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authorPatrick Georgi <patrick@georgi-clan.de>2016-01-27 08:18:16 +0100
committerMartin Roth <martinroth@google.com>2016-01-28 23:25:53 +0100
commitff8076d75ace8da247b927f7de37f3ed5081b55e (patch)
tree239a0d035ffc5fd4d46e3cfb8b3b88191fbe08e7 /src/include/stddef.h
parentcc728f02846a1752215503dc7897caf6fc5a1fc1 (diff)
downloadcoreboot-ff8076d75ace8da247b927f7de37f3ed5081b55e.tar.xz
Provide a gcc-safe zero pointer
zeroptr is a linker object pointing at 0 that can be used to thwart GCC's (and other compilers') "dereferencing NULL is undefined" optimization strategy when it gets in the way. Change-Id: I6aa6f28283281ebae73d6349811e290bf1b99483 Signed-off-by: Patrick Georgi <patrick@georgi-clan.de> Reviewed-on: https://review.coreboot.org/12294 Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com> Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com>
Diffstat (limited to 'src/include/stddef.h')
-rw-r--r--src/include/stddef.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/src/include/stddef.h b/src/include/stddef.h
index b58f645a3b..35326ed6c6 100644
--- a/src/include/stddef.h
+++ b/src/include/stddef.h
@@ -34,4 +34,12 @@ typedef unsigned int wint_t;
#define MAYBE_STATIC static
#endif
+#ifndef __ROMCC__
+/* Provide a pointer to address 0 that thwarts any "accessing this is
+ * undefined behaviour and do whatever" trickery in compilers.
+ * Use when you _really_ need to read32(zeroptr) (ie. read address 0).
+ */
+extern void *zeroptr;
+#endif
+
#endif /* STDDEF_H */