[PATCH 09/10] asm-generic: pgalloc: Provide generic __pgd_{alloc,free}

Kevin Brodsky
2024-12-19T16:56:07Z

We already have a generic implementation of alloc/free up to P4D
level, as well as pgd_free(). Let's finish the work and add a
generic PGD-level alloc helper as well.

Unlike at lower levels, almost all architectures need some specific
magic at PGD level (typically initialising PGD entries), so
introducing a generic pgd_alloc() isn't worth it. Instead we
introduce two new helpers, __pgd_alloc() and __pgd_free(), and make
use of them in the arch-specific pgd_alloc() and pgd_free() wherever
possible. To accommodate as many arch as possible, __pgd_alloc()
takes a page alocation order.

Because pagetable_alloc() allocates zeroed pages, we are also able
to get rid of zeroing code in some implementations of pgd_alloc().
Some trivial implementations of pgd_free() also become unnecessary
once __pgd_alloc() is used; remove them.

Another small improvement is consistent accounting of PGD pages by
using GFP_PGTABLE_{USER,KERNEL} as appropriate.

Not all PGD allocations can be handled by the generic helpers. In
particular, multiple architectures allocate PGDs from a kmem_cache,
and those PGDs may not be page-sized.

Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
arch/alpha/mm/init.c | 2 +-
arch/arc/include/asm/pgalloc.h | 9 ++-------
arch/arm/mm/pgd.c | 8 +++-----
arch/arm64/mm/pgd.c | 4 ++--
arch/csky/include/asm/pgalloc.h | 2 +-
arch/hexagon/include/asm/pgalloc.h | 2 +-
arch/loongarch/mm/pgtable.c | 7 +++----
arch/m68k/include/asm/sun3_pgalloc.h | 2 +-
arch/microblaze/include/asm/pgalloc.h | 7 +------
arch/mips/include/asm/pgalloc.h | 6 ------
arch/mips/mm/pgtable.c | 8 +++-----
arch/nios2/mm/pgtable.c | 3 ++-
arch/openrisc/include/asm/pgalloc.h | 6 ++----
arch/parisc/include/asm/pgalloc.h | 16 +---------------
arch/riscv/include/asm/pgalloc.h | 3 +--
arch/um/kernel/mem.c | 7 +++----
arch/x86/mm/pgtable.c | 24 +++++++++++-------------
arch/xtensa/include/asm/pgalloc.h | 2 +-
include/asm-generic/pgalloc.h | 27 ++++++++++++++++++++++++++-
19 files changed, 65 insertions(+), 80 deletions(-)

diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c
index 4fe618446e4c..61c2198b1359 100644
--- a/arch/alpha/mm/init.c
+++ b/arch/alpha/mm/init.c
@@ -42,7 +42,7 @@ pgd_alloc(struct mm_struct *mm)
{
pgd_t *ret, *init;

- ret = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+ ret = __pgd_alloc(mm, 0);
init = pgd_offset(&init_mm, 0UL);
if (ret) {
#ifdef CONFIG_ALPHA_LARGE_VMALLOC
diff --git a/arch/arc/include/asm/pgalloc.h b/arch/arc/include/asm/pgalloc.h
index 096b8ef58edb..dfae070fe8d5 100644
--- a/arch/arc/include/asm/pgalloc.h
+++ b/arch/arc/include/asm/pgalloc.h
@@ -53,19 +53,14 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t pte_

static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *ret = (pgd_t *) __get_free_page(GFP_KERNEL);
+ pgd_t *ret = __pgd_alloc(mm, 0);

if (ret) {
int num, num2;
- num = USER_PTRS_PER_PGD + USER_KERNEL_GUTTER / PGDIR_SIZE;
- memzero(ret, num * sizeof(pgd_t));

+ num = USER_PTRS_PER_PGD + USER_KERNEL_GUTTER / PGDIR_SIZE;
num2 = VMALLOC_SIZE / PGDIR_SIZE;
memcpy(ret + num, swapper_pg_dir + num, num2 * sizeof(pgd_t));
-
- memzero(ret + num + num2,
- (PTRS_PER_PGD - num - num2) * sizeof(pgd_t));
-
}
return ret;
}
diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c
index 2a1077747758..4eb81b7ed03a 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -17,11 +17,11 @@
#include "mm.h"

