From cl@xxxxxxxxxx Fri Dec 8 13:11:58 2023
From: "Christoph Lameter (Ampere)" <cl@xxxxxxxxxx>
To: Catalin Marinas <catalin.marinas@xxxxxxx>, Marc Zyngier
<maz@xxxxxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Ryan Roberts
<ryan.roberts@xxxxxxx>, Mark Rutland <mark.rutland@xxxxxxx>, Vishal
Moola <vishal.moola@xxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx
Subject: [PATCH] ARM64: Implement arch_report_meminfo()
V1->V2 hotplug and umapping support
X86 has information in /proc/meminfo showing the use of large mappings
for the kernel direct map. This has now also become important for
ARM since the kernel default CONFIG_RODATA_FULL_DEFAULT_ENABLED
forces 4K PTE use for the direct map and users may not be aware
of the performance impact of the increased TLB use etc.
The output of /proc/meminfo on ARM64 is then after this patch:
4K page size:
Hugepagesize: 2048 kB
Hugetlb: 0 kB
DirectMap4k: 155912 kB
CONT DMap4k: 1176 kB
DirectMap2M: 722944 kB
CONT DMap2M: 28672 kB
DirectMap1G: 534773760 kB
64K page size:
Hugepagesize: 524288 kB
Hugetlb: 0 kB
DirectMap64k: 882624 kB
CONT DMap64k: 19904 kB
DirectMap512M: 534773760 kB
CONT DMap512M: 0 kB
DirectMap4096G: 0 kB
Signed-off-by: Christoph Lameter (Ampere) <cl@xxxxxxxxx>
Index: linux/arch/arm64/mm/mmu.c
===================================================================
--- linux.orig/arch/arm64/mm/mmu.c
+++ linux/arch/arm64/mm/mmu.c
@@ -76,6 +76,13 @@ EXPORT_SYMBOL(empty_zero_page);
static DEFINE_SPINLOCK(swapper_pgdir_lock);
static DEFINE_MUTEX(fixmap_lock);
+static atomic_t nr_pte;
+static atomic_t nr_pmd;
+static atomic_t nr_pud;
+static atomic_t nr_pte_cont;
+static atomic_t nr_pmd_cont;
+
+
void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
{
pgd_t *fixmap_pgdp;
@@ -179,6 +186,7 @@ static void init_pte(pmd_t *pmdp, unsign
pte_t old_pte = READ_ONCE(*ptep);
set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot));
+ atomic_inc(&nr_pte);
/*
* After the PTE entry has been populated once, we
@@ -223,8 +231,10 @@ static void alloc_init_cont_pte(pmd_t *p
/* use a contiguous mapping if the range is suitably aligned */
if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
- (flags & NO_CONT_MAPPINGS) == 0)
+ (flags & NO_CONT_MAPPINGS) == 0) {
__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
+ atomic_inc(&nr_pte_cont);
+ }
init_pte(pmdp, addr, next, phys, __prot);
@@ -249,6 +259,7 @@ static void init_pmd(pud_t *pudp, unsign
if (((addr | next | phys) & ~PMD_MASK) == 0 &&
(flags & NO_BLOCK_MAPPINGS) == 0) {
pmd_set_huge(pmdp, phys, prot);
+ atomic_inc(&nr_pmd);
/*
* After the PMD entry has been populated once, we
@@ -301,8 +312,10 @@ static void alloc_init_cont_pmd(pud_t *p
/* use a contiguous mapping if the range is suitably aligned */
if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
- (flags & NO_CONT_MAPPINGS) == 0)
+ (flags & NO_CONT_MAPPINGS) == 0) {
__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
+ atomic_inc(&nr_pmd_cont);
+ }
init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags);
@@ -346,7 +359,7 @@ static void alloc_init_pud(pgd_t *pgdp,
((addr | next | phys) & ~PUD_MASK) == 0 &&
(flags & NO_BLOCK_MAPPINGS) == 0) {
pud_set_huge(pudp, phys, prot);
-
+ atomic_inc(&nr_pud);
/*
* After the PUD entry has been populated once, we
* only allow updates to the permission attributes.
