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drasko |
#include <l4/lib/mutex.h>
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#include <l4/lib/printk.h>
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#include <l4/generic/scheduler.h>
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#include <l4/generic/tcb.h>
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#include <l4/generic/resource.h>
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#include <l4/generic/tcb.h>
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#include <l4/generic/space.h>
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#include <l4/generic/capability.h>
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#include <l4/generic/container.h>
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#include <l4/api/ipc.h>
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#include <l4/api/kip.h>
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#include <l4/api/errno.h>
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#include <l4/api/exregs.h>
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/* Copy each register to task's context if its valid bit is set */
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void exregs_write_registers(struct ktcb *task, struct exregs_data *exregs)
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{
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task_context_t *context = &task->context;
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if (!exregs->valid_vect)
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goto flags;
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/*
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* NOTE:
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* We don't care if register values point at invalid addresses
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* since memory protection would prevent any kernel corruption.
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* We do however, make sure spsr is not modified
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*/
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/* Check register valid bit and copy registers */
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r0))
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context->r0 = exregs->context.r0;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r1))
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context->r1 = exregs->context.r1;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r2))
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context->r2 = exregs->context.r2;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r3))
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context->r3 = exregs->context.r3;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r4))
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context->r4 = exregs->context.r4;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r5))
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context->r5 = exregs->context.r5;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r6))
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context->r6 = exregs->context.r6;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r7))
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context->r7 = exregs->context.r7;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r8))
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context->r8 = exregs->context.r8;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r9))
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context->r9 = exregs->context.r9;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r10))
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context->r10 = exregs->context.r10;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r11))
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context->r11 = exregs->context.r11;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r12))
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context->r12 = exregs->context.r12;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, sp))
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context->sp = exregs->context.sp;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, lr))
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context->lr = exregs->context.lr;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, pc))
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context->pc = exregs->context.pc;
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flags:
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/* Set thread's pager if one is supplied */
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if (exregs->flags & EXREGS_SET_PAGER)
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task->pagerid = exregs->pagerid;
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/* Set thread's utcb if supplied */
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if (exregs->flags & EXREGS_SET_UTCB) {
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task->utcb_address = exregs->utcb_address;
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/*
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* If task is the one currently runnable,
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* update utcb reference
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*/
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if (task == current)
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task_update_utcb(task);
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}
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}
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void exregs_read_registers(struct ktcb *task, struct exregs_data *exregs)
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{
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task_context_t *context = &task->context;
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if (!exregs->valid_vect)
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goto flags;
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/* Check register valid bit and copy registers */
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r0))
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exregs->context.r0 = context->r0;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r1))
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exregs->context.r1 = context->r1;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r2))
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exregs->context.r2 = context->r2;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r3))
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exregs->context.r3 = context->r3;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r4))
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exregs->context.r4 = context->r4;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r5))
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exregs->context.r5 = context->r5;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r6))
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exregs->context.r6 = context->r6;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r7))
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exregs->context.r7 = context->r7;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r8))
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exregs->context.r8 = context->r8;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r9))
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exregs->context.r9 = context->r9;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r10))
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exregs->context.r10 = context->r10;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r11))
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exregs->context.r11 = context->r11;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, r12))
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exregs->context.r12 = context->r12;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, sp))
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exregs->context.sp = context->sp;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, lr))
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exregs->context.lr = context->lr;
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if (exregs->valid_vect & FIELD_TO_BIT(exregs_context_t, pc))
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exregs->context.pc = context->pc;
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flags:
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/* Read thread's pager if pager flag supplied */
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if (exregs->flags & EXREGS_SET_PAGER)
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exregs->pagerid = task->pagerid;
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/* Read thread's utcb if utcb flag supplied */
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if (exregs->flags & EXREGS_SET_UTCB)
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exregs->utcb_address = task->utcb_address;
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}
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/*
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* exchange_registers()
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*
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* This call is used by the pagers to set (and in the future read)
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* the register context of a thread. The thread's registers that are
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* set by this call are loaded whenever the thread gets a chance to
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* run in user mode.
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*
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* It is ensured that whenever this call is made, the thread is
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* either already running in user mode, or has been suspended in
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* kernel mode, just before returning to user mode.
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*
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* A newly created thread that is the copy of another thread (forked
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* or cloned) will also be given its user mode context on the first
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* chance to execute so such threads can also be modified by this
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* call before execution.
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*
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* A thread executing in the kernel cannot be modified since this
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* would compromise the kernel. Also the thread must be in suspended
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* condition so that the scheduler does not execute it as we modify
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* its context.
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*
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* FIXME: Still looks like suspended threads in the kernel
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* need to be made immutable. see src/glue/arm/systable.c
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*/
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int sys_exchange_registers(struct exregs_data *exregs, l4id_t tid)
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{
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int err = 0;
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struct ktcb *task;
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if ((err = check_access((unsigned long)exregs,
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sizeof(*exregs),
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MAP_USR_RW, 1)) < 0)
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return err;
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/* Find tcb from its list */
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if (!(task = tcb_find(tid)))
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return -ESRCH;
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/*
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* This lock ensures task is not
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* inadvertently resumed by a syscall
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*/
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if (!mutex_trylock(&task->thread_control_lock))
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return -EAGAIN;
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/*
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* Now check that the task is suspended.
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*
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* Only modification of non-register fields are
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* allowed on active tasks and those tasks must
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* be the pagers making the call on themselves.
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*/
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if (task->state != TASK_INACTIVE && exregs->valid_vect &&
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current != task && task->pagerid != current->tid) {
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err = -EACTIVE;
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goto out;
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}
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if ((err = cap_exregs_check(task, exregs)) < 0)
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return -ENOCAP;
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/* Copy registers */
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if (exregs->flags & EXREGS_READ)
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exregs_read_registers(task, exregs);
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else
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exregs_write_registers(task, exregs);
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out:
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/* Unlock and return */
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mutex_unlock(&task->thread_control_lock);
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return err;
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}
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