If the distance is too big we are in trouble - as our relocation
distance can surely be clipped, or still have a valid width - but
cause an overflow of distance.
On various architectures the maximum displacement for a unconditional
branch/jump varies. ARM32 is +/- 32MB, ARM64 is +/- 128MB while x86
for 32-bit relocations is +/- 2G.
Note: On x86 we could use the 64-bit jmpq instruction which
would provide much bigger displacement to do a jump, but we would
still have issues with the new function not being able to reach
any of the old functions (as all the relocations would assume 32-bit
displacement). And "furthermore would require an register or
memory location to load/store the address to." (From Jan).
On ARM the conditional branch supports even a smaller displacement
but fortunately we are not using that.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Konrad Rzeszutek Wilk
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