From 8370e417c306dc9f0a37f0dc50afa1879a705c3a Mon Sep 17 00:00:00 2001 From: Huang Pei Date: Tue, 1 Sep 2020 14:53:09 +0800 Subject: [PATCH] MIPS: add missing MSACSR and upper MSA initialization In ff8801728ee8 ("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: ff8801728ee8 ("MIPS: Simplify FP context initialization") Signed-off-by: Huang Pei Signed-off-by: Thomas Bogendoerfer --- 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 38aa07ccdbcc2..cf788591f0911 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -1287,6 +1287,18 @@ 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); } -- 2.39.5