unsigned long numpages;
int flags;
unsigned long pfn;
- unsigned force_split : 1;
+ unsigned force_split : 1,
+ force_static_prot : 1;
int curpage;
struct page **pages;
};
+enum cpa_warn {
+ CPA_CONFLICT,
+ CPA_PROTECT,
+ CPA_DETECT,
+};
+
+static const int cpa_warn_level = CPA_PROTECT;
+
/*
* Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings)
* using cpa_lock. So that we don't allow any other cpu, with stale large tlb
static inline void split_page_count(int level) { }
#endif
+#ifdef CONFIG_X86_CPA_STATISTICS
+
+static unsigned long cpa_1g_checked;
+static unsigned long cpa_1g_sameprot;
+static unsigned long cpa_1g_preserved;
+static unsigned long cpa_2m_checked;
+static unsigned long cpa_2m_sameprot;
+static unsigned long cpa_2m_preserved;
+static unsigned long cpa_4k_checked;
+static unsigned long cpa_4k_install;
+
+static inline void cpa_inc_1g_checked(void)
+{
+ cpa_1g_checked++;
+}
+
+static inline void cpa_inc_2m_checked(void)
+{
+ cpa_2m_checked++;
+}
+
+static inline void cpa_inc_4k_checked(void)
+{
+ cpa_4k_checked++;
+}
+
+static inline void cpa_inc_4k_install(void)
+{
+ cpa_4k_install++;
+}
+
+static inline void cpa_inc_lp_sameprot(int level)
+{
+ if (level == PG_LEVEL_1G)
+ cpa_1g_sameprot++;
+ else
+ cpa_2m_sameprot++;
+}
+
+static inline void cpa_inc_lp_preserved(int level)
+{
+ if (level == PG_LEVEL_1G)
+ cpa_1g_preserved++;
+ else
+ cpa_2m_preserved++;
+}
+
+static int cpastats_show(struct seq_file *m, void *p)
+{
+ seq_printf(m, "1G pages checked: %16lu\n", cpa_1g_checked);
+ seq_printf(m, "1G pages sameprot: %16lu\n", cpa_1g_sameprot);
+ seq_printf(m, "1G pages preserved: %16lu\n", cpa_1g_preserved);
+ seq_printf(m, "2M pages checked: %16lu\n", cpa_2m_checked);
+ seq_printf(m, "2M pages sameprot: %16lu\n", cpa_2m_sameprot);
+ seq_printf(m, "2M pages preserved: %16lu\n", cpa_2m_preserved);
+ seq_printf(m, "4K pages checked: %16lu\n", cpa_4k_checked);
+ seq_printf(m, "4K pages set-checked: %16lu\n", cpa_4k_install);
+ return 0;
+}
+
+static int cpastats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, cpastats_show, NULL);
+}
+
+static const struct file_operations cpastats_fops = {
+ .open = cpastats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init cpa_stats_init(void)
+{
+ debugfs_create_file("cpa_stats", S_IRUSR, arch_debugfs_dir, NULL,
+ &cpastats_fops);
+ return 0;
+}
+late_initcall(cpa_stats_init);
+#else
+static inline void cpa_inc_1g_checked(void) { }
+static inline void cpa_inc_2m_checked(void) { }
+static inline void cpa_inc_4k_checked(void) { }
+static inline void cpa_inc_4k_install(void) { }
+static inline void cpa_inc_lp_sameprot(int level) { }
+static inline void cpa_inc_lp_preserved(int level) { }
+#endif
+
+
static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
}
#endif
+static inline bool conflicts(pgprot_t prot, pgprotval_t val)
+{
+ return (pgprot_val(prot) & ~val) != pgprot_val(prot);
+}
+
+static inline void check_conflict(int warnlvl, pgprot_t prot, pgprotval_t val,
+ unsigned long start, unsigned long end,
+ unsigned long pfn, const char *txt)
+{
+ static const char *lvltxt[] = {
+ [CPA_CONFLICT] = "conflict",
+ [CPA_PROTECT] = "protect",
+ [CPA_DETECT] = "detect",
+ };
+
+ if (warnlvl > cpa_warn_level || !conflicts(prot, val))
+ return;
+
+ pr_warn("CPA %8s %10s: 0x%016lx - 0x%016lx PFN %lx req %016llx prevent %016llx\n",
+ lvltxt[warnlvl], txt, start, end, pfn, (unsigned long long)pgprot_val(prot),
+ (unsigned long long)val);
+}
+
/*
* Certain areas of memory on x86 require very specific protection flags,
* for example the BIOS area or kernel text. Callers don't always get this
* checks and fixes these known static required protection bits.
