riscv: Define a SV48 memory map

No functional change intended.

Reviewed by:	kib, jhb
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D34273
This commit is contained in:
Mark Johnston 2022-03-01 09:04:38 -05:00
parent 59f192c507
commit 35d0f443cf

View file

@ -116,14 +116,19 @@
* Address space layout.
*
* RISC-V implements multiple paging modes with different virtual address space
* sizes: SV32, SV39 and SV48. SV39 permits a virtual address space size of
* 512GB and uses a three-level page table. Since this is large enough for most
* purposes, we currently use SV39 for both userland and the kernel, avoiding
* the extra translation step required by SV48.
* sizes: SV32, SV39, SV48 and SV57. Only SV39 and SV48 are supported by
* FreeBSD. SV39 provides a 512GB virtual address space and uses three-level
* page tables, while SV48 provides a 256TB virtual address space and uses
* four-level page tables. 64-bit RISC-V implementations are required to provide
* at least SV39 mode; locore initially enables SV39 mode while bootstrapping
* page tables, and pmap_bootstrap() optionally switches to SV48 mode.
*
* The address space is split into two regions at each end of the 64-bit address
* space:
* space; the lower region is for use by user mode software, while the upper
* region is used for various kernel maps. The kernel map layout in SV48 mode
* is currently identical to that used in SV39 mode.
*
* SV39 memory map:
* 0x0000000000000000 - 0x0000003fffffffff 256GB user map
* 0x0000004000000000 - 0xffffffbfffffffff unmappable
* 0xffffffc000000000 - 0xffffffc7ffffffff 32GB kernel map
@ -131,6 +136,15 @@
* 0xffffffd000000000 - 0xffffffefffffffff 128GB direct map
* 0xfffffff000000000 - 0xffffffffffffffff 64GB unused
*
* SV48 memory map:
* 0x0000000000000000 - 0x00007fffffffffff 128TB user map
* 0x0000800000000000 - 0xffff7fffffffffff unmappable
* 0xffff800000000000 - 0xffffffc7ffffffff 127.75TB hole
* 0xffffffc000000000 - 0xffffffc7ffffffff 32GB kernel map
* 0xffffffc800000000 - 0xffffffcfffffffff 32GB unused
* 0xffffffd000000000 - 0xffffffefffffffff 128GB direct map
* 0xfffffff000000000 - 0xffffffffffffffff 64GB unused
*
* The kernel is loaded at the beginning of the kernel map.
*
* We define some interesting address constants:
@ -180,9 +194,9 @@
((va) - DMAP_MIN_ADDRESS) + dmap_phys_base; \
})
#define VM_MIN_USER_ADDRESS_SV39 (0x0000000000000000UL)
#define VM_MIN_USER_ADDRESS (0x0000000000000000UL)
#define VM_MAX_USER_ADDRESS_SV39 (0x0000004000000000UL)
#define VM_MIN_USER_ADDRESS VM_MIN_USER_ADDRESS_SV39
#define VM_MAX_USER_ADDRESS_SV48 (0x0000800000000000UL)
#define VM_MAX_USER_ADDRESS VM_MAX_USER_ADDRESS_SV39
#define VM_MINUSER_ADDRESS (VM_MIN_USER_ADDRESS)
@ -194,9 +208,13 @@
#define KERNBASE (VM_MIN_KERNEL_ADDRESS)
#define SHAREDPAGE_SV39 (VM_MAX_USER_ADDRESS_SV39 - PAGE_SIZE)
#define SHAREDPAGE_SV48 (VM_MAX_USER_ADDRESS_SV48 - PAGE_SIZE)
#define SHAREDPAGE SHAREDPAGE_SV39
#define USRSTACK SHAREDPAGE_SV39
#define USRSTACK_SV39 SHAREDPAGE_SV39
#define USRSTACK_SV48 SHAREDPAGE_SV48
#define USRSTACK USRSTACK_SV39
#define PS_STRINGS_SV39 (USRSTACK_SV39 - sizeof(struct ps_strings))
#define PS_STRINGS_SV48 (USRSTACK_SV48 - sizeof(struct ps_strings))
#define VM_EARLY_DTB_ADDRESS (VM_MAX_KERNEL_ADDRESS - (2 * L2_SIZE))