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MIPS: Loongson-3: Enable COP2 usage in kernel

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Loongson-3's COP2 is Multi-Media coprocessor, it is disabled in kernel
mode by default. However, gslq/gssq (16-bytes load/store instructions)
overrides the instruction format of lwc2/swc2. If we wan't to use gslq/
gssq for optimization in kernel, we should enable COP2 usage in kernel.

Please pay attention that in this patch we only enable COP2 in kernel,
which means it will lose ST0_CU2 when a process go to user space (try
to use COP2 in user space will trigger an exception and then grab COP2,
which is similar to FPU). And as a result, we need to modify the context
switching code because the new scheduled process doesn't contain ST0_CU2
in its THERAD_STATUS probably.

For zboot, we disable gslq/gssq be generated by toolchain.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Huacai Chen 2020-09-21 17:12:27 +08:00 • committed by Thomas Bogendoerfer
parent 4e43e5df58
commit 195615ecc8
6 changed files with 19 additions and 7 deletions
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6
arch/mips/include/asm/stackframe.h
View file

@ -450,7 +450,7 @@
*/
.macro CLI
mfc0 t0, CP0_STATUS
li t1, ST0_CU0 | STATMASK
li t1, ST0_KERNEL_CUMASK | STATMASK
or t0, t1
xori t0, STATMASK
mtc0 t0, CP0_STATUS
@ -463,7 +463,7 @@
*/
.macro STI
mfc0 t0, CP0_STATUS
li t1, ST0_CU0 | STATMASK
li t1, ST0_KERNEL_CUMASK | STATMASK
or t0, t1
xori t0, STATMASK & ~1
mtc0 t0, CP0_STATUS
@ -477,7 +477,7 @@
*/
.macro KMODE
mfc0 t0, CP0_STATUS
li t1, ST0_CU0 | (STATMASK & ~1)
li t1, ST0_KERNEL_CUMASK | (STATMASK & ~1)
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
andi t2, t0, ST0_IEP
srl t2, 2