[Xen-changelog] [xen stable-4.5] arm64: fix fls()

[patchbot@xxxxxxx]

commit 3771b5a015f71374bdc8295ade13da6a6e0db334
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jan 23 15:02:39 2015 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Apr 2 11:45:19 2015 +0100

    arm64: fix fls()
    
    It using CLZ on a 64-bit register while specifying the input operand as
    only 32 bits wide is wrong: An operand intentionally shrunk down to 32
    bits at the source level doesn't imply respective zero extension also
    happens at the machine instruction level, and hence the wrong result
    could get returned.
    
    Add suitable inline assembly abstraction so that the function can
    remain shared between arm32 and arm64. The need to include asm_defns.h
    in bitops.h makes it necessary to adjust processor.h though - it is
    generally wrong to include public headers without making sure that
    integer types are properly defined. (I didn't innvestigate or try
    whether the possible alternative of moving the public/arch-arm.h
    inclusion down in the file would also work.)
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    (cherry picked from commit e9c1747a25763c66de4a06923946c59a9f043069)
---
 xen/include/asm-arm/asm_defns.h |    9 +++++++++
 xen/include/asm-arm/bitops.h    |    7 ++++---
 xen/include/asm-arm/processor.h |    5 +++--
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/xen/include/asm-arm/asm_defns.h b/xen/include/asm-arm/asm_defns.h
index 36e72ff..02be83e 100644
--- a/xen/include/asm-arm/asm_defns.h
+++ b/xen/include/asm-arm/asm_defns.h
@@ -7,6 +7,15 @@
 #endif
 #include <asm/processor.h>
 
+/* For generic assembly code: use macros to define operand sizes. */
+#if defined(CONFIG_ARM_32)
+# define __OP32
+#elif defined(CONFIG_ARM_64)
+# define __OP32 "w"
+#else
+# error "unknown ARM variant"
+#endif
+
 #endif /* __ARM_ASM_DEFNS_H__ */
 /*
  * Local variables:
diff --git a/xen/include/asm-arm/bitops.h b/xen/include/asm-arm/bitops.h
index 25f96c8..d69a7c3 100644
--- a/xen/include/asm-arm/bitops.h
+++ b/xen/include/asm-arm/bitops.h
@@ -9,6 +9,8 @@
 #ifndef _ARM_BITOPS_H
 #define _ARM_BITOPS_H
 
+#include <asm/asm_defns.h>
+
 /*
  * Non-atomic bit manipulation.
  *
@@ -140,9 +142,8 @@ static inline int fls(int x)
         if (__builtin_constant_p(x))
                return constant_fls(x);
 
-        asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
-        ret = BITS_PER_LONG - ret;
-        return ret;
+        asm("clz\t%"__OP32"0, %"__OP32"1" : "=r" (ret) : "r" (x));
+        return 32 - ret;
 }
 
 
diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index b7ef817..fcd26fb 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -3,6 +3,9 @@
 
 #include <asm/cpregs.h>
 #include <asm/sysregs.h>
+#ifndef __ASSEMBLY__
+#include <xen/types.h>
+#endif
 #include <public/arch-arm.h>
 
 /* MIDR Main ID Register */
@@ -220,8 +223,6 @@
 
 #ifndef __ASSEMBLY__
 
-#include <xen/types.h>
-
 struct cpuinfo_arm {
     union {
         uint32_t bits;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.5

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