From 7304e20731980078a7bfe138a20a8d13653fed7b Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sat, 27 Feb 2021 18:24:38 +0100
Subject: Started basic paging port from skiftOS

---
 libc/inc/cpu.h | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'libc/inc/cpu.h')

diff --git a/libc/inc/cpu.h b/libc/inc/cpu.h
index fa82fbe..5c55913 100644
--- a/libc/inc/cpu.h
+++ b/libc/inc/cpu.h
@@ -27,6 +27,12 @@ void cpu_print(void);
 void cpu_enable_features(void);
 void fpu_restore(void);
 
+u32 cr0_get(void);
+void cr0_set(u32 cr0);
+void cr3_set(u32 cr3);
+u32 cr4_get(void);
+void cr4_set(u32 cr4);
+
 void cli(void);
 void sti(void);
 void hlt(void);
-- 
cgit v1.2.3


From 38cfba2f71bfa9bdea562cb6465b9dc0155fc467 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Mon, 8 Mar 2021 19:30:48 +0100
Subject: Better randomization (soon: random memory locs)

---
 kernel/main.c     |   1 +
 libc/cpu.c        |  19 ++++++---
 libc/inc/cpu.h    | 116 ++++++++++++++++++++++++++++--------------------------
 libc/inc/random.h |   2 +
 libc/random.c     |  29 ++++++++++++++
 5 files changed, 106 insertions(+), 61 deletions(-)

(limited to 'libc/inc/cpu.h')

diff --git a/kernel/main.c b/kernel/main.c
index 2e2e030..f0bfc3c 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -37,6 +37,7 @@ void kernel_main(struct mem_info *mem_info, struct vid_info *vid_info)
 
 	cpu_enable_features();
 	cpu_print();
+	srand(rdseed());
 
 	// Install drivers
 	vfs_install();
diff --git a/libc/cpu.c b/libc/cpu.c
index b74ed57..cb9aa49 100644
--- a/libc/cpu.c
+++ b/libc/cpu.c
@@ -99,10 +99,16 @@ void cr4_set(u32 cr4)
 	__asm__ volatile("movl %%eax, %%cr4" ::"a"(cr4));
 }
 
-static u32 cpu_features = 0;
-static u8 cpu_has_feature(u32 feature)
+static u32 cpu_cfeatures = 0;
+u8 cpu_has_cfeature(enum cpuid_features feature)
 {
-	return (cpu_features & feature) != 0;
+	return (cpu_cfeatures & feature) != 0;
+}
+
+static u32 cpu_dfeatures = 0;
+u8 cpu_has_dfeature(enum cpuid_features feature)
+{
+	return (cpu_dfeatures & feature) != 0;
 }
 
 static void fpu_handler(struct regs *r)
@@ -121,8 +127,9 @@ void cpu_enable_features(void)
 {
 	u32 a, b, c, d;
 	cpuid(CPUID_FEATURES, &a, &b, &c, &d);
-	cpu_features = d;
-	if (cpu_has_feature(CPUID_FEAT_EDX_SSE)) {
+	cpu_cfeatures = c;
+	cpu_dfeatures = d;
+	if (cpu_has_dfeature(CPUID_FEAT_EDX_SSE)) {
 		cr0_set(cr0_get() & ~(1 << 2));
 		cr0_set(cr0_get() | (1 << 1));
 		cr4_set(cr4_get() | (3 << 9));
@@ -130,7 +137,7 @@ void cpu_enable_features(void)
 		panic("No SSE support!\n");
 	}
 
