[OpenBIOS] [PATCH v3] ppc: use rfid when running under a CPU from the 970 family.
Alexander Graf
agraf at suse.de
Wed Jun 22 09:41:20 CEST 2016
> Am 22.06.2016 um 09:29 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.
>
> Changes since v2 :
>
> - make it nicer
>
> arch/ppc/qemu/ofmem.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 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 +478,30 @@ 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.
Please use
/*
* Comments like this
*/
and explain exactly why "we can not use rfi anymore", so that someone looking at the code in 5 years will still know what's going on.
> + */
> +#define RFI 0x4c000064
> +#define RFID 0x4c000024
> +
> +extern char __vectors[];
> +extern char __vectors_end[];
> +
> +static void patch_rfi(void)
> +{
> + uint32_t* ptr;
> + uint32_t* vec_start = (uint32_t*) 0x100UL;
> + uint32_t* vec_end = (uint32_t*) (__vectors_end - __vectors);
> +
> + if (!is_ppc64())
> + return;
> +
> + for (ptr = vec_start; ptr < vec_end; ptr++) {
Last time I asked < was not really defined for pointers. You can only match (==, !=) or convert to numbers (uintptr_t) them. The smaller comparison might work for now, but I can't guarantee it won't break in gcc7 or so.
In short, please just make it != :).
Alex
> + if (*ptr == RFI)
> + *ptr = RFID;
> + }
> + flush_icache_range((char*) vec_start , (char*) vec_end);
> +}
>
> /************************************************************************/
> /* init / cleanup */
> @@ -532,6 +556,8 @@ setup_mmu(unsigned long ramsize)
>
> memcpy((void *)get_rom_base(), (void *)OF_CODE_START, OF_CODE_SIZE);
>
> + patch_rfi();
> +
> /* Enable MMU */
>
> mtmsr(mfmsr() | MSR_IR | MSR_DR);
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