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31656519e1
random uvesafb failures were reported against Gentoo: http://bugs.gentoo.org/show_bug.cgi?id=222799 and Mihai Moldovan bisected it back to: >8f4d37ec07is first bad commit > commit8f4d37ec07> Author: Peter Zijlstra <a.p.zijlstra@chello.nl> > Date: Fri Jan 25 21:08:29 2008 +0100 > > sched: high-res preemption tick Linus suspected it to be hrtick + vm86 interaction and observed: > Btw, Peter, Ingo: I think that commit is doing bad things. They aren't > _incorrect_ per se, but they are definitely bad. > > Why? > > Using random _TIF_WORK_MASK flags is really impolite for doing > "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S > special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of > vm86 mode unnecessarily. > > See the "work_notifysig_v86" label, and how it does that > "save_v86_state()" thing etc etc. Right, I never liked having to fiddle with those TIF flags. Initially I needed it because the hrtimer base lock could not nest in the rq lock. That however is fixed these days. Currently the only reason left to fiddle with the TIF flags is remote wakeups. We cannot program a remote cpu's hrtimer. I've been thinking about using the new and improved IPI function call stuff to implement hrtimer_start_on(). However that does require that smp_call_function_single(.wait=0) works from interrupt context - /me looks at the latest series from Jens - Yes that does seem to be supported, good. Here's a stab at cleaning this stuff up ... Mihai reported test success as well. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Mihai Moldovan <ionic@ionic.de> Cc: Michal Januszewski <spock@gentoo.org> Cc: Antonino Daplas <adaplas@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
257 lines
7.5 KiB
C
257 lines
7.5 KiB
C
/* thread_info.h: low-level thread information
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds and Dave Miller
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*/
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#ifndef _ASM_X86_THREAD_INFO_H
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#define _ASM_X86_THREAD_INFO_H
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#include <linux/compiler.h>
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#include <asm/page.h>
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#include <asm/types.h>
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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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*/
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#ifndef __ASSEMBLY__
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struct task_struct;
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struct exec_domain;
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#include <asm/processor.h>
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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unsigned long flags; /* low level flags */
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__u32 status; /* thread synchronous flags */
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__u32 cpu; /* current CPU */
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int preempt_count; /* 0 => preemptable,
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<0 => BUG */
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mm_segment_t addr_limit;
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struct restart_block restart_block;
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void __user *sysenter_return;
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#ifdef CONFIG_X86_32
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unsigned long previous_esp; /* ESP of the previous stack in
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case of nested (IRQ) stacks
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*/
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__u8 supervisor_stack[0];
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#endif
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};
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = 1, \
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.addr_limit = KERNEL_DS, \
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.restart_block = { \
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.fn = do_no_restart_syscall, \
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}, \
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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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#else /* !__ASSEMBLY__ */
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#include <asm/asm-offsets.h>
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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
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* may need to 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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* Warning: layout of LSW is hardcoded in entry.S
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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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 /* reenable singlestep on user return*/
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#define TIF_IRET 5 /* force IRET */
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#ifdef CONFIG_X86_32
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#define TIF_SYSCALL_EMU 6 /* syscall emulation active */
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#endif
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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#define TIF_SECCOMP 8 /* secure computing */
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#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
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#define TIF_NOTSC 16 /* TSC is not accessible in userland */
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#define TIF_IA32 17 /* 32bit process */
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#define TIF_FORK 18 /* ret_from_fork */
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#define TIF_ABI_PENDING 19
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#define TIF_MEMDIE 20
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#define TIF_DEBUG 21 /* uses debug registers */
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#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
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#define TIF_FREEZE 23 /* is freezing for suspend */
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#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
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#define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
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#define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
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#define TIF_BTS_TRACE_TS 27 /* record scheduling event timestamps */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_IRET (1 << TIF_IRET)
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#ifdef CONFIG_X86_32
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#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU)
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#else
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#define _TIF_SYSCALL_EMU 0
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#endif
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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#define _TIF_SECCOMP (1 << TIF_SECCOMP)
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#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
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#define _TIF_NOTSC (1 << TIF_NOTSC)
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#define _TIF_IA32 (1 << TIF_IA32)
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#define _TIF_FORK (1 << TIF_FORK)
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#define _TIF_ABI_PENDING (1 << TIF_ABI_PENDING)
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#define _TIF_DEBUG (1 << TIF_DEBUG)
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#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
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#define _TIF_FREEZE (1 << TIF_FREEZE)
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#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
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#define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
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#define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
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#define _TIF_BTS_TRACE_TS (1 << TIF_BTS_TRACE_TS)
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/* work to do on interrupt/exception return */
