kernel常用函式、巨集、結構體
阿新 • • 發佈：2019-01-23
1 __setup
在include/linux/init.h檔案中定義
#define __setup_param(str, unique_id, fn, early) \
static const char __setup_str_##unique_id[] __initconst \
__aligned(1) = str; \
static struct obs_kernel_param __setup_##unique_id \
__used __section(.init.setup) \
__attribute__((aligned((sizeof __setup在kernel啟動時用來讀取、解析cmdline。str可以當成一個變數，fn是用來處理str變數的函式
ldb.c kernel_imx\drivers\video\mxc檔案使用到這個巨集
static int __init ldb_setup(char *options)
{
if 當前使用的cmdline部分內容為
bootargs=console=ttymxc0,115200 androidboot.console=ttymxc0 vmalloc=400M init=/init video=mxcfb0:dev=ldb,LDB-1080P60,if=RGB24,bpp=32 ldb=spl0ldb=spl0，那麼ldb_setup的引數就是spl0。巨集的展開
__setup("ldb=", ldb_setup);
__setup_param("ldb=", ldb_setup, ldb_setup， 0) //定義兩個變數
static const char __setup_str_ldb_setup[] __initconst __aligned(1) = "ldb="; //字串陣列
static struct obs_kernel_param __setup_ldb_setup __used __section(.init.setup) //結構體 __attribute__((aligned((sizeof(long))))) = {
__setup_str_ldb_setup, ldb_setup, 0
}2 early_param
定義如下，除了__setup_param的最後一個引數，其他的跟__setup的定義是一樣的，定義兩個變數，引數不同。
#define early_param(str, fn) /
__setup_param(str, fn, fn, 1)early_param和__setup定義的變數都是在main.c (kernel_imx\init) start_kernel函式中處理的。
parse_early_param()； //處理early_param定義的變數，實際最後還是呼叫了parse_args函式，引數不一樣
parse_args("Booting kernel", static_command_line, __start___param,
__stop___param - __start___param,
&unknown_bootoption);//處理 __setup定義的變數3 MACHINE_START
4 __attribute__編譯屬性 section
本節內容從__attribute__編譯屬性—section轉載
__attribute__ 是gcc編譯屬性，主要用於改變所宣告或定義的函式或資料的特性，它有很多子項，用於改變作用物件的特性。比如對函式，noline將禁止進行內聯擴充套件、noreturn表示沒有返回值、pure表明函式除返回值外，不會通過其它（如全域性變數、指標）對函式外部產生任何影響。核心中出現比較多是section, section對程式碼段起作用。
目前支援以下變數屬性
• address (addr)
• aligned (alignment)
• boot
• deprecated
• fillupper
• far
• mode (mode)
• near
• noload
• packed
• persistent
• reverse (alignment)
• section ("section-name")
• secure
• sfr (address)
• space (space)
• transparent_union
• unordered
• unused
• weak
__attribute__的section子項的使用格式為：
__attribute__((section("section_name")))
其作用是將作用的函式或資料放入指定名為"section_name"輸入段。 輸入段和輸出段是相對於要生成最終的elf或binary時的Link過程說的，Link過程的輸入大都是由原始碼編繹生成的目標檔案.o，那麼這些.o檔案中包含的段相對link過程來說就是輸入段，而Link的輸出一般是可執行檔案elf或庫等，這些輸出檔案中也包含有段，這些輸出檔案中的段就叫做輸出段。輸入段和輸出段本來沒有什麼必然的聯絡，是互相獨立，只是在Link過程中，Link程式會根據一定的規則（這些規則其實來源於Link Script），將不同的輸入段重新組合到不同的輸出段中，即使是段的名字，輸入段和輸出段可以完全不同。
int var __attribute__((section(".xdata"))) = 0;
