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powerpc/book3e-64: Fix debug support for userspace

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With the introduction of CONFIG_PPC_ADV_DEBUG_REGS user space debug is
broken on Book-E 64-bit parts that support delayed debug events.  When
switch_booke_debug_regs() sets DBCR0 we'll start getting debug events as
MSR_DE is also set and we aren't able to handle debug events from kernel
space.

We can remove the hack that always enables MSR_DE and loads up DBCR0 and
just utilize switch_booke_debug_regs() to get user space debug working
again.

We still need to handle critical/debug exception stacks & proper
save/restore of state for those exception levles to support debug events
from kernel space like we have on 32-bit.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Kumar Gala 2011-10-06 02:53:40 +00:00 committed by Benjamin Herrenschmidt
parent b95bc21914
commit 187b9f2aa7
2 changed files with 1 additions and 23 deletions
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2
arch/powerpc/include/asm/reg_booke.h
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@ -31,7 +31,7 @@
#define MSR_ MSR_ME | MSR_CE #define MSR_ MSR_ME | MSR_CE
#define MSR_KERNEL MSR_ | MSR_64BIT #define MSR_KERNEL MSR_ | MSR_64BIT
#define MSR_USER32 MSR_ | MSR_PR | MSR_EE | MSR_DE #define MSR_USER32 MSR_ | MSR_PR | MSR_EE
#define MSR_USER64 MSR_USER32 | MSR_64BIT #define MSR_USER64 MSR_USER32 | MSR_64BIT
#elif defined (CONFIG_40x) #elif defined (CONFIG_40x)
#define MSR_KERNEL (MSR_ME|MSR_RI|MSR_IR|MSR_DR|MSR_CE) #define MSR_KERNEL (MSR_ME|MSR_RI|MSR_IR|MSR_DR|MSR_CE)

22
arch/powerpc/kernel/process.c
View file

@ -486,28 +486,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
new_thread = &new->thread; new_thread = &new->thread;
old_thread = &current->thread; old_thread = &current->thread;
#if defined(CONFIG_PPC_BOOK3E_64)
/* XXX Current Book3E code doesn't deal with kernel side DBCR0,
* we always hold the user values, so we set it now.
*
* However, we ensure the kernel MSR:DE is appropriately cleared too
* to avoid spurrious single step exceptions in the kernel.
*
* This will have to change to merge with the ppc32 code at some point,
* but I don't like much what ppc32 is doing today so there's some
* thinking needed there
*/
if ((new_thread->dbcr0 | old_thread->dbcr0) & DBCR0_IDM) {
u32 dbcr0;
mtmsr(mfmsr() & ~MSR_DE);
isync();
dbcr0 = mfspr(SPRN_DBCR0);
dbcr0 = (dbcr0 & DBCR0_EDM) | new_thread->dbcr0;
mtspr(SPRN_DBCR0, dbcr0);
}
#endif /* CONFIG_PPC64_BOOK3E */
#ifdef CONFIG_PPC64 #ifdef CONFIG_PPC64
/* /*
* Collect processor utilization data per process * Collect processor utilization data per process