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MIPS: add missing MSACSR and upper MSA initialization 

[ Upstream commit bb06748207 ]

In cc97ab235f ("MIPS: Simplify FP context initialization), init_fp_ctx
just initialize the fp/msa context, and own_fp_inatomic just restore
FCSR and 64bit FP regs from it, but miss MSACSR and upper MSA regs for
MSA, so MSACSR and MSA upper regs's value from previous task on current
cpu can leak into current task and cause unpredictable behavior when MSA
context not initialized.

Fixes: cc97ab235f ("MIPS: Simplify FP context initialization")
Signed-off-by: Huang Pei <huangpei@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Huang Pei 2020-09-01 14:53:09 +08:00 committed by Greg Kroah-Hartman
parent 612e2b7ec9
commit 58591dd6af
1 changed files with 12 additions and 0 deletions
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12
arch/mips/kernel/traps.c
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@ -1240,6 +1240,18 @@ static int enable_restore_fp_context(int msa)
err = own_fpu_inatomic(1);
if (msa && !err) {
enable_msa();
/*
* with MSA enabled, userspace can see MSACSR
* and MSA regs, but the values in them are from
* other task before current task, restore them
* from saved fp/msa context
*/
write_msa_csr(current->thread.fpu.msacsr);
/*
* own_fpu_inatomic(1) just restore low 64bit,
* fix the high 64bit
*/
init_msa_upper();
set_thread_flag(TIF_USEDMSA);
set_thread_flag(TIF_MSA_CTX_LIVE);
}