-	if (cpu_has_feature(CPUID_FEAT_EDX_FPU)) {
+	if (cpu_has_dfeature(CPUID_FEAT_EDX_FPU)) {
 		__asm__ volatile("fninit");
 		__asm__ volatile("fxsave %0" : "=m"(fpu_state));
 		irq_install_handler(7, fpu_handler);
diff --git a/libc/inc/cpu.h b/libc/inc/cpu.h
index 5c55913..161b7a4 100644
--- a/libc/inc/cpu.h
+++ b/libc/inc/cpu.h
@@ -41,63 +41,69 @@ void loop(void);
 
 enum cpuid_requests { CPUID_VENDOR_STRING, CPUID_FEATURES, CPUID_TLB, CPUID_SERIAL };
 enum cpuid_features {
-	CPUID_FEAT_ECX_SSE3 = 1 << 0,
-	CPUID_FEAT_ECX_PCLMUL = 1 << 1,
-	CPUID_FEAT_ECX_DTES64 = 1 << 2,
-	CPUID_FEAT_ECX_MONITOR = 1 << 3,
-	CPUID_FEAT_ECX_DS_CPL = 1 << 4,
-	CPUID_FEAT_ECX_VMX = 1 << 5,
-	CPUID_FEAT_ECX_SMX = 1 << 6,
-	CPUID_FEAT_ECX_EST = 1 << 7,
-	CPUID_FEAT_ECX_TM2 = 1 << 8,
-	CPUID_FEAT_ECX_SSSE3 = 1 << 9,
-	CPUID_FEAT_ECX_CID = 1 << 10,
-	CPUID_FEAT_ECX_FMA = 1 << 12,
-	CPUID_FEAT_ECX_CX16 = 1 << 13,
-	CPUID_FEAT_ECX_ETPRD = 1 << 14,
-	CPUID_FEAT_ECX_PDCM = 1 << 15,
-	CPUID_FEAT_ECX_PCIDE = 1 << 17,
-	CPUID_FEAT_ECX_DCA = 1 << 18,
-	CPUID_FEAT_ECX_SSE4_1 = 1 << 19,
-	CPUID_FEAT_ECX_SSE4_2 = 1 << 20,
-	CPUID_FEAT_ECX_x2APIC = 1 << 21,
-	CPUID_FEAT_ECX_MOVBE = 1 << 22,
-	CPUID_FEAT_ECX_POPCNT = 1 << 23,
-	CPUID_FEAT_ECX_AES = 1 << 25,
-	CPUID_FEAT_ECX_XSAVE = 1 << 26,
-	CPUID_FEAT_ECX_OSXSAVE = 1 << 27,
-	CPUID_FEAT_ECX_AVX = 1 << 28,
+	CPUID_FEAT_ECX_SSE3 = 1u << 0,
+	CPUID_FEAT_ECX_PCLMUL = 1u << 1,
+	CPUID_FEAT_ECX_DTES64 = 1u << 2,
+	CPUID_FEAT_ECX_MONITOR = 1u << 3,
+	CPUID_FEAT_ECX_DS_CPL = 1u << 4,
+	CPUID_FEAT_ECX_VMX = 1u << 5,
+	CPUID_FEAT_ECX_SMX = 1u << 6,
+	CPUID_FEAT_ECX_EST = 1u << 7,
+	CPUID_FEAT_ECX_TM2 = 1u << 8,
+	CPUID_FEAT_ECX_SSSE3 = 1u << 9,
+	CPUID_FEAT_ECX_CID = 1u << 10,
+	CPUID_FEAT_ECX_FMA = 1u << 12,
+	CPUID_FEAT_ECX_CX16 = 1u << 13,
+	CPUID_FEAT_ECX_ETPRD = 1u << 14,
+	CPUID_FEAT_ECX_PDCM = 1u << 15,
+	CPUID_FEAT_ECX_PCIDE = 1u << 17,
+	CPUID_FEAT_ECX_DCA = 1u << 18,
+	CPUID_FEAT_ECX_SSE4_1 = 1u << 19,
+	CPUID_FEAT_ECX_SSE4_2 = 1u << 20,
+	CPUID_FEAT_ECX_x2APIC = 1u << 21,
+	CPUID_FEAT_ECX_MOVBE = 1u << 22,
+	CPUID_FEAT_ECX_POPCNT = 1u << 23,
+	CPUID_FEAT_ECX_AES = 1u << 25,
+	CPUID_FEAT_ECX_XSAVE = 1u << 26,
+	CPUID_FEAT_ECX_OSXSAVE = 1u << 27,
+	CPUID_FEAT_ECX_AVX = 1u << 28,
+	CPUID_FEAT_ECX_F16C = 1u << 29,
+	CPUID_FEAT_ECX_RDRND = 1u << 30,
 
