[PATCH 2/6] x86/alternative: Add alternative_io_2

Ross Zwisler
2014-11-11T18:45:09Z

Add alternative_io_2 in the spirit of alternative_input_2 and
alternative_io. This will allow us to have instructions with an output
parameter that vary based on two CPU features.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: H Peter Anvin <h.peter.anvin@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Cc: x86@kernel.org
---
arch/x86/include/asm/alternative.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 473bdbe..7d9ead9 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -180,6 +180,20 @@ static inline int alternatives_text_reserved(void *start, void *end)
asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
: output : "i" (0), ## input)

+/*
+ * This is similar to alternative_io. But it has two features and
+ * respective instructions.
+ *
+ * If CPU has feature2, newinstr2 is used.
+ * Otherwise, if CPU has feature1, newinstr1 is used.
+ * Otherwise, oldinstr is used.
+ */
+#define alternative_io_2(oldinstr, newinstr1, feature1, newinstr2, \
+ feature2, output, input...) \
+ asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
+ newinstr2, feature2) \
+ : output : "i" (0), ## input)
+
/* Like alternative_io, but for replacing a direct call with another one. */
#define alternative_call(oldfunc, newfunc, feature, output, input...) \
asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
--
1.9.3