A subtle bug sneaked into iSeries recently. On this platform, we must
not normally clear MSR:EE (the hardware external interrupt enable)
except for short periods of time. Taking an interrupt while
soft-disabled doesn't cause us to clear it for example.
The iSeries kernel expects to mostly run with MSR:EE enabled at all
times except in a few exception entry/exit code paths. Thus
local_irq_enable() doesn't check if it needs to hard-enable as it
expects this to be unnecessary on iSeries.
However, hard_irq_disable() _does_ cause MSR:EE to be cleared,
including on iSeries. A call to it was recently added to the
context switch code, thus causing interrupts to become disabled
for a long periods of time, causing the iSeries watchdog to kick
in under some circumstances and other nasty things.
This patch fixes it by making local_irq_enable() properly re-enable
MSR:EE on iSeries. It basically removes a return statement here
to make iSeries use the same code path as everybody else. That does
mean that we might occasionally get spurious decrementer interrupts
but I don't think that matters.
Another option would have been to make hard_irq_disable() a nop
on iSeries but I didn't like it much, in case we have good reasons
to hard-disable.
Part of the patch is fixes to make sure the hard_enabled PACA field
is properly set on iSeries as it used not to be before, since it
was mostly unused.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
ori r4,r4,MSR_EE
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
ori r4,r4,MSR_EE
+ li r8,1
+ stb r8,PACAHARDIRQEN(r13)
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
BEGIN_FW_FTR_SECTION
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
BEGIN_FW_FTR_SECTION
- stb r7,PACASOFTIRQEN(r13)
stb r7,PACAHARDIRQEN(r13)
END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
stb r7,PACAHARDIRQEN(r13)
END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
+ stb r7,PACASOFTIRQEN(r13)
mtspr SPRN_SRR0,r3
mtspr SPRN_SRR1,r4
mtspr SPRN_SRR0,r3
mtspr SPRN_SRR1,r4
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
mfmsr r5
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
mfmsr r5
- ori r5,r5,MSR_EE /* Hard Enabled */
+ ori r5,r5,MSR_EE /* Hard Enabled on iSeries*/
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
-BEGIN_FW_FTR_SECTION
- stb r5,PACAHARDIRQEN(r13)
-END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
+ stb r5,PACAHARDIRQEN(r13) /* Hard Disabled on others */
/* Not reached */
BUG_OPCODE
/* Not reached */
BUG_OPCODE
*/
if (local_paca->lppaca_ptr->int_dword.any_int)
iseries_handle_interrupts();
*/
if (local_paca->lppaca_ptr->int_dword.any_int)
iseries_handle_interrupts();