-	CPUID_FEAT_EDX_FPU = 1 << 0,
-	CPUID_FEAT_EDX_VME = 1 << 1,
-	CPUID_FEAT_EDX_DE = 1 << 2,
-	CPUID_FEAT_EDX_PSE = 1 << 3,
-	CPUID_FEAT_EDX_TSC = 1 << 4,
-	CPUID_FEAT_EDX_MSR = 1 << 5,
-	CPUID_FEAT_EDX_PAE = 1 << 6,
-	CPUID_FEAT_EDX_MCE = 1 << 7,
-	CPUID_FEAT_EDX_CX8 = 1 << 8,
-	CPUID_FEAT_EDX_APIC = 1 << 9,
-	CPUID_FEAT_EDX_SEP = 1 << 11,
-	CPUID_FEAT_EDX_MTRR = 1 << 12,
-	CPUID_FEAT_EDX_PGE = 1 << 13,
-	CPUID_FEAT_EDX_MCA = 1 << 14,
-	CPUID_FEAT_EDX_CMOV = 1 << 15,
-	CPUID_FEAT_EDX_PAT = 1 << 16,
-	CPUID_FEAT_EDX_PSE36 = 1 << 17,
-	CPUID_FEAT_EDX_PSN = 1 << 18,
-	CPUID_FEAT_EDX_CLF = 1 << 19,
-	CPUID_FEAT_EDX_DTES = 1 << 21,
-	CPUID_FEAT_EDX_ACPI = 1 << 22,
-	CPUID_FEAT_EDX_MMX = 1 << 23,
-	CPUID_FEAT_EDX_FXSR = 1 << 24,
-	CPUID_FEAT_EDX_SSE = 1 << 25,
-	CPUID_FEAT_EDX_SSE2 = 1 << 26,
-	CPUID_FEAT_EDX_SS = 1 << 27,
-	CPUID_FEAT_EDX_HTT = 1 << 28,
-	CPUID_FEAT_EDX_TM1 = 1 << 29,
-	CPUID_FEAT_EDX_IA64 = 1 << 30,
+	CPUID_FEAT_EDX_FPU = 1u << 0,
+	CPUID_FEAT_EDX_VME = 1u << 1,
+	CPUID_FEAT_EDX_DE = 1u << 2,
+	CPUID_FEAT_EDX_PSE = 1u << 3,
+	CPUID_FEAT_EDX_TSC = 1u << 4,
+	CPUID_FEAT_EDX_MSR = 1u << 5,
+	CPUID_FEAT_EDX_PAE = 1u << 6,
+	CPUID_FEAT_EDX_MCE = 1u << 7,
+	CPUID_FEAT_EDX_CX8 = 1u << 8,
+	CPUID_FEAT_EDX_APIC = 1u << 9,
+	CPUID_FEAT_EDX_SEP = 1u << 11,
+	CPUID_FEAT_EDX_MTRR = 1u << 12,
+	CPUID_FEAT_EDX_PGE = 1u << 13,
+	CPUID_FEAT_EDX_MCA = 1u << 14,
+	CPUID_FEAT_EDX_CMOV = 1u << 15,
+	CPUID_FEAT_EDX_PAT = 1u << 16,
+	CPUID_FEAT_EDX_PSE36 = 1u << 17,
+	CPUID_FEAT_EDX_PSN = 1u << 18,
+	CPUID_FEAT_EDX_CLF = 1u << 19,
+	CPUID_FEAT_EDX_DTES = 1u << 21,
+	CPUID_FEAT_EDX_ACPI = 1u << 22,
+	CPUID_FEAT_EDX_MMX = 1u << 23,
+	CPUID_FEAT_EDX_FXSR = 1u << 24,
+	CPUID_FEAT_EDX_SSE = 1u << 25,
+	CPUID_FEAT_EDX_SSE2 = 1u << 26,
+	CPUID_FEAT_EDX_SS = 1u << 27,
+	CPUID_FEAT_EDX_HTT = 1u << 28,
+	CPUID_FEAT_EDX_TM1 = 1u << 29,
+	CPUID_FEAT_EDX_IA64 = 1u << 30,
 };
+
+u8 cpu_has_cfeature(enum cpuid_features feature);
+u8 cpu_has_dfeature(enum cpuid_features feature);
+
 #endif
 
