CL 209899 worked around an issue that corrupts vector registers in
recent versions of the Linux kernel by mlocking the top page of every
signal stack on amd64. However, the underlying issue also affects the
XMM registers on 386. This CL applies the mlock fix to both amd64 and
386.

Fixes golang#35777 (again).

Change-Id: I9886f2dc4c23625421296bd5518d5fd3288bfe48
Reviewed-on: https://go-review.googlesource.com/c/go/+/210345
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes golang#34930

Change-Id: Ie0ddd8de6e40f5a192c4d2267399126e449fe5f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/210340
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Some Linux distributions will continue to provide 5.3.x kernels for a
while rather than 5.4.x.

Updates golang#35777

Change-Id: I493ef8338d94475f4fb1402ffb9040152832b0fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/210299
Reviewed-by: Austin Clements <austin@google.com>

Change-Id: Ic79d97c2aa107c0e5c4a8906ad757b0390228bef
Reviewed-on: https://go-review.googlesource.com/c/go/+/210417
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

…onse

Fixes golang#28012

Change-Id: I711ebaabf63194e3d2c608d829da49c51a294d74
Reviewed-on: https://go-review.googlesource.com/c/go/+/210286
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

AIX doesn't allow to mmap an already mmap address. The previous way to
deal with this behavior was to munmap before calling mmap again.
However, mprotect syscall is able to change protections on a memory
range. Thus, memory mapped by sysReserve can be remap using it. Note
that sysMap is always called with a non-nil pointer so mprotect is
always possible.

Updates: golang#35451

Change-Id: I1fd1e1363d9ed9eb5a8aa7c8242549bd6dad8cd0
Reviewed-on: https://go-review.googlesource.com/c/go/+/207237
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

The relocation of MIPS64 family ELF is different with other architecure according
to the document from Linux-MIPS

https://www.linux-mips.org/pub/linux/mips/doc/ABI/elf64-2.4.pdf

In "2.9 Relocation" it shows relocation section contains five parts:

1. r_sym Elf64_Word Symbol index
2. r_ssym Elf64_Byte Special symbol
3. r_type3 Elf64_Byte Relocation type
4. r_type2 Elf64_Byte Relocation type
5. r_type Elf64_Byte Relocation type

This CL makes loadelf aware the difference.

Update golang#35779

Change-Id: Ib221665641972b1c2bfea5a496e3118e5dc0bc45
Reviewed-on: https://go-review.googlesource.com/c/go/+/209317
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>