Date: Thu, 2 Aug 2018 18:50:30 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@FreeBSD.org> Cc: Ruslan Bukin <br@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r337127 - head/sys/riscv/riscv Message-ID: <20180802155030.GA40119@kib.kiev.ua> In-Reply-To: <7842b7e4-d14e-805f-719e-b393fc80b74c@FreeBSD.org> References: <201808021213.w72CDqQV065424@repo.freebsd.org> <7842b7e4-d14e-805f-719e-b393fc80b74c@FreeBSD.org>
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On Thu, Aug 02, 2018 at 08:16:59AM -0700, John Baldwin wrote: > On 8/2/18 5:13 AM, Ruslan Bukin wrote: > > Author: br > > Date: Thu Aug 2 12:13:52 2018 > > New Revision: 337127 > > URL: https://svnweb.freebsd.org/changeset/base/337127 > > > > Log: > > Don't overwrite tp in set_mcontext(). > > > > This makes libthr/swapcontext_test:swapcontext1 happy. > > > > Sponsored by: DARPA, AFRL > > This seems a bit odd. Is get_mcontext() not setting gp_tp correctly, or is > makecontext() not preserving it perhaps? > > In general I feel like we should be saving/restoring 'tp' in the trapframe > on kernel entry/exit like other GPRs instead of in the pcb and then > including it in 'struct reg'. This makes it possible for debuggers to > handle TLS variables more sanely (and in general we need to fix the various > struct reg in FreeBSD architectures to include TLS registers when possible, > such as adding fs_base and gs_base on x86). It would be nice if RISC-V > started off on the correct foot here. I wanted to do this on x86, but I gave up due to the ABI issues. When FSGSBASE instructions are supported on amd64, we save base on context switch and restore on return to usermode.home | help
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