x86: fix exec mappings comments

- noexec32 is on by default for years already
- add noexec32 to kernel-parameters and fix noexec typo in there

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Documentation/kernel-parameters.txt

@@ -1280,8 +1280,16 @@ and is between 256 and 4096 characters. It is defined in the file
 	noexec		[IA-64]
 
 	noexec		[X86-32,X86-64]
+			On X86-32 available only on PAE configured kernels.
 			noexec=on: enable non-executable mappings (default)
-			noexec=off: disable nn-executable mappings
+			noexec=off: disable non-executable mappings
+
+	noexec32	[X86-64]
+			This affects only 32-bit executables.
+			noexec32=on: enable non-executable mappings (default)
+				read doesn't imply executable mappings
+			noexec32=off: disable non-executable mappings
+				read implies executable mappings
 
 	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
 			register save and restore. The kernel will only save

arch/x86/kernel/setup64.c

@@ -74,8 +74,8 @@ int force_personality32 = 0;
 Control non executable heap for 32bit processes.
 To control the stack too use noexec=off
 
-on	PROT_READ does not imply PROT_EXEC for 32bit processes
-off	PROT_READ implies PROT_EXEC (default)
+on	PROT_READ does not imply PROT_EXEC for 32bit processes (default)
+off	PROT_READ implies PROT_EXEC
 */
 static int __init nonx32_setup(char *str)
 {