From: Huang Pei huangpei@loongson.cn
[ Upstream commit bb06748207cfb1502d11b90325eba7f8c44c9f02 ]
In cc97ab235f3f ("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: cc97ab235f3f ("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 --- arch/mips/kernel/traps.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 6a25364600266..8282d0feb0b21 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -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); }