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.
Hi Leonid,
I'm not sure I understand what you're trying to say here. Do you have an
example of a program that demonstrates the behaviour you believe to be
broken?
Thanks,
Paul
> 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
> /*
> * 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
>
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