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| author | Huacai Chen <chenhc@lemote.com> | 2020-09-21 11:12:27 +0200 |
|---|---|---|
| committer | Thomas Bogendoerfer <tsbogend@alpha.franken.de> | 2020-09-21 22:15:03 +0200 |
| commit | 195615ecc8309082a524433cf552eda722b26c1c (patch) | |
| tree | 08d25c30f8af71ab927275237f96e6fdd4b0abfe /arch/mips/kernel/process.c | |
| parent | MIPS: context switch: Use save/restore instead of set/clear for Status.CU2 (diff) | |
| download | linux-195615ecc8309082a524433cf552eda722b26c1c.tar.xz linux-195615ecc8309082a524433cf552eda722b26c1c.zip | |
MIPS: Loongson-3: Enable COP2 usage in kernel
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>
Diffstat (limited to 'arch/mips/kernel/process.c')
| -rw-r--r-- | arch/mips/kernel/process.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index f5dc316a826a..b36297ee2b37 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -68,7 +68,7 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) unsigned long status; /* New thread loses kernel privileges. */ - status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); + status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK); status |= KU_USER; regs->cp0_status = status; lose_fpu(0); @@ -133,7 +133,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, childregs = (struct pt_regs *) childksp - 1; /* Put the stack after the struct pt_regs. */ childksp = (unsigned long) childregs; - p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); + p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK; if (unlikely(p->flags & PF_KTHREAD)) { /* kernel thread */ unsigned long status = p->thread.cp0_status; |