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powerpc: Call do_page_fault() with interrupts off

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We currently turn interrupts back to their previous state before
calling do_page_fault(). This can be annoying when debugging as
a bad fault will potentially have lost some processor state before
getting into the debugger.

We also end up calling some generic code with interrupts enabled
such as notify_page_fault() with interrupts enabled, which could
be unexpected.

This changes our code to behave more like other architectures,
and make the assembly entry code call into do_page_faults() with
interrupts disabled. They are conditionally re-enabled from
within do_page_fault() in the same spot x86 does it.

While there, add the might_sleep() test in the case of a successful
trylock of the mmap semaphore, again like x86.

Also fix a bug in the existing assembly where r12 (_MSR) could get
clobbered by C calls (the DTL accounting in the exception common
macro and DISABLE_INTS) in some cases.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

v2. Add the r12 clobber fix
This commit is contained in:
Benjamin Herrenschmidt
2012-03-07 16:48:45 +11:00
parent 1b70117924
commit a546498f3b
9 changed files with 54 additions and 59 deletions
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5
arch/powerpc/kernel/exceptions-64e.S
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@@ -313,7 +313,7 @@ interrupt_end_book3e:
NORMAL_EXCEPTION_PROLOG(0x300, PROLOG_ADDITION_2REGS)
mfspr r14,SPRN_DEAR
mfspr r15,SPRN_ESR
EXCEPTION_COMMON(0x300, PACA_EXGEN, INTS_KEEP)
EXCEPTION_COMMON(0x300, PACA_EXGEN, INTS_DISABLE_ALL)
b storage_fault_common
/* Instruction Storage Interrupt */
@@ -321,7 +321,7 @@ interrupt_end_book3e:
NORMAL_EXCEPTION_PROLOG(0x400, PROLOG_ADDITION_2REGS)
li r15,0
mr r14,r10
EXCEPTION_COMMON(0x400, PACA_EXGEN, INTS_KEEP)
EXCEPTION_COMMON(0x400, PACA_EXGEN, INTS_DISABLE_ALL)
b storage_fault_common
/* External Input Interrupt */
@@ -591,7 +591,6 @@ storage_fault_common:
mr r5,r15
ld r14,PACA_EXGEN+EX_R14(r13)
ld r15,PACA_EXGEN+EX_R15(r13)
INTS_RESTORE_HARD
bl .do_page_fault
cmpdi r3,0
bne- 1f