 #endif
diff --git a/libc/inc/random.h b/libc/inc/random.h
index 59add9b..a82524c 100644
--- a/libc/inc/random.h
+++ b/libc/inc/random.h
@@ -6,6 +6,8 @@
 #include <def.h>
 
 void srand(u32 seed);
+u32 rdrand(void);
+u32 rdseed(void);
 u32 rand(void);
 char *randstr(u32 size);
 
diff --git a/libc/random.c b/libc/random.c
index 8c8076f..cfd082d 100644
--- a/libc/random.c
+++ b/libc/random.c
@@ -1,5 +1,6 @@
 // MIT License, Copyright (c) 2020 Marvin Borner
 
+#include <cpu.h>
 #include <def.h>
 #include <mem.h>
 #include <random.h>
@@ -11,6 +12,34 @@ void srand(u32 seed)
 	g_seed = seed;
 }
 
+u32 rdrand(void)
+{
+#ifdef kernel
+	if (!cpu_has_cfeature(CPUID_FEAT_ECX_RDRND))
+		return rand();
+
+	u32 rd;
+	__asm__ volatile("rdrand %%eax" : "=a"(rd));
+	return rd;
+#else
+	return rand();
+#endif
+}
+
+u32 rdseed(void)
+{
+#ifdef kernel
+	if (!cpu_has_cfeature(CPUID_FEAT_ECX_RDRND))
+		return rand();
+
+	u32 rd;
+	__asm__ volatile("rdseed %%eax" : "=a"(rd));
+	return rd;
+#else
+	return rand();
+#endif
+}
+
 u32 rand(void)
 {
 	g_seed = g_seed * 1103515245 + 12345;
-- 
cgit v1.2.3


From 0aef683b9d1e08555791426ba12223ed78051353 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Fri, 12 Mar 2021 17:27:01 +0100
Subject: Boots successfully...

---
 Makefile               |  2 +-
 apps/Makefile          |  2 +-
 apps/idle.c            |  7 +++++++
 apps/init.c            |  1 +
 kernel/features/load.c | 17 ++++-------------
 kernel/features/mm.c   | 24 +++++++++++++++---------
 kernel/features/proc.c | 19 +++++--------------
 kernel/inc/load.h      |  1 -
 kernel/inc/mm.h        |  9 ++++++++-
 libc/cpu.c             |  7 +++++++
 libc/inc/cpu.h         |  1 +
 libc/print.c           |  1 +
 12 files changed, 51 insertions(+), 40 deletions(-)
 create mode 100644 apps/idle.c

