Messages in this thread | | | Date | Tue, 12 Nov 2013 09:36:29 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: [PATCH v2] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions |
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On Tue, 12 Nov 2013, Måns Rullgård wrote:
> Nicolas Pitre <nicolas.pitre@linaro.org> writes: > > > What about this patch which I think is currently your best option. Note > > it would need to use the facilities from asm/opcodes.h to make it endian > > agnostic. > > > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > > index 6a1b8a81b1..379cffe4ab 100644 > > --- a/arch/arm/kernel/setup.c > > +++ b/arch/arm/kernel/setup.c > > @@ -383,6 +383,34 @@ static void __init cpuid_init_hwcaps(void) > > elf_hwcap |= HWCAP_IDIVT; > > } > > > > + /* > > + * Patch our division routines with the corresponding opcode > > + * if the hardware supports it. > > + */ > > + if (IS_ENABLED(CONFIG_THUMB2_KERNEL) && (elf_hwcap & HWCAP_IDIVT)) { > > + extern char __aeabi_uidiv, __aeabi_idiv; > > It would be safer to declare these as arrays of unspecified size. > Otherwise the compiler might do evil things with what to it looks like > out of bounds indexing.
Right.
> > There should also be some cache maintenance after this patching, or is > that already happening for some other reason?
This is so early during boot that the MMU isn't even fully initialized yet. The cache will be flushed.
Nicolas | |