I attached the additional patch I was referring to.
Unfortunately it is against our internel kernel base. I have not had
time to adapt it to the linux-mips.org base yet. But it should be
easy to adapt it.
Let me know if it makes things better.
Jun
On Fri, Dec 20, 2002 at 02:51:24PM +0000, Colin.Helliwell@Zarlink.Com wrote:
>
> Think I'm ok with respect to interrupt handling, but what does making
> globals "safe or taken care of" consist of?
>
>
>
>
>
> Jun Sun
> <jsun@mvista.com> To: Colin.Helliwell@Zarlink.Com
> cc: linux-mips@linux-mips.org, rml@mvista.com, jsun@mvista.com
> 19-Dec-2002 05:59 Subject: Re: Problems with CONFIG_PREEMPT
> PM
>
>
>
>
>
>
> On Thu, Dec 19, 2002 at 09:10:40AM +0000, Colin.Helliwell@Zarlink.Com
> wrote:
> >
> > Thanks for the patch, but unfortunately the problem is still the same.
>
> If the problem happens very soon after you boot up, there is something
> *obviously* wrong. The most common problem is that you have an interupt
> handling path not going through standard do_IRQ(). Then you need to
> do similar treatment like those in ll_timer_interrupt().
>
> The second thing is to look for any *new* global variables you may
> introduce in your kernel. Most of current global variables are either
> safe or taken care of (Although another update patch will come out
> today or tomorrow to really close the final hole we have).
>
> > I'm
> > not sure whether it occurs as a result of interrupts, or just after a
> > certain amount of scheduler 'activity' as it sits there copying the
> initrd
> > into ram disk. A few interrupts are enabled, but its only the MIPS timer
> > which should be generating any interrupts at that point (I'll check that,
> > in case its relevant).
>
> FYI, I have mips kernel with initrd running just fine with preemptible
> kernel.
> In fact, it has passed some very stressful tests with initrd.
>
> > I presume the change from "sti()" to "__sti()" was a semantic (or SMP)
> > thing, since the former is #defined to the latter anyway? Please note
> also
> > the following modification which was required to 2.4.19:
> >
>
> This is true. Since our kernel had synchronize_irq() added long time ago,
> I probably forgot about it when I created the pre-k patch.
>
> Jun
>
>
>
>
>
diff -Nru linux2/arch/mips/kernel/traps.c.orig linux2/arch/mips/kernel/traps.c
--- linux2/arch/mips/kernel/traps.c.orig Wed Dec 18 17:41:11 2002
+++ linux2/arch/mips/kernel/traps.c Fri Dec 20 15:05:08 2002
@@ -131,12 +131,14 @@
else if (get_user(value, vaddr))
signal = SIGSEGV;
else {
+ preempt_disable();
if (ll_task == NULL || ll_task == current) {
ll_bit = 1;
} else {
ll_bit = 0;
}
ll_task = current;
+ preempt_enable();
regp->regs[(opcode & RT) >> 16] = value;
}
if (compute_return_epc(regp))
@@ -168,6 +170,7 @@
sc_ops++;
#endif
+ preempt_disable();
if ((unsigned long)vaddr & 3)
signal = SIGBUS;
else if (ll_bit == 0 || ll_task != current)
@@ -176,6 +179,7 @@
signal = SIGSEGV;
else
regp->regs[reg] = 1;
+ preempt_enable();
if (compute_return_epc(regp))
return;
if (signal)
@@ -551,6 +555,9 @@
TRACE_TRAP_ENTRY(CAUSE_EXCCODE(regs), CAUSE_EPC(regs));
if (fcr31 & FPU_CSR_UNI_X) {
int sig;
+
+ preempt_disable();
+
/*
* Unimplemented operation exception. If we've got the
* full software emulator on-board, let's use it...