這樣定義的變數var將被放入名為.xdata的輸入段，（注意：attribute這種用法中的括號很嚴格，這裡的幾個括號好象一個也不能少。）__attribute__的section屬性只指定物件的輸入段，它並不能影響所指定物件最終會放在可執行檔案的什麼段。
__init 巨集最常用的地方是驅動模組初始化函式的定義處，其目的是將驅動模組的初始化函式放入名叫.init.text的輸入段。對於__initdata來說，用於資料定義，目的是將資料放入名叫.init.data的輸入段。
4.1 initcall巨集定義
原始碼
#define __define_initcall(level,fn,id) \
static initcall_t __initcall_##fn##id __used \
__attribute__((__section__(".initcall" level ".init"*強調內容*))) = fn 其用來定義型別為initcall_t的static函式指標，函式指標的名稱由引數fn和id決定：_initcall##fn##id，這就是函式指標的名稱，它其實是一個變數名稱。從該名稱的定義方法我們其學到了巨集定義的一種高階用法，即利用巨集的引數產生名稱，這要藉助於”##”這一符號組合的作用。
這一函式指標變數放入什麼輸入段呢，請看__attribute__ ((__section__ (“.initcall” levle “.init”)))，輸入段的名稱由level決定，如果level=”1”，則輸入段是.initcall1.init，如果level=”3s”，則輸入段是.initcall3s.init。這一函式指標變數就是放在用這種方法決定的輸入段中的。
5 current
kernel中current是一個巨集，返回當前程序task_struct結構的指標。參考文件
定義如下，
/* arch/arm/include/asm/current.h */
static inline struct task_struct *get_current(void)
{
return current_thread_info()->task;
}
// current巨集
#define current (get_current()) sp為當前程序核心棧棧頂地址
/* arch/arm/include/asm/thread_info.h */
static inline struct thread_info *current_thread_info(void)
{
register unsigned long sp asm ("sp");
return (struct thread_info *)(sp & ~(THREAD_SIZE - 1));
} 每個程序在核心態下都會開闢一個核心棧，一般就是8KB，一般把thread_info這個結構體和核心棧放在一起，這樣核心就可以很方便從ESP暫存器中獲取當前CPU上正在執行的thread_info。具體的位置是thread_info結構儲存在8K起始位置，如下圖所示：
無論esp是指向哪裡，只要將其低13位遮蔽掉，總能找到8K的起始地址，也就是圖中的0x015fa000，這樣我們就找到了thread_info，而task也就是tast_struct結構休是thread_info的成員，thread_info->task就是當前程序task_struct結構體指標。
上圖是以x86架構畫的圖，arm cpu也是一樣的處理邏輯，只是 將esp改成sp
struct thread_info結構體
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
__u32 cpu; /* cpu */
__u32 cpu_domain; /* cpu domain */
struct cpu_context_save cpu_context; /* cpu context */
__u32 syscall; /* syscall number */
__u8 used_cp[16]; /* thread used copro */
unsigned long tp_value;
struct crunch_state crunchstate;
union fp_state fpstate __attribute__((aligned(8)));
union vfp_state vfpstate;
#ifdef CONFIG_ARM_THUMBEE
unsigned long thumbee_state; /* ThumbEE Handler Base register */
#endif
struct restart_block restart_block;
};核心做的大部分動作是代表一個特定程序的，可以將核心看作是一個特殊的程序，應用層的是普通程序。在一個系統呼叫執行期間，例如 open 或者 read， 當前程序是發出呼叫的程序。核心程式碼可以通過使用 current 來使用程序特定的資訊，此時的current是發出呼叫的程序的task_struct指標。
6 關於開啟裝置結點(struct inode和struct file)
當在應用層多個終端或者檔案上同時開啟同一個裝置結點，如：/dev/stdin時，fd = open(“/dev/stdin”, O_RDWR)
返回的fd不總是同一個值，由當前終端決定，有可能相同，也有可能不同，也就是說fd是不確定的，由系統的環境決定。