#ifdef CONFIG_ARM_LPAE
-#define _pgd_alloc(mm) kmalloc_array(PTRS_PER_PGD, sizeof(pgd_t), GFP_KERNEL)
+#define _pgd_alloc(mm) kmalloc_array(PTRS_PER_PGD, sizeof(pgd_t), GFP_KERNEL | __GFP_ZERO)
#define _pgd_free(mm, pgd) kfree(pgd)
#else
-#define _pgd_alloc(mm) (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
-#define _pgd_free(mm, pgd) free_pages((unsigned long)pgd, 2)
+#define _pgd_alloc(mm) __pgd_alloc(mm, 2)
+#define _pgd_free(mm, pgd) __pgd_free(mm, pgd)
#endif

/*
@@ -39,8 +39,6 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
if (!new_pgd)
goto no_pgd;

- memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
-
/*
* Copy over the kernel and IO PGD entries
*/
diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 0c501cabc238..8160cff35089 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -33,7 +33,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
gfp_t gfp = GFP_PGTABLE_USER;

if (pgdir_is_page_size())
- return (pgd_t *)__get_free_page(gfp);
+ return __pgd_alloc(mm, 0);
else
return kmem_cache_alloc(pgd_cache, gfp);
}
@@ -41,7 +41,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
if (pgdir_is_page_size())
- free_page((unsigned long)pgd);
+ __pgd_free(mm, pgd);
else
kmem_cache_free(pgd_cache, pgd);
}
diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
index 9c84c9012e53..9a3bbf16f03f 100644
--- a/arch/csky/include/asm/pgalloc.h
+++ b/arch/csky/include/asm/pgalloc.h
@@ -44,7 +44,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
pgd_t *ret;
pgd_t *init;

- ret = (pgd_t *) __get_free_page(GFP_KERNEL);
+ ret = __pgd_alloc(mm, 0);
if (ret) {
init = pgd_offset(&init_mm, 0UL);
pgd_init((unsigned long *)ret);
diff --git a/arch/hexagon/include/asm/pgalloc.h b/arch/hexagon/include/asm/pgalloc.h
index 55988625e6fb..289dace6d76d 100644
--- a/arch/hexagon/include/asm/pgalloc.h
+++ b/arch/hexagon/include/asm/pgalloc.h
@@ -22,7 +22,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;

- pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+ pgd = __pgd_alloc(mm, 0);

/*
* There may be better ways to do this, but to ensure
diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c
index 3fa69b23ff84..22a94bb3e6e8 100644
--- a/arch/loongarch/mm/pgtable.c
+++ b/arch/loongarch/mm/pgtable.c
@@ -23,11 +23,10 @@ EXPORT_SYMBOL(tlb_virt_to_page);

pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *init, *ret = NULL;
- struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, 0);
+ pgd_t *init, *ret;

- if (ptdesc) {
- ret = (pgd_t *)ptdesc_address(ptdesc);
+ ret = __pgd_alloc(mm, 0);
+ if (ret) {
init = pgd_offset(&init_mm, 0UL);
pgd_init(ret);
memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
diff --git a/arch/m68k/include/asm/sun3_pgalloc.h b/arch/m68k/include/asm/sun3_pgalloc.h
index 4a137eecb6fe..e91b0133df5d 100644
--- a/arch/m68k/include/asm/sun3_pgalloc.h
+++ b/arch/m68k/include/asm/sun3_pgalloc.h
@@ -43,7 +43,7 @@ static inline pgd_t * pgd_alloc(struct mm_struct *mm)
{
pgd_t *new_pgd;

- new_pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+ new_pgd = __pgd_alloc(mm, 0);
memcpy(new_pgd, swapper_pg_dir, PAGE_SIZE);
memset(new_pgd, 0, (PAGE_OFFSET >> PGDIR_SHIFT));
return new_pgd;
diff --git a/arch/microblaze/include/asm/pgalloc.h b/arch/microblaze/include/asm/pgalloc.h
index 6c33b05f730f..084a8a0dc239 100644
--- a/arch/microblaze/include/asm/pgalloc.h
+++ b/arch/microblaze/include/asm/pgalloc.h
@@ -21,12 +21,7 @@

extern void __bad_pte(pmd_t *pmd);

