Subject: bug#32083: 26.1.50; temacs bootstrap execs itself forever on alpha-unknown-linux-gnu

From: Ulrich Mueller <[email-masked]>
Date: Sun, 8 Jul 2018 00:30:28 +0200

>>>>> On Sat, 7 Jul 2018, Paul Eggert wrote:

> Thanks for the bug report. Please try the attached patch; if it
> works around the bug for you, I'll install it on the emacs-26 branch
> and it should appear in the next Emacs release.

Thank you. The patch fixes the problem here.

> It would also be helpful to file a bug report with the Alpha Linux
> kernel folks, as there does seem to be a kernel bug here (or at
> least, an unexpected inconsistency with x86-64 with respect to how
> process personalities survive exec).

Indeed it is different. In Linux, the SET_PERSONALITY macro in
arch/alpha/include/asm/elf.h simply does:

   set_personality(PER_LINUX)

whereas elsewhere (e.g., ppc) the same macro has additional masking
(with PER_MASK being the lowest 8 bits, so ADDR_NO_RANDOMIZE would be
preserved):

   set_personality(PER_LINUX | (current->personality & (~PER_MASK)))

We'll investigate and report a bug to Linux upstream.