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Groups > linux.kernel > #1695289 > unrolled thread

[PATCH RESEND] x86/boot: #undef memcpy etc in string.c

Started byMatthias Kaehlcke <mka@chromium.org>
First post2017-07-25 02:00 +0200
Last post2017-07-25 16:00 +0200
Articles 2 — 2 participants

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  [PATCH RESEND] x86/boot: #undef memcpy etc in string.c Matthias Kaehlcke <mka@chromium.org> - 2017-07-25 02:00 +0200
    [tip:x86/urgent] x86/boot: #undef memcpy() et al in string.c tip-bot for Michael Davidson <tipbot@zytor.com> - 2017-07-25 16:00 +0200

#1695289 — [PATCH RESEND] x86/boot: #undef memcpy etc in string.c

FromMatthias Kaehlcke <mka@chromium.org>
Date2017-07-25 02:00 +0200
Subject[PATCH RESEND] x86/boot: #undef memcpy etc in string.c
Message-ID<u6Vqx-3D8-5@gated-at.bofh.it>
From: Michael Davidson <md@google.com>

undef memcpy and friends in boot/string.c so that the functions
defined here will have the correct names, otherwise we end up
up trying to redefine __builtin_memcpy etc.
Surprisingly, gcc allows this (and, helpfully, discards the
__builtin_ prefix from the function name when compiling it),
but clang does not.

Adding these #undef's appears to preserve what I assume was
the original intent of the code.

Signed-off-by: Michael Davidson <md@google.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
Original post: https://lkml.org/lkml/2017/3/16/1035

 arch/x86/boot/string.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
index 630e3664906b..16f49123d747 100644
--- a/arch/x86/boot/string.c
+++ b/arch/x86/boot/string.c
@@ -16,6 +16,15 @@
 #include "ctype.h"
 #include "string.h"
 
+/*
+ * Undef these macros so that the functions that we provide
+ * here will have the correct names regardless of how string.h
+ * may have chosen to #define them.
+ */
+#undef memcpy
+#undef memset
+#undef memcmp
+
 int memcmp(const void *s1, const void *s2, size_t len)
 {
 	bool diff;
-- 
2.14.0.rc0.284.gd933b75aa4-goog

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#1695750 — [tip:x86/urgent] x86/boot: #undef memcpy() et al in string.c

Fromtip-bot for Michael Davidson <tipbot@zytor.com>
Date2017-07-25 16:00 +0200
Subject[tip:x86/urgent] x86/boot: #undef memcpy() et al in string.c
Message-ID<u78xs-3uy-25@gated-at.bofh.it>
In reply to#1695289
Commit-ID:  18d5e6c34a8eda438d5ad8b3b15f42dab01bf05d
Gitweb:     http://git.kernel.org/tip/18d5e6c34a8eda438d5ad8b3b15f42dab01bf05d
Author:     Michael Davidson <md@google.com>
AuthorDate: Mon, 24 Jul 2017 16:51:55 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 25 Jul 2017 11:13:55 +0200

x86/boot: #undef memcpy() et al in string.c

undef memcpy() and friends in boot/string.c so that the functions
defined here will have the correct names, otherwise we end up
up trying to redefine __builtin_memcpy() etc.

Surprisingly, GCC allows this (and, helpfully, discards the
__builtin_ prefix from the function name when compiling it),
but clang does not.

Adding these #undef's appears to preserve what I assume was
the original intent of the code.

Signed-off-by: Michael Davidson <md@google.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bernhard.Rosenkranzer@linaro.org
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170724235155.79255-1-mka@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/boot/string.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
index 630e366..16f4912 100644
--- a/arch/x86/boot/string.c
+++ b/arch/x86/boot/string.c
@@ -16,6 +16,15 @@
 #include "ctype.h"
 #include "string.h"
 
+/*
+ * Undef these macros so that the functions that we provide
+ * here will have the correct names regardless of how string.h
+ * may have chosen to #define them.
+ */
+#undef memcpy
+#undef memset
+#undef memcmp
+
 int memcmp(const void *s1, const void *s2, size_t len)
 {
 	bool diff;

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