[Bug binutils/31228] New: ld (aarch64): undefined reference to `no symbol' for adrp with constant value

[petemoore at gmx dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=31228

            Bug ID: 31228
           Summary: ld (aarch64): undefined reference to `no symbol' for
                    adrp with constant value
           Product: binutils
           Version: 2.39
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: petemoore at gmx dot net
  Target Milestone: ---

Consider the following assembly:

```
$ cat adrp.s 
.global _start
_start: adrp x0, 0x8000
```

After assembling and linking:

```
$ aarch64-none-elf-as -o adrp.o adrp.s 
$ aarch64-none-elf-ld -Ttext=0x0 -o adrp.elf adrp.o
aarch64-none-elf-ld: adrp.o: in function `_start':
(.text+0x0): undefined reference to `no symbol'
```

Note, the following trick works (if e.g. _start is known to be 0):

```
$ cat adrp.s 
.global _start
_start: adrp x0, 0x8000 + _start
```

which assembles as desired:

```
$ aarch64-none-elf-objdump -d adrp.elf

adrp.elf:     file format elf64-littleaarch64


Disassembly of section .text:

0000000000000000 <_start>:
   0:   90000040        adrp    x0, 8000 <_start+0x8000>
```

However, this only works if _start is fixed and known. Being able to specify an
absolute (rather than relative) value for the immediate of the adrp instruction
is useful for e.g. referencing peripherals at fixed locations which are known
to be in the +/- 4GB range of the current address. My particular use case is
referencing Raspberry Pi peripheral base addresses when the MMU is not enabled.

Originally reported in bug 27217 comment 30.

```
$ aarch64-none-elf-ld --version
GNU ld (GNU Binutils) 2.39
```

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