134475a9ab
Not all tasks have a vDSO mapped, for example kthreads never do. If such
a task ever ends up calling stack_top(), it will derefence the NULL vdso
pointer and crash.
This can for example happen when using kunit:
[<9000000000203874>] stack_top+0x58/0xa8
[<90000000002956cc>] arch_pick_mmap_layout+0x164/0x220
[<90000000003c284c>] kunit_vm_mmap_init+0x108/0x12c
[<90000000003c1fbc>] __kunit_add_resource+0x38/0x8c
[<90000000003c2704>] kunit_vm_mmap+0x88/0xc8
[<9000000000410b14>] usercopy_test_init+0xbc/0x25c
[<90000000003c1db4>] kunit_try_run_case+0x5c/0x184
[<90000000003c3d54>] kunit_generic_run_threadfn_adapter+0x24/0x48
[<900000000022e4bc>] kthread+0xc8/0xd4
[<9000000000200ce8>] ret_from_kernel_thread+0xc/0xa4
Fixes: 803b0fc5c3
("LoongArch: Add process management")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
378 lines
9.2 KiB
C
378 lines
9.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Author: Huacai Chen <chenhuacai@loongson.cn>
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*
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* Derived from MIPS:
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* Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
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* Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
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* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
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* Copyright (C) 2004 Thiemo Seufer
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* Copyright (C) 2013 Imagination Technologies Ltd.
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*/
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#include <linux/cpu.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/task.h>
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#include <linux/sched/task_stack.h>
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#include <linux/hw_breakpoint.h>
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#include <linux/mm.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/export.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/personality.h>
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#include <linux/sys.h>
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#include <linux/completion.h>
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#include <linux/kallsyms.h>
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#include <linux/random.h>
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#include <linux/prctl.h>
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#include <linux/nmi.h>
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#include <asm/asm.h>
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#include <asm/bootinfo.h>
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#include <asm/cpu.h>
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#include <asm/elf.h>
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#include <asm/exec.h>
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#include <asm/fpu.h>
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#include <asm/lbt.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#include <asm/irq_regs.h>
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#include <asm/loongarch.h>
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#include <asm/pgtable.h>
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#include <asm/processor.h>
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#include <asm/reg.h>
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#include <asm/unwind.h>
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#include <asm/vdso.h>
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#ifdef CONFIG_STACKPROTECTOR
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#include <linux/stackprotector.h>
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unsigned long __stack_chk_guard __read_mostly;
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EXPORT_SYMBOL(__stack_chk_guard);
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#endif
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/*
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* Idle related variables and functions
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*/
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unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
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EXPORT_SYMBOL(boot_option_idle_override);
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asmlinkage void ret_from_fork(void);
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asmlinkage void ret_from_kernel_thread(void);
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void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
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{
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unsigned long crmd;
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unsigned long prmd;
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unsigned long euen;
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/* New thread loses kernel privileges. */
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crmd = regs->csr_crmd & ~(PLV_MASK);
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crmd |= PLV_USER;
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regs->csr_crmd = crmd;
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prmd = regs->csr_prmd & ~(PLV_MASK);
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prmd |= PLV_USER;
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regs->csr_prmd = prmd;
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euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
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regs->csr_euen = euen;
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lose_fpu(0);
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lose_lbt(0);
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current->thread.fpu.fcsr = boot_cpu_data.fpu_csr0;
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clear_thread_flag(TIF_LSX_CTX_LIVE);
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clear_thread_flag(TIF_LASX_CTX_LIVE);
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clear_thread_flag(TIF_LBT_CTX_LIVE);
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clear_used_math();
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regs->csr_era = pc;
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regs->regs[3] = sp;
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}
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void flush_thread(void)
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{
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flush_ptrace_hw_breakpoint(current);
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}
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void exit_thread(struct task_struct *tsk)
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{
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}
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int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
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{
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/*
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* Save any process state which is live in hardware registers to the
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* parent context prior to duplication. This prevents the new child
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* state becoming stale if the parent is preempted before copy_thread()
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* gets a chance to save the parent's live hardware registers to the
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* child context.
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*/
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preempt_disable();
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if (is_fpu_owner()) {
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if (is_lasx_enabled())
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save_lasx(current);
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else if (is_lsx_enabled())
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save_lsx(current);
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else
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save_fp(current);
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}
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preempt_enable();
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if (!used_math())
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memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
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else
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memcpy(dst, src, offsetof(struct task_struct, thread.lbt.scr0));
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#ifdef CONFIG_CPU_HAS_LBT
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memcpy(&dst->thread.lbt, &src->thread.lbt, sizeof(struct loongarch_lbt));
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#endif
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return 0;
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}
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/*
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* Copy architecture-specific thread state
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*/
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int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
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{
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unsigned long childksp;
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unsigned long tls = args->tls;
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unsigned long usp = args->stack;
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unsigned long clone_flags = args->flags;
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struct pt_regs *childregs, *regs = current_pt_regs();
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childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
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/* set up new TSS. */
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childregs = (struct pt_regs *) childksp - 1;
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/* Put the stack after the struct pt_regs. */
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childksp = (unsigned long) childregs;
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p->thread.sched_cfa = 0;
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p->thread.csr_euen = 0;
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p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
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p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
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p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
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if (unlikely(args->fn)) {
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/* kernel thread */
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p->thread.reg03 = childksp;
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p->thread.reg23 = (unsigned long)args->fn;
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p->thread.reg24 = (unsigned long)args->fn_arg;
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p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
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p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
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memset(childregs, 0, sizeof(struct pt_regs));
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childregs->csr_euen = p->thread.csr_euen;
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childregs->csr_crmd = p->thread.csr_crmd;
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childregs->csr_prmd = p->thread.csr_prmd;
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childregs->csr_ecfg = p->thread.csr_ecfg;
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goto out;
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}
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/* user thread */
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*childregs = *regs;
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childregs->regs[4] = 0; /* Child gets zero as return value */
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if (usp)
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childregs->regs[3] = usp;
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p->thread.reg03 = (unsigned long) childregs;
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p->thread.reg01 = (unsigned long) ret_from_fork;
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p->thread.sched_ra = (unsigned long) ret_from_fork;
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/*
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* New tasks lose permission to use the fpu. This accelerates context
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* switching for most programs since they don't use the fpu.
