summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAlexander Korotkov2021-02-12 14:14:33 +0000
committerAlexander Korotkov2021-02-12 14:23:35 +0000
commit993bdb9f935a751935a03c80d30857150ba2b645 (patch)
tree5744c7b3abd6a42a74abccb574595ff61f251d5e
parentc8b21b0378141948a2dc0ddde6f57407321787ea (diff)
pg_attribute_no_sanitize_alignment() macro
Modern gcc and clang compilers offer alignment sanitizers, which help to detect pointer misalignment. However, our codebase already contains x86-specific crc32 computation code, which uses unalignment access. Thankfully, those compilers also support the attribute, which disables alignment sanitizers at the function level. This commit adds pg_attribute_no_sanitize_alignment(), which wraps this attribute, and applies it to pg_comp_crc32c_sse42() function. Discussion: https://postgr.es/m/CAPpHfdsne3%3DT%3DfMNU45PtxdhSL_J2PjLTeS8rwKnJzUR4YNd4w%40mail.gmail.com Discussion: https://postgr.es/m/475514.1612745257%40sss.pgh.pa.us Author: Alexander Korotkov, revised by Tom Lane Reviewed-by: Tom Lane
-rw-r--r--src/include/c.h12
-rw-r--r--src/port/pg_crc32c_sse42.c1
2 files changed, 13 insertions, 0 deletions
diff --git a/src/include/c.h b/src/include/c.h
index ae978830daf..a86342093eb 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -133,6 +133,18 @@
#endif
/*
+ * Place this macro before functions that should be allowed to make misaligned
+ * accesses. Think twice before using it on non-x86-specific code!
+ * Testing can be done with "-fsanitize=alignment -fsanitize-trap=alignment"
+ * on clang, or "-fsanitize=alignment -fno-sanitize-recover=alignment" on gcc.
+ */
+#if __clang_major__ >= 7 || __GNUC__ >= 5
+#define pg_attribute_no_sanitize_alignment() __attribute__((no_sanitize("alignment")))
+#else
+#define pg_attribute_no_sanitize_alignment()
+#endif
+
+/*
* Append PG_USED_FOR_ASSERTS_ONLY to definitions of variables that are only
* used in assert-enabled builds, to avoid compiler warnings about unused
* variables in assert-disabled builds.
diff --git a/src/port/pg_crc32c_sse42.c b/src/port/pg_crc32c_sse42.c
index 3b94a7388ab..10fc01e1f06 100644
--- a/src/port/pg_crc32c_sse42.c
+++ b/src/port/pg_crc32c_sse42.c
@@ -18,6 +18,7 @@
#include "port/pg_crc32c.h"
+pg_attribute_no_sanitize_alignment()
pg_crc32c
pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len)
{