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Message-ID: <20251003-x86-init-cleanup-v1-4-f2b7994c2ad6@google.com>
Date: Fri, 03 Oct 2025 16:56:44 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH 4/4] x86/mm: simplify calculation of max_pfn_mapped
The phys_*_init()s return the "last physical address mapped". The exact
definition of this is pretty fiddly, but only when there is a mismatch
between the alignment of the requested range and the page sizes allowed
by page_size_mask, or when the range ends in a region that is not mapped
according to e820.
The only user that looks at the ultimate return value of this logic is
init_memory_mapping(), which doesn't fulfill those conditions; it's
calling kernel_physical_mapping_init() for ranges that exist, and
with the page_size_mask set according to the alignment of their edges.
In that case, the return value is just paddr_end. And the caller already
has that value, hence it can be dropped.
Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
arch/x86/mm/init.c | 11 +++---
arch/x86/mm/init_32.c | 5 +--
arch/x86/mm/init_64.c | 90 ++++++++++++++++-------------------------------
arch/x86/mm/mm_internal.h | 6 ++--
4 files changed, 39 insertions(+), 73 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index d97e8407989c536078ee4419bbb94c21bc6abf4c..eb91f35410eec3b8298d04d867094d80a970387c 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -544,12 +544,13 @@ void __ref init_memory_mapping(unsigned long start,
memset(mr, 0, sizeof(mr));
nr_range = split_mem_range(mr, 0, start, end);
- for (i = 0; i < nr_range; i++)
- paddr_last = kernel_physical_mapping_init(mr[i].start, mr[i].end,
- mr[i].page_size_mask,
- prot);
+ for (i = 0; i < nr_range; i++) {
+ kernel_physical_mapping_init(mr[i].start, mr[i].end,
+ mr[i].page_size_mask, prot);
+ paddr_last = mr[i].end;
+ }
- add_pfn_range_mapped(start >> PAGE_SHIFT, paddr_last >> PAGE_SHIFT);
+ add_pfn_range_mapped(start >> PAGE_SHIFT, paddr_last);
}
/*
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 8a34fff6ab2b19f083f4fdf706de3ca0867416ba..b197736d90892b200002e4665e82f22125fa4bab 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -245,14 +245,13 @@ static inline int is_x86_32_kernel_text(unsigned long addr)
* of max_low_pfn pages, by creating page tables starting from address
* PAGE_OFFSET:
*/
-unsigned long __init
+void __init
kernel_physical_mapping_init(unsigned long start,
unsigned long end,
unsigned long page_size_mask,
pgprot_t prot)
{
int use_pse = page_size_mask == (1<<PG_LEVEL_2M);
- unsigned long last_map_addr = end;
unsigned long start_pfn, end_pfn;
pgd_t *pgd_base = swapper_pg_dir;
int pgd_idx, pmd_idx, pte_ofs;
@@ -356,7 +355,6 @@ kernel_physical_mapping_init(unsigned long start,
pages_4k++;
if (mapping_iter == 1) {
set_pte(pte, pfn_pte(pfn, init_prot));
- last_map_addr = (pfn << PAGE_SHIFT) + PAGE_SIZE;
} else
set_pte(pte, pfn_pte(pfn, prot));
}
@@ -382,7 +380,6 @@ kernel_physical_mapping_init(unsigned long start,
mapping_iter = 2;
goto repeat;
}
- return last_map_addr;
}
#ifdef CONFIG_HIGHMEM
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 7462f813052ccd45f0199b98bd0ad6499a164f6f..60f1a7493844ea399dd08dca50126f22a50d63d7 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -464,16 +464,12 @@ void __init cleanup_highmap(void)
}
}
-/*
- * Create PTE level page table mapping for physical addresses.
- * It returns the last physical address mapped.
- */
-static unsigned long __meminit
+/* Create PTE level page table mapping for physical addresses. */
+static void __meminit
phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
pgprot_t prot, bool init)
{
unsigned long pages = 0, paddr_next;
- unsigned long paddr_last = paddr_end;
pte_t *pte;
int i;
@@ -492,8 +488,6 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
continue;
}
- paddr_last = paddr_next;
-
/*
* We will re-use the existing mapping.
