b235beea9e
We've had the thread info allocated together with the thread stack for most architectures for a long time (since the thread_info was split off from the task struct), but that is about to change. But the patches that move the thread info to be off-stack (and a part of the task struct instead) made it clear how confused the allocator and freeing functions are. Because the common case was that we share an allocation with the thread stack and the thread_info, the two pointers were identical. That identity then meant that we would have things like ti = alloc_thread_info_node(tsk, node); ... tsk->stack = ti; which certainly _worked_ (since stack and thread_info have the same value), but is rather confusing: why are we assigning a thread_info to the stack? And if we move the thread_info away, the "confusing" code just gets to be entirely bogus. So remove all this confusion, and make it clear that we are doing the stack allocation by renaming and clarifying the function names to be about the stack. The fact that the thread_info then shares the allocation is an implementation detail, and not really about the allocation itself. This is a pure renaming and type fix: we pass in the same pointer, it's just that we clarify what the pointer means. The ia64 code that actually only has one single allocation (for all of task_struct, thread_info and kernel thread stack) now looks a bit odd, but since "tsk->stack" is actually not even used there, that oddity doesn't matter. It would be a separate thing to clean that up, I intentionally left the ia64 changes as a pure brute-force renaming and type change. Acked-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
163 lines
4.4 KiB
C
163 lines
4.4 KiB
C
/* MN10300 Low-level thread information
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _ASM_THREAD_INFO_H
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#define _ASM_THREAD_INFO_H
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#ifdef __KERNEL__
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#include <asm/page.h>
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#ifdef CONFIG_4KSTACKS
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#define THREAD_SIZE (4096)
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#define THREAD_SIZE_ORDER (0)
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#else
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#define THREAD_SIZE (8192)
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#define THREAD_SIZE_ORDER (1)
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#endif
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#define STACK_WARN (THREAD_SIZE / 8)
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/*
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* low level task data that entry.S needs immediate access to
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* - this struct should fit entirely inside of one cache line
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* - this struct shares the supervisor stack pages
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* - if the contents of this structure are changed, the assembly constants
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* must also be changed
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*/
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#ifndef __ASSEMBLY__
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typedef struct {
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unsigned long seg;
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} mm_segment_t;
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct pt_regs *frame; /* current exception frame */
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unsigned long flags; /* low level flags */
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__u32 cpu; /* current CPU */
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__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
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mm_segment_t addr_limit; /* thread address space:
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0-0xBFFFFFFF for user-thead
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0-0xFFFFFFFF for kernel-thread
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*/
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__u8 supervisor_stack[0];
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};
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#define thread_info_to_uregs(ti) \
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((struct pt_regs *) \
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((unsigned long)ti + THREAD_SIZE - sizeof(struct pt_regs)))
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#else /* !__ASSEMBLY__ */
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#ifndef __ASM_OFFSETS_H__
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#include <asm/asm-offsets.h>
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#endif
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#endif
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/*
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* macros/functions for gaining access to the thread information structure
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*/
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#ifndef __ASSEMBLY__
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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.addr_limit = KERNEL_DS, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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#define init_uregs \
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((struct pt_regs *) \
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((unsigned long) init_stack + THREAD_SIZE - sizeof(struct pt_regs)))
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extern struct thread_info *__current_ti;
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/* how to get the thread information struct from C */
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static inline __attribute__((const))
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struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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asm("mov sp,%0\n"
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"and %1,%0\n"
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: "=d" (ti)
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: "i" (~(THREAD_SIZE - 1))
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: "cc");
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return ti;
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}
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static inline __attribute__((const))
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struct pt_regs *current_frame(void)
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{
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return current_thread_info()->frame;
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}
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/* how to get the current stack pointer from C */
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static inline unsigned long current_stack_pointer(void)
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{
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unsigned long sp;
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asm("mov sp,%0; ":"=r" (sp));
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return sp;
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}
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#ifndef CONFIG_KGDB
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void arch_release_thread_stack(unsigned long *stack);
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#endif
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#define get_thread_info(ti) get_task_struct((ti)->task)
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#define put_thread_info(ti) put_task_struct((ti)->task)
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#else /* !__ASSEMBLY__ */
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#ifndef __VMLINUX_LDS__
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/* how to get the thread information struct from ASM */
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.macro GET_THREAD_INFO reg
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mov sp,\reg
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and -THREAD_SIZE,\reg
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.endm
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#endif
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#endif
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/*
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* thread information flags
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* - these are process state flags that various assembly files may need to
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* access
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* - pending work-to-be-done flags are in LSW
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* - other flags in MSW
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_NOTIFY_RESUME 1 /* resumption notification requested */
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#define TIF_SIGPENDING 2 /* signal pending */
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#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
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#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
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#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
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#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
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#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
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#define _TIF_SYSCALL_TRACE +(1 << TIF_SYSCALL_TRACE)
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#define _TIF_NOTIFY_RESUME +(1 << TIF_NOTIFY_RESUME)
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#define _TIF_SIGPENDING +(1 << TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED +(1 << TIF_NEED_RESCHED)
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#define _TIF_SINGLESTEP +(1 << TIF_SINGLESTEP)
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#define _TIF_POLLING_NRFLAG +(1 << TIF_POLLING_NRFLAG)
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#define _TIF_WORK_MASK 0x0000FFFE /* work to do on interrupt/exception return */
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#define _TIF_ALLWORK_MASK 0x0000FFFF /* work to do on any return to u-space */
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#endif /* __KERNEL__ */
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#endif /* _ASM_THREAD_INFO_H */
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