Re: [musl] musl-libc/MIPS: detached thread exit broken since kernel commit 46e12c07b

From: Ralf Baechle
Date: Fri Jun 19 2015 - 06:06:47 EST


On Thu, Jun 18, 2015 at 10:50:32PM -0400, Rich Felker wrote:

> This is kernel ABI breakage that should be fixed -- people running old
> kernel versions with old musl binaries might suffer a regression when
> upgrading, and perhaps more importantly the failure mode is just
> really bad. But I think we can also work around it on the userspace
> side in musl by pointing the stack pointer at some rodata (or even at
> pc, e.g. copying $25 to $sp) before making the syscall.

Just to be on the safe side, make sure it is something that's readable. Core
might me mapped execute-only, that is not readable and that is a feature
which the affected kernels do support on suitable hardware.

Ralf
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