[PATCH v1 1/4] perf utils: Add support functions for sha1 utils

[Yuzhuo Jing <yuzhuo@google.com>]

Add missing functions to the shrunk down version tools headers from the
kernel headers to support sha1 utils.

Signed-off-by: Yuzhuo Jing <yuzhuo@google.com>
---
 tools/include/linux/bitops.h   | 10 ++++++++++
 tools/include/linux/compiler.h | 17 +++++++++++++++++
 tools/include/linux/string.h   | 22 ++++++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/tools/include/linux/bitops.h b/tools/include/linux/bitops.h
index b4e4cd071f8c..6a027031225c 100644
--- a/tools/include/linux/bitops.h
+++ b/tools/include/linux/bitops.h
@@ -89,6 +89,16 @@ static inline __u32 rol32(__u32 word, unsigned int shift)
 	return (word << shift) | (word >> ((-shift) & 31));
 }
 
+/**
+ * ror32 - rotate a 32-bit value right
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline __u32 ror32(__u32 word, unsigned int shift)
+{
+	return (word >> (shift & 31)) | (word << ((-shift) & 31));
+}
+
 /**
  * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
  * @value: value to sign extend
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 9c05a59f0184..72e92b202976 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -40,6 +40,23 @@
 /* The "volatile" is due to gcc bugs */
 #define barrier() __asm__ __volatile__("": : :"memory")
 
+#ifndef barrier_data
+/*
+ * This version is i.e. to prevent dead stores elimination on @ptr
+ * where gcc and llvm may behave differently when otherwise using
+ * normal barrier(): while gcc behavior gets along with a normal
+ * barrier(), llvm needs an explicit input variable to be assumed
+ * clobbered. The issue is as follows: while the inline asm might
+ * access any memory it wants, the compiler could have fit all of
+ * @ptr into memory registers instead, and since @ptr never escaped
+ * from that, it proved that the inline asm wasn't touching any of
+ * it. This version works well with both compilers, i.e. we're telling
+ * the compiler that the inline asm absolutely may see the contents
+ * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
+ */
+# define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
+#endif
+
 #ifndef __always_inline
 # define __always_inline	inline __attribute__((always_inline))
 #endif
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 8499f509f03e..df3c95792a51 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -3,6 +3,7 @@
 #define _TOOLS_LINUX_STRING_H_
 
 #include <linux/types.h>	/* for size_t */
+#include <linux/compiler.h>	/* for barrier_data */
 #include <string.h>
 
 void *memdup(const void *src, size_t len);
@@ -52,4 +53,25 @@ extern void remove_spaces(char *s);
 
 extern void *memchr_inv(const void *start, int c, size_t bytes);
 extern unsigned long long memparse(const char *ptr, char **retptr);
+
+/**
+ * memzero_explicit - Fill a region of memory (e.g. sensitive
+ *		      keying data) with 0s.
+ * @s: Pointer to the start of the area.
+ * @count: The size of the area.
+ *
+ * Note: usually using memset() is just fine (!), but in cases
+ * where clearing out _local_ data at the end of a scope is
+ * necessary, memzero_explicit() should be used instead in
+ * order to prevent the compiler from optimising away zeroing.
+ *
+ * memzero_explicit() doesn't need an arch-specific version as
+ * it just invokes the one of memset() implicitly.
+ */
+static inline void memzero_explicit(void *s, size_t count)
+{
+	memset(s, 0, count);
+	barrier_data(s);
+}
+
 #endif /* _TOOLS_LINUX_STRING_H_ */
-- 
2.49.0.1164.gab81da1b16-goog