*/
static inline pgprot_t static_protections(pgprot_t prot, unsigned long start,
- unsigned long pfn, unsigned long npg)
+ unsigned long pfn, unsigned long npg,
+ int warnlvl)
{
- pgprotval_t forbidden;
+ pgprotval_t forbidden, res;
unsigned long end;
+ /*
+ * There is no point in checking RW/NX conflicts when the requested
+ * mapping is setting the page !PRESENT.
+ */
+ if (!(pgprot_val(prot) & _PAGE_PRESENT))
+ return prot;
+
/* Operate on the virtual address */
end = start + npg * PAGE_SIZE - 1;
- forbidden = protect_kernel_text(start, end);
- forbidden |= protect_kernel_text_ro(start, end);
+
+ res = protect_kernel_text(start, end);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Text NX");
+ forbidden = res;
+
+ res = protect_kernel_text_ro(start, end);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Text RO");
+ forbidden |= res;
/* Check the PFN directly */
- forbidden |= protect_pci_bios(pfn, pfn + npg - 1);
- forbidden |= protect_rodata(pfn, pfn + npg - 1);
+ res = protect_pci_bios(pfn, pfn + npg - 1);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "PCIBIOS NX");
+ forbidden |= res;
+
+ res = protect_rodata(pfn, pfn + npg - 1);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Rodata RO");
+ forbidden |= res;
return __pgprot(pgprot_val(prot) & ~forbidden);
}
struct cpa_data *cpa)
{
unsigned long numpages, pmask, psize, lpaddr, addr, pfn, old_pfn;
- pgprot_t old_prot, new_prot, req_prot;
+ pgprot_t old_prot, new_prot, req_prot, chk_prot;
pte_t new_pte, old_pte, *tmp;
enum pg_level level;
int i;
case PG_LEVEL_2M:
old_prot = pmd_pgprot(*(pmd_t *)kpte);
old_pfn = pmd_pfn(*(pmd_t *)kpte);
+ cpa_inc_2m_checked();
break;
case PG_LEVEL_1G:
old_prot = pud_pgprot(*(pud_t *)kpte);
old_pfn = pud_pfn(*(pud_t *)kpte);
+ cpa_inc_1g_checked();
break;
default:
return -EINVAL;
numpages = psize >> PAGE_SHIFT;
/*
- * Make sure that the requested pgprot does not violate the static
- * protections. Check the full large page whether one of the pages
- * in it results in a different pgprot than the first one of the
- * requested range. If yes, then the page needs to be split.
+ * Sanity check that the existing mapping is correct versus the static
+ * protections. static_protections() guards against !PRESENT, so no
+ * extra conditional required here.
+ */
+ chk_prot = static_protections(old_prot, lpaddr, old_pfn, numpages,
+ CPA_CONFLICT);
+
+ if (WARN_ON_ONCE(pgprot_val(chk_prot) != pgprot_val(old_prot))) {
+ /*
+ * Split the large page and tell the split code to
+ * enforce static protections.
+ */
+ cpa->force_static_prot = 1;
+ return 1;
+ }
+
+ /*
+ * Optimization: If the requested pgprot is the same as the current
+ * pgprot, then the large page can be preserved and no updates are
+ * required independent of alignment and length of the requested
+ * range. The above already established that the current pgprot is
+ * correct, which in consequence makes the requested pgprot correct
+ * as well if it is the same. The static protection scan below will
+ * not come to a different conclusion.
*/
- new_prot = static_protections(req_prot, address, pfn, 1);
+ if (pgprot_val(req_prot) == pgprot_val(old_prot)) {
+ cpa_inc_lp_sameprot(level);
+ return 0;
+ }
+
+ /*
+ * Optimization: Check whether the requested pgprot is conflicting
+ * with a static protection requirement in the large page. If not,
+ * then checking whether the requested range is fully covering the
+ * large page can be done right here.
+ */
+ new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages,
+ CPA_DETECT);
+
+ if (pgprot_val(req_prot) == pgprot_val(new_prot)) {
+ if (address != lpaddr || cpa->numpages != numpages)
+ return 1;
+ goto setlp;
+ }
+
+ /*
+ * Slow path. The full large page check above established that the
+ * requested pgprot cannot be applied to the full large page due to
+ * conflicting requirements of static protection regions. It might
+ * turn out that the whole requested range is covered by the
+ * modified protection of the first 4k segment at @address. This
+ * might result in the ability to preserve the large page
+ * nevertheless.
