On 4/15/19 1:54 PM, Peter Zijlstra wrote:
> So how about we do something like:
>
> +static struct bp_patching_desc {
> + int nr_entries;
> + struct text_patch_loc vec[PAGE_SIZE / sizeof(struct text_patch_loc)];
> +} bp_patching;
>
> and call it a day?
>
> Then we have static storage, no allocation, no fail paths.
>
> Also note that I removed that whole in_progress thing, as that is
> completely redudant vs !!nr_entries.
Hi Peter,
I am finishing the next version, but now I am in a dilemma.
If I use:
static struct bp_patching_desc {
int nr_entries;
struct text_patch_loc vec[PAGE_SIZE / sizeof(struct text_patch_loc)];
} bp_patching;
The in_progress is still needed because nr_entries will increase while
queuing... and so we would enter in the int3 before we actually need.
It will also need a new function on alternative.c to queue each entry into the
vector and change the text_poke_bp_batch() to a text_poke_bp_apply() without
arguments, +- replicating the arch_jump_label_transform_queue() and
arch_jump_label_transform_apply().
[ and probably also take the text_mutex while queuing... and release in the
apply ]
OR
I can declare a vector and a counter in arch/x86/jump_label.c, like this:
#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_patch_loc))
static struct text_patch_loc tp_vec[TP_VEC_MAX];
int tp_nr_entries = 0;
and use the arch_jump_label_transform_batch() as it is now, i.e:
void text_poke_bp_batch(struct text_patch_loc *tp, unsigned int nr_entries)
In this case, we do not need the in_progress because the
bp_patching_desc.nr_entries is filled only when in progress.
so, which path should I take?
Thanks
-- Daniel
