在2023年11月30日十一月 下午4:36，Thomas Bogendoerfer写道：

io_uring sets up the io worker kernel thread via a syscall out of an user space prrocess. This process might have used FPU and since copy_thread() didn't clear FPU states for kernel threads a BUG() is triggered for using FPU inside kernel. Move code around to always clear FPU state for user and kernel threads.

Cc: stable@vger.kernel.org Reported-by: Aurelien Jarno aurel32@debian.org Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1055021 Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de

Reviewed-by: Jiaxun Yang jiaxun.yang@flygoat.com

Perhaps Suggested-by: Jiaxun Yang jiaxun.yang@flygoat.com

As well :-)

Thanks - Jiaxun

---

arch/mips/kernel/process.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)

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

2.35.3