[OpenBIOS] [PATCH v2] ppc: use rfid when running under a CPU from the 970 family.

[Alexander Graf]

> Am 21.06.2016 um 23:36 schrieb Cédric Le Goater <clg at kaod.org>:
> 
> A recent attempt to restrict the use of rfi on 64bit cpus in qemu
> broke 32bit OpenBIOS when run under a 970.
> 
> This patches memory to replace rfi instructions with rfid in the
> vector code.
> 
> Signed-off-by: Cédric Le Goater <clg at kaod.org>
> Suggested-by: Alexander Graf <agraf at suse.de>
> ---
> 
> Tested on qemu.
> 
> arch/ppc/qemu/ofmem.c |   24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
> 
> Index: openbios.git/arch/ppc/qemu/ofmem.c
> ===================================================================
> --- openbios.git.orig/arch/ppc/qemu/ofmem.c
> +++ openbios.git/arch/ppc/qemu/ofmem.c
> @@ -478,6 +478,26 @@ isi_exception(void)
>     hash_page(nip, phys, mode);
> }
> 
> +/* When running on ppc64, we cannot use rfi anymore. Let's patch the
> + * vectors to use rfid instead.
> + */
> +#define RFI     0x4c000064
> +#define RFID    0x4c000024
> +
> +static void patch_rfi(char *from, uint32_t len)
> +{
> +    int i;
> +
> +    for (i = 0; i < len; i += 4)  {
> +        uint32_t* addr = (uint32_t *) (from + i);

If you use a uint32* here you can just increment by 1 ...

> +        if (*addr == RFI)
> +            *addr = RFID;
> +    }
> +    flush_icache_range(from, from + len);
> +}
> +
> +extern char __vectors[];
> +extern char __vectors_end[];

And in fact you can just loop from vectors until ptr==vectors_end.

uint32_t *ptr;

for (ptr = __vectors; ptr != __vectors_end; ptr++)

> 
> /************************************************************************/
> /*    init / cleanup                            */
> @@ -532,6 +552,10 @@ setup_mmu(unsigned long ramsize)
> 
>     memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
> 
> +    if (is_ppc64()) {
> +        patch_rfi(0x0, (uint32_t) __vectors_end - (uint32_t) __vectors);
> +    }

Just fold all of this together. Make patch_rfi have no parameters and just call it unconditionally. Then check for ppc64 in there.

Alex

> +
>     /* Enable MMU */
> 
>     mtmsr(mfmsr() | MSR_IR | MSR_DR);