@@ -576,6 +583,8 @@
/* Restore the hardware register state */
restore_fp(current);
+ preempt_enable();
+
/* If something went wrong, signal */
if (sig)
force_sig(sig, current);
@@ -756,6 +765,8 @@
die_if_kernel("do_cpu invoked from kernel context!", regs);
+ preempt_disable();
+
own_fpu();
if (current->used_math) { /* Using the FPU again. */
restore_fp(current);
@@ -772,6 +783,8 @@
}
}
+ preempt_enable();
+
TRACE_TRAP_EXIT();
return;
diff -Nru linux2/arch/mips/kernel/process.c.orig linux2/arch/mips/kernel/process.c
--- linux2/arch/mips/kernel/process.c.orig Wed Dec 18 17:41:11 2002
+++ linux2/arch/mips/kernel/process.c Fri Dec 20 15:04:38 2002
@@ -80,9 +80,11 @@
childksp = (unsigned long)p + KERNEL_STACK_SIZE - 32;
+ preempt_disable();
if (is_fpu_owner()) {
save_fp(p);
}
+ preempt_enable();
/* set up new TSS. */
childregs = (struct pt_regs *) childksp - 1;
diff -Nru linux2/arch/mips/kernel/signal.c.orig linux2/arch/mips/kernel/signal.c
--- linux2/arch/mips/kernel/signal.c.orig Wed Dec 18 17:41:11 2002
+++ linux2/arch/mips/kernel/signal.c Fri Dec 20 15:04:54 2002
@@ -214,6 +214,8 @@
err |= __get_user(current->used_math, &sc->sc_used_math);
+ preempt_disable();
+
if (current->used_math) {
own_fpu();
err |= restore_fp_context(sc);
@@ -221,6 +223,8 @@
loose_fpu();
}
+ preempt_enable();
+
return err;
}
@@ -348,6 +352,8 @@
if (!current->used_math)
goto out;
+ preempt_disable();
+
/* There exists FP thread state that may be trashed by signal */
if (!is_fpu_owner()) {
own_fpu();
@@ -357,6 +363,8 @@
/* fp is active. Save context from FPU */
err |= save_fp_context(sc);
+ preempt_enable();
+
out:
return err;
}
diff -Nru linux2/include/asm-mips/pgalloc.h.orig linux2/include/asm-mips/pgalloc.h
--- linux2/include/asm-mips/pgalloc.h.orig Mon Dec 16 18:16:04 2002
+++ linux2/include/asm-mips/pgalloc.h Wed Dec 18 17:46:06 2002
@@ -11,6 +11,7 @@
#include <linux/config.h>
#include <linux/mm.h>
+#include <linux/sched.h>
#include <asm/fixmap.h>
/* TLB flushing:
@@ -84,20 +85,26 @@
{
unsigned long *ret;
+ preempt_disable();
if((ret = pgd_quicklist) != NULL) {
pgd_quicklist = (unsigned long *)(*ret);
ret[0] = ret[1];
pgtable_cache_size--;
- } else
+ preempt_enable();
+ } else {
+ preempt_enable();
ret = (unsigned long *)get_pgd_slow();
+ }
return (pgd_t *)ret;
}
extern __inline__ void free_pgd_fast(pgd_t *pgd)
{
+ preempt_disable();
*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
pgd_quicklist = (unsigned long *) pgd;
pgtable_cache_size++;
+ preempt_enable();
}
extern __inline__ void free_pgd_slow(pgd_t *pgd)
@@ -109,19 +116,23 @@
{
unsigned long *ret;
+ preempt_disable();
if((ret = (unsigned long *)pte_quicklist) != NULL) {
pte_quicklist = (unsigned long *)(*ret);
ret[0] = ret[1];
pgtable_cache_size--;
}
+ preempt_enable();
return (pte_t *)ret;
}
extern __inline__ void free_pte_fast(pte_t *pte)
{
+ preempt_disable();
*(unsigned long *)pte = (unsigned long) pte_quicklist;
pte_quicklist = (unsigned long *) pte;
pgtable_cache_size++;
+ preempt_enable();
}
extern __inline__ void free_pte_slow(pte_t *pte)
diff -Nru linux2/include/asm-mips/fpu.h.orig linux2/include/asm-mips/fpu.h
--- linux2/include/asm-mips/fpu.h.orig Wed Dec 18 17:53:17 2002
+++ linux2/include/asm-mips/fpu.h Fri Dec 20 15:03:32 2002
@@ -120,11 +120,14 @@
static inline unsigned long long *get_fpu_regs(struct task_struct *tsk)
{
+ preempt_disable();
if(mips_cpu.options & MIPS_CPU_FPU) {
if ((tsk == current) && is_fpu_owner())
_save_fp(current);
+ preempt_enable();
return (unsigned long long *)&tsk->thread.fpu.hard.fp_regs[0];
} else {
+ preempt_enable();
return (unsigned long long *)tsk->thread.fpu.soft.regs;
}
}
