From dc40c2f6adf53e7ad8411d98bc7129665570e496 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Wed, 5 Sep 2018 22:26:23 -0700
Subject: [PATCH] Changes from the reorg branch

Add CR4 options: global pages, FXSAVE, PCIDs
Better page manager page-in flags
Remove obsolete rflags-saving in create_process
---
 src/kernel/memory_bootstrap.cpp |  8 ++++++++
 src/kernel/page_manager.cpp     | 11 +++++++----
 src/kernel/scheduler.cpp        |  4 ----
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/kernel/memory_bootstrap.cpp b/src/kernel/memory_bootstrap.cpp
index 097ba8d..071789a 100644
--- a/src/kernel/memory_bootstrap.cpp
+++ b/src/kernel/memory_bootstrap.cpp
@@ -429,6 +429,14 @@ memory_initialize(const void *memory_map, size_t map_length, size_t desc_length)
 	__asm__ __volatile__ ( "mov %%cr3, %0" : "=r" (cr3) );
 	page_table *tables = reinterpret_cast<page_table *>(cr3 & ~0xfffull);
 
+	// We'll need to make sure the options we want in CR4 are set
+	uint64_t cr4;
+	__asm__ __volatile__ ( "mov %%cr4, %0" : "=r" (cr4) );
+	cr4 |= 0x00080; // Enable global pages
+	cr4 |= 0x00200; // Enable FXSAVE/FXRSTOR
+	cr4 |= 0x20000; // Enable PCIDs
+	__asm__ __volatile__ ( "mov %0, %%cr4" :: "r" (cr4) );
+
 	// Now go through EFi's memory map and find a region of scratch space.
 	const unsigned want_pages = 32;
 	uint64_t free_region_start_phys =
diff --git a/src/kernel/page_manager.cpp b/src/kernel/page_manager.cpp
index 968cc30..e66273f 100644
--- a/src/kernel/page_manager.cpp
+++ b/src/kernel/page_manager.cpp
@@ -379,8 +379,7 @@ void *
 page_manager::map_pages(addr_t address, size_t count, bool user, page_table *pml4)
 {
 	void *ret = reinterpret_cast<void *>(address);
-	if (pml4 == nullptr)
-		pml4 = get_pml4();
+	if (!pml4) pml4 = get_pml4();
 
 	while (count) {
 		kassert(m_free, "page_manager::map_pages ran out of free pages!");
@@ -537,6 +536,10 @@ page_manager::page_in(page_table *pml4, addr_t phys_addr, addr_t virt_addr, size
 	page_table_indices idx{virt_addr};
 	page_table *tables[4] = {pml4, nullptr, nullptr, nullptr};
 
+	uint64_t flags = user ?
+		0x00f:	// writethru, user, write, present
+		0x10b;	// global, writethru, write, present
+
 	for (; idx[0] < 512; idx[0] += 1) {
 		check_needs_page(tables[0], idx[0], user);
 		tables[1] = tables[0]->get(idx[0]);
@@ -550,7 +553,7 @@ page_manager::page_in(page_table *pml4, addr_t phys_addr, addr_t virt_addr, size
 					count >= 512 &&
 					tables[2]->get(idx[2]) == nullptr) {
 					// Do a 2MiB page instead
-					tables[2]->entries[idx[2]] = phys_addr | (user ? 0x8f : 0x8b);
+					tables[2]->entries[idx[2]] = phys_addr | flags | 0x80;
 					phys_addr += page_size * 512;
 					count -= 512;
 					if (count == 0) return;
@@ -561,7 +564,7 @@ page_manager::page_in(page_table *pml4, addr_t phys_addr, addr_t virt_addr, size
 				tables[3] = tables[2]->get(idx[2]);
 
 				for (; idx[3] < 512; idx[3] += 1) {
-					tables[3]->entries[idx[3]] = phys_addr | (user ? 0xf : 0xb);
+					tables[3]->entries[idx[3]] = phys_addr | flags;
 					phys_addr += page_size;
 					if (--count == 0) return;
 				}
diff --git a/src/kernel/scheduler.cpp b/src/kernel/scheduler.cpp
index 25a681c..33f78cf 100644
--- a/src/kernel/scheduler.cpp
+++ b/src/kernel/scheduler.cpp
@@ -19,7 +19,6 @@ extern "C" {
 	void taskA();
 	void taskAend();
 	void ramdisk_process_loader();
-
 	void load_process(void *copy_start, size_t butes, cpu_state state);
 };
 
@@ -55,9 +54,6 @@ load_process(void *copy_start, size_t bytes, cpu_state state)
 static process
 create_process(uint16_t pid)
 {
-	uint64_t flags;
-	__asm__ __volatile__ ( "pushf; pop %0" : "=r" (flags) );
-
 	uint16_t kcs = (1 << 3) | 0; // Kernel CS is GDT entry 1, ring 0
 	uint16_t cs = (5 << 3) | 3;  // User CS is GDT entry 5, ring 3