On Wed, Aug 26, 2020 at 04:17:43PM +0300, Sergei Shtylyov wrote:
>From 218f23077352a7befd2aaad3fa46b93112d4051b Mon Sep 17 00:00:00 2001
From: Huang Pei <huangpei@xxxxxxxxxxx>
Date: Fri, 21 Aug 2020 10:48:40 +0800
Subject: [PATCH] MIPS: add missing MSACSR and upper MSA 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.
Signed-off-by: Huang Pei <huangpei@xxxxxxxxxxx>
---
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 38aa07ccdbcc..cf788591f091 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);
}
--
2.17.1
> On 8/26/20 1:10 PM, Huang Pei wrote:
>
> > From 0f4003eb418737df75cb8be79d4da34b1500f3d7 Mon Sep 17 00:00:00 2001
> > From: Huang Pei <huangpei@xxxxxxxxxxx>
> > Date: Fri, 21 Aug 2020 10:48:40 +0800
> > Subject: [PATCH] MIPS: add missing MSACSR and upper MSA 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.
> >
> > Signed-off-by: Huang Pei <huangpei@xxxxxxxxxxx>
> > ---
> > arch/mips/kernel/traps.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> > index 38aa07ccdbcc..e843b38486b8 100644
> > --- a/arch/mips/kernel/traps.c
> > +++ b/arch/mips/kernel/traps.c
> > @@ -1287,6 +1287,16 @@ 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
> > + */
>
> This comment style is acceptable only for the networking code, all the other code
> should have the 1st comment line empty.
>
> [...]
>
> MBR, Sergei
