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[tip:x86/asm] x86, asm: define CC_SET() and CC_OUT() macros

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Commit-ID:  ff3554b409b82d349f71e9d7082648b7b0a1a5bb
Gitweb:     http://git.kernel.org/tip/ff3554b409b82d349f71e9d7082648b7b0a1a5bb
Author:     H. Peter Anvin <hpa@zytor.com>
AuthorDate: Wed, 8 Jun 2016 12:38:40 -0700
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Wed, 8 Jun 2016 12:41:20 -0700

x86, asm: define CC_SET() and CC_OUT() macros

The CC_SET() and CC_OUT() macros can be used together to take
advantage of the new __GCC_ASM_FLAG_OUTPUTS__ feature in gcc 6+ while
remaining backwards compatible.  CC_SET() generates a SET instruction
on older compilers; CC_OUT() makes sure the output is received in the
correct variable.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-5-git-send-email-hpa@linux.intel.com
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/include/asm/asm.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index f5063b6..7acb51c 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -42,6 +42,18 @@
 #define _ASM_SI		__ASM_REG(si)
 #define _ASM_DI		__ASM_REG(di)
 
+/*
+ * Macros to generate condition code outputs from inline assembly,
+ * The output operand must be type "bool".
+ */
+#ifdef __GCC_ASM_FLAG_OUTPUTS__
+# define CC_SET(c) "\n\t/* output condition code " #c "*/\n"
+# define CC_OUT(c) "=@cc" #c
+#else
+# define CC_SET(c) "\n\tset" #c " %[_cc_" #c "]\n"
+# define CC_OUT(c) [_cc_ ## c] "=qm"
+#endif
+
 /* Exception table entry */
 #ifdef __ASSEMBLY__
 # define _ASM_EXTABLE_HANDLE(from, to, handler)			\

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[PATCH v2 00/10] x86: use gcc 6+ asm flag output feature "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:40 +0200
  [PATCH v2 10/10] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has() in archrandom.h "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:40 +0200
    [tip:x86/asm] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has()  in archrandom.h "tip-bot for H. Peter Anvin" <tipbot@zytor.com> - 2016-06-08 22:00 +0200
    Re: [PATCH v2 10/10] x86, asm: Use CC_SET()/CC_OUT() and  static_cpu_has() in archrandom.h Borislav Petkov <bp@alien8.de> - 2016-06-09 17:50 +0200
  [PATCH v2 04/10] x86, asm: define CC_SET() and CC_OUT() macros "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:40 +0200
    [tip:x86/asm] x86, asm: define CC_SET() and CC_OUT() macros "tip-bot for H. Peter Anvin" <tipbot@zytor.com> - 2016-06-08 21:50 +0200
  [PATCH v2 06/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/bitops.h> "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  [PATCH v2 02/10] x86, asm: use bool for bitops and other assembly outputs "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  [PATCH v2 08/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/rwsem.h> "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  [PATCH v2 07/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/percpu.h> "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  [PATCH v2 05/10] x86, asm: change GEN_*_RMWcc() to use CC_SET()/CC_OUT() "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  [PATCH v2 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition "H. Peter Anvin" <hpa@linux.intel.com> - 2016-06-08 21:50 +0200
  Re: [PATCH v2 00/10] x86: use gcc 6+ asm flag output feature "H. Peter Anvin" <hpa@zytor.com> - 2016-06-08 23:40 +0200

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