* Xen for example has some special requirements, like mapping
@@ -511,21 +505,17 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
}
update_page_count(PG_LEVEL_4K, pages);
-
- return paddr_last;
}
/*
* Create PMD level page table mapping for physical addresses. The virtual
* and physical address have to be aligned at this level.
- * It returns the last physical address mapped.
*/
-static unsigned long __meminit
+static void __meminit
phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
unsigned long page_size_mask, pgprot_t prot, bool init)
{
unsigned long pages = 0, paddr_next;
- unsigned long paddr_last = paddr_end;
int i = pmd_index(paddr);
@@ -549,9 +539,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
if (!pmd_leaf(*pmd)) {
spin_lock(&init_mm.page_table_lock);
pte = (pte_t *)pmd_page_vaddr(*pmd);
- paddr_last = phys_pte_init(pte, paddr,
- paddr_end, prot,
- init);
+ phys_pte_init(pte, paddr, paddr_end, prot, init);
spin_unlock(&init_mm.page_table_lock);
continue;
}
@@ -570,7 +558,6 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
if (page_size_mask & (1 << PG_LEVEL_2M)) {
if (!after_bootmem)
pages++;
- paddr_last = paddr_next;
continue;
}
new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
@@ -583,33 +570,29 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
pfn_pmd(paddr >> PAGE_SHIFT, prot_sethuge(prot)),
init);
spin_unlock(&init_mm.page_table_lock);
- paddr_last = paddr_next;
continue;
}
pte = alloc_low_page();
- paddr_last = phys_pte_init(pte, paddr, paddr_end, new_prot, init);
+ phys_pte_init(pte, paddr, paddr_end, new_prot, init);
spin_lock(&init_mm.page_table_lock);
pmd_populate_kernel_init(&init_mm, pmd, pte, init);
spin_unlock(&init_mm.page_table_lock);
}
update_page_count(PG_LEVEL_2M, pages);
- return paddr_last;
}
/*
* Create PUD level page table mapping for physical addresses. The virtual
* and physical address do not have to be aligned at this level. KASLR can
* randomize virtual addresses up to this level.
- * It returns the last physical address mapped.
*/
-static unsigned long __meminit
+static void __meminit
phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
unsigned long page_size_mask, pgprot_t _prot, bool init)
{
unsigned long pages = 0, paddr_next;
- unsigned long paddr_last = paddr_end;
unsigned long vaddr = (unsigned long)__va(paddr);
int i = pud_index(vaddr);
@@ -635,10 +618,8 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
if (!pud_none(*pud)) {
if (!pud_leaf(*pud)) {
pmd = pmd_offset(pud, 0);
- paddr_last = phys_pmd_init(pmd, paddr,
- paddr_end,
- page_size_mask,
- prot, init);
+ phys_pmd_init(pmd, paddr, paddr_end,
+ page_size_mask, prot, init);
continue;
}
/*
@@ -656,7 +637,6 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
if (page_size_mask & (1 << PG_LEVEL_1G)) {
if (!after_bootmem)
pages++;
- paddr_last = paddr_next;
continue;
}
prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
@@ -669,13 +649,11 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
pfn_pud(paddr >> PAGE_SHIFT, prot_sethuge(prot)),
init);
spin_unlock(&init_mm.page_table_lock);
- paddr_last = paddr_next;
continue;
}
pmd = alloc_low_page();
- paddr_last = phys_pmd_init(pmd, paddr, paddr_end,
- page_size_mask, prot, init);
+ phys_pmd_init(pmd, paddr, paddr_end, page_size_mask, prot, init);
spin_lock(&init_mm.page_table_lock);
pud_populate_init(&init_mm, pud, pmd, init);
@@ -683,23 +661,22 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
}
update_page_count(PG_LEVEL_1G, pages);
-
- return paddr_last;
}
-static unsigned long __meminit
+static void __meminit
phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
unsigned long page_size_mask, pgprot_t prot, bool init)
{
- unsigned long vaddr, vaddr_end, vaddr_next, paddr_next, paddr_last;
+ unsigned long vaddr, vaddr_end, vaddr_next, paddr_next;
- paddr_last = paddr_end;