但是在kernel所有開啟的結點都指向同一個inode(struct inode)，也就是說，無論應用層開啟多少次，在kernel看來都是同一個檔案。其呼叫的方法、使用的資料都是一致的。但是每次開啟結點檔案，kernel都會分配一個struct file *filp，file是與上層應用的檔案描述符想對應的，在一個程序(無論是否在一個程序、執行緒)，多次開啟結點，會分配多個struct file結構體，並返回不同的fd。
不僅是結點檔案，普通檔案同樣適用。
總結：應用層多次開啟檔案，kernel只分配一次struct inode，多次分配struct file，返回多個不同的fd
7 struct page
struct page 表示一個記憶體頁框，是記憶體管理的最小單位，通常一個頁框的大小是4K，kernel會為每個記憶體頁框分配一個struct page結構體。下面是struct page部分程式碼
struct page {
/* First double word block */
unsigned long flags; /* 體系結構無關的標記，用於描述頁的屬性，flags中的每一個bit，定義了page的一種屬性 */
struct address_space *mapping; /* a: 如果mapping = 0，說明該page屬於交換快取（swap cache）；當需要使用地址空間時會指定交換分割槽的地址空間swapper_space。
b: 如果mapping != 0，bit[0] = 0，說明該page屬於頁快取或檔案對映，mapping指向檔案的地址空間address_space。
c: 如果mapping != 0，bit[0] != 0，說明該page為匿名對映，mapping指向struct anon_vma物件。
通過mapping恢復anon_vma的方法：anon_vma = (struct anon_vma *)(mapping - PAGE_MAPPING_ANON)。
*/
/* Second double word */
struct {
union {
pgoff_t index; /* Our offset within mapping.在對映的虛擬空間（vma_area）內的偏移；一個檔案可能只對映一部分，
假設映射了1M的空間，index指的是在1M空間內的偏移，而不是在整個檔案內的偏移 */
void *freelist; /* slub first free object */
};
union {
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
/* Used for cmpxchg_double in slub */
unsigned long counters;
#else
/*
* Keep _count separate from slub cmpxchg_double data.
* As the rest of the double word is protected by
* slab_lock but _count is not.
*/
unsigned counters;
#endif
struct {
union {
/*
被頁表對映的次數，也就是說該page同時被多少個程序共享。初始值為-1，如果只被一個程序的頁表映射了，該值為0 。
如果該page處於夥伴系統中，該值為PAGE_BUDDY_MAPCOUNT_VALUE（-128），核心通過判斷該值是否為PAGE_BUDDY_MAPCOUNT_VALUE
來確定該page是否屬於夥伴系統
*/
atomic_t _mapcount;
struct {
unsigned inuse:16;
unsigned objects:15;
unsigned frozen:1;
};
};
atomic_t _count; /* 表示核心中引用該頁的次數。當值為0時，表示page當前沒有使用者，那麼這個page可以被釋放，
否則的話表示這個page有使用者。_mapcount表示的是對映次數，而_count表示的是使用次數；
被映射了不一定在使用，但要使用必須先對映
*/
};
};
};
/* Third double word block */
union {
struct list_head lru; /* Pageout list, eg. active_list
* protected by zone->lru_lock !
*/
struct { /* slub per cpu partial pages */
struct page *next; /* Next partial slab */
#ifdef CONFIG_64BIT
int pages; /* Nr of partial slabs left */
int pobjects; /* Approximate # of objects */
#else
short int pages;
short int pobjects;
#endif
};
};
/* Remainder is not double word aligned */
union {
unsigned long private; /* Mapping-private opaque data:
* usually used for buffer_heads
* if PagePrivate set; used for
* swp_entry_t if PageSwapCache;
* indicates order in the buddy
* system if PG_buddy is set.
