In ARMv7 and previous, the program counter is an ordinary register, so you can perform a load relative to the PC for anything that doesn't fit into a register's literal field. Compilers typically emit so-called literal pools before the entry or after the exit point of each function (or sometimes before a basic block inside very large functions). Some compilers support literal pool merging as a code size reduction technique, too.

Edit: Also, ARMv8 has dedicated instructions for for pc-relative loads and jumps.

On ARM1156, and ARMv7 and newer, use MOVW, which takes a simple 16-bit immediate. If 16 bits doesn’t do it, use a MOVW/MOVT pair which can load any 32-bit value.

On older ARMs, either do a load immediate followed by an immediate arithmetic, like so:

    MOV R0, 0x0100
    ADD R0, R0, 0x01

Or use a PC relative load:

    LDR R0, [PC, offset where you stored 0x101]

Which the assembler allows you to abbreviate as:

    LDR R0, =0x101

And it will find a spot for 0x101 and generate the correct PC relative load.

Use two instructions; load part of it then load the rest.