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Use adrp in the arm64 efi loader

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On startup the arm64 efi loaders need to know PC-relative addresses.
Previously we used the adr instruction to find this address, however this
instruction is limited to +/- 1MiB.

Switch to adrp to find the 4k page the address is within and an add to
set the bottom 12 bits. This lets us address +/- 4GiB which should be
large enough for now.

Reported by:	imp
MFC after:	2 weeks
Sponsored by:	Innovate UK
This commit is contained in:
Andrew Turner 2020-10-13 16:51:05 +00:00
parent d524c46fb8
commit b9aa4537b2
1 changed files with 10 additions and 5 deletions
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15
stand/efi/loader/arch/arm64/start.S
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@ -142,8 +142,10 @@ _start:
/* Save the boot params to the stack */
stp x0, x1, [sp, #-16]!
adr x0, __bss_start
adr x1, __bss_end
adrp x0, __bss_start
add x0, x0, :lo12:__bss_start
adrp x1, __bss_end
add x1, x1, :lo12:__bss_end
b 2f
@ -153,8 +155,10 @@ _start:
cmp x0, x1
b.lo 1b
adr x0, ImageBase
adr x1, _DYNAMIC
adrp x0, ImageBase
add x0, x0, :lo12:ImageBase
adrp x1, _DYNAMIC
add x1, x1, :lo12:_DYNAMIC
bl self_reloc
@ -165,7 +169,8 @@ _start:
* Load the stack to use. The default stack may be too small for
* the lua loader.
*/
adr x2, initstack_end
adrp x2, initstack_end
add x2, x2, :lo12:initstack_end
mov sp, x2
#endif