On Sat, Nov 18, 2023 at 04:36:45PM +0100, Aurelien Jarno wrote:
Anyway, I have been able to test a backport of the patch onto the 5.10 kernel (with minor adjustments) and I confirm it fixes the reported issue.
Tested-by: Aurelien Jarno aurel32@debian.org
It seems that this patch hasn't been merged yet, either in Linus' tree or in the MIPS tree. Is there anything blocking?
sorry, took some time to get really back from vacation...
I don't like the patch doing too much code restructing. I can't reproduce on my loongson machine, so I can't test below patch...
What cmake version do I need and what would be a package to reproduce the bug ?
Thomas.
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 5387ed0a5186..b630604c577f 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -121,6 +121,19 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) /* Put the stack after the struct pt_regs. */ childksp = (unsigned long) childregs; p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK; + + /* + * New tasks lose permission to use the fpu. This accelerates context + * switching for most programs since they don't use the fpu. + */ + clear_tsk_thread_flag(p, TIF_USEDFPU); + clear_tsk_thread_flag(p, TIF_USEDMSA); + clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); + +#ifdef CONFIG_MIPS_MT_FPAFF + clear_tsk_thread_flag(p, TIF_FPUBOUND); +#endif /* CONFIG_MIPS_MT_FPAFF */ + if (unlikely(args->fn)) { /* kernel thread */ unsigned long status = p->thread.cp0_status; @@ -149,20 +162,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.reg29 = (unsigned long) childregs; p->thread.reg31 = (unsigned long) ret_from_fork;
- /* - * New tasks lose permission to use the fpu. This accelerates context - * switching for most programs since they don't use the fpu. - */ childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
- clear_tsk_thread_flag(p, TIF_USEDFPU); - clear_tsk_thread_flag(p, TIF_USEDMSA); - clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); - -#ifdef CONFIG_MIPS_MT_FPAFF - clear_tsk_thread_flag(p, TIF_FPUBOUND); -#endif /* CONFIG_MIPS_MT_FPAFF */ - #ifdef CONFIG_MIPS_FP_SUPPORT atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE); #endif