On Tue, 04 Sep 2007 14:46:54 +0200, Franck Bui-Huu <vagabon.xyz@xxxxxxxxx> wrote:
> One thing you might want to try is:
>
> $ echo 0 > /proc/sys/kernel/randomize_va_space
>
> and see if your system still works fine. This command should avoid a
> data cache flush when moving the stack around. See shift_arg_pages().
>
> With this, maybe you could give this testcase a try:
>
> $ /bin/echo "`seq 10000`" > seq.txt
>
> and see if seq.txt is correct. This command should pass to echo (not
> the bash builtin one) a long argument that should fill your
> dcache.
I tried this and everything worked fine with/without the
flush_kernel_dcache_page() ;)
> That said the execve syscall code is quite 'hairy' and it may not be
> suprising that after this syscall the dcache has been completly
> flushed and thus make the problem disappear.
Yes, there is an yet another path to "flush all dcache".
do_execve()
copy_strings()
flush_kernel_dcache_page()
search_binary_handler()
load_elf_binary()
flush_old_exec()
exec_mmap()
mmput()
exit_mmap()
flush_cache_mm()
r4k_blast_dcache()
Anyway, the implementation of flush_kernel_dcache_page() is very
simple so that we can believe it works correctly without any testcase.
Too optimistic? :)
---
Atsushi Nemoto
