sparc64: Adjust __raw_local_irq_save() to cooperate in NMIs.

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From: Linux Kernel Mailing List
Date: Tuesday, April 13, 2010 - 12:59 pm

Gitweb:     http://git.kernel.org/linus/0c25e9e6cbe7b233bb91d14d0e2c258bf8e6ec83
Commit:     0c25e9e6cbe7b233bb91d14d0e2c258bf8e6ec83
Parent:     cb256aa60409efd803806cfb0528a4b3f8397dba
Author:     David S. Miller <davem@davemloft.net>
AuthorDate: Mon Apr 12 22:21:52 2010 -0700
Committer:  David S. Miller <davem@davemloft.net>
CommitDate: Mon Apr 12 22:21:52 2010 -0700

    sparc64: Adjust __raw_local_irq_save() to cooperate in NMIs.
    
    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@davemloft.net>
---
 arch/sparc/include/asm/irqflags_64.h |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/include/asm/irqflags_64.h b/arch/sparc/include/asm/irqflags_64.h
index 8b49bf9..a16e94c 100644
--- a/arch/sparc/include/asm/irqflags_64.h
+++ b/arch/sparc/include/asm/irqflags_64.h
@@ -76,9 +76,19 @@ 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.
+	 */
+	__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;
 }
--

Previous thread: sparc64: Add HAVE_FUNCTION_TRACE_MCOUNT_TEST and tidy up. by Linux Kernel Mailing List on Tuesday, April 13, 2010 - 12:59 pm. (1 message)

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