[PATCH 3/3] LoongArch: mm: Add unified function populate_kernel_pte

[Bibo Mao <maobibo@xxxxxxxxxxx>]

Function pcpu_populate_pte and fixmap_pte are similar, they populate
one page from kernel address space. And there is confusion between
pgd and p4d in function fixmap_pte, such as pgd_none always returns
zero. This patch adds unified function populate_kernel_pte and replaces
pcpu_populate_pte and fixmap_pte.

Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/loongarch/include/asm/pgalloc.h |  1 +
 arch/loongarch/kernel/numa.c         | 40 +--------------------
 arch/loongarch/mm/init.c             | 52 ++++++++++++++++------------
 3 files changed, 32 insertions(+), 61 deletions(-)

diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
index af1d1e4a6965..ca17b573dba6 100644
--- a/arch/loongarch/include/asm/pgalloc.h
+++ b/arch/loongarch/include/asm/pgalloc.h
@@ -91,4 +91,5 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
 
 #endif /* __PAGETABLE_PUD_FOLDED */
 
+extern pte_t * __init populate_kernel_pte(unsigned long addr);
 #endif /* _ASM_PGALLOC_H */
diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
index 778e1c20bfb0..24a693b76873 100644
--- a/arch/loongarch/kernel/numa.c
+++ b/arch/loongarch/kernel/numa.c
@@ -67,46 +67,8 @@ static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
 
 void __init pcpu_populate_pte(unsigned long addr)
 {
-	pgd_t *pgd = pgd_offset_k(addr);
-	p4d_t *p4d = p4d_offset(pgd, addr);
-	pud_t *pud;
-	pmd_t *pmd;
-
-	if (p4d_none(*p4d)) {
-		pud = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
-		if (!pud)
-			goto err_alloc;
-		p4d_populate(&init_mm, p4d, pud);
-#ifndef __PAGETABLE_PUD_FOLDED
-		pud_init(pud);
-#endif
-	}
-
-	pud = pud_offset(p4d, addr);
-	if (pud_none(*pud)) {
-		pmd = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
-		if (!pmd)
-			goto err_alloc;
-		pud_populate(&init_mm, pud, pmd);
-#ifndef __PAGETABLE_PMD_FOLDED
-		pmd_init(pmd);
-#endif
-	}
-
-	pmd = pmd_offset(pud, addr);
-	if (!pmd_present(*pmd)) {
-		pte_t *pte;
-
-		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
-		if (!pte)
-			goto err_alloc;
-		pmd_populate_kernel(&init_mm, pmd, pte);
-	}
-
+	populate_kernel_pte(addr);
 	return;
-
-err_alloc:
-	panic("%s: Failed to allocate memory\n", __func__);
 }
 
 void __init setup_per_cpu_areas(void)
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 3b7d8129570b..6cd2948373ae 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -191,46 +191,49 @@ void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *al
 #endif
 #endif
 
-static pte_t *fixmap_pte(unsigned long addr)
+pte_t * __init populate_kernel_pte(unsigned long addr)
 {
-	pgd_t *pgd;
-	p4d_t *p4d;
+	pgd_t *pgd = pgd_offset_k(addr);
+	p4d_t *p4d = p4d_offset(pgd, addr);
 	pud_t *pud;
 	pmd_t *pmd;
 
-	pgd = pgd_offset_k(addr);
-	p4d = p4d_offset(pgd, addr);
-
-	if (pgd_none(*pgd)) {
-		pud_t *new __maybe_unused;
-
-		new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
-		pgd_populate(&init_mm, pgd, new);
+	if (p4d_none(*p4d)) {
+		pud = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
+		if (!pud)
+			goto err_alloc;
+		p4d_populate(&init_mm, p4d, pud);
 #ifndef __PAGETABLE_PUD_FOLDED
-		pud_init(new);
+		pud_init(pud);
 #endif
 	}
 
 	pud = pud_offset(p4d, addr);
 	if (pud_none(*pud)) {
-		pmd_t *new __maybe_unused;
-
-		new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
-		pud_populate(&init_mm, pud, new);
+		pmd = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
+		if (!pmd)
+			goto err_alloc;
+		pud_populate(&init_mm, pud, pmd);
 #ifndef __PAGETABLE_PMD_FOLDED
-		pmd_init(new);
+		pmd_init(pmd);
 #endif
 	}
 
 	pmd = pmd_offset(pud, addr);
-	if (pmd_none(*pmd)) {
-		pte_t *new __maybe_unused;
+	if (!pmd_present(*pmd)) {
+		pte_t *pte;
 
-		new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
-		pmd_populate_kernel(&init_mm, pmd, new);
+		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+		if (!pte)
+			goto err_alloc;
+		pmd_populate_kernel(&init_mm, pmd, pte);
 	}
 
 	return pte_offset_kernel(pmd, addr);
+
+err_alloc:
+	panic("%s: Failed to allocate memory\n", __func__);
+	return NULL;
 }
 
 void __init __set_fixmap(enum fixed_addresses idx,
@@ -241,7 +244,12 @@ void __init __set_fixmap(enum fixed_addresses idx,
 
 	BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
 
-	ptep = fixmap_pte(addr);
+	/*
+	 * Now only FIX_EARLYCON_MEM_BASE fixed map is used
+	 * __set_fixmap must be called before mem_init since function
+	 * populate_kernel_pte allocates memory with memblock_alloc method.
+	 */
+	ptep = populate_kernel_pte(addr);
 	if (!pte_none(*ptep)) {
 		pte_ERROR(*ptep);
 		return;
-- 
2.27.0