[Xen-ia64-devel] [PATCH 04/17] ia64/pv_ops: preparation: introduce ia64_get_psr_i() to make kernel paravirtualization friendly.

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

__local_irq_save() and local_save_flags() are used to mask interruptions.
They read all psr bits that requres whole bit emulation.
On the other hand, reading only psr.i, the single bit, can be virtualized
cheaply.

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
 include/asm-ia64/intrinsics.h |    2 ++
 include/asm-ia64/system.h     |   10 ++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/asm-ia64/intrinsics.h b/include/asm-ia64/intrinsics.h
index 9b83f8f..a3b9689 100644
--- a/include/asm-ia64/intrinsics.h
+++ b/include/asm-ia64/intrinsics.h
@@ -18,6 +18,8 @@
 # include <asm/gcc_intrin.h>
 #endif
 
+#define ia64_get_psr_i()       (ia64_getreg(_IA64_REG_PSR) & IA64_PSR_I)
+
 #define ia64_set_rr0_to_rr4(val0, val1, val2, val3, val4)      \
 do {                                                           \
        ia64_set_rr(0x0000000000000000UL, (val0));              \
diff --git a/include/asm-ia64/system.h b/include/asm-ia64/system.h
index 0db8c98..927a381 100644
--- a/include/asm-ia64/system.h
+++ b/include/asm-ia64/system.h
@@ -123,10 +123,16 @@ extern struct ia64_boot_param {
  *   write a floating-point register right before reading the PSR
  *   and that writes to PSR.mfl
  */
+#ifdef CONFIG_PARAVIRT
+#define __local_save_flags()   ia64_get_psr_i()
+#else
+#define __local_save_flags()   ia64_getreg(_IA64_REG_PSR)
+#endif
+
 #define __local_irq_save(x)                    \
 do {                                           \
        ia64_stop();                            \
-       (x) = ia64_getreg(_IA64_REG_PSR);       \
+       (x) = __local_save_flags();             \
        ia64_stop();                            \
        ia64_rsm(IA64_PSR_I);                   \
 } while (0)
@@ -174,7 +180,7 @@ do {                                                        
        \
 #endif /* !CONFIG_IA64_DEBUG_IRQ */
 
 #define local_irq_enable()     ({ ia64_stop(); ia64_ssm(IA64_PSR_I); 
ia64_srlz_d(); })
-#define local_save_flags(flags)        ({ ia64_stop(); (flags) = 
ia64_getreg(_IA64_REG_PSR); })
+#define local_save_flags(flags)        ({ ia64_stop(); (flags) = 
__local_save_flags(); })
 
 #define irqs_disabled()                                \
 ({                                             \
-- 
1.5.3


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