-static inline pgd_t *get_pgd(void)
-{
- return (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
-}
-
-#define pgd_alloc(mm) get_pgd()
+#define pgd_alloc(mm) __pgd_alloc(mm, 0)

extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm);

diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
index f4440edcd8fe..9ee8426b2e9d 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -15,7 +15,6 @@

#define __HAVE_ARCH_PMD_ALLOC_ONE
#define __HAVE_ARCH_PUD_ALLOC_ONE
-#define __HAVE_ARCH_PGD_FREE
#include <asm-generic/pgalloc.h>

static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
@@ -49,11 +48,6 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
extern void pgd_init(void *addr);
extern pgd_t *pgd_alloc(struct mm_struct *mm);

-static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
-{
- pagetable_free(virt_to_ptdesc(pgd));
-}
-
#define __pte_free_tlb(tlb, pte, address) \
do { \
pagetable_pte_dtor(page_ptdesc(pte)); \
diff --git a/arch/mips/mm/pgtable.c b/arch/mips/mm/pgtable.c
index 1506e458040d..10835414819f 100644
--- a/arch/mips/mm/pgtable.c
+++ b/arch/mips/mm/pgtable.c
@@ -10,12 +10,10 @@

pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *init, *ret = NULL;
- struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM,
- PGD_TABLE_ORDER);
+ pgd_t *init, *ret;

- if (ptdesc) {
- ret = ptdesc_address(ptdesc);
+ ret = __pgd_alloc(mm, PGD_TABLE_ORDER);
+ if (ret) {
init = pgd_offset(&init_mm, 0UL);
pgd_init(ret);
memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
diff --git a/arch/nios2/mm/pgtable.c b/arch/nios2/mm/pgtable.c
index 7c76e8a7447a..6470ed378782 100644
--- a/arch/nios2/mm/pgtable.c
+++ b/arch/nios2/mm/pgtable.c
@@ -11,6 +11,7 @@
#include <linux/sched.h>

#include <asm/cpuinfo.h>
+#include <asm/pgalloc.h>

/* pteaddr:
* ptbase | vpn* | zero
@@ -54,7 +55,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *ret, *init;

- ret = (pgd_t *) __get_free_page(GFP_KERNEL);
+ ret = __pgd_alloc(mm, 0);
if (ret) {
init = pgd_offset(&init_mm, 0UL);
pgd_init(ret);
diff --git a/arch/openrisc/include/asm/pgalloc.h b/arch/openrisc/include/asm/pgalloc.h
index c6a73772a546..c068c4942467 100644
--- a/arch/openrisc/include/asm/pgalloc.h
+++ b/arch/openrisc/include/asm/pgalloc.h
@@ -41,15 +41,13 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
*/
static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *ret = (pgd_t *)__get_free_page(GFP_KERNEL);
+ pgd_t *ret = __pgd_alloc(mm, 0);

- if (ret) {
- memset(ret, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
+ if (ret)
memcpy(ret + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));

- }
return ret;
}

diff --git a/arch/parisc/include/asm/pgalloc.h b/arch/parisc/include/asm/pgalloc.h
index 3e8dbd79670b..2ca74a56415c 100644
--- a/arch/parisc/include/asm/pgalloc.h
+++ b/arch/parisc/include/asm/pgalloc.h
@@ -11,26 +11,12 @@
#include <asm/cache.h>

#define __HAVE_ARCH_PMD_ALLOC_ONE
-#define __HAVE_ARCH_PGD_FREE
#include <asm-generic/pgalloc.h>

/* Allocate the top level pgd (page directory) */
static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *pgd;
-
- pgd = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_TABLE_ORDER);
- if (unlikely(pgd == NULL))
- return NULL;
-
- memset(pgd, 0, PAGE_SIZE << PGD_TABLE_ORDER);
-
- return pgd;
-}
-
-static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
-{
- free_pages((unsigned long)pgd, PGD_TABLE_ORDER);
+ return __pgd_alloc(mm, PGD_TABLE_ORDER);
}

#if CONFIG_PGTABLE_LEVELS == 3
diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 3c364ecc3100..d527f141be1c 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -128,9 +128,8 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;

- pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
+ pgd = __pgd_alloc(mm, 0);
if (likely(pgd != NULL)) {
- memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
/* Copy kernel mappings */
sync_kernel_mappings(pgd);
}
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 53248ed04771..d98812907493 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -214,14 +214,13 @@ void free_initmem(void)

pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
+ pgd_t *pgd = __pgd_alloc(mm, 0);

