thread_info (RISC-V, v6.6-rc4)

MySprtlty·2023년 10월 2일
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Kernel

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🏷️thread_info (RISC-V, v6.6-rc4)

  • ISA에 독립적인 PCB와 다르게, TCB(Thread Control Block)은 종속적이다.
/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2009 Chen Liqin <liqin.chen@sunplusct.com>
 * Copyright (C) 2012 Regents of the University of California
 * Copyright (C) 2017 SiFive
 */

#ifndef _ASM_RISCV_THREAD_INFO_H
#define _ASM_RISCV_THREAD_INFO_H

#include <asm/page.h>
#include <linux/const.h>

/* thread information allocation */
#define THREAD_SIZE_ORDER	CONFIG_THREAD_SIZE_ORDER
#define THREAD_SIZE		(PAGE_SIZE << THREAD_SIZE_ORDER)

/*
 * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
 * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
 * assembly.
 */
#ifdef CONFIG_VMAP_STACK
#define THREAD_ALIGN            (2 * THREAD_SIZE)
#else
#define THREAD_ALIGN            THREAD_SIZE
#endif

#define THREAD_SHIFT            (PAGE_SHIFT + THREAD_SIZE_ORDER)
#define OVERFLOW_STACK_SIZE     SZ_4K
#define SHADOW_OVERFLOW_STACK_SIZE (1024)

#define IRQ_STACK_SIZE		THREAD_SIZE

#ifndef __ASSEMBLY__

extern long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE / sizeof(long)];
extern unsigned long spin_shadow_stack;

#include <asm/processor.h>
#include <asm/csr.h>

/*
 * low level task data that entry.S needs immediate access to
 * - this struct should fit entirely inside of one cache line
 * - if the members of this struct changes, the assembly constants
 *   in asm-offsets.c must be updated accordingly
 * - thread_info is included in task_struct at an offset of 0.  This means that
 *   tp points to both thread_info and task_struct.
 */
struct thread_info {
	unsigned long		flags;		/* low level flags */
	int                     preempt_count;  /* 0=>preemptible, <0=>BUG */
	/*
	 * These stack pointers are overwritten on every system call or
	 * exception.  SP is also saved to the stack it can be recovered when
	 * overwritten.
	 */
	long			kernel_sp;	/* Kernel stack pointer */
	long			user_sp;	/* User stack pointer */
	int			cpu;
	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
};

/*
 * macros/functions for gaining access to the thread information structure
 *
 * preempt_count needs to be 1 initially, until the scheduler is functional.
 */
#define INIT_THREAD_INFO(tsk)			\
{						\
	.flags		= 0,			\
	.preempt_count	= INIT_PREEMPT_COUNT,	\
}

void arch_release_task_struct(struct task_struct *tsk);
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);

#endif /* !__ASSEMBLY__ */

/*
 * thread information flags
 * - these are process state flags that various assembly files may need to
 *   access
 * - pending work-to-be-done flags are in lowest half-word
 * - other flags in upper half-word(s)
 */
#define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
#define TIF_SIGPENDING		2	/* signal pending */
#define TIF_NEED_RESCHED	3	/* rescheduling necessary */
#define TIF_RESTORE_SIGMASK	4	/* restore signal mask in do_signal() */
#define TIF_MEMDIE		5	/* is terminating due to OOM killer */
#define TIF_NOTIFY_SIGNAL	9	/* signal notifications exist */
#define TIF_UPROBE		10	/* uprobe breakpoint or singlestep */
#define TIF_32BIT		11	/* compat-mode 32bit process */

#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
#define _TIF_UPROBE		(1 << TIF_UPROBE)

#define _TIF_WORK_MASK \
	(_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \
	 _TIF_NOTIFY_SIGNAL | _TIF_UPROBE)

#endif /* _ASM_RISCV_THREAD_INFO_H */

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