description/scheduler: scheduler eBPF vs ghOSt

2026-09-20 19:33:40 +08:00 · 2021-09-27 15:00:12 +08:00
parent b10951aa25
commit 2fca15093d
5 changed files with 249 additions and 4 deletions
@@ -0,0 +1,32 @@
+ifneq ($(KERNELRELEASE),)
+
+obj-m := list_vma.o
+
+else
+
+KERNELDIR ?= /lib/modules/$(shell uname -r)/build
+
+PWD := $(shell pwd)
+
+all:
+	make -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	make -C $(KERNELDIR) M=$(PWD) clean
+
+
+endif
+
+
+
+insmod:
+	sudo insmod ./kv2p.ko
+
+rmmod:
+	sudo rmmod kv2p
+
+reinsmod:
+	make rmmod
+	make insmod
+
+
@@ -0,0 +1,155 @@
+| 日期 | 内核版本 | 架构| 作者 | GitHub| CSDN |
+| ------------- |:-------------:|:-------------:|:-------------:|:-------------:|:-------------:|
+| 2016-07-21  | [Linux-4.7](http://lxr.free-electrons.com/source/?v=4.7) | X86 & arm | [gatieme](http://blog.csdn.net/gatieme) | [LinuxDeviceDrivers](https://github.com/gatieme/LDD-LinuxDeviceDrivers) | [Linux进程管理与调度](http://blog.csdn.net/gatieme/article/category/6393814) |
+
+
+
+#1	内核虚拟地址与物理地址的转换
+-------
+
+| 函数 | 描述 | 底层函数 |
+|:---:|:---:|:--------:|
+| phys_addr_t virt_to_phys(volatile void *address) | 将内核的虚拟地址转换为物理地址 | \__pa或者  \__virt_to_phys |
+| void *phys_to_virt(phys_addr_t x) | 将物理地址转换为虚拟内核 | \__va或者\__phys_to_virt |
+
+其中phy_addr_t用以表示一个内存地址, 定义在[include/linux/types.h](http://lxr.free-electrons.com/source/include/linux/types.h#L161)中
+
+```c
+#ifdef CONFIG_PHYS_ADDR_T_64BIT
+	typedef u64 phys_addr_t;
+#else
+	typedef u32 phys_addr_t;
+#endif
+```
+
+可以通过搜索我们内核的.config文件搜索CONFIG_PHYS_ADDR_T_64BIT这个配置参数
+
+```c
+cat /usr/src/linux-headers-4.2.0-36-generic/.config | grep CONFIG_PHYS_ADDR_T_64BIT
+```
+
+![CONFIG_PHYS_ADDR_T_64BIT参数](./images/CONFIG_PHYS_ADDR_T_64BIT.png)
+
+
+#2	virt_to_phys/phys_to_virt实现
+-------
+
+##2.1	不同架构的实现
+-------
+
+
+| 架构     | 定义    |
+|:-------:|:-------:|
+| 标准     | [include/asm-generic/io.h, line 724](http://lxr.free-electrons.com/source/include/asm-generic/io.h?v4.7#L724)
+| arm     | [arch/arm/include/asm/memory.h, line 272](http://lxr.free-electrons.com/source/arch/arm/include/asm/memory.h?v4.7#L272) |
+| arm64   | [arch/arm64/include/asm/memory.h](http://lxr.free-electrons.com/source/arch/arm64/include/asm/memory.h?v4.7#L189) |
+| x86     |[arch/x86/include/asm/io.h, line 118](http://lxr.free-electrons.com/source/arch/x86/include/asm/io.h?v4.7#L118)
+
+
+
+*	virt_to_phys函数在内核中是通过\__pa或者\__virt_to_phys函数实现的
+
+*	phys_to_virt函数在内核中是通过\__va或者\__phys_to_virt函数实现的
+
+
+
+
+##2.2	arm64上的实现
+
+不同架构的实现有细微差别, 但是其基本思路是一致的
+
+
+下面我们就以arm64上的实现为例进行讲解, 定义在[arch/arm64/include/asm/memory.h](http://lxr.free-electrons.com/source/arch/arm64/include/asm/memory.h?v4.7#L184)
+
+```c
+/*
+ * These are *only* valid on the kernel direct mapped RAM memory.
