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Re: ARM: Clear icache when creating a closure
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Andrew Haley <aph at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, "libffi-discuss at sourceware dot org" <libffi-discuss at sourceware dot org>
- Date: Tue, 12 Jul 2011 10:12:10 +0100
- Subject: Re: ARM: Clear icache when creating a closure
- References: <4E1B2384.5080001@redhat.com>
On 11/07/11 17:23, Andrew Haley wrote:
> On a multicore ARM, you really do have to clear both caches, not just the
> dcache. This bug may exist in other ports too.
>
> Andrew.
>
>
> 2011-07-11 Andrew Haley <aph@redhat.com>
>
> * src/arm/ffi.c (FFI_INIT_TRAMPOLINE): Clear icache.
>
> diff --git a/src/arm/ffi.c b/src/arm/ffi.c
> index 885a9cb..b2e7667 100644
> --- a/src/arm/ffi.c
> +++ b/src/arm/ffi.c
> @@ -558,12 +558,16 @@ ffi_closure_free (void *ptr)
> ({ unsigned char *__tramp = (unsigned char*)(TRAMP); \
> unsigned int __fun = (unsigned int)(FUN); \
> unsigned int __ctx = (unsigned int)(CTX); \
> + unsigned char *insns = (unsigned char *)(CTX); \
> *(unsigned int*) &__tramp[0] = 0xe92d000f; /* stmfd sp!, {r0-r3} */ \
> *(unsigned int*) &__tramp[4] = 0xe59f0000; /* ldr r0, [pc] */ \
> *(unsigned int*) &__tramp[8] = 0xe59ff000; /* ldr pc, [pc] */ \
> *(unsigned int*) &__tramp[12] = __ctx; \
> *(unsigned int*) &__tramp[16] = __fun; \
> - __clear_cache((&__tramp[0]), (&__tramp[19])); \
> + __clear_cache((&__tramp[0]), (&__tramp[19])); /* Clear data mapping. */ \
> + __clear_cache(insns, insns + 3 * sizeof (unsigned int)); \
> + /* Clear instruction \
> + mapping. */ \
> })
>
> #endif
>
>
Your patch looks sane, but I'll observe here that the poking of
instruction values is wrong on cores that run in BE-8 mode (where
instructions are always little-endian).
R.