On Tue, May 19, 2015 at 02:13:51PM -0700, Leonid Yegoshin wrote: > During thread cloning the new (child) thread should have MSA disabled even > at first thread entry. So, the code to disable MSA is moved from macro > 'switch_to' to assembler function 'resume' before it switches kernel stack > to 'next' (new) thread. Call of 'disable_msa' after 'resume' in 'switch_to' > macro never called a first time entry into thread. > > Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx> > --- > arch/mips/include/asm/switch_to.h | 1 - > arch/mips/kernel/r4k_switch.S | 6 ++++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h > index e92d6c4b5ed1..0d0f7f8f8b3a 100644 > --- a/arch/mips/include/asm/switch_to.h > +++ b/arch/mips/include/asm/switch_to.h > @@ -104,7 +104,6 @@ do { \ > if (test_and_clear_tsk_thread_flag(prev, TIF_USEDMSA)) \ > __fpsave = FP_SAVE_VECTOR; \ > (last) = resume(prev, next, task_thread_info(next), __fpsave); \ > - disable_msa(); \ > } while (0) > > #define finish_arch_switch(prev) \ > diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S > index 04cbbde3521b..7dbb64656bfe 100644 > --- a/arch/mips/kernel/r4k_switch.S > +++ b/arch/mips/kernel/r4k_switch.S > @@ -25,6 +25,7 @@ > /* preprocessor replaces the fp in ".set fp=64" with $30 otherwise */ > #undef fp > > +#define t4 $12 You're kidding, right? > /* > * Offset to the current process status flags, the first 32 bytes of the > * stack are not used. > @@ -73,6 +74,11 @@ > cfc1 t1, fcr31 > msa_save_all a0 > .set pop /* SET_HARDFLOAT */ > + li t4, MIPS_CONF5_MSAEN > + mfc0 t3, CP0_CONFIG, 5 > + or t3, t3, t4 > + xor t3, t3, t4 > + mtc0 t3, CP0_CONFIG, 5 > > sw t1, THREAD_FCR31(a0) > b 2f Just move the call to finish_arch_switch(). Your rewrite also dropped the if (cpu_has_msa) condition from disable_msa() probably causing havoc on lots of CPUs which will likely not decode the set bits of the MFC0/MTC0 instructions thus end up accessing Config0. Ralf