(limited to 'libc/inc/cpu.h')

diff --git a/Makefile b/Makefile
index a9817cd..1e20a7a 100644
--- a/Makefile
+++ b/Makefile
@@ -6,7 +6,7 @@ CFLAGS_DEFAULT = $(CFLAGS_WARNINGS) $(CFLAGS_OPTIMIZATION) -std=c99 -m32 -nostdl
 
 all: compile
 
-debug: CFLAGS_DEFAULT += -Wno-error -ggdb3 -s -fstack-protector-all -fsanitize=undefined
+debug: CFLAGS_DEFAULT += -Wno-error -ggdb3 -s -fsanitize=undefined # -fstack-protector-all # TODO: Fix stack protector in userspace
 debug: compile
 
 export
diff --git a/apps/Makefile b/apps/Makefile
index 8426b9c..2c6c643 100644
--- a/apps/Makefile
+++ b/apps/Makefile
@@ -1,6 +1,6 @@
 # MIT License, Copyright (c) 2020 Marvin Borner
 
-COBJS = init.o wm.o test.o window.o #mandelbrot.o window.o exec.o files.o test.o cc.o browser.o server.o
+COBJS = init.o idle.o wm.o test.o window.o #mandelbrot.o window.o exec.o files.o test.o cc.o browser.o server.o
 CC = ccache ../cross/opt/bin/i686-elf-gcc
 LD = ccache ../cross/opt/bin/i686-elf-ld
 OC = ccache ../cross/opt/bin/i686-elf-objcopy
diff --git a/apps/idle.c b/apps/idle.c
new file mode 100644
index 0000000..3f10c3e
--- /dev/null
+++ b/apps/idle.c
@@ -0,0 +1,7 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+int main(void)
+{
+	while (1)
+		;
+}
diff --git a/apps/init.c b/apps/init.c
index 7044365..9e57078 100644
--- a/apps/init.c
+++ b/apps/init.c
@@ -8,6 +8,7 @@
 
 int main(int argc, char **argv)
 {
+	log("Loaded!\n");
 	while (1) {
 	};
 	(void)argc;
diff --git a/kernel/features/load.c b/kernel/features/load.c
index ec9a387..4ad2cbf 100644
--- a/kernel/features/load.c
+++ b/kernel/features/load.c
@@ -8,25 +8,16 @@
 
 #define PROC_STACK_SIZE 0x4000
 
-/*void proc_load(struct proc *proc, u32 entry)
-{
-	u32 stack = (u32)memory_alloc(proc->page_dir, PROC_STACK_SIZE, MEMORY_USER | MEMORY_CLEAR);
-
-	proc->regs.ebp = stack;
-	proc->regs.useresp = stack;
-	proc->regs.eip = entry;
-	proc->entry = entry;
-}*/
-
 int bin_load(const char *path, struct proc *proc)
 {
 	struct stat s = { 0 };
 	vfs_stat(path, &s);
-	struct proc *current = proc_current();
-	struct page_dir *prev = current ? current->page_dir : virtual_kernel_dir();
 
-	u32 size = PAGE_ALIGN_UP(s.size);
+	struct page_dir *prev;
+	memory_backup_dir(&prev);
 	memory_switch_dir(proc->page_dir);
+
+	u32 size = PAGE_ALIGN_UP(s.size);
 	u32 data = (u32)memory_alloc(proc->page_dir, size, MEMORY_USER | MEMORY_CLEAR);
 
 	if (!vfs_read(path, (void *)data, 0, s.size)) {
diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index c39b8b7..5fe70fd 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -15,10 +15,10 @@ static struct page_table kernel_tables[256] ALIGNED(PAGE_SIZE) = { 0 };
  * Lowlevel paging
  */
 
-static void paging_disable(void)
+/*static void paging_disable(void)
 {
 	cr0_set(cr0_get() | 0x7fffffff);
-}
+}*/
 
 static void paging_enable(void)
 {
@@ -27,7 +27,6 @@ static void paging_enable(void)
 
 static void paging_switch_dir(u32 dir)
 {
-	assert(dir);
 	cr3_set(dir);
 }
 
@@ -154,7 +153,7 @@ struct memory_range physical_alloc(u32 size)
 	return memory_range(0, 0);
 }
 