vaddr = (unsigned long)__va(paddr);
vaddr_end = (unsigned long)__va(paddr_end);
- if (!pgtable_l5_enabled())
- return phys_pud_init((pud_t *) p4d_page, paddr, paddr_end,
- page_size_mask, prot, init);
+ if (!pgtable_l5_enabled()) {
+ phys_pud_init((pud_t *) p4d_page, paddr, paddr_end,
+ page_size_mask, prot, init);
+ return;
+ }
for (; vaddr < vaddr_end; vaddr = vaddr_next) {
p4d_t *p4d = p4d_page + p4d_index(vaddr);
@@ -721,33 +698,30 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
if (!p4d_none(*p4d)) {
pud = pud_offset(p4d, 0);
- paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end),
- page_size_mask, prot, init);
+ phys_pud_init(pud, paddr, __pa(vaddr_end),
+ page_size_mask, prot, init);
continue;
}
pud = alloc_low_page();
- paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end),
- page_size_mask, prot, init);
+ phys_pud_init(pud, paddr, __pa(vaddr_end),
+ page_size_mask, prot, init);
spin_lock(&init_mm.page_table_lock);
p4d_populate_init(&init_mm, p4d, pud, init);
spin_unlock(&init_mm.page_table_lock);
}
-
- return paddr_last;
}
-static unsigned long __meminit
+static void __meminit
__kernel_physical_mapping_init(unsigned long paddr_start,
unsigned long paddr_end,
unsigned long page_size_mask,
pgprot_t prot, bool init)
{
bool pgd_changed = false;
- unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;
+ unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next;
- paddr_last = paddr_end;
vaddr = (unsigned long)__va(paddr_start);
vaddr_end = (unsigned long)__va(paddr_end);
vaddr_start = vaddr;
@@ -760,16 +734,14 @@ __kernel_physical_mapping_init(unsigned long paddr_start,
if (pgd_val(*pgd)) {
p4d = (p4d_t *)pgd_page_vaddr(*pgd);
- paddr_last = phys_p4d_init(p4d, __pa(vaddr),
- __pa(vaddr_end),
- page_size_mask,
- prot, init);
+ phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end),
+ page_size_mask, prot, init);
continue;
}
p4d = alloc_low_page();
- paddr_last = phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end),
- page_size_mask, prot, init);
+ phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end),
+ page_size_mask, prot, init);
spin_lock(&init_mm.page_table_lock);
if (pgtable_l5_enabled())
@@ -784,8 +756,6 @@ __kernel_physical_mapping_init(unsigned long paddr_start,
if (pgd_changed)
sync_global_pgds(vaddr_start, vaddr_end - 1);
-
- return paddr_last;
}
@@ -793,15 +763,15 @@ __kernel_physical_mapping_init(unsigned long paddr_start,
* Create page table mapping for the physical memory for specific physical
* addresses. Note that it can only be used to populate non-present entries.
* The virtual and physical addresses have to be aligned on PMD level
- * down. It returns the last physical address mapped.
+ * down.
*/
-unsigned long __meminit
+void __meminit
kernel_physical_mapping_init(unsigned long paddr_start,
unsigned long paddr_end,
unsigned long page_size_mask, pgprot_t prot)
{
- return __kernel_physical_mapping_init(paddr_start, paddr_end,
- page_size_mask, prot, true);
+ __kernel_physical_mapping_init(paddr_start, paddr_end,
+ page_size_mask, prot, true);
}
/*
diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
index 436396936dfbe5d48b46872628d25de317ae6ced..0fa6bbcb5ad21af6f1e4240eeb486f2f310ed39c 100644
--- a/arch/x86/mm/mm_internal.h
+++ b/arch/x86/mm/mm_internal.h
@@ -10,10 +10,8 @@ static inline void *alloc_low_page(void)
void early_ioremap_page_table_range_init(void);
-unsigned long kernel_physical_mapping_init(unsigned long start,
- unsigned long end,
- unsigned long page_size_mask,
- pgprot_t prot);
+void kernel_physical_mapping_init(unsigned long start, unsigned long end,
+ unsigned long page_size_mask, pgprot_t prot);
void kernel_physical_mapping_change(unsigned long start, unsigned long end,
unsigned long page_size_mask);
void zone_sizes_init(void);
--
2.50.1
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