This is the mail archive of the
libffi-discuss@sourceware.org
mailing list for the libffi project.
Re: ARM: Clear icache when creating a closure
- From: Andrew Haley <aph at redhat dot com>
- To: Richard Earnshaw <rearnsha at arm 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 10:15:59 +0100
- Subject: Re: ARM: Clear icache when creating a closure
- References: <4E1B2384.5080001@redhat.com> <4E1C0FEA.4040209@arm.com>
On 12/07/11 10:12, Richard Earnshaw wrote:
> 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).
Oh dear. How would one test for BE-8 mode on a Linux system?
Thanks,
Andrew.