-static void physical_free(struct memory_range range)
+void physical_free(struct memory_range range)
 {
 	assert(PAGE_ALIGNED(range.base) && PAGE_ALIGNED(range.size));
 	physical_set_free(range);
@@ -297,11 +296,6 @@ struct page_dir *virtual_create_dir(void)
 	return dir;
 }
 
-struct page_dir *virtual_kernel_dir(void)
-{
-	return &kernel_dir;
-}
-
 void virtual_destroy_dir(struct page_dir *dir)
 {
 	assert(dir != &kernel_dir);
@@ -326,6 +320,11 @@ void virtual_destroy_dir(struct page_dir *dir)
 	memory_free(&kernel_dir, memory_range((u32)dir, sizeof(*dir)));
 }
 
+struct page_dir *virtual_kernel_dir(void)
+{
+	return &kernel_dir;
+}
+
 /**
  * Memory wrappers
  */
@@ -405,6 +404,13 @@ void memory_switch_dir(struct page_dir *dir)
 	paging_switch_dir(virtual_to_physical(&kernel_dir, (u32)dir));
 }
 
+void memory_backup_dir(struct page_dir **backup)
+{
+	struct proc *proc = proc_current();
+	struct page_dir *dir = proc ? proc->page_dir : virtual_kernel_dir();
+	*backup = dir;
+}
+
 struct memory_range memory_range_from(u32 base, u32 size)
 {
 	u32 align = PAGE_SIZE - base % PAGE_SIZE;
diff --git a/kernel/features/proc.c b/kernel/features/proc.c
index 4d1311e..db2291c 100644
--- a/kernel/features/proc.c
+++ b/kernel/features/proc.c
@@ -76,12 +76,6 @@ void scheduler(struct regs *regs)
 	/* printf("{%d}", ((struct proc *)current->data)->pid); */
 }
 
-static void kernel_idle(void)
-{
-	while (1)
-		;
-}
-
 void proc_print(void)
 {
 	struct node *node = proc_list->head;
@@ -328,7 +322,7 @@ static s32 procfs_write(const char *path, void *buf, u32 offset, u32 count, stru
 		}
 	}
 
-	printf("%s - off: %d, cnt: %d, buf: %x, dev %x\n", path, offset, count, buf, dev);
+	printf("ERR: %s - off: %d, cnt: %d, buf: %x, dev %x\n", path, offset, count, buf, dev);
 	return -1;
 }
 
@@ -472,11 +466,10 @@ void proc_init(void)
 	vfs_mount(dev, "/proc/");
 
 	// Idle proc
-	/* struct proc *kernel_proc = proc_make(PROC_PRIV_NONE); */
-	/* proc_load(kernel_proc, (u32)kernel_idle); */
-	/* strcpy(kernel_proc->name, "idle"); */
-	/* kernel_proc->state = PROC_SLEEPING; */
-	/* idle_proc = list_add(proc_list, kernel_proc); */
+	struct proc *kernel_proc = proc_make(PROC_PRIV_NONE);
+	bin_load("/bin/idle", kernel_proc);
+	kernel_proc->state = PROC_SLEEPING;
+	idle_proc = list_add(proc_list, kernel_proc);
 
 	// Init proc (root)
 	struct node *new = list_add(proc_list, proc_make(PROC_PRIV_ROOT));
@@ -496,9 +489,7 @@ void proc_init(void)
 	/* ((u32 *)_esp)[-1] = (u32)argv; // Second argument (argv) */
 
 	printf("Jumping to userspace!\n");
-	/* printf("%x\n", ((u32 *)((struct proc *)new->data)->entry)[5]); */
 	memory_switch_dir(((struct proc *)new->data)->page_dir);
-	/* printf("%x\n", ((u32 *)((struct proc *)new->data)->entry)[5]); */
 	proc_jump_userspace();
 	while (1) {
 	};
diff --git a/kernel/inc/load.h b/kernel/inc/load.h
index 330caca..f493e84 100644
--- a/kernel/inc/load.h
+++ b/kernel/inc/load.h
@@ -5,7 +5,6 @@
 
