diff options
author | Ingo van Lil <inguin@gmx.de> | 2011-09-14 16:21:23 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-09-14 18:09:37 -0700 |
commit | fbfe9c847edf57ac8232aeafb290f272289893a3 (patch) | |
tree | da25f3f4ece74b9fa328ce3884f19ff18eff516d /arch/um/kernel | |
parent | b40997b872cdb70140f127af6069f00a86b6cf81 (diff) | |
download | op-kernel-dev-fbfe9c847edf57ac8232aeafb290f272289893a3.zip op-kernel-dev-fbfe9c847edf57ac8232aeafb290f272289893a3.tar.gz |
um: Save FPU registers between task switches
Some time ago Jeff prepared 42daba316557 ("uml: stop saving process FP
state") for UML to stop saving the process FP state between task
switches. The assumption was that since with SKAS0 every guest process
runs inside a host process context the host OS will take care of keeping
the proper FP state.
Unfortunately this is not true for multi-threaded applications, where
all guest threads share a single host process context yet all may use
the FPU on their own. Although I haven't verified it I suspect things
to be even worse in SKAS3 mode where all guest processes run inside a
single host process.
The patch reintroduces the saving and restoring of the FP context
between task switches.
[richard@nod.at: Ingo posted this patch in 2009, sadly it was never applied
and got lost. Now in 2011 the problem was reported by Gunnar.]
Signed-off-by: Ingo van Lil <inguin@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
Reported-by: <gunnarlindroth@hotmail.com>
Tested-by: <gunnarlindroth@hotmail.com>
Cc: Stanislav Meduna <stano@meduna.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/kernel')
-rw-r--r-- | arch/um/kernel/process.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index fab4371..21c1ae7 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -202,7 +202,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, arch_copy_thread(¤t->thread.arch, &p->thread.arch); } else { - get_safe_registers(p->thread.regs.regs.gp); + get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp); p->thread.request.u.thread = current->thread.request.u.thread; handler = new_thread_handler; } |