riscv: support DEBUG_WX

Support DEBUG_WX to check whether there are mapping with write and execute
permission at the same time.

[akpm@linux-foundation.org: replace macros with C]
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/282e266311bced080bc6f7c255b92f87c1eb65d6.1587455584.git.zong.li@sifive.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/riscv/Kconfig

@@ -16,6 +16,7 @@ config RISCV
 	select OF_EARLY_FLATTREE
 	select OF_IRQ
 	select ARCH_HAS_BINFMT_FLAT
+	select ARCH_HAS_DEBUG_WX
 	select ARCH_WANT_FRAME_POINTERS
 	select CLONE_BACKWARDS
 	select COMMON_CLK

arch/riscv/include/asm/ptdump.h

@@ -8,4 +8,15 @@
 
 void ptdump_check_wx(void);
 
+#ifdef CONFIG_DEBUG_WX
+static inline void debug_checkwx(void)
+{
+	ptdump_check_wx();
+}
+#else
+static inline void debug_checkwx(void)
+{
+}
+#endif
+
 #endif /* _ASM_RISCV_PTDUMP_H */

arch/riscv/mm/init.c

@@ -19,6 +19,7 @@
 #include <asm/sections.h>
 #include <asm/pgtable.h>
 #include <asm/io.h>
+#include <asm/ptdump.h>
 
 #include "../kernel/head.h"
 
@@ -514,6 +515,8 @@ void mark_rodata_ro(void)
 	set_memory_ro(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
 	set_memory_nx(rodata_start, (data_start - rodata_start) >> PAGE_SHIFT);
 	set_memory_nx(data_start, (max_low - data_start) >> PAGE_SHIFT);
+
+	debug_checkwx();
 }
 #endif