[PATCH] invalid instructions in kernel mode

[Kumar Gala]

What is the crash01 test doing that causes this code to get invoked?  
is the kernel you are using using build with math emulation on or off?

- kumar

On Mar 31, 2005, at 11:47 AM, Fillod Stephane wrote:

> Hi,
>
> When CPU has no (classic) FPU, and math emulation is disabled,
>  fp instructions are not allowed in kernel mode.
>  This bug has been found with crashme (crash01) of LTP, on a e500 
> system.
>
> The patch was made against linux 2.6.11.6.
>  A trivial typo fix has been appended.
>
> Rem: a CONFIG_PPCFPU define could make life easier.
>
>
>
> Signed-off-by: Stephane Fillod <fillods at gmail.com>
>
> --- linux/arch/ppc/kernel/align.c       6 Dec 2004 16:18:11 -0000
>  1.1.1.1
>  +++ linux/arch/ppc/kernel/align.c       31 Mar 2005 16:33:25 -0000
>  @@ -333,10 +333,14 @@
>          }
>   
>          if (flags & F) {
>  +#if !(defined(CONFIG_4xx) || defined(CONFIG_8xx) ||
>  defined(CONFIG_E500)) || defined(CONFIG_MATH_EMULATION)
>                 preempt_disable();
>                 if (regs->msr & MSR_FP)
>                          giveup_fpu(current);
>                 preempt_enable();
> +#else
>  +               return 0;
>  +#endif
>          }
>   
>          /* If we read the operand, copy it in, else get register 
> values
> */
>  @@ -366,6 +370,8 @@
>                  }
>                  break;
>   
>  +#if !(defined(CONFIG_4xx) || defined(CONFIG_8xx) ||
>  defined(CONFIG_E500)) || defined(CONFIG_MATH_EMULATION)
> +
>          /* Single-precision FP load and store require conversions... 
> */
>          case LD+F+S:
>                  preempt_disable();
> @@ -379,6 +385,7 @@
>                  cvt_df(&data.d, &data.f, &current->thread.fpscr);
>                 preempt_enable();
>                 break;
>  +#endif
>          }
>   
>          if (flags & ST) {
>  --- linux/arch/ppc/kernel/misc.S        26 Mar 2005 03:28:36 -0000
>  1.1.1.2
>  +++ linux/arch/ppc/kernel/misc.S        31 Mar 2005 16:33:25 -0000
>  @@ -1096,7 +1096,8 @@
>    * and exceptions as if the cpu had performed the load or store.
>    */
>   
>  -#if defined(CONFIG_4xx) || defined(CONFIG_E500)
> +#if !(defined(CONFIG_4xx) || defined(CONFIG_E500) ||
>  defined(CONFIG_8xx)) ||  defined(CONFIG_MATH_EMULATION)
> +#if defined(CONFIG_4xx) || defined(CONFIG_E500)
>  _GLOBAL(cvt_fd)
>         lfs     0,0(r3)
>          stfd    0,0(r4)
>  @@ -1125,6 +1126,7 @@
>          stfd    0,-4(r5)
>          blr
>   #endif
>  +#endif
>   
>   /*
>    * Create a kernel thread
>  --- linux/arch/ppc/kernel/process.c     26 Mar 2005 03:28:20 -0000
>  1.1.1.2
>  +++ linux/arch/ppc/kernel/process.c     31 Mar 2005 16:33:25 -0000
>  @@ -342,7 +342,7 @@
>          printk("\n");
>   #ifdef CONFIG_KALLSYMS
>         /*
>  -        * Lookup NIP late so we have the best change of getting the
>  +        * Lookup NIP late so we have the best chance of getting the
>           * above info out without failing
>           */
>          printk("NIP [%08lx] ", regs->nip);
>
>
>
> Best Regards,
>
> -- 
> Stephane