git: 659f1a6aad04 - Improve address generation in the early arm64 boot

[Andrew Turner]

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=659f1a6aad04adf0a0d27415f7a967d231ce4cfb

commit 659f1a6aad04adf0a0d27415f7a967d231ce4cfb
Author:     Andrew Turner <andrew at FreeBSD.org>
AuthorDate: 2020-12-23 07:24:07 +0000
Commit:     Andrew Turner <andrew at FreeBSD.org>
CommitDate: 2020-12-23 07:54:59 +0000

    Improve address generation in the early arm64 boot
    
    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
---
 sys/arm64/arm64/locore.S | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/sys/arm64/arm64/locore.S b/sys/arm64/arm64/locore.S
index f438865a961a..6f8d007b2efa 100644
--- a/sys/arm64/arm64/locore.S
+++ b/sys/arm64/arm64/locore.S
@@ -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