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#define _TIF_WORK_MASK \
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(0x0000FFFF & \
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~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP| \
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_TIF_SECCOMP|_TIF_SYSCALL_EMU))
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/* work to do on any return to user space */
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#define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)
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/* Only used for 64 bit */
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#define _TIF_DO_NOTIFY_MASK \
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(_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY)
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/* flags to check in __switch_to() */
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#define _TIF_WORK_CTXSW \
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(_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_BTS_TRACE_TS| \
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_TIF_NOTSC)
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#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW
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#define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG)
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#define PREEMPT_ACTIVE 0x10000000
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/* thread information allocation */
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#ifdef CONFIG_DEBUG_STACK_USAGE
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#define THREAD_FLAGS (GFP_KERNEL | __GFP_ZERO)
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#else
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#define THREAD_FLAGS GFP_KERNEL
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#endif
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#define alloc_thread_info(tsk) \
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((struct thread_info *)__get_free_pages(THREAD_FLAGS, THREAD_ORDER))
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#ifdef CONFIG_X86_32
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#define STACK_WARN (THREAD_SIZE/8)
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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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* preempt_count needs to be 1 initially, until the scheduler is functional.
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*/
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#ifndef __ASSEMBLY__
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/* how to get the current stack pointer from C */
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register unsigned long current_stack_pointer asm("esp") __used;
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/* how to get the thread information struct from C */
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static inline struct thread_info *current_thread_info(void)
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{
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return (struct thread_info *)
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(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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#else /* !__ASSEMBLY__ */
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/* how to get the thread information struct from ASM */
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#define GET_THREAD_INFO(reg) \
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movl $-THREAD_SIZE, reg; \
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andl %esp, reg
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/* use this one if reg already contains %esp */
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#define GET_THREAD_INFO_WITH_ESP(reg) \
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andl $-THREAD_SIZE, reg
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#endif
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#else /* X86_32 */
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#include <asm/pda.h>
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/*
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* macros/functions for gaining access to the thread information structure
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* preempt_count needs to be 1 initially, until the scheduler is functional.
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*/
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#ifndef __ASSEMBLY__
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static inline struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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ti = (void *)(read_pda(kernelstack) + PDA_STACKOFFSET - THREAD_SIZE);
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return ti;
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}
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/* do not use in interrupt context */
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static inline struct thread_info *stack_thread_info(void)
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{
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struct thread_info *ti;
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asm("andq %%rsp,%0; " : "=r" (ti) : "0" (~(THREAD_SIZE - 1)));
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return ti;
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}
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#else /* !__ASSEMBLY__ */
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/* how to get the thread information struct from ASM */
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#define GET_THREAD_INFO(reg) \
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movq %gs:pda_kernelstack,reg ; \
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subq $(THREAD_SIZE-PDA_STACKOFFSET),reg
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#endif
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#endif /* !X86_32 */
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/*
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* Thread-synchronous status.
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*
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* This is different from the flags in that nobody else
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* ever touches our thread-synchronous status, so we don't
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* have to worry about atomic accesses.
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*/
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#define TS_USEDFPU 0x0001 /* FPU was used by this task
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this quantum (SMP) */
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#define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/
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#define TS_POLLING 0x0004 /* true if in idle loop
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and not sleeping */
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#define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */
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#define tsk_is_polling(t) (task_thread_info(t)->status & TS_POLLING)
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#ifndef __ASSEMBLY__
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#define HAVE_SET_RESTORE_SIGMASK 1
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static inline void set_restore_sigmask(void)
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{
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struct thread_info *ti = current_thread_info();
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ti->status |= TS_RESTORE_SIGMASK;
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set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
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}
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#endif /* !__ASSEMBLY__ */
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#ifndef __ASSEMBLY__
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extern void arch_task_cache_init(void);
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extern void free_thread_info(struct thread_info *ti);
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extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
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#define arch_task_cache_init arch_task_cache_init
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#endif
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#endif /* _ASM_X86_THREAD_INFO_H */
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