Fix incorrect pointer conversion in SMC_UUID_RET()
Casting a pointer to a struct uuid into a pointer to uint32_t may
result in a pointer that is not correctly aligned, which constitutes
an undefined behaviour. In the case of TF, this also generates a data
abort because alignment fault checking is enabled (through the SCTLR.A
bit).
This patch modifies the SMC_UUID_RET() macro to read the uuid
structure without any pointer aliasing. A helper function then
combines every set of 4 bytes into a 32-bit value suitable to be
returned through the x0-x3 registers.
This fixes a violation of MISRA rule 11.3.
Change-Id: I53ee73bb4cb332f4d8286055ceceb6f347caa080
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/include/lib/smccc.h b/include/lib/smccc.h
index cb722b0..a07e510 100644
--- a/include/lib/smccc.h
+++ b/include/lib/smccc.h
@@ -84,5 +84,32 @@
{ _n0, _n1, _n2, _n3, _n4, _n5 } \
}
+/*
+ * Return a UUID in the SMC return registers.
+ *
+ * Acccording to section 5.3 of the SMCCC, UUIDs are returned as a single
+ * 128-bit value using the SMC32 calling convention. This value is mapped to
+ * argument registers x0-x3 on AArch64 (resp. r0-r3 on AArch32). x0 for example
+ * shall hold bytes 0 to 3, with byte 0 in the low-order bits.
+ */
+static inline uint32_t smc_uuid_word(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3)
+{
+ return ((uint32_t) b0) | (((uint32_t) b1) << 8) |
+ (((uint32_t) b2) << 16) | (((uint32_t) b3) << 24);
+}
+
+#define SMC_UUID_RET(_h, _uuid) \
+ SMC_RET4(handle, \
+ smc_uuid_word((_uuid).time_low[0], (_uuid).time_low[1], \
+ (_uuid).time_low[2], (_uuid).time_low[3]), \
+ smc_uuid_word((_uuid).time_mid[0], (_uuid).time_mid[1], \
+ (_uuid).time_hi_and_version[0], \
+ (_uuid).time_hi_and_version[1]), \
+ smc_uuid_word((_uuid).clock_seq_hi_and_reserved, \
+ (_uuid).clock_seq_low, (_uuid).node[0], \
+ (_uuid).node[1]), \
+ smc_uuid_word((_uuid).node[2], (_uuid).node[3], \
+ (_uuid).node[4], (_uuid).node[5]))
+
#endif /*__ASSEMBLY__*/
#endif /* __SMCCC_H__ */