*/
#if defined(WANT_PAGE_VIRTUAL)
void *virtual; /* Kernel virtual address (NULL if not kmapped, ie. highmem)指向本頁框的核心虛擬地址，
virtual只用於高階記憶體中的頁，這是因為高階記憶體的頁，無法簡單的通過該頁的實體地址計算出線性地址。
當然如果高階記憶體還沒有對映到kernel時，地址為空 */
#endif /* WANT_PAGE_VIRTUAL */
}8 struct mm_struct
轉載
task_struct，叫做程序描述符，而mm_struct 叫做記憶體描述符，描述linux下程序的地址空間的所有的資訊。
一個程序的虛擬地址空間主要由兩個資料結構來描述。一個是最高層次的：mm_struct，一個是較高層次的：vm_area_struct。最高層次的mm_struct結構描述了一個程序的整個虛擬地址空間。較高層次的結構vm_area_truct描述了虛擬地址空間的一個區間（簡稱虛擬區）。每個程序只有一個mm_struct結構，在每個程序的task_struct結構中，有一個指向該程序的結構。下面來看下mm_struct在核心中的位置。
圖8-1 程序的地址空間的分佈
mm_struct儲存了一個程序程式碼段(start_code ~ end_code)、DATA段(start_data ~ end_data)、BSS段、堆(start_brk ~ brk)棧(stack_start ~ stack_end)、mmap(mmap_base是維護共享對映區的起始地址) 地址。這些地址通過頁錶轉換可以找到對應的實體地址。task_struct用mm、active_mm變數來指向當前程序的mm_struct結構體。
每一個程序都會有自己獨立的mm_struct，這樣每一個程序都會有自己獨立的地址空間，這樣才能互不干擾。當程序之間的地址空間被共享的時候，我們可以理解為這個時候是多個程序使用一份地址空間，這就是執行緒。
圖 8-2 程序虛擬地址空間
多個程序的地址空間分佈如 圖8-2 一樣，每一個程序的使用者空間在32位的平臺上就是上面這個圖的情況，對於實體記憶體當中的核心kernel，是隻存在一份，所有的程序是用來共享的，核心當中會利用PCB（程序控制塊）來管理不同的程序。
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs， 連結串列，每個vm_area_struct虛擬記憶體區間，就是mm_struct的一段 */
struct rb_root mm_rb; /* 紅黑樹，跟mmap一樣用來組織各個段，使用的演算法不一樣，用紅黑樹來管理 */
struct vm_area_struct * mmap_cache; /* 用來儲存最後使用的 vm_area_struct，如果下次還要使用就不用從連結串列中找 */
#ifdef CONFIG_MMU
unsigned long (*get_unmapped_area) (struct file *filp,
unsigned long addr, unsigned long len,
unsigned long pgoff, unsigned long flags);
void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
#endif
unsigned long mmap_base; /* base of mmap area, mmap的起始地址*/
unsigned long task_size; /* size of task vm space 當前程序虛擬地址空間大小 */
unsigned long cached_hole_size; /* if non-zero, the largest hole below free_area_cache */
unsigned long free_area_cache; /* first hole of size cached_hole_size or larger */
pgd_t * pgd; /* pgt區間是用來維護頁表的目錄，每一個程序的都有自己的頁表目錄，需要注意程序的頁目錄和核心的頁目錄
是不一樣的，當程式排程器排程程式執行的時候，這個時候這個地址就會轉換成為實體地址，linux一般採用
三級頁表進行轉換。 */
atomic_t mm_users; /* How many users with user space? 程序數量值（在多執行緒的情況下尤為適用） */
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) 引用計數 */
int map_count; /* number of VMAs mmap連結串列中個數 */
spinlock_t page_table_lock; /* Protects page tables and some counters 頁表鎖 */
struct rw_semaphore mmap_sem;
struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung
* together off init_mm.mmlist, and are protected
* by mmlist_lock，通過mmlist將當前mm_struct新增到系統全域性的mm_struct連結串列中
*/
unsigned long hiwater_rss; /* High-watermark of RSS usage */
unsigned long hiwater_vm; /* High-water virtual memory usage */
//程序地址空間的大小，鎖住無法換頁的個數，共享檔案記憶體對映的頁數，可執行記憶體對映中的頁數
unsigned long total_vm; /* Total pages mapped */
unsigned long locked_vm; /* Pages that have PG_mlocked set */
unsigned long pinned_vm; /* Refcount permanently increased */
unsigned long shared_vm; /* Shared pages (files) */
unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE */
//使用者態堆疊的頁數
unsigned long stack_vm; /* VM_GROWSUP/DOWN */
unsigned long reserved_vm; /* VM_RESERVED|VM_IO pages */
unsigned long def_flags;
unsigned long nr_ptes; /* Page table pages */
//維護程式碼段和資料段
unsigned long start_code, end_code, start_data, end_data;
//維護堆和棧
unsigned long start_brk, brk, start_stack;
//維護命令列引數，命令列引數的起始地址和最後地址，以及環境變數的起始地址和最後地址
unsigned long arg_start, arg_end, env_start, env_end;
unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
/*
* Special counters, in some configurations protected by the
* page_table_lock, in other configurations by being atomic.
*/
struct mm_rss_stat rss_stat;
struct linux_binfmt *binfmt;
cpumask_var_t cpu_vm_mask_var;
/* Architecture-specific MM context */
mm_context_t context;
/* Swap token stuff */
/*
* Last value of global fault stamp as seen by this process.
