[tip:,x86/urgent] lib/string: Make memzero_explicit() inline instead of external

Commit Message

thermal-bot for Julien Panis Oct. 8, 2019, 11:33 a.m. UTC

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     bec500777089b3c96c53681fc0aa6fee59711d4a
Gitweb:        https://git.kernel.org/tip/bec500777089b3c96c53681fc0aa6fee59711d4a
Author:        Arvind Sankar <[e-mail]>
AuthorDate:    Mon, 07 Oct 2019 18:00:02 -04:00
Committer:     Ingo Molnar <[e-mail]>
CommitterDate: Tue, 08 Oct 2019 13:27:05 +02:00

lib/string: Make memzero_explicit() inline instead of external

With the use of the barrier implied by barrier_data(), there is no need
for memzero_explicit() to be extern. Making it inline saves the overhead
of a function call, and allows the code to be reused in arch/*/purgatory
without having to duplicate the implementation.

Tested-by: Hans de Goede <[e-mail]>
Signed-off-by: Arvind Sankar <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: H . Peter Anvin <[e-mail]>
Cc: Herbert Xu <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephan Mueller <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Fixes: 906a4bb97f5d ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit")
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>
---
 include/linux/string.h | 21 ++++++++++++++++++++-
 lib/string.c           | 21 ---------------------
 2 files changed, 20 insertions(+), 22 deletions(-)

Patch

diff --git a/include/linux/string.h b/include/linux/string.h
index b2f9df7..b6ccdc2 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -227,7 +227,26 @@  static inline bool strstarts(const char *str, const char *prefix)
 }
 
 size_t memweight(const void *ptr, size_t bytes);
-void memzero_explicit(void *s, size_t count);
+
+/**
+ * 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);
+}
 
 /**
  * kbasename - return the last part of a pathname.
diff --git a/lib/string.c b/lib/string.c
index cd7a10c..08ec58c 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -748,27 +748,6 @@  void *memset(void *s, int c, size_t count)
 EXPORT_SYMBOL(memset);
 #endif
 
-/**
- * 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.
- */
-void memzero_explicit(void *s, size_t count)
-{
-	memset(s, 0, count);
-	barrier_data(s);
-}
-EXPORT_SYMBOL(memzero_explicit);
-
 #ifndef __HAVE_ARCH_MEMSET16
 /**
  * memset16() - Fill a memory area with a uint16_t