[PATCH 1/4] LoongArch: Set pte entry with PAGE_GLOBAL for kernel space

[Bibo Mao]

Unlike general architectures, there are two pages for one TLB entry
on LoongArch system. For kernel space, it requires both two pte
entries with PAGE_GLOBAL set, else HW treats it as non-global tlb,
there will be potential problems if tlb entry for kernel space is
not global. Such as fail to flush kernel tlb with function
local_flush_tlb_kernel_range() which only flush tlb with global bit.

Here function kernel_pte_init() is added, it can be used to init
pte table when it is created, so the default inital pte is
PAGE_GLOBAL rather than zero at beginning.

Kernel space areas includes fixmap, percpu, vmalloc and kasan areas
set default pte entry with PAGE_GLOBAL set.

Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/loongarch/include/asm/pgalloc.h | 13 +++++++++++++
 arch/loongarch/include/asm/pgtable.h |  1 +
 arch/loongarch/mm/init.c             |  4 +++-
 arch/loongarch/mm/kasan_init.c       |  4 +++-
 arch/loongarch/mm/pgtable.c          | 22 ++++++++++++++++++++++
 5 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
index 4e2d6b7ca2ee..b2698c03dc2c 100644
--- a/arch/loongarch/include/asm/pgalloc.h
+++ b/arch/loongarch/include/asm/pgalloc.h
@@ -10,8 +10,21 @@
 
 #define __HAVE_ARCH_PMD_ALLOC_ONE
 #define __HAVE_ARCH_PUD_ALLOC_ONE
+#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
 #include <asm-generic/pgalloc.h>
 
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
+{
+	pte_t *pte;
+
+	pte = (pte_t *) __get_free_page(GFP_KERNEL);
+	if (!pte)
+		return NULL;
+
+	kernel_pte_init(pte);
+	return pte;
+}
+
 static inline void pmd_populate_kernel(struct mm_struct *mm,
 				       pmd_t *pmd, pte_t *pte)
 {
diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
index 9965f52ef65b..22e3a8f96213 100644
--- a/arch/loongarch/include/asm/pgtable.h
+++ b/arch/loongarch/include/asm/pgtable.h
@@ -269,6 +269,7 @@ extern void set_pmd_at(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, pm
 extern void pgd_init(void *addr);
 extern void pud_init(void *addr);
 extern void pmd_init(void *addr);
+extern void kernel_pte_init(void *addr);
 
 /*
  * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 8a87a482c8f4..9f26e933a8a3 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -198,9 +198,11 @@ pte_t * __init populate_kernel_pte(unsigned long addr)
 	if (!pmd_present(pmdp_get(pmd))) {
 		pte_t *pte;
 
-		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+		pte = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
 		if (!pte)
 			panic("%s: Failed to allocate memory\n", __func__);
+
+		kernel_pte_init(pte);
 		pmd_populate_kernel(&init_mm, pmd, pte);
 	}
 
diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
index 427d6b1aec09..34988573b0d5 100644
--- a/arch/loongarch/mm/kasan_init.c
+++ b/arch/loongarch/mm/kasan_init.c
@@ -152,6 +152,8 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 		phys_addr_t page_phys = early ?
 					__pa_symbol(kasan_early_shadow_page)
 					      : kasan_alloc_zeroed_page(node);
+		if (!early)
+			kernel_pte_init(__va(page_phys));
 		next = addr + PAGE_SIZE;
 		set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 	} while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep)));
@@ -287,7 +289,7 @@ void __init kasan_init(void)
 		set_pte(&kasan_early_shadow_pte[i],
 			pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
 
-	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
+	kernel_pte_init(kasan_early_shadow_page);
 	csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
 	local_flush_tlb_all();
 
diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c
index eb6a29b491a7..228ffc1db0a3 100644
--- a/arch/loongarch/mm/pgtable.c
+++ b/arch/loongarch/mm/pgtable.c
@@ -38,6 +38,28 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 }
 EXPORT_SYMBOL_GPL(pgd_alloc);
 
+void kernel_pte_init(void *addr)
+{
+	unsigned long *p, *end;
+	unsigned long entry;
+
+	entry = (unsigned long)_PAGE_GLOBAL;
+	p = (unsigned long *)addr;
+	end = p + PTRS_PER_PTE;
+
+	do {
+		p[0] = entry;
+		p[1] = entry;
+		p[2] = entry;
+		p[3] = entry;
+		p[4] = entry;
+		p += 8;
+		p[-3] = entry;
+		p[-2] = entry;
+		p[-1] = entry;
+	} while (p != end);
+}
+
 void pgd_init(void *addr)
 {
 	unsigned long *p, *end;
-- 
2.39.3