[patch V163 07/51] x86/mm/64: Improve the memory map documentation

From: Thomas Gleixner
Date: Mon Dec 18 2017 - 06:54:02 EST


From: Andy Lutomirski <luto@xxxxxxxxxx>

The old docs had the vsyscall range wrong* and were missing the fixmap.
Fix both.

There used to be 8 MB reserved for future vsyscalls, but that's long gone.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>

---
Documentation/x86/x86_64/mm.txt | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -19,8 +19,9 @@ ffffff0000000000 - ffffff7fffffffff (=39
ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
... unused hole ...
ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
-ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space (variable)
-ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
+ffffffffa0000000 - [fixmap start] (~1526 MB) module mapping space (variable)
+[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
+ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole

Virtual memory map with 5 level page tables:
@@ -41,8 +42,9 @@ ffffff0000000000 - ffffff7fffffffff (=39
ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
... unused hole ...
ffffffff80000000 - ffffffff9fffffff (=512 MB) kernel text mapping, from phys 0
-ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space
-ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
+ffffffffa0000000 - [fixmap start] (~1526 MB) module mapping space
+[fixmap start] - ffffffffff5fffff kernel-internal fixmap range
+ffffffffff600000 - ffffffffff600fff (=4 kB) legacy vsyscall ABI
ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole

Architecture defines a 64-bit virtual address. Implementations can support