[PATCH next] riscv: Add ARCH_HAS_FORTIFY_SOURCE

[Kefeng Wang]

FORTIFY_SOURCE could detect various overflows at compile and run time.
ARCH_HAS_FORTIFY_SOURCE means that the architecture can be built and
run with CONFIG_FORTIFY_SOURCE. Select it in RISCV.

See more about this feature from commit 6974f0c4555e
("include/linux/string.h: add the option of fortified string.h functions").

Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
---
 arch/riscv/Kconfig              | 1 +
 arch/riscv/include/asm/string.h | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 53e66347366f..fa30fbf66879 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -20,6 +20,7 @@ config RISCV
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEBUG_WX
+	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h
index 5477e7ecb6e1..909049366555 100644
--- a/arch/riscv/include/asm/string.h
+++ b/arch/riscv/include/asm/string.h
@@ -23,5 +23,10 @@ extern asmlinkage void *__memmove(void *, const void *, size_t);
 #define memcpy(dst, src, len) __memcpy(dst, src, len)
 #define memset(s, c, n) __memset(s, c, n)
 #define memmove(dst, src, len) __memmove(dst, src, len)
+
+#ifndef __NO_FORTIFY
+#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
+#endif
+
 #endif
 #endif /* _ASM_RISCV_STRING_H */
-- 
2.17.1