* In other words, this value gives an indication of how long
* it has been since this task got the token.
* Look at mm/thrash.c
*/
unsigned int faultstamp;
unsigned int token_priority;
unsigned int last_interval;
unsigned long flags; /* Must use atomic bitops to access the bits */
struct core_state *core_state; /* coredumping support */
#ifdef CONFIG_AIO
spinlock_t ioctx_lock;
struct hlist_head ioctx_list;
#endif
#ifdef CONFIG_MM_OWNER
/*
* "owner" points to a task that is regarded as the canonical
* user/owner of this mm. All of the following must be true in
* order for it to be changed:
*
* current == mm->owner
* current->mm != mm
* new_owner->mm == mm
* new_owner->alloc_lock is held
*/
struct task_struct __rcu *owner;
#endif
/* store ref to file /proc/<pid>/exe symlink points to */
struct file *exe_file;
unsigned long num_exe_file_vmas;
#ifdef CONFIG_MMU_NOTIFIER
struct mmu_notifier_mm *mmu_notifier_mm;
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
struct cpumask cpumask_allocation;
#endif
};9 struct task_struct
struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped volatile關鍵字是降低編譯器對程式碼的優化，state變數一直從變數的記憶體中讀取內容而不是暫存器 */
void *stack; //用來維護程序的核心棧
atomic_t usage;
unsigned int flags; /* per process flags, defined below */
unsigned int ptrace;
#ifdef CONFIG_SMP
struct llist_node wake_entry;
int on_cpu;
#endif
int on_rq;
//優先順序,用於程序排程
/*
static_prio 用來儲存靜態優先順序，可以呼叫nice系統直接來修改取值範圍為100~139
rt_priority 用來儲存實時優先順序,取值範圍為0~99
prio 用來儲存動態優先順序
normal_prio 它的值取決於靜態優先順序和排程策略
*/
int prio, static_prio, normal_prio;
unsigned int rt_priority;
const struct sched_class *sched_class;
struct sched_entity se;
struct sched_rt_entity rt;
#ifdef CONFIG_CGROUP_SCHED
struct task_group *sched_task_group;
#endif
#ifdef CONFIG_PREEMPT_NOTIFIERS
/* list of struct preempt_notifier: */
struct hlist_head preempt_notifiers;
#endif
/*
* fpu_counter contains the number of consecutive context switches
* that the FPU is used. If this is over a threshold, the lazy fpu
* saving becomes unlazy to save the trap. This is an unsigned char
* so that after 256 times the counter wraps and the behavior turns
* lazy again; this to deal with bursty apps that only use FPU for
* a short time
*/
unsigned char fpu_counter;
#ifdef CONFIG_BLK_DEV_IO_TRACE
unsigned int btrace_seq;
#endif
unsigned int policy;
cpumask_t cpus_allowed;
#ifdef CONFIG_PREEMPT_RCU
int rcu_read_lock_nesting;
char rcu_read_unlock_special;
struct list_head rcu_node_entry;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
#ifdef CONFIG_TREE_PREEMPT_RCU
struct rcu_node *rcu_blocked_node;
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
#ifdef CONFIG_RCU_BOOST
struct rt_mutex *rcu_boost_mutex;
#endif /* #ifdef CONFIG_RCU_BOOST */
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
struct sched_info sched_info;
#endif
struct list_head tasks;
#ifdef CONFIG_SMP
struct plist_node pushable_tasks;
#endif
//程序地址空間,mm指定mm_struct連結串列，active_mm指定mm_struct紅黑樹
struct mm_struct *mm, *active_mm;
#ifdef CONFIG_COMPAT_BRK
unsigned brk_randomized:1;
#endif
#if defined(SPLIT_RSS_COUNTING)
struct task_rss_stat rss_stat;
#endif
/* task state */
int exit_state;
int exit_code, exit_signal;
int pdeath_signal; /* The signal sent when the parent dies */
unsigned int jobctl; /* JOBCTL_*, siglock protected */
/* ??? */
unsigned int personality;
unsigned did_exec:1;
unsigned in_execve:1; /* Tell the LSMs that the process is doing an
* execve */
unsigned in_iowait:1;
/* task may not gain privileges */
unsigned no_new_privs:1;
/* Revert to default priority/policy when forking */
unsigned sched_reset_on_fork:1;
unsigned sched_contributes_to_load:1;
#ifdef CONFIG_GENERIC_HARDIRQS
/* IRQ handler threads */
unsigned irq_thread:1;
#endif
pid_t pid; //程序的識別符號
pid_t tgid; //執行緒組識別符號
#ifdef CONFIG_CC_STACKPROTECTOR
/* Canary value for the -fstack-protector gcc feature */
unsigned long stack_canary;
#endif
/* 程序之間的親屬關係
* pointers to (original) parent process, youngest child, younger sibling,
* older sibling, respectively. (p->father can be replaced with
* p->real_parent->pid)
*/
struct task_struct __rcu *real_parent; /* real parent process */
struct task_struct __rcu *parent; /* recipient of SIGCHLD, wait4() reports */
/*
* children/sibling forms the list of my natural children
*/
struct list_head children; /* list of my children */
struct list_head sibling; /* linkage in my parent's children list */
struct task_struct *group_leader; /* threadgroup leader */
/*
* ptraced is the list of tasks this task is using ptrace on.
