[coreboot-gerrit] New patch to review for coreboot: 8038999 Make common macros double-evaluation-safe

Patrick Georgi (pgeorgi@google.com) gerrit at coreboot.org
Mon Jun 1 10:56:14 CEST 2015


Patrick Georgi (pgeorgi at google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/10393

-gerrit

commit 8038999a29f6740d0bd1d67fd0757594897cdb20
Author: Julius Werner <jwerner at chromium.org>
Date:   Fri May 22 18:09:48 2015 -0700

    Make common macros double-evaluation-safe
    
    Our MIN(), MAX() and ALIGN*() macros are currently vulnerable to
    double-evaluation (e.g. x = ALIGN_UP(y, big_func_with_side_effects(y));
    doesn't do what you'd think it should). GCC (and mostly GCC-compatible
    compilers like clang) long had the statement expression and typeof()
    extensions to deal with problems like this. We should use them.
    
    BRANCH=None
    BUG=None
    TEST=None
    
    Change-Id: I4cc368a2f9966139c988257afc013151cd90c7ab
    Signed-off-by: Patrick Georgi <pgeorgi at chromium.org>
    Original-Commit-Id: 985abba1a9b8fa659a9f40e224f81266d7e542bb
    Original-Change-Id: I2519d552b67096c9277c5206964f83dda97c8d01
    Original-Signed-off-by: Julius Werner <jwerner at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/273009
    Original-Reviewed-by: Patrick Georgi <pgeorgi at chromium.org>
---
 payloads/libpayload/include/libpayload.h | 12 ++++++++++--
 payloads/libpayload/include/stdlib.h     |  6 +++++-
 src/include/stdlib.h                     | 18 +++++++++++++++---
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h
index 781a41d..198f4f2 100644
--- a/payloads/libpayload/include/libpayload.h
+++ b/payloads/libpayload/include/libpayload.h
@@ -62,8 +62,16 @@
 #include <lar.h>
 #endif
 
-#define MIN(a,b) ((a) < (b) ? (a) : (b))
-#define MAX(a,b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ({ \
+	typeof(a) _a = a; \
+	typeof(b) _b = b; \
+	_a < _b ? _a : _b; \
+})
+#define MAX(a, b) ({ \
+	typeof(a) _a = a; \
+	typeof(b) _b = b; \
+	_a > _b ? _a : _b; \
+})
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
 
 static inline u32 div_round_up(u32 n, u32 d) { return n + d - 1 / d; }
diff --git a/payloads/libpayload/include/stdlib.h b/payloads/libpayload/include/stdlib.h
index 08c7d06..71610c1 100644
--- a/payloads/libpayload/include/stdlib.h
+++ b/payloads/libpayload/include/stdlib.h
@@ -35,8 +35,12 @@
 #include <stddef.h>
 #include <string.h>
 
+#define __ALIGN_MASK(x, mask)    ({ \
+	typeof(mask) _mask = mask; \
+	((x) + _mask) & ~_mask; \
+})
+
 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1UL)
-#define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
 #define ALIGN_UP(x,a)           ALIGN((x),(a))
 #define ALIGN_DOWN(x,a)         ((x) & ~((typeof(x))(a)-1UL))
 #define IS_ALIGNED(x,a)         (((x) & ((typeof(x))(a)-1UL)) == 0)
diff --git a/src/include/stdlib.h b/src/include/stdlib.h
index 35e8b32..37ed6ef 100644
--- a/src/include/stdlib.h
+++ b/src/include/stdlib.h
@@ -5,14 +5,26 @@
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
 
+#define __ALIGN_MASK(x, mask)    ({ \
+	typeof(mask) _mask = mask; \
+	((x) + _mask) & ~_mask; \
+})
+
 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1UL)
-#define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
 #define ALIGN_UP(x,a)           ALIGN((x),(a))
 #define ALIGN_DOWN(x,a)         ((x) & ~((typeof(x))(a)-1UL))
 #define IS_ALIGNED(x,a)         (((x) & ((typeof(x))(a)-1UL)) == 0)
 
-#define MIN(a,b) ((a) < (b) ? (a) : (b))
-#define MAX(a,b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ({ \
+	typeof(a) _a = a; \
+	typeof(b) _b = b; \
+	_a < _b ? _a : _b; \
+})
+#define MAX(a, b) ({ \
+	typeof(a) _a = a; \
+	typeof(b) _b = b; \
+	_a > _b ? _a : _b; \
+})
 #define ABS(a) (((a) < 0) ? (-(a)) : (a))
 #define CEIL_DIV(a, b)  (((a) + (b) - 1) / (b))
 #define IS_POWER_OF_2(x)  (((x) & ((x) - 1)) == 0)



More information about the coreboot-gerrit mailing list