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*/
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childregs->csr_euen = 0;
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if (clone_flags & CLONE_SETTLS)
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childregs->regs[2] = tls;
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out:
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ptrace_hw_copy_thread(p);
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clear_tsk_thread_flag(p, TIF_USEDFPU);
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clear_tsk_thread_flag(p, TIF_USEDSIMD);
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clear_tsk_thread_flag(p, TIF_USEDLBT);
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clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
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clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
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clear_tsk_thread_flag(p, TIF_LBT_CTX_LIVE);
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return 0;
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}
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unsigned long __get_wchan(struct task_struct *task)
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{
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unsigned long pc = 0;
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struct unwind_state state;
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if (!try_get_task_stack(task))
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return 0;
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for (unwind_start(&state, task, NULL);
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!unwind_done(&state); unwind_next_frame(&state)) {
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pc = unwind_get_return_address(&state);
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if (!pc)
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break;
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if (in_sched_functions(pc))
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continue;
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break;
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}
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put_task_stack(task);
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return pc;
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}
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bool in_irq_stack(unsigned long stack, struct stack_info *info)
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{
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unsigned long nextsp;
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unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
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unsigned long end = begin + IRQ_STACK_START;
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if (stack < begin || stack >= end)
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return false;
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nextsp = *(unsigned long *)end;
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if (nextsp & (SZREG - 1))
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return false;
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info->begin = begin;
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info->end = end;
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info->next_sp = nextsp;
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info->type = STACK_TYPE_IRQ;
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return true;
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}
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bool in_task_stack(unsigned long stack, struct task_struct *task,
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struct stack_info *info)
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{
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unsigned long begin = (unsigned long)task_stack_page(task);
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unsigned long end = begin + THREAD_SIZE;
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if (stack < begin || stack >= end)
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return false;
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info->begin = begin;
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info->end = end;
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info->next_sp = 0;
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info->type = STACK_TYPE_TASK;
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return true;
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}
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int get_stack_info(unsigned long stack, struct task_struct *task,
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struct stack_info *info)
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{
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task = task ? : current;
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if (!stack || stack & (SZREG - 1))
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goto unknown;
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if (in_task_stack(stack, task, info))
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return 0;
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if (task != current)
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goto unknown;
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if (in_irq_stack(stack, info))
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return 0;
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unknown:
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info->type = STACK_TYPE_UNKNOWN;
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return -EINVAL;
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}
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unsigned long stack_top(void)
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{
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unsigned long top = TASK_SIZE & PAGE_MASK;
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if (current->thread.vdso) {
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/* Space for the VDSO & data page */
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top -= PAGE_ALIGN(current->thread.vdso->size);
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top -= VVAR_SIZE;
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/* Space to randomize the VDSO base */
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if (current->flags & PF_RANDOMIZE)
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top -= VDSO_RANDOMIZE_SIZE;
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}
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return top;
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}
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/*
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* Don't forget that the stack pointer must be aligned on a 8 bytes
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* boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
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*/
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unsigned long arch_align_stack(unsigned long sp)
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{
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if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
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sp -= get_random_u32_below(PAGE_SIZE);
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return sp & STACK_ALIGN;
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}
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static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
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static struct cpumask backtrace_csd_busy;
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static void handle_backtrace(void *info)
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{
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nmi_cpu_backtrace(get_irq_regs());
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cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
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}
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static void raise_backtrace(cpumask_t *mask)
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{
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call_single_data_t *csd;
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int cpu;
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for_each_cpu(cpu, mask) {
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/*
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* If we previously sent an IPI to the target CPU & it hasn't
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* cleared its bit in the busy cpumask then it didn't handle
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* our previous IPI & it's not safe for us to reuse the
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* call_single_data_t.
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*/
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if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
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pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
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cpu);
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continue;
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}
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csd = &per_cpu(backtrace_csd, cpu);
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csd->func = handle_backtrace;
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smp_call_function_single_async(cpu, csd);
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}
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}
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void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
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{
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nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
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}
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#ifdef CONFIG_64BIT
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void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
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{
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unsigned int i;
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for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
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uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
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}
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uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
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uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
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uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
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uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
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uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
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uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
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uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
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uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
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}
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#endif /* CONFIG_64BIT */
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