Hi Dave,
On 10/31/21 23:47, John David Anglin wrote:
> My sense is the invalidate patch isn't correct. The main difference between pdc and fdc is that
> it is optional whether pdc writes the cache line back to memory when it's dirty at priority 0.
That's true, nevertheless I've seen different behaviour on real hardware.
It might be, that:
- flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
+ invalidate_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
(here the flush might be sufficient)
if (mapped)
patch_unmap(FIX_TEXT_POKE0, &flags);
+ invalidate_kernel_vmap_range((void *)start, end - start);
(but here the pdc is necessary to actually drop data from I-cache)
flush_icache_range(start, end);
I can test tomorrow...
> Note also that flush_kernel_vmap_range and invalidate_kernel_vmap_range both have this hunk
> which may behave differently:
>
> if ((!IS_ENABLED(CONFIG_SMP) || !arch_irqs_disabled()) &&
> (unsigned long)size >= parisc_cache_flush_threshold) {
> flush_tlb_kernel_range(start, end);
> flush_data_cache();
> return;
> }
Yes, but even when patching 4 bytes the patch above did worked (and
parisc_cache_flush_threshold was bigger).
Helge
>
> Dave
>
> On 2021-10-31 5:22 p.m., Helge Deller wrote:
>> On 10/27/21 22:14, John David Anglin wrote:
>>> On 2021-10-27 3:09 p.m., Helge Deller wrote:
>>>> In the archives I found this old thread, which might be related:
>>>> https://www.spinics.net/lists/linux-parisc/msg09391.html
>>> These seems unlikely as both 7100LC and 7300LC are PA-RISC 1.1 processors (1.1c vs. 1.1e). Big difference
>>> seems to be cache.
>> Yes, there were at least two problems.
>> I just sent two patches to the list which fix the crashes.
>> But FTRACE still doesn't work on PA1.x machines as expected,
>> while the same code seems to work on PA2.x machines (running the same 32bit kernel).
>
>
