[RFC 2/9] Add x86 specifc files for Popcorn

[Javier Malave <javier.malave@narfindustries.com>]

Popcorn Linux is a Linux kernel-based software stack
that enables applications to execute, with a shared
source base, on distributed hosts.

This Popcorn patch adds x86_64 functionality only. 
Future iterations of Popcorn will support
heterogeneous architectures.
---
 arch/x86/Kconfig               |  3 +++
 arch/x86/include/asm/pgtable.h | 11 +++++++++++
 arch/x86/kernel/Makefile       |  1 +
 arch/x86/mm/fault.c            | 18 ++++++++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2bbbd4d1b..4ca75c6c3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -88,6 +88,7 @@ config X86
 	select ARCH_SUPPORTS_ACPI
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
+	select ARCH_SUPPORTS_POPCORN	if X86_64
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
@@ -353,6 +354,8 @@ config PGTABLE_LEVELS
 	default 3 if X86_PAE
 	default 2
 
+source "kernel/Kconfig.popcorn"
+
 config CC_HAS_SANE_STACKPROTECTOR
 	bool
 	default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 5e0509b41..7a0171c67 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -210,9 +210,13 @@ static inline u64 protnone_mask(u64 val);
 
 static inline unsigned long pte_pfn(pte_t pte)
 {
+#ifdef CONFIG_POPCORN
+	return (pte_val(pte) & PTE_PFN_MASK) >> PAGE_SHIFT;
+#else
 	phys_addr_t pfn = pte_val(pte);
 	pfn ^= protnone_mask(pfn);
 	return (pfn & PTE_PFN_MASK) >> PAGE_SHIFT;
+#endif
 }
 
 static inline unsigned long pmd_pfn(pmd_t pmd)
@@ -602,7 +606,11 @@ static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask);
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
+#ifndef CONFIG_POPCORN
 	pteval_t val = pte_val(pte), oldval = val;
+#else
+	pteval_t val = pte_val(pte);
+#endif
 
 	/*
 	 * Chop off the NX bit (if present), and add the NX portion of
@@ -610,8 +618,11 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 	 */
 	val &= _PAGE_CHG_MASK;
 	val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK;
+#ifndef CONFIG_POPCORN
 	val = flip_protnone_guard(oldval, val, PTE_PFN_MASK);
+#endif
 	return __pte(val);
+
 }
 
 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index ce1b5cc36..3fb863285 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -133,6 +133,7 @@ obj-$(CONFIG_EFI)			+= sysfb_efi.o
 
 obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
 obj-$(CONFIG_TRACING)			+= tracepoint.o
+obj-$(CONFIG_POPCORN)		+= process_server.o
 obj-$(CONFIG_SCHED_MC_PRIO)		+= itmt.o
 obj-$(CONFIG_X86_INTEL_UMIP)		+= umip.o
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 46df4c6aa..14b9755f9 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -33,6 +33,11 @@
 #define CREATE_TRACE_POINTS
 #include <asm/trace/exceptions.h>
 
+#ifdef CONFIG_POPCORN
+#include <popcorn/types.h>
+#include <popcorn/vma_server.h>
+#endif
+
 /*
  * Returns 0 if mmiotrace is disabled, or if the fault is not
  * handled by mmiotrace:
@@ -1416,6 +1421,19 @@ void do_user_addr_fault(struct pt_regs *regs,
 	}
 
 	vma = find_vma(mm, address);
+#ifdef CONFIG_POPCORN
+	/* vma worker should not fault */
+	BUG_ON(tsk->is_worker);
+
+	if (distributed_remote_process(tsk)) {
+		if (!vma || vma->vm_start > address) {
+			if (vma_server_fetch_vma(tsk, address) == 0) {
+				/* Replace with updated VMA */
+				vma = find_vma(mm, address);
+			}
+		}
+	}
+#endif
 	if (unlikely(!vma)) {
 		bad_area(regs, hw_error_code, address);
 		return;
-- 
2.17.1