runtime: factor amd64 specifics from vdso_linux.go
This is a preparation step for adding vDSO support on linux/386.
This change relocates the elf64 and amd64 specifics from
vdso_linux.go to a new vdso_linux_amd64.go.
This should enable vdso_linux.go to be used for vDSO
support on linux architectures other than amd64.
- Relocate the elf64X structure definitions appropriate to amd64,
and change their names to elfX so that the code in vdso_linux.go
is ELFnn-agnostic.
- Relocate the sym_keys and corresponding __vdso_* variables
appropriate to amd64.
- Provide an amd64-specific constant for the maximum byte size of
an array, and use this in vdso_linux.go to compute constants for
sizing the elf structure arrays traversed in the loaded vDSO.
Change-Id: I1edb4e4ec9f2d79b7533aa95fbd09f771fa4edef
Reviewed-on: https://go-review.googlesource.com/69391
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>