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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-03-07 16:48:45 +1100
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-03-09 10:55:08 +1100
commita546498f3bf9aac311c66f965186373aee2ca0b0 (patch)
tree86fb9a778aba26df3810acd8e52a921a2d84489b /arch/powerpc/mm
parent1b70117924a4f254840ed70fbe3020d4519a1a9a (diff)
downloadop-kernel-dev-a546498f3bf9aac311c66f965186373aee2ca0b0.zip
op-kernel-dev-a546498f3bf9aac311c66f965186373aee2ca0b0.tar.gz
powerpc: Call do_page_fault() with interrupts off
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
Diffstat (limited to 'arch/powerpc/mm')
-rw-r--r--arch/powerpc/mm/fault.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2f0d1b0..7e89006 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -179,6 +179,10 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
}
#endif
+ /* We restore the interrupt state now */
+ if (!arch_irq_disabled_regs(regs))
+ local_irq_enable();
+
if (in_atomic() || mm == NULL) {
if (!user_mode(regs))
return SIGSEGV;
@@ -213,6 +217,13 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
goto bad_area_nosemaphore;
down_read(&mm->mmap_sem);
+ } else {
+ /*
+ * The above down_read_trylock() might have succeeded in
+ * which case we'll have missed the might_sleep() from
+ * down_read():
+ */
+ might_sleep();
}
vma = find_vma(mm, address);
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