@@ -859,6 +872,11 @@ static void unmap_hotplug_pte_range(pmd_
continue;
WARN_ON(!pte_present(pte));
+
+ if (pte_cont(pte))
+ atomic_dec(&nr_pte_cont);
+ atomic_dec(&nr_pte);
+
pte_clear(&init_mm, addr, ptep);
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
if (free_mapped)
@@ -883,6 +901,11 @@ static void unmap_hotplug_pmd_range(pud_
WARN_ON(!pmd_present(pmd));
if (pmd_sect(pmd)) {
+
+ if (pmd_cont(pmd))
+ atomic_dec(&nr_pmd_cont);
+ atomic_dec(&nr_pmd);
+
pmd_clear(pmdp);
/*
@@ -916,6 +939,9 @@ static void unmap_hotplug_pud_range(p4d_
WARN_ON(!pud_present(pud));
if (pud_sect(pud)) {
+
+ atomic_dec(&nr_pud);
+
pud_clear(pudp);
/*
@@ -1010,6 +1036,7 @@ static void free_empty_pte_table(pmd_t *
return;
}
+ atomic_dec(&nr_pmd);
pmd_clear(pmdp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(ptep));
@@ -1050,6 +1077,7 @@ static void free_empty_pmd_table(pud_t *
return;
}
+ atomic_dec(&nr_pud);
pud_clear(pudp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(pmdp));
@@ -1225,6 +1253,7 @@ int pmd_free_pte_page(pmd_t *pmdp, unsig
}
table = pte_offset_kernel(pmdp, addr);
+ atomic_dec(&nr_pmd);
pmd_clear(pmdp);
__flush_tlb_kernel_pgtable(addr);
pte_free_kernel(NULL, table);
@@ -1253,6 +1282,7 @@ int pud_free_pmd_page(pud_t *pudp, unsig
pmd_free_pte_page(pmdp, next);
} while (pmdp++, next += PMD_SIZE, next != end);
+ atomic_dec(&nr_pud);
pud_clear(pudp);
__flush_tlb_kernel_pgtable(addr);
pmd_free(NULL, table);
@@ -1486,3 +1516,36 @@ void ptep_modify_prot_commit(struct vm_a
{
set_pte_at(vma->vm_mm, addr, ptep, pte);
}
+
+
+#ifdef CONFIG_PROC_FS
+void arch_report_meminfo(struct seq_file *m)
+{
+ unsigned long pagesize_in_kb = PAGE_SIZE / 1024;
+
+ seq_printf(m, "DirectMap%luk: %8lu kB\n",
+ pagesize_in_kb,
+ (unsigned long)atomic_read(&nr_pte) * pagesize_in_kb);
+
+ seq_printf(m, "CONT DMap%luk: %8lu kB\n",
+ pagesize_in_kb,
+ (unsigned long)atomic_read(&nr_pte_cont) * pagesize_in_kb);
+
+ pagesize_in_kb = PMD_SIZE / 1024;
+
+ seq_printf(m, "DirectMap%luM: %8lu kB\n",
+ pagesize_in_kb / 1024,
+ (unsigned long)atomic_read(&nr_pmd) * pagesize_in_kb);
+
+ seq_printf(m, "CONT DMap%luM: %8lu kB\n",
+ pagesize_in_kb / 1024,
+ (unsigned long)atomic_read(&nr_pmd_cont) * pagesize_in_kb);
+
+ pagesize_in_kb = PUD_SIZE / 1024;
+
+ seq_printf(m, "DirectMap%luG: %10lu kB\n",
+ pagesize_in_kb >> 20,
+ (unsigned long)atomic_read(&nr_pud) * pagesize_in_kb);
+}
+#endif
+