* This includes both natural children and PTRACE_ATTACH targets.
* p->ptrace_entry is p's link on the p->parent->ptraced list.
*/
struct list_head ptraced;
struct list_head ptrace_entry;
/* PID/PID hash table linkage. */
struct pid_link pids[PIDTYPE_MAX];
struct list_head thread_group;
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */
cputime_t utime, stime, utimescaled, stimescaled;
cputime_t gtime;
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
cputime_t prev_utime, prev_stime;
#endif
unsigned long nvcsw, nivcsw; /* context switch counts */
struct timespec start_time; /* monotonic time */
struct timespec real_start_time; /* boot based time */
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
unsigned long min_flt, maj_flt;
struct task_cputime cputime_expires;
struct list_head cpu_timers[3];
/* process credentials */
const struct cred __rcu *real_cred; /* objective and real subjective task
* credentials (COW) */
const struct cred __rcu *cred; /* effective (overridable) subjective task
* credentials (COW) */
struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */
char comm[TASK_COMM_LEN]; /* executable name excluding path
- access with [gs]et_task_comm (which lock
it with task_lock())
- initialized normally by setup_new_exec */
/* file system info */
int link_count, total_link_count;
#ifdef CONFIG_SYSVIPC
/* ipc stuff */
struct sysv_sem sysvsem;
#endif
#ifdef CONFIG_DETECT_HUNG_TASK
/* hung task detection */
unsigned long last_switch_count;
#endif
/* CPU-specific state of this task */
struct thread_struct thread;
/* filesystem information */
struct fs_struct *fs;
/* open file information */
struct files_struct *files;
/* namespaces */
struct nsproxy *nsproxy;
/* signal handlers */
struct signal_struct *signal;
struct sighand_struct *sighand;
sigset_t blocked, real_blocked;
sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */
struct sigpending pending;
unsigned long sas_ss_sp;
size_t sas_ss_size;
int (*notifier)(void *priv);
void *notifier_data;
sigset_t *notifier_mask;
struct audit_context *audit_context;
#ifdef CONFIG_AUDITSYSCALL
uid_t loginuid;
unsigned int sessionid;
#endif
struct seccomp seccomp;
/* Thread group tracking */
u32 parent_exec_id;
u32 self_exec_id;
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed,
* mempolicy */
spinlock_t alloc_lock;
/* Protection of the PI data structures: */
raw_spinlock_t pi_lock;
#ifdef CONFIG_RT_MUTEXES
/* PI waiters blocked on a rt_mutex held by this task */
struct plist_head pi_waiters;
/* Deadlock detection and priority inheritance handling */
struct rt_mutex_waiter *pi_blocked_on;
#endif
#ifdef CONFIG_DEBUG_MUTEXES
/* mutex deadlock detection */
struct mutex_waiter *blocked_on;
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
unsigned int irq_events;
unsigned long hardirq_enable_ip;
unsigned long hardirq_disable_ip;
unsigned int hardirq_enable_event;
unsigned int hardirq_disable_event;
int hardirqs_enabled;
int hardirq_context;
unsigned long softirq_disable_ip;
unsigned long softirq_enable_ip;
unsigned int softirq_disable_event;
unsigned int softirq_enable_event;
int softirqs_enabled;
int softirq_context;
#endif
#ifdef CONFIG_LOCKDEP
# define MAX_LOCK_DEPTH 48UL
u64 curr_chain_key;
int lockdep_depth;
unsigned int lockdep_recursion;
struct held_lock held_locks[MAX_LOCK_DEPTH];
gfp_t lockdep_reclaim_gfp;
#endif
