Commit a9b3c355 authored by Kevin Brodsky's avatar Kevin Brodsky Committed by Andrew Morton
Browse files

asm-generic: pgalloc: provide generic __pgd_{alloc,free} 

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 allocation order.

Because pagetable_alloc() allocates zeroed pages, explicit zeroing in
pgd_alloc() becomes redundant and we can get rid of it.  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.

Link: https://lkml.kernel.org/r/20250103184415.2744423-6-kevin.brodsky@arm.com


Signed-off-by: default avatarKevin Brodsky <kevin.brodsky@arm.com>
Acked-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 94771023

arch/alpha/mm/init.c

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/arc/include/asm/pgalloc.h

+2 −7
Original line number Diff line number Diff line
@@ -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;

}

arch/arm/mm/pgd.c

+3 −5
Original line number Diff line number Diff line
@@ -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

	 */

arch/arm64/mm/pgd.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

}

arch/csky/include/asm/pgalloc.h

+1 −1
Original line number Diff line number Diff line
@@ -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);