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f56141e3e2
If an attacker can cause a controlled kernel stack overflow, overwriting the restart block is a very juicy exploit target. This is because the restart_block is held in the same memory allocation as the kernel stack. Moving the restart block to struct task_struct prevents this exploit by making the restart_block harder to locate. Note that there are other fields in thread_info that are also easy targets, at least on some architectures. It's also a decent simplification, since the restart code is more or less identical on all architectures. [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: David Miller <davem@davemloft.net> Acked-by: Richard Weinberger <richard@nod.at> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Steven Miao <realmz6@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
195 lines
6.0 KiB
C
195 lines
6.0 KiB
C
/* thread_info.h: PowerPC low-level thread information
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* adapted from the i386 version by Paul Mackerras
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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_POWERPC_THREAD_INFO_H
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#define _ASM_POWERPC_THREAD_INFO_H
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#ifdef __KERNEL__
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/* We have 8k stacks on ppc32 and 16k on ppc64 */
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#if defined(CONFIG_PPC64)
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#define THREAD_SHIFT 14
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#elif defined(CONFIG_PPC_256K_PAGES)
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#define THREAD_SHIFT 15
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#else
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#define THREAD_SHIFT 13
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#endif
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#define THREAD_SIZE (1 << THREAD_SHIFT)
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#ifdef CONFIG_PPC64
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#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(clrrdi dest, sp, THREAD_SHIFT)
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#else
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#define CURRENT_THREAD_INFO(dest, sp) stringify_in_c(rlwinm dest, sp, 0, 0, 31-THREAD_SHIFT)
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#endif
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#ifndef __ASSEMBLY__
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#include <linux/cache.h>
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#include <asm/processor.h>
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#include <asm/page.h>
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#include <linux/stringify.h>
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/*
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* low level task data.
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*/
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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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int cpu; /* cpu we're on */
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int preempt_count; /* 0 => preemptable,
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<0 => BUG */
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unsigned long local_flags; /* private flags for thread */
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/* low level flags - has atomic operations done on it */
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unsigned long flags ____cacheline_aligned_in_smp;
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};
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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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#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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.cpu = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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.flags = 0, \
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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 THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)
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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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unsigned long val;
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asm (CURRENT_THREAD_INFO(%0,1) : "=r" (val));
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return (struct thread_info *)val;
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}
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#endif /* __ASSEMBLY__ */
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/*
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* thread information flag bit numbers
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_POLLING_NRFLAG 3 /* true if poll_idle() is polling
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TIF_NEED_RESCHED */
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#define TIF_32BIT 4 /* 32 bit binary */
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#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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#define TIF_SINGLESTEP 8 /* singlestepping active */
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#define TIF_NOHZ 9 /* in adaptive nohz mode */
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#define TIF_SECCOMP 10 /* secure computing */
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#define TIF_RESTOREALL 11 /* Restore all regs (implies NOERROR) */
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#define TIF_NOERROR 12 /* Force successful syscall return */
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#define TIF_NOTIFY_RESUME 13 /* callback before returning to user */
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#define TIF_UPROBE 14 /* breakpointed or single-stepping */
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#define TIF_SYSCALL_TRACEPOINT 15 /* syscall tracepoint instrumentation */
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#define TIF_EMULATE_STACK_STORE 16 /* Is an instruction emulation
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for stack store? */
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#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
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#if defined(CONFIG_PPC64)
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#define TIF_ELF2ABI 18 /* function descriptors must die! */
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#endif
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/* as above, but as bit values */
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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_NEED_RESCHED (1<<TIF_NEED_RESCHED)
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#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
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#define _TIF_32BIT (1<<TIF_32BIT)
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#define _TIF_RESTORE_TM (1<<TIF_RESTORE_TM)
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#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
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#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
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#define _TIF_SECCOMP (1<<TIF_SECCOMP)
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#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
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#define _TIF_NOERROR (1<<TIF_NOERROR)
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#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
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#define _TIF_UPROBE (1<<TIF_UPROBE)
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#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
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#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
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#define _TIF_NOHZ (1<<TIF_NOHZ)
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#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
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_TIF_NOHZ)
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#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
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_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
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_TIF_RESTORE_TM)
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#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
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/* Bits in local_flags */
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/* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
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#define TLF_NAPPING 0 /* idle thread enabled NAP mode */
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#define TLF_SLEEPING 1 /* suspend code enabled SLEEP mode */
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#define TLF_RESTORE_SIGMASK 2 /* Restore signal mask in do_signal */
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#define TLF_LAZY_MMU 3 /* tlb_batch is active */
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#define TLF_RUNLATCH 4 /* Is the runlatch enabled? */
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#define _TLF_NAPPING (1 << TLF_NAPPING)
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#define _TLF_SLEEPING (1 << TLF_SLEEPING)
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#define _TLF_RESTORE_SIGMASK (1 << TLF_RESTORE_SIGMASK)
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#define _TLF_LAZY_MMU (1 << TLF_LAZY_MMU)
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#define _TLF_RUNLATCH (1 << TLF_RUNLATCH)
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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->local_flags |= _TLF_RESTORE_SIGMASK;
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WARN_ON(!test_bit(TIF_SIGPENDING, &ti->flags));
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}
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static inline void clear_restore_sigmask(void)
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{
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current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;
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}
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static inline bool test_restore_sigmask(void)
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{
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return current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK;
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}
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static inline bool test_and_clear_restore_sigmask(void)
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{
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struct thread_info *ti = current_thread_info();
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if (!(ti->local_flags & _TLF_RESTORE_SIGMASK))
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return false;
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ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
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return true;
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}
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static inline bool test_thread_local_flags(unsigned int flags)
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{
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struct thread_info *ti = current_thread_info();
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return (ti->local_flags & flags) != 0;
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}
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#ifdef CONFIG_PPC64
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#define is_32bit_task() (test_thread_flag(TIF_32BIT))
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#else
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#define is_32bit_task() (1)
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#endif
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#if defined(CONFIG_PPC64)
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#define is_elf2_task() (test_thread_flag(TIF_ELF2ABI))
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#else
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#define is_elf2_task() (0)
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#endif
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#endif /* !__ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_THREAD_INFO_H */
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