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Kernel: adjust FPU state upon process slot swap

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This fixes seemingly random FPU exceptions and kernel panics occurring
after a system server restart.
This commit is contained in:
David van Moolenbroek 2012-03-03 01:05:27 +01:00
parent 831450aacc
commit 4b6a98de5f
1 changed files with 26 additions and 1 deletions
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27
kernel/system/do_update.c
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@ -23,6 +23,8 @@ FORWARD _PROTOTYPE(void adjust_proc_slot, (struct proc *rp,
struct proc *from_rp));
FORWARD _PROTOTYPE(void adjust_priv_slot, (struct priv *privp,
struct priv *from_privp));
FORWARD _PROTOTYPE(void swap_fpu_state, (struct proc *a_rp,
struct proc *b_orig_rp, struct proc *b_copy_rp));
FORWARD _PROTOTYPE(void swap_proc_slot_pointer, (struct proc **rpp,
struct proc *src_rp, struct proc *dst_rp));
@ -109,6 +111,10 @@ PUBLIC int do_update(struct proc * caller, message * m_ptr)
adjust_priv_slot(priv(src_rp), &orig_src_priv);
adjust_priv_slot(priv(dst_rp), &orig_dst_priv);
/* Swap FPU state. Can only be done after adjusting the process slots. */
swap_fpu_state(src_rp, dst_rp, &orig_dst_proc);
swap_fpu_state(dst_rp, src_rp, &orig_src_proc);
/* Swap global process slot addresses. */
swap_proc_slot_pointer(get_cpulocal_var_ptr(ptproc), src_rp, dst_rp);
@ -140,12 +146,13 @@ PUBLIC int do_update(struct proc * caller, message * m_ptr)
*===========================================================================*/
PRIVATE void adjust_proc_slot(struct proc *rp, struct proc *from_rp)
{
/* Preserve endpoints, slot numbers, priv structure, and IPC. */
/* Preserve endpoints, slot numbers, priv structure, IPC, FPU pointer. */
rp->p_endpoint = from_rp->p_endpoint;
rp->p_nr = from_rp->p_nr;
rp->p_priv = from_rp->p_priv;
priv(rp)->s_proc_nr = from_rp->p_nr;
rp->p_caller_q = from_rp->p_caller_q;
rp->p_fpu_state.fpu_save_area_p = from_rp->p_fpu_state.fpu_save_area_p;
/* preserve scheduling */
rp->p_scheduler = from_rp->p_scheduler;
@ -169,6 +176,24 @@ PRIVATE void adjust_priv_slot(struct priv *privp, struct priv *from_privp)
privp->s_alarm_timer = from_privp->s_alarm_timer;
}
/*===========================================================================*
* swap_fpu_state *
*===========================================================================*/
PRIVATE void swap_fpu_state(struct proc *a_rp, struct proc *b_orig_rp,
struct proc *b_copy_rp)
{
/* Copy the FPU state from process B's copied slot, using B's original FPU
* save area alignment, into process A's slot.
*/
int align;
align = (int) ((char *) b_orig_rp->p_fpu_state.fpu_save_area_p -
(char *) &b_orig_rp->p_fpu_state.fpu_image);
memcpy(a_rp->p_fpu_state.fpu_save_area_p,
b_copy_rp->p_fpu_state.fpu_image + align, FPU_XFP_SIZE);
}
/*===========================================================================*
* swap_proc_slot_pointer *
*===========================================================================*/