...
> -static void sgx_sanitize_section(struct sgx_epc_section *section)
> +static void sgx_sanitize_section(struct list_head *laundry)
> {
Does this need a better function name now that it's not literally
dealing with sections at *all*?
sgx_sanitize_pages()
perhaps.
> struct sgx_epc_page *page;
> LIST_HEAD(dirty);
> int ret;
>
> /* init_laundry_list is thread-local, no need for a lock: */
> - while (!list_empty(§ion->init_laundry_list)) {
> + while (!list_empty(laundry)) {
> if (kthread_should_stop())
> return;
>
> - /* needed for access to ->page_list: */
> - spin_lock(§ion->lock);
> -
> - page = list_first_entry(§ion->init_laundry_list,
> - struct sgx_epc_page, list);
> + page = list_first_entry(laundry, struct sgx_epc_page, list);
>
> ret = __eremove(sgx_get_epc_virt_addr(page));
> - if (!ret)
> - list_move(&page->list, §ion->page_list);
> - else
> + if (!ret) {
> + /* The page is clean - move to the free list. */
> + list_del(&page->list);
> + sgx_free_epc_page(page);
> + } else {
> + /* The page is not yet clean - move to the dirty list.
> */
> list_move_tail(&page->list, &dirty);
> -
> - spin_unlock(§ion->lock);
> + }
>
> cond_resched();
> }
>
> - list_splice(&dirty, §ion->init_laundry_list);
> + list_splice(&dirty, laundry);
> }
>
> static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page)
> @@ -400,6 +398,7 @@ static bool sgx_should_reclaim(unsigned long watermark)
>
> static int ksgxd(void *p)
> {
> + struct list_head *laundry = p;
> int i;
>
> set_freezable();
> @@ -408,16 +407,13 @@ static int ksgxd(void *p)
> * Sanitize pages in order to recover from kexec(). The 2nd pass is
> * required for SECS pages, whose child pages blocked EREMOVE.
> */
> - for (i = 0; i < sgx_nr_epc_sections; i++)
> - sgx_sanitize_section(&sgx_epc_sections[i]);
> + sgx_sanitize_section(laundry);
> + sgx_sanitize_section(laundry);
Did you intend to call this twice?
> - for (i = 0; i < sgx_nr_epc_sections; i++) {
> - sgx_sanitize_section(&sgx_epc_sections[i]);
> + if (!list_empty(laundry))
> + WARN(1, "EPC section %d has unsanitized pages.\n", i);
>
> - /* Should never happen. */
> - if (!list_empty(&sgx_epc_sections[i].init_laundry_list))
> - WARN(1, "EPC section %d has unsanitized pages.\n", i);
> - }
> + kfree(laundry);
This is a bit unfortunate. 'laundry' is allocated up in another thread
and the lifetime isn't obvious. It's just 32 bytes, but this is just
asking to be leaked.
> while (!kthread_should_stop()) {
> if (try_to_freeze())
> @@ -436,11 +432,11 @@ static int ksgxd(void *p)
> return 0;
> }
>
> -static bool __init sgx_page_reclaimer_init(void)
> +static bool __init sgx_page_reclaimer_init(struct list_head *laundry)
> {
> struct task_struct *tsk;
>
> - tsk = kthread_run(ksgxd, NULL, "ksgxd");
> + tsk = kthread_run(ksgxd, laundry, "ksgxd");
> if (IS_ERR(tsk))
> return false;
>
> @@ -614,7 +610,8 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
>
> static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
> unsigned long index,
> - struct sgx_epc_section *section)
> + struct sgx_epc_section *section,
> + struct list_head *laundry)
> {
I think this at least need a comment somewhere about what this function
is doing with 'laundry'.
> unsigned long nr_pages = size >> PAGE_SHIFT;
> unsigned long i;
> @@ -632,13 +629,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr,
> u64 size,
> section->phys_addr = phys_addr;
> spin_lock_init(§ion->lock);
> INIT_LIST_HEAD(§ion->page_list);
> - INIT_LIST_HEAD(§ion->init_laundry_list);
>
> for (i = 0; i < nr_pages; i++) {
> section->pages[i].section = index;
> section->pages[i].flags = 0;
> section->pages[i].owner = NULL;
> - list_add_tail(§ion->pages[i].list,
> §ion->init_laundry_list);
> + list_add_tail(§ion->pages[i].list, laundry);
> }
>
> section->free_cnt = nr_pages;
> @@ -656,7 +652,7 @@ static inline u64 __init sgx_calc_section_metric(u64 low,
> u64 high)
> ((high & GENMASK_ULL(19, 0)) << 32);
> }
>
> -static bool __init sgx_page_cache_init(void)
> +static bool __init sgx_page_cache_init(struct list_head *laundry)
> {
> u32 eax, ebx, ecx, edx, type;
> u64 pa, size;
> @@ -679,7 +675,7 @@ static bool __init sgx_page_cache_init(void)
>
> pr_info("EPC section 0x%llx-0x%llx\n", pa, pa + size - 1);
>
> - if (!sgx_setup_epc_section(pa, size, i, &sgx_epc_sections[i])) {
> + if (!sgx_setup_epc_section(pa, size, i, &sgx_epc_sections[i],
> laundry)) {
> pr_err("No free memory for an EPC section\n");
> break;
> }
This is a great place for a comment about what is coming back on 'laundry'.
> @@ -697,18 +693,25 @@ static bool __init sgx_page_cache_init(void)
>
> static int __init sgx_init(void)
> {
> + struct list_head *laundry;
> int ret;
> int i;
>
> if (!cpu_feature_enabled(X86_FEATURE_SGX))
> return -ENODEV;
>
> - if (!sgx_page_cache_init()) {
> + laundry = kzalloc(sizeof(*laundry), GFP_KERNEL);
> + if (!laundry)
> + return -ENOMEM;
> +
> + INIT_LIST_HEAD(laundry);
> +
> + if (!sgx_page_cache_init(laundry)) {
> ret = -ENOMEM;
> goto err_page_cache;
> }
>
> - if (!sgx_page_reclaimer_init()) {
> + if (!sgx_page_reclaimer_init(laundry)) {
> ret = -ENOMEM;
> goto err_page_cache;
> }
I really don't like this being dynamically allocated, especially since
it's freed in another task in a non-obvious place.
Wouldn't this all just be a lot simpler if we had a global list_head?
That will eat a whopping 16 bytes of space.
