> @@ -37,6 +53,11 @@ typedef struct {
> #endif
> } mm_context_t;
>
> +#define INIT_MM_CONTEXT(mm) \
> + .context = { \
> + .ctx_id = 1, \
So ctx_id of 0 is invalid?
Let's state that explicitly. We could even use it to sanity-check mms or
whatever.
> + }
> +
> void leave_mm(int cpu);
>
> #endif /* _ASM_X86_MMU_H */
> diff --git a/arch/x86/include/asm/mmu_context.h
> b/arch/x86/include/asm/mmu_context.h
> index ecfcb6643c9b..e5295d485899 100644
> --- a/arch/x86/include/asm/mmu_context.h
> +++ b/arch/x86/include/asm/mmu_context.h
> @@ -129,9 +129,14 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
> struct task_struct *tsk)
> this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
> }
>
> +extern atomic64_t last_mm_ctx_id;
I think we prefer externs/variable defines at the beginning of the file,
not intermixed with functions.
> +
> static inline int init_new_context(struct task_struct *tsk,
> struct mm_struct *mm)
> {
> + mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
> + atomic64_set(&mm->context.tlb_gen, 0);
> +
> #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
> if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
> /* pkey 0 is the default and always allocated */
> diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
> index 50ea3482e1d1..1eb946c0507e 100644
> --- a/arch/x86/include/asm/tlbflush.h
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -57,6 +57,23 @@ static inline void invpcid_flush_all_nonglobals(void)
> __invpcid(0, 0, INVPCID_TYPE_ALL_NON_GLOBAL);
> }
>
> +static inline u64 bump_mm_tlb_gen(struct mm_struct *mm)
inc_mm_tlb_gen() I guess. git grep says like "inc" more :-)
> +{
> + u64 new_tlb_gen;
> +
> + /*
> + * Bump the generation count. This also serves as a full barrier
> + * that synchronizes with switch_mm: callers are required to order
Please end function names with parentheses.
> + * their read of mm_cpumask after their writes to the paging
> + * structures.
> + */
> + smp_mb__before_atomic();
> + new_tlb_gen = atomic64_inc_return(&mm->context.tlb_gen);
> + smp_mb__after_atomic();
> +
> + return new_tlb_gen;
> +}
> +
> #ifdef CONFIG_PARAVIRT
> #include <asm/paravirt.h>
> #else
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
