3 files changed, 63 insertions, 21 deletions

diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
index 7fbf6a3ccff7..5d08e5adf3d5 100644
--- a/arch/arm64/include/asm/trans_pgd.h
+++ b/arch/arm64/include/asm/trans_pgd.h
@@ -33,4 +33,7 @@ int trans_pgd_create_copy(struct trans_pgd_info *info, pgd_t **trans_pgd,
 int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
 		       void *page, unsigned long dst_addr, pgprot_t pgprot);
 
+int trans_pgd_idmap_page(struct trans_pgd_info *info, phys_addr_t *trans_ttbr0,
+			 unsigned long *t0sz, void *page);
+
 #endif /* _ASM_TRANS_TABLE_H */
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 94fc275cdd21..9df32ba0d574 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -194,7 +194,6 @@ static void *hibernate_page_alloc(void *arg)
  * page system.
  */
 static int create_safe_exec_page(void *src_start, size_t length,
-				 unsigned long dst_addr,
 				 phys_addr_t *phys_dst_addr)
 {
 	struct trans_pgd_info trans_info = {
@@ -203,7 +202,8 @@ static int create_safe_exec_page(void *src_start, size_t length,
 	};
 
 	void *page = (void *)get_safe_page(GFP_ATOMIC);
-	pgd_t *trans_pgd;
+	phys_addr_t trans_ttbr0;
+	unsigned long t0sz;
 	int rc;
 
 	if (!page)
@@ -211,13 +211,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
 
 	memcpy(page, src_start, length);
 	__flush_icache_range((unsigned long)page, (unsigned long)page + length);
-
-	trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
-	if (!trans_pgd)
-		return -ENOMEM;
-
-	rc = trans_pgd_map_page(&trans_info, trans_pgd, page, dst_addr,
-				PAGE_KERNEL_EXEC);
+	rc = trans_pgd_idmap_page(&trans_info, &trans_ttbr0, &t0sz, page);
 	if (rc)
 		return rc;
 
@@ -230,12 +224,15 @@ static int create_safe_exec_page(void *src_start, size_t length,
 	 * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI
 	 * runtime services), while for a userspace-driven test_resume cycle it
 	 * points to userspace page tables (and we must point it at a zero page
-	 * ourselves). Elsewhere we only (un)install the idmap with preemption
-	 * disabled, so T0SZ should be as required regardless.
+	 * ourselves).
+	 *
+	 * We change T0SZ as part of installing the idmap. This is undone by
+	 * cpu_uninstall_idmap() in __cpu_suspend_exit().
 	 */
 	cpu_set_reserved_ttbr0();
 	local_flush_tlb_all();
-	write_sysreg(phys_to_ttbr(virt_to_phys(trans_pgd)), ttbr0_el1);
+	__cpu_set_tcr_t0sz(t0sz);
+	write_sysreg(trans_ttbr0, ttbr0_el1);
 	isb();
 
 	*phys_dst_addr = virt_to_phys(page);
@@ -434,7 +431,6 @@ int swsusp_arch_resume(void)
 	void *zero_page;
 	size_t exit_size;
 	pgd_t *tmp_pg_dir;
-	phys_addr_t phys_hibernate_exit;
 	void __noreturn (*hibernate_exit)(phys_addr_t, phys_addr_t, void *,
 					  void *, phys_addr_t, phys_addr_t);
 	struct trans_pgd_info trans_info = {
@@ -462,19 +458,13 @@ int swsusp_arch_resume(void)
 		return -ENOMEM;
 	}
 
-	/*
-	 * Locate the exit code in the bottom-but-one page, so that *NULL
-	 * still has disastrous affects.
-	 */
-	hibernate_exit = (void *)PAGE_SIZE;
 	exit_size = __hibernate_exit_text_end - __hibernate_exit_text_start;
 	/*
 	 * Copy swsusp_arch_suspend_exit() to a safe page. This will generate
 	 * a new set of ttbr0 page tables and load them.
 	 */
 	rc = create_safe_exec_page(__hibernate_exit_text_start, exit_size,
-				   (unsigned long)hibernate_exit,
-				   &phys_hibernate_exit);
+				   (phys_addr_t *)&hibernate_exit);
 	if (rc) {
 		pr_err("Failed to create safe executable page for hibernate_exit code.\n");
 		return rc;
@@ -493,7 +483,7 @@ int swsusp_arch_resume(void)
 	 * We can skip this step if we booted at EL1, or are running with VHE.
 	 */
 	if (el2_reset_needed()) {
-		phys_addr_t el2_vectors = phys_hibernate_exit;  /* base */
+		phys_addr_t el2_vectors = (phys_addr_t)hibernate_exit;
 		el2_vectors += hibernate_el2_vectors -
 			       __hibernate_exit_text_start;     /* offset */
 
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
index ded8e2ba0308..527f0a39c3da 100644
--- a/arch/arm64/mm/trans_pgd.c
+++ b/arch/arm64/mm/trans_pgd.c
@@ -273,3 +273,52 @@ int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
 
 	return 0;
 }
+
+/*
+ * The page we want to idmap may be outside the range covered by VA_BITS that
+ * can be built using the kernel's p?d_populate() helpers. As a one off, for a
+ * single page, we build these page tables bottom up and just assume that will
+ * need the maximum T0SZ.
+ *
+ * Returns 0 on success, and -ENOMEM on failure.
+ * On success trans_ttbr0 contains page table with idmapped page, t0sz is set to
+ * maximum T0SZ for this page.
+ */
+int trans_pgd_idmap_page(struct trans_pgd_info *info, phys_addr_t *trans_ttbr0,
+			 unsigned long *t0sz, void *page)
+{
+	phys_addr_t dst_addr = virt_to_phys(page);
+	unsigned long pfn = __phys_to_pfn(dst_addr);
+	int max_msb = (dst_addr & GENMASK(52, 48)) ? 51 : 47;
+	int bits_mapped = PAGE_SHIFT - 4;
+	unsigned long level_mask, prev_level_entry, *levels[4];
+	int this_level, index, level_lsb, level_msb;
+
+	dst_addr &= PAGE_MASK;
+	prev_level_entry = pte_val(pfn_pte(pfn, PAGE_KERNEL_EXEC));
+
+	for (this_level = 3; this_level >= 0; this_level--) {
+		levels[this_level] = trans_alloc(info);
+		if (!levels[this_level])
+			return -ENOMEM;
+
+		level_lsb = ARM64_HW_PGTABLE_LEVEL_SHIFT(this_level);
+		level_msb = min(level_lsb + bits_mapped, max_msb);
+		level_mask = GENMASK_ULL(level_msb, level_lsb);
+
+		index = (dst_addr & level_mask) >> level_lsb;
+		*(levels[this_level] + index) = prev_level_entry;
+
+		pfn = virt_to_pfn(levels[this_level]);
+		prev_level_entry = pte_val(pfn_pte(pfn,
+						   __pgprot(PMD_TYPE_TABLE)));
+
+		if (level_msb == max_msb)
+			break;
+	}
+
+	*trans_ttbr0 = phys_to_ttbr(__pfn_to_phys(pfn));
+	*t0sz = TCR_T0SZ(max_msb + 1);
+
+	return 0;
+}