From 69e9aab1ff93a859309fcf263c6b87d92dad8c5c Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Wed, 12 Jul 2017 09:40:30 +0100
Subject: [PATCH] ptdump, need make arch ifdefs

---
 kernel_module/Makefile          |  8 +++
 kernel_module/README.md         |  1 +
 kernel_module/page_table_dump.c | 98 +++++++++++++++++++++++++++++++++
 3 files changed, 107 insertions(+)
 create mode 100644 kernel_module/page_table_dump.c

diff --git a/kernel_module/Makefile b/kernel_module/Makefile
index a4e48d9..eaf60d8 100644
--- a/kernel_module/Makefile
+++ b/kernel_module/Makefile
@@ -1,6 +1,14 @@
 obj-m += $(addsuffix .o, $(notdir $(basename $(wildcard $(BR2_EXTERNAL_KERNEL_MODULE_PATH)/*.c))))
 ccflags-y := -DDEBUG -g -std=gnu99 -Wno-declaration-after-statement
 
+#ifneq ($(BR2_ARCH), x86_64)
+#	obj-m := $(filter-out page_table_dump.o, $(obj-m))
+#endif
+#
+#ifneq ($(BR2_ARCH), arm)
+#	obj-m := $(filter-out platform_device.o, $(obj-m))
+#endif
+
 .PHONY: all clean
 
 all:
diff --git a/kernel_module/README.md b/kernel_module/README.md
index 8913db3..2315b56 100644
--- a/kernel_module/README.md
+++ b/kernel_module/README.md
@@ -25,6 +25,7 @@
         1. [dep](dep.c)
         1. [dep2](dep2.c)
     1.  [character_device](character_device.c)
+    1.  [page_table_dump](page_table_dump.c)
     1.  Hardware device drivers
         1. [pci_min](pci_min.c)
         1. [pci](pci.c)
diff --git a/kernel_module/page_table_dump.c b/kernel_module/page_table_dump.c
new file mode 100644
index 0000000..fc9e9a0
--- /dev/null
+++ b/kernel_module/page_table_dump.c
@@ -0,0 +1,98 @@
+/*
+Adapted from: https://github.com/jethrogb/ptdump
+
+TODO: use kernel constants instead of hard-coding everything to make this
+more platform independent.
+*/
+
+#error
+
+#include <asm/io.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+#define pte_address(p) ((p)&0x000ffffffffff000UL)
+typedef unsigned long long ullong;
+
+static void output(void* p, void* data, ullong len) {
+	seq_write((struct seq_file *)p, data, len);
+}
+
+static ullong * read_page(void* p, ullong address) {
+	return (ullong*)phys_to_virt(address);
+}
+
+static ullong* ptdump_dump(void *p, ullong address) {
+	ullong* page = read_page(p, address);
+	if (page) {
+		output(p, &address, 8);
+		output(p, page, 4096);
+	}
+	return page;
+}
+
+static void ptdump_page(void *p, ullong address, int levels_remaining);
+
+static void ptdump_recurse(void *p, ullong* page, int levels_remaining) {
+	int i;
+	for (i = 0; i < 512; i++) {
+		if ((page[i] & 1) && !(page[i] & (1 << 7)))
+			ptdump_page(p, pte_address(page[i]), levels_remaining - 1);
+	}
+}
+
+static void ptdump_page(void *p, ullong address, int levels_remaining) {
+	ullong* page = ptdump_dump(p, address);
+	if (!page) return;
+	if (levels_remaining > 0)
+		ptdump_recurse(p, page, levels_remaining);
+}
+
+static ullong get_base(void* p) {
+	return read_cr3();
+}
+
+static void ptdump(void *p, int levels) {
+	ptdump_page(p, get_base(p), levels);
+}
+
+static int do_ptdump(struct seq_file *m, void* v) {
+	ptdump(m, (int)(unsigned long)(m->private));
+	return 0;
+}
+
+static int ptdump_open(struct inode *inode, struct file *fp) {
+	return single_open(fp, do_ptdump, PDE_DATA(inode));
+}
+
+static const struct file_operations ptdump_fops = {
+	.open    = ptdump_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = single_release,
+};
+
+static struct proc_dir_entry *proc_page_table0;
+static struct proc_dir_entry *proc_page_table1;
+static struct proc_dir_entry *proc_page_table2;
+static struct proc_dir_entry *proc_page_table3;
+
+static int __init ptdump_module_init(void) {
+	proc_page_table0 = proc_create_data("page_table_0", 0444, NULL, &ptdump_fops,(void*)0);
+	proc_page_table1 = proc_create_data("page_table_1", 0444, NULL, &ptdump_fops,(void*)1);
+	proc_page_table2 = proc_create_data("page_table_2", 0444, NULL, &ptdump_fops,(void*)2);
+	proc_page_table3 = proc_create_data("page_table_3", 0444, NULL, &ptdump_fops,(void*)3);
+	return 0;
+}
+
+static void __exit ptdump_module_exit(void) {
+	proc_remove(proc_page_table0);
+	proc_remove(proc_page_table1);
+	proc_remove(proc_page_table2);
+	proc_remove(proc_page_table3);
+}
+
+module_init(ptdump_module_init);
+module_exit(ptdump_module_exit);
+MODULE_LICENSE("GPL");