d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Improve address generation in the early arm64 boot

Browse Source 
The adr instruction allows for an address of +-1M from the instruction.
If we replace these with an adrp and an add instruction we can generate
an address +-4G. The adrp will get an address of the 4k page the label
is within, and the add uses the :lo12: prefix to add just the low bits
to this address.

This will allow us to move things around with fewer issues than if we
needed to keep them within the +-1MB range.

Sponsored by:	Innovate UK
This commit is contained in:
Andrew Turner 2020-12-23 07:24:07 +00:00
parent 906a73e791
commit 659f1a6aad
1 changed files with 22 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
sys/arm64/arm64/locore.S
View File

@ -127,7 +127,8 @@ _start:
bl start_mmu
/* Load the new ttbr0 pagetable */
adr x27, pagetable_l0_ttbr0
adrp x27, pagetable_l0_ttbr0
add x27, x27, :lo12:pagetable_l0_ttbr0
/* Jump to the virtual address space */
ldr x15, .Lvirtdone
@ -135,7 +136,8 @@ _start:
virtdone:
/* Set up the stack */
adr x25, initstack_end
adrp x25, initstack_end
add x25, x25, :lo12:initstack_end
mov sp, x25
sub sp, sp, #PCB_SIZE
@ -163,7 +165,8 @@ virtdone:
str x1, [x0, #BP_MODULEP]
str x26, [x0, #BP_KERN_L1PT]
str x29, [x0, #BP_KERN_DELTA]
adr x25, initstack
adrp x25, initstack
add x25, x25, :lo12:initstack
str x25, [x0, #BP_KERN_STACK]
str x24, [x0, #BP_KERN_L0PT]
str x27, [x0, #BP_KERN_TTBR0]
@ -206,15 +209,18 @@ ENTRY(mpentry)
msr contextidr_el1, xzr
/* Load the kernel page table */
adr x24, pagetable_l0_ttbr1
adrp x24, pagetable_l0_ttbr1
add x24, x24, :lo12:pagetable_l0_ttbr1
/* Load the identity page table */
adr x27, pagetable_l0_ttbr0_boostrap
adrp x27, pagetable_l0_ttbr0_boostrap
add x27, x27, :lo12:pagetable_l0_ttbr0_boostrap
/* Enable the mmu */
bl start_mmu
/* Load the new ttbr0 pagetable */
adr x27, pagetable_l0_ttbr0
adrp x27, pagetable_l0_ttbr0
add x27, x27, :lo12:pagetable_l0_ttbr0
/* Jump to the virtual address space */
ldr x15, =mp_virtdone
@ -282,7 +288,8 @@ drop_to_el1:
msr cntvoff_el2, xzr
/* Hypervisor trap functions */
adr x2, hyp_vectors
adrp x2, hyp_vectors
add x2, x2, :lo12:hyp_vectors
msr vbar_el2, x2
mov x2, #(PSR_F | PSR_I | PSR_A | PSR_D | PSR_M_EL1h)
@ -345,7 +352,8 @@ hyp_vectors:
*/
get_virt_delta:
/* Load the physical address of virt_map */
adr x29, virt_map
adrp x29, virt_map
add x29, x29, :lo12:virt_map
/* Load the virtual address of virt_map stored in virt_map */
ldr x28, [x29]
/* Find PA - VA as PA' = VA' - VA + PA = VA' + (PA - VA) = VA' + x29 */
@ -383,9 +391,11 @@ create_pagetables:
mov x5, x30
/* Clean the page table */
adr x6, pagetable
adrp x6, pagetable
add x6, x6, :lo12:pagetable
mov x26, x6
adr x27, pagetable_end
adrp x27, pagetable_end
add x27, x27, :lo12:pagetable_end
1:
stp xzr, xzr, [x6], #16
stp xzr, xzr, [x6], #16
@ -474,7 +484,8 @@ common:
/* Link the DMAP tables */
ldr x8, =DMAP_MIN_ADDRESS
adr x9, pagetable_dmap;
adrp x9, pagetable_dmap
add x9, x9, :lo12:pagetable_dmap
mov x10, #DMAP_TABLES
bl link_l0_pagetable