+ */
+ new_prot = static_protections(req_prot, address, pfn, 1, CPA_DETECT);
pfn = old_pfn;
for (i = 0, addr = lpaddr; i < numpages; i++, addr += PAGE_SIZE, pfn++) {
- pgprot_t chk_prot = static_protections(req_prot, addr, pfn, 1);
-
+ chk_prot = static_protections(req_prot, addr, pfn, 1,
+ CPA_DETECT);
+ cpa_inc_4k_checked();
if (pgprot_val(chk_prot) != pgprot_val(new_prot))
return 1;
}
/* If there are no changes, return. */
- if (pgprot_val(new_prot) == pgprot_val(old_prot))
+ if (pgprot_val(new_prot) == pgprot_val(old_prot)) {
+ cpa_inc_lp_sameprot(level);
return 0;
+ }
/*
* Verify that the address is aligned and the number of pages
if (address != lpaddr || cpa->numpages != numpages)
return 1;
+setlp:
/* All checks passed. Update the large page mapping. */
new_pte = pfn_pte(old_pfn, new_prot);
__set_pmd_pte(kpte, address, new_pte);
cpa->flags |= CPA_FLUSHTLB;
+ cpa_inc_lp_preserved(level);
return 0;
}
return do_split;
}
+static void split_set_pte(struct cpa_data *cpa, pte_t *pte, unsigned long pfn,
+ pgprot_t ref_prot, unsigned long address,
+ unsigned long size)
+{
+ unsigned int npg = PFN_DOWN(size);
+ pgprot_t prot;
+
+ /*
+ * If should_split_large_page() discovered an inconsistent mapping,
+ * remove the invalid protection in the split mapping.
+ */
+ if (!cpa->force_static_prot)
+ goto set;
+
+ prot = static_protections(ref_prot, address, pfn, npg, CPA_PROTECT);
+
+ if (pgprot_val(prot) == pgprot_val(ref_prot))
+ goto set;
+
+ /*
+ * If this is splitting a PMD, fix it up. PUD splits cannot be
+ * fixed trivially as that would require to rescan the newly
+ * installed PMD mappings after returning from split_large_page()
+ * so an eventual further split can allocate the necessary PTE
+ * pages. Warn for now and revisit it in case this actually
+ * happens.
+ */
+ if (size == PAGE_SIZE)
+ ref_prot = prot;
+ else
+ pr_warn_once("CPA: Cannot fixup static protections for PUD split\n");
+set:
+ set_pte(pte, pfn_pte(pfn, ref_prot));
+}
+
static int
__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
struct page *base)
{
+ unsigned long lpaddr, lpinc, ref_pfn, pfn, pfninc = 1;
pte_t *pbase = (pte_t *)page_address(base);
- unsigned long ref_pfn, pfn, pfninc = 1;
unsigned int i, level;
- pte_t *tmp;
pgprot_t ref_prot;
+ pte_t *tmp;
spin_lock(&pgd_lock);
/*
* PAT bit to correct position.
*/
ref_prot = pgprot_large_2_4k(ref_prot);
-
ref_pfn = pmd_pfn(*(pmd_t *)kpte);
+ lpaddr = address & PMD_MASK;
+ lpinc = PAGE_SIZE;
break;
case PG_LEVEL_1G:
ref_prot = pud_pgprot(*(pud_t *)kpte);
ref_pfn = pud_pfn(*(pud_t *)kpte);
pfninc = PMD_PAGE_SIZE >> PAGE_SHIFT;
-
+ lpaddr = address & PUD_MASK;
+ lpinc = PMD_SIZE;
/*
* Clear the PSE flags if the PRESENT flag is not set
* otherwise pmd_present/pmd_huge will return true
* Get the target pfn from the original entry:
*/
pfn = ref_pfn;
- for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
- set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
+ for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc, lpaddr += lpinc)
+ split_set_pte(cpa, pbase + i, pfn, ref_prot, lpaddr, lpinc);
if (virt_addr_valid(address)) {
unsigned long pfn = PFN_DOWN(__pa(address));
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
- new_prot = static_protections(new_prot, address, pfn, 1);
+ cpa_inc_4k_install();
+ new_prot = static_protections(new_prot, address, pfn, 1,
+ CPA_PROTECT);
new_prot = pgprot_clear_protnone_bits(new_prot);
projects / linux.git / blobdiff