Re: CONFIG_HAVE_ARCH_TRACEHOOK and you

Russell King
2008-09-12T13:14:13Z

Okay, let's comment on each bit separately.

Regsets
-------

These don't appear to be a problem for ARM, and turn out to be relatively
clean. The only thing I did do was invent some alternative simpler
helper functions rather than using the user_regset_copy* functions (to
avoid taking the address of function arguments, which needlessly forces
them onto the stack.)

However, in looking at other architectures, I notice that sparc does this
when initializing its regsets:

.n = 38 * sizeof(u32),
.size = sizeof(u32), .align = sizeof(u32),

and sparc64:

.n = 36 * sizeof(u64),
.size = sizeof(u64), .align = sizeof(u64),

which, given that fs/binfmt_elf.c does this:

size_t size = regset->n * regset->size;
void *data = kmalloc(size, GFP_KERNEL);
if (unlikely(!data))
return 0;

means sparc ends up allocating 38 * sizeof(u32) * sizeof(u32), and
sparc64 ends up with 36 * sizeof(u64) * sizeof(u64), which must surely
be wrong?

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/