[PATCHv2 08/10] arm64/mmu_include.c: disable WARN_ON() and BUG_ON() when booting.

[Pingfan Liu]

This patch is still one of the preparation for calling
__create_pgd_mapping() from head.S

When calling from head.S, printk is not ready to work. Hence define
SAFE_BUG_ON()/SAFE_WARN_ON(), wrapping around BUG_ON()/WARN_ON() to
protect against early calling.

Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Kristina Martsenko <kristina.martsenko at arm.com>
Cc: James Morse <james.morse at arm.com>
Cc: Steven Price <steven.price at arm.com>
Cc: Jonathan Cameron <Jonathan.Cameron at huawei.com>
Cc: Pavel Tatashin <pasha.tatashin at soleen.com>
Cc: Anshuman Khandual <anshuman.khandual at arm.com>
Cc: Atish Patra <atish.patra at wdc.com>
Cc: Mike Rapoport <rppt at kernel.org>
Cc: Logan Gunthorpe <logang at deltatee.com>
Cc: Mark Brown <broonie at kernel.org>
To: linux-arm-kernel at lists.infradead.org
---
 arch/arm64/include/asm/pgalloc.h |  1 +
 arch/arm64/mm/mmu_include.c      | 36 +++++++++++++++++++-------------
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 8e6638b4d1dd..c3875af99432 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -105,5 +105,6 @@ extern void create_idmap(pgd_t *pgdir, phys_addr_t phys,
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)
 #define NO_FIXMAP	BIT(2)
+#define BOOT_HEAD	BIT(3)
 
 #endif
diff --git a/arch/arm64/mm/mmu_include.c b/arch/arm64/mm/mmu_include.c
index 98c560197ea9..746cb2b502a3 100644
--- a/arch/arm64/mm/mmu_include.c
+++ b/arch/arm64/mm/mmu_include.c
@@ -5,6 +5,14 @@
  * and MMU-enable
  */
 
+/*
+ * printk is not ready in the very early stage. And this pair macro should be used
+ * instead
+ */
+#define SAFE_BUG_ON(x, y)	if (likely(!(x & BOOT_HEAD))) { BUG_ON(y); }
+#define SAFE_WARN_ON(x, y)	\
+	({ int _ret; _ret = (x & BOOT_HEAD) ? false : WARN_ON(y); })
+
 static bool pgattr_change_is_safe(u64 old, u64 new)
 {
 	/*
@@ -57,7 +65,7 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
 		 * After the PTE entry has been populated once, we
 		 * only allow updates to the permission attributes.
 		 */
-		BUG_ON(!pgattr_change_is_safe(pte_val(old_pte),
+		SAFE_BUG_ON(flags, !pgattr_change_is_safe(pte_val(old_pte),
 					      READ_ONCE(pte_val(*ptep))));
 
 		phys += PAGE_SIZE;
@@ -77,16 +85,16 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
 	unsigned long next;
 	pmd_t pmd = READ_ONCE(*pmdp);
 
-	BUG_ON(pmd_sect(pmd));
+	SAFE_BUG_ON(flags, pmd_sect(pmd));
 	if (pmd_none(pmd)) {
 		phys_addr_t pte_phys;
 
-		BUG_ON(!allocator);
+		SAFE_BUG_ON(flags, !allocator);
 		pte_phys = allocator(PAGE_SHIFT, info);
 		__pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
 		pmd = READ_ONCE(*pmdp);
 	}
-	BUG_ON(pmd_bad(pmd));
+	SAFE_BUG_ON(flags, pmd_bad(pmd));
 
 	do {
 		pgprot_t __prot = prot;
@@ -131,13 +139,13 @@ static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
 			 * After the PMD entry has been populated once, we
 			 * only allow updates to the permission attributes.
 			 */
-			BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
+			SAFE_BUG_ON(flags, !pgattr_change_is_safe(pmd_val(old_pmd),
 						      READ_ONCE(pmd_val(*pmdp))));
 		} else {
 			alloc_init_cont_pte(pmdp, addr, next, phys, prot,
 					    allocator, info, flags);
 
-			BUG_ON(pmd_val(old_pmd) != 0 &&
+			SAFE_BUG_ON(flags, pmd_val(old_pmd) != 0 &&
 			       pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp)));
 		}
 		phys += next - addr;
@@ -160,16 +168,16 @@ static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
 	/*
 	 * Check for initial section mappings in the pgd/pud.
 	 */
-	BUG_ON(pud_sect(pud));
+	SAFE_BUG_ON(flags, pud_sect(pud));
 	if (pud_none(pud)) {
 		phys_addr_t pmd_phys;
 
-		BUG_ON(!allocator);
+		SAFE_BUG_ON(flags, !allocator);
 		pmd_phys = allocator(PMD_SHIFT, info);
 		__pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE);
 		pud = READ_ONCE(*pudp);
 	}
-	BUG_ON(pud_bad(pud));
+	SAFE_BUG_ON(flags, pud_bad(pud));
 
 	do {
 		pgprot_t __prot = prot;
@@ -213,12 +221,12 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 	if (p4d_none(p4d)) {
 		phys_addr_t pud_phys;
 
-		BUG_ON(!allocator);
+		SAFE_BUG_ON(flags, !allocator);
 		pud_phys = allocator(PUD_SHIFT, info);
 		__p4d_populate(p4dp, pud_phys, PUD_TYPE_TABLE);
 		p4d = READ_ONCE(*p4dp);
 	}
-	BUG_ON(p4d_bad(p4d));
+	SAFE_BUG_ON(flags, p4d_bad(p4d));
 
 	if (likely(!(flags & NO_FIXMAP)))
 		pudp = pud_set_fixmap_offset(p4dp, addr);
@@ -240,13 +248,13 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 			 * After the PUD entry has been populated once, we
 			 * only allow updates to the permission attributes.
 			 */
-			BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
+			SAFE_BUG_ON(flags, !pgattr_change_is_safe(pud_val(old_pud),
 						      READ_ONCE(pud_val(*pudp))));
 		} else {
 			alloc_init_cont_pmd(pudp, addr, next, phys, prot,
 					    allocator, info, flags);
 
-			BUG_ON(pud_val(old_pud) != 0 &&
+			SAFE_BUG_ON(flags, pud_val(old_pud) != 0 &&
 			       pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
 		}
 		phys += next - addr;
@@ -275,7 +283,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, unsigned int entries_cnt, phys_ad
 	 * If the virtual and physical address don't have the same offset
 	 * within a page, we cannot map the region as the caller expects.
 	 */
-	if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
+	if (SAFE_WARN_ON(flags, (phys ^ virt) & ~PAGE_MASK))
 		return;
 
 	phys &= PAGE_MASK;
-- 
2.29.2