 #include <proc.h>
 
-void proc_load(struct proc *proc, u32 entry);
 int bin_load(const char *path, struct proc *proc);
 
 #endif
diff --git a/kernel/inc/mm.h b/kernel/inc/mm.h
index aad4ffd..6a1c063 100644
--- a/kernel/inc/mm.h
+++ b/kernel/inc/mm.h
@@ -16,6 +16,7 @@ struct memory_range {
  */
 
 struct memory_range physical_alloc(u32 size);
+void physical_free(struct memory_range range);
 
 /**
  * Virtual
@@ -70,11 +71,14 @@ struct page_dir {
 	union page_dir_entry entries[PAGE_COUNT];
 } PACKED;
 
+u8 virtual_present(struct page_dir *dir, u32 vaddr);
 u32 virtual_to_physical(struct page_dir *dir, u32 vaddr);
 void virtual_map(struct page_dir *dir, struct memory_range prange, u32 vaddr, u32 flags);
 struct memory_range virtual_alloc(struct page_dir *dir, struct memory_range physical_range,
 				  u32 flags);
+void virtual_free(struct page_dir *dir, struct memory_range vrange);
 struct page_dir *virtual_create_dir(void);
+void virtual_destroy_dir(struct page_dir *dir);
 struct page_dir *virtual_kernel_dir(void);
 
 /**
@@ -89,10 +93,13 @@ struct page_dir *virtual_kernel_dir(void);
 struct memory_range memory_range_from(u32 base, u32 size);
 struct memory_range memory_range_around(u32 base, u32 size);
 
-void memory_install(struct mem_info *mem_info);
 void *memory_alloc(struct page_dir *dir, u32 size, u32 flags);
 void *memory_alloc_identity(struct page_dir *dir, u32 flags);
+void memory_map_identity(struct page_dir *dir, struct memory_range prange, u32 flags);
 void memory_free(struct page_dir *dir, struct memory_range vrange);
 void memory_switch_dir(struct page_dir *dir);
+void memory_backup_dir(struct page_dir **backup);
+
+void memory_install(struct mem_info *mem_info);
 
 #endif
diff --git a/libc/cpu.c b/libc/cpu.c
index cb9aa49..8ca4d27 100644
--- a/libc/cpu.c
+++ b/libc/cpu.c
@@ -82,6 +82,13 @@ void cr0_set(u32 cr0)
 	__asm__ volatile("movl %%eax, %%cr0" ::"a"(cr0));
 }
 
+u32 cr3_get(void)
+{
+	u32 cr3;
+	__asm__ volatile("movl %%cr0, %%eax" : "=a"(cr3));
+	return cr3;
+}
+
 void cr3_set(u32 cr3)
 {
 	__asm__ volatile("movl %%eax, %%cr3" ::"a"(cr3));
diff --git a/libc/inc/cpu.h b/libc/inc/cpu.h
index 161b7a4..d709d86 100644
--- a/libc/inc/cpu.h
+++ b/libc/inc/cpu.h
@@ -29,6 +29,7 @@ void fpu_restore(void);
 
 u32 cr0_get(void);
 void cr0_set(u32 cr0);
+u32 cr3_get(void);
 void cr3_set(u32 cr3);
 u32 cr4_get(void);
 void cr4_set(u32 cr4);
diff --git a/libc/print.c b/libc/print.c
index 173e117..1c577e5 100644
--- a/libc/print.c
+++ b/libc/print.c
@@ -238,6 +238,7 @@ NORETURN void panic(const char *format, ...)
 	vsprintf(buf, format, ap);
 	va_end(ap);
 #ifdef kernel
+	print("--- DON'T PANIC! ---\n");
 	print(buf);
 	loop();
 #else
-- 
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