/* journalling filesystem info */
void *journal_info;
/* stacked block device info */
struct bio_list *bio_list;
#ifdef CONFIG_BLOCK
/* stack plugging */
struct blk_plug *plug;
#endif
/* VM state */
struct reclaim_state *reclaim_state;
struct backing_dev_info *backing_dev_info;
struct io_context *io_context;
unsigned long ptrace_message;
siginfo_t *last_siginfo; /* For ptrace use. */
struct task_io_accounting ioac;
#if defined(CONFIG_TASK_XACCT)
u64 acct_rss_mem1; /* accumulated rss usage */
u64 acct_vm_mem1; /* accumulated virtual memory usage */
cputime_t acct_timexpd; /* stime + utime since last update */
#endif
#ifdef CONFIG_CPUSETS
nodemask_t mems_allowed; /* Protected by alloc_lock */
seqcount_t mems_allowed_seq; /* Seqence no to catch updates */
int cpuset_mem_spread_rotor;
int cpuset_slab_spread_rotor;
#endif
#ifdef CONFIG_CGROUPS
/* Control Group info protected by css_set_lock */
struct css_set __rcu *cgroups;
/* cg_list protected by css_set_lock and tsk->alloc_lock */
struct list_head cg_list;
#endif
#ifdef CONFIG_FUTEX
struct robust_list_head __user *robust_list;
#ifdef CONFIG_COMPAT
struct compat_robust_list_head __user *compat_robust_list;
#endif
struct list_head pi_state_list;
struct futex_pi_state *pi_state_cache;
#endif
#ifdef CONFIG_PERF_EVENTS
struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];
struct mutex perf_event_mutex;
struct list_head perf_event_list;
#endif
#ifdef CONFIG_NUMA
struct mempolicy *mempolicy; /* Protected by alloc_lock */
short il_next;
short pref_node_fork;
#endif
struct rcu_head rcu;
/*
* cache last used pipe for splice
*/
struct pipe_inode_info *splice_pipe;
#ifdef CONFIG_TASK_DELAY_ACCT
struct task_delay_info *delays;
#endif
#ifdef CONFIG_FAULT_INJECTION
int make_it_fail;
#endif
/*
* when (nr_dirtied >= nr_dirtied_pause), it's time to call
* balance_dirty_pages() for some dirty throttling pause
*/
int nr_dirtied;
int nr_dirtied_pause;
unsigned long dirty_paused_when; /* start of a write-and-pause period */
#ifdef CONFIG_LATENCYTOP
int latency_record_count;
struct latency_record latency_record[LT_SAVECOUNT];
#endif
/*
* time slack values; these are used to round up poll() and
* select() etc timeout values. These are in nanoseconds.
*/
unsigned long timer_slack_ns;
unsigned long default_timer_slack_ns;
struct list_head *scm_work_list;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* Index of current stored address in ret_stack */
int curr_ret_stack;
/* Stack of return addresses for return function tracing */
struct ftrace_ret_stack *ret_stack;
/* time stamp for last schedule */
unsigned long long ftrace_timestamp;
/*
* Number of functions that haven't been traced
* because of depth overrun.
*/
atomic_t trace_overrun;
/* Pause for the tracing */
atomic_t tracing_graph_pause;
#endif
#ifdef CONFIG_TRACING
/* state flags for use by tracers */
unsigned long trace;
/* bitmask and counter of trace recursion */
unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
#ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */
struct memcg_batch_info {
int do_batch; /* incremented when batch uncharge started */
struct mem_cgroup *memcg; /* target memcg of uncharge */
unsigned long nr_pages; /* uncharged usage */
unsigned long memsw_nr_pages; /* uncharged mem+swap usage */
} memcg_batch;
#endif
#ifdef CONFIG_HAVE_HW_BREAKPOINT
atomic_t ptrace_bp_refcnt;
#endif
};