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author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-04-09 19:17:36 +0200 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-05-05 22:11:58 +1000 |
commit | 36e5f9ee776cb6db6ab8cb9b056076c4492b9871 (patch) | |
tree | abac8092337b74d7588ec94fe53de4c51b1c170a /arch/powerpc/mm | |
parent | 5cf7f9a0a54e93a6d3361de5f4ba4358b054c6c2 (diff) | |
download | linux-36e5f9ee776cb6db6ab8cb9b056076c4492b9871.tar.gz linux-36e5f9ee776cb6db6ab8cb9b056076c4492b9871.tar.bz2 linux-36e5f9ee776cb6db6ab8cb9b056076c4492b9871.zip |
powerpc/mm: Convert to default topdown mmap layout
Select CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT and
remove arch/powerpc/mm/mmap.c
This change reuses the generic framework added by
commit 67f3977f805b ("arm64, mm: move generic mmap layout
functions to mm") without any functional change.
Comparison between powerpc implementation and the generic one:
- mmap_is_legacy() is identical.
- arch_mmap_rnd() does exactly the same allthough it's written
slightly differently.
- MIN_GAP and MAX_GAP are identical.
- mmap_base() does the same but uses STACK_RND_MASK which provides
the same values as stack_maxrandom_size().
- arch_pick_mmap_layout() is identical.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/518f9def87d3c889d5958103e7463cf45a2f673d.1649523076.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/mm')
-rw-r--r-- | arch/powerpc/mm/Makefile | 2 | ||||
-rw-r--r-- | arch/powerpc/mm/mmap.c | 105 |
2 files changed, 1 insertions, 106 deletions
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index d4c20484dad9..503a6e249940 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -5,7 +5,7 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC) -obj-y := fault.o mem.o pgtable.o mmap.o maccess.o pageattr.o \ +obj-y := fault.o mem.o pgtable.o maccess.o pageattr.o \ init_$(BITS).o pgtable_$(BITS).o \ pgtable-frag.o ioremap.o ioremap_$(BITS).o \ init-common.o mmu_context.o drmem.o \ diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c deleted file mode 100644 index d9eae456558a..000000000000 --- a/arch/powerpc/mm/mmap.c +++ /dev/null @@ -1,105 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later -/* - * flexible mmap layout support - * - * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. - * All Rights Reserved. - * - * Started by Ingo Molnar <mingo@elte.hu> - */ - -#include <linux/personality.h> -#include <linux/mm.h> -#include <linux/random.h> -#include <linux/sched/signal.h> -#include <linux/sched/mm.h> -#include <linux/elf-randomize.h> -#include <linux/security.h> -#include <linux/mman.h> - -/* - * Top of mmap area (just below the process stack). - * - * Leave at least a ~128 MB hole. - */ -#define MIN_GAP (128*1024*1024) -#define MAX_GAP (TASK_SIZE/6*5) - -static inline int mmap_is_legacy(struct rlimit *rlim_stack) -{ - if (current->personality & ADDR_COMPAT_LAYOUT) - return 1; - - if (rlim_stack->rlim_cur == RLIM_INFINITY) - return 1; - - return sysctl_legacy_va_layout; -} - -unsigned long arch_mmap_rnd(void) -{ - unsigned long shift, rnd; - - shift = mmap_rnd_bits; -#ifdef CONFIG_COMPAT - if (is_32bit_task()) - shift = mmap_rnd_compat_bits; -#endif - rnd = get_random_long() % (1ul << shift); - - return rnd << PAGE_SHIFT; -} - -static inline unsigned long stack_maxrandom_size(void) -{ - if (!(current->flags & PF_RANDOMIZE)) - return 0; - - /* 8MB for 32bit, 1GB for 64bit */ - if (is_32bit_task()) - return (1<<23); - else - return (1<<30); -} - -static inline unsigned long mmap_base(unsigned long rnd, - struct rlimit *rlim_stack) -{ - unsigned long gap = rlim_stack->rlim_cur; - unsigned long pad = stack_maxrandom_size() + stack_guard_gap; - - /* Values close to RLIM_INFINITY can overflow. */ - if (gap + pad > gap) - gap += pad; - - if (gap < MIN_GAP) - gap = MIN_GAP; - else if (gap > MAX_GAP) - gap = MAX_GAP; - - return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd); -} - -/* - * This function, called very early during the creation of a new - * process VM image, sets up which VM layout function to use: - */ -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) -{ - unsigned long random_factor = 0UL; - - if (current->flags & PF_RANDOMIZE) - random_factor = arch_mmap_rnd(); - - /* - * Fall back to the standard layout if the personality - * bit is set, or if the expected stack growth is unlimited: - */ - if (mmap_is_legacy(rlim_stack)) { - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; - mm->get_unmapped_area = arch_get_unmapped_area; - } else { - mm->mmap_base = mmap_base(random_factor, rlim_stack); - mm->get_unmapped_area = arch_get_unmapped_area_topdown; - } -} |