- if (pgd) {
- memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
+ if (pgd)
memcpy(pgd + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
- }
+
return pgd;
}

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index c1bfdf7b4767..00917ef609b6 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -395,15 +395,14 @@ void __init pgtable_cache_init(void)
SLAB_PANIC, NULL);
}

-static inline pgd_t *_pgd_alloc(void)
+static inline pgd_t *_pgd_alloc(struct mm_struct *mm)
{
/*
* If no SHARED_KERNEL_PMD, PAE kernel is running as a Xen domain.
* We allocate one page for pgd.
*/
if (!SHARED_KERNEL_PMD)
- return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
- PGD_ALLOCATION_ORDER);
+ return __pgd_alloc(mm, PGD_ALLOCATION_ORDER);

/*
* Now PAE kernel is not running as a Xen domain. We can allocate
@@ -412,24 +411,23 @@ static inline pgd_t *_pgd_alloc(void)
return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_USER);
}

-static inline void _pgd_free(pgd_t *pgd)
+static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
if (!SHARED_KERNEL_PMD)
- free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
+ __pgd_free(mm, pgd);
else
kmem_cache_free(pgd_cache, pgd);
}
#else

-static inline pgd_t *_pgd_alloc(void)
+static inline pgd_t *_pgd_alloc(struct mm_struct *mm)
{
- return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
- PGD_ALLOCATION_ORDER);
+ return __pgd_alloc(mm, PGD_ALLOCATION_ORDER);
}

-static inline void _pgd_free(pgd_t *pgd)
+static inline void _pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
- free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
+ __pgd_free(mm, pgd);
}
#endif /* CONFIG_X86_PAE */

@@ -439,7 +437,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS];
pmd_t *pmds[MAX_PREALLOCATED_PMDS];

- pgd = _pgd_alloc();
+ pgd = _pgd_alloc(mm);

if (pgd == NULL)
goto out;
@@ -482,7 +480,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
if (sizeof(pmds) != 0)
free_pmds(mm, pmds, PREALLOCATED_PMDS);
out_free_pgd:
- _pgd_free(pgd);
+ _pgd_free(mm, pgd);
out:
return NULL;
}
@@ -492,7 +490,7 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd)
pgd_mop_up_pmds(mm, pgd);
pgd_dtor(pgd);
paravirt_pgd_free(mm, pgd);
- _pgd_free(pgd);
+ _pgd_free(mm, pgd);
}

/*
diff --git a/arch/xtensa/include/asm/pgalloc.h b/arch/xtensa/include/asm/pgalloc.h
index 7fc0f9126dd3..1919ee9c3dd6 100644
--- a/arch/xtensa/include/asm/pgalloc.h
+++ b/arch/xtensa/include/asm/pgalloc.h
@@ -29,7 +29,7 @@
static inline pgd_t*
pgd_alloc(struct mm_struct *mm)
{
- return (pgd_t*) __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ return __pgd_alloc(mm, 0);
}

static inline void ptes_clear(pte_t *ptep)
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index bb482eeca0c3..daa8bea36952 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -262,10 +262,35 @@ static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)

#endif /* CONFIG_PGTABLE_LEVELS > 4 */

+static inline pgd_t *__pgd_alloc_noprof(struct mm_struct *mm, unsigned int order)
+{
+ gfp_t gfp = GFP_PGTABLE_USER;
+ struct ptdesc *ptdesc;
+
+ if (mm == &init_mm)
+ gfp = GFP_PGTABLE_KERNEL;
+ gfp &= ~__GFP_HIGHMEM;
+
+ ptdesc = pagetable_alloc_noprof(gfp, order);
+ if (!ptdesc)
+ return NULL;
+
+ return ptdesc_address(ptdesc);
+}
+#define __pgd_alloc(...) alloc_hooks(__pgd_alloc_noprof(__VA_ARGS__))
+
+static inline void __pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+ struct ptdesc *ptdesc = virt_to_ptdesc(pgd);
+
+ BUG_ON((unsigned long)pgd & (PAGE_SIZE-1));
+ pagetable_free(ptdesc);
+}
+
#ifndef __HAVE_ARCH_PGD_FREE
static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
- pagetable_free(virt_to_ptdesc(pgd));
+ __pgd_free(mm, pgd);
}
#endif

--
2.47.0