+ * Note: Drivers should NOT use these.  They are the wrong
+ * translation for translating DMA addresses.  Use the driver
+ * DMA support - see dma-mapping.h.
+ */
+#define virt_to_phys virt_to_phys
+static inline phys_addr_t virt_to_phys(const volatile void *x)
+{
+    return __virt_to_phys((unsigned long)(x));
+}
+
+#define phys_to_virt phys_to_virt
+static inline void *phys_to_virt(phys_addr_t x)
+{
+    return (void *)__phys_to_virt(x);
+}
+
+/*
+ * Drivers should NOT use these either.
+ */
+#define __pa(x)         __virt_to_phys((unsigned long)(x))
+#define __va(x)         ((void *)__phys_to_virt((phys_addr_t)(x)))
+#define pfn_to_kaddr(pfn)       __va((phys_addr_t)(pfn) << PAGE_SHIFT)
+```
+
+
+可以看到真是的实现是__virt_to_phys和__phys_to_virt函数实现的
+
+
+
+##2.3	__virt_to_phys函数
+-------
+
+__virt_to_phys函数定义在[arch/arm64/include/asm/memory.h, line 109](http://lxr.free-electrons.com/source/arch/arm64/include/asm/memory.h?v=4.7#L109)
+
+```c
+/*
+ * Physical vs virtual RAM address space conversion.  These are
+ * private definitions which should NOT be used outside memory.h
+ * files.  Use virt_to_phys/phys_to_virt/__pa/__va instead.
+ */
+#define __virt_to_phys(x) ({                        \
+    phys_addr_t __x = (phys_addr_t)(x);                 \
+    __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET :   \
+                 (__x - kimage_voffset); })
+
+```
+
+其中\__x中间变量是内核的一点小技巧, 通过宏实现的函数没有检查, 比如传入一个x++
+
+其主要操作就是
+
+```c
+__x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : (__x - kimage_voffset); })
+```
+
+##2.4	__phys_to_virt函数
+-------
+
+__phys_to_virt函数定义在[arch/arm64/include/asm/memory.h, line 114](http://lxr.free-electrons.com/source/arch/arm64/include/asm/memory.h?v=4.7#L114)
+
+
+```c
+#define __phys_to_virt(x)       ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
+```
+
+##2.5	__phys_to_kimg函数
+-------
+
+```c
+#define __phys_to_kimg(x)       ((unsigned long)((x) + kimage_voffset))
+```
+
+##2.6	page_to_phys和phys_to_page函数
+-------
+
+```c
+/*
+ * Convert a page to/from a physical address
+ */
+#define page_to_phys(page)      (__pfn_to_phys(page_to_pfn(page)))
+#define phys_to_page(phys)      (pfn_to_page(__phys_to_pfn(phys)))
+```
+
+
+
+
+
+
+
@@ -0,0 +1,45 @@
+/*****************************************************************
+文件名：mem.c
+输入参数：
+pid 接收待查询进程的PID
+va 接收待查询的虚拟地址
+*****************************************************************/
+
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+
+MODULE_LICENSE("GPL");
+
+
+static unsigned long VA;
+module_param(VA, ulong, 0644);
+
+
+
+static int __init kv2p_init(void)
+{
+    int value = 10;
+    // use virt_to_phys
+    // http://lxr.free-electrons.com/source/arch/arm64/include/asm/memory.h?v4.7#L189
+
+    phys_addr_t phyaddr = virt_to_phys((const volatile void *)&value);
+    printk("0x%lx\n", (unsigned long )phyaddr);
+
+    return 0;
+}
+
+
+
+static void __exit kv2p_exit(void)
+{
+    printk(KERN_INFO"Goodbye!\n");
+}
+
+module_init(kv2p_init);
+module_exit(kv2p_exit);