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From: Greg KH on 10 May 2010 19:30
2.6.33-stable review patch. If anyone has any objections, please let us know.

------------------


From: David S. Miller <davem(a)davemloft.net>

[ Upstream commits 0c25e9e6cbe7b233bb91d14d0e2c258bf8e6ec83 and
c011f80ba0912486fe51dd2b3f71d9b33a151188 ]

If we are in an NMI then doing a plain raw_local_irq_disable() will
write PIL_NORMAL_MAX into %pil, which is lower than PIL_NMI, and thus
we'll re-enable NMIs and recurse.

Doing a simple:

%pil = %pil | PIL_NORMAL_MAX

does what we want, if we're already at PIL_NMI (15) we leave it at
that setting, else we set it to PIL_NORMAL_MAX (14).

This should get the function tracer working on sparc64.

Signed-off-by: David S. Miller <davem(a)davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
---
arch/sparc/include/asm/irqflags_64.h | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

--- a/arch/sparc/include/asm/irqflags_64.h
+++ b/arch/sparc/include/asm/irqflags_64.h
@@ -76,9 +76,26 @@ static inline int raw_irqs_disabled(void
*/
static inline unsigned long __raw_local_irq_save(void)
{
- unsigned long flags = __raw_local_save_flags();
+ unsigned long flags, tmp;

- raw_local_irq_disable();
+ /* Disable interrupts to PIL_NORMAL_MAX unless we already
+ * are using PIL_NMI, in which case PIL_NMI is retained.
+ *
+ * The only values we ever program into the %pil are 0,
+ * PIL_NORMAL_MAX and PIL_NMI.
+ *
+ * Since PIL_NMI is the largest %pil value and all bits are
+ * set in it (0xf), it doesn't matter what PIL_NORMAL_MAX
+ * actually is.
+ */
+ __asm__ __volatile__(
+ "rdpr %%pil, %0\n\t"
+ "or %0, %2, %1\n\t"
+ "wrpr %1, 0x0, %%pil"
+ : "=r" (flags), "=r" (tmp)
+ : "i" (PIL_NORMAL_MAX)
+ : "memory"
+ );

return flags;
}


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