| Message ID | de169ef3c9ecc6fafbec4d4d4cc85a4555338a7d.1637862579.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Convert powerpc to default topdown mmap layout | expand |
Excerpts from Christophe Leroy's message of November 26, 2021 3:52 am: > Select CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT and > remove arch/powerpc/mm/mmap.c > > This change provides standard randomisation of mmaps. > > See commit 8b8addf891de ("x86/mm/32: Enable full randomization on i386 > and X86_32") for all the benefits of mmap randomisation. What's the actual difference before/after this patch? The mm/util.c code looks very similar to the code removed with a few small differences. Can these differences be explained in this patch? Thanks, Nick > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > v2: Also remove selection of ARCH_HAS_ELF_RANDOMIZE as it is already selected by CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT > --- > arch/powerpc/Kconfig | 2 +- > arch/powerpc/include/asm/processor.h | 2 - > arch/powerpc/mm/Makefile | 2 +- > arch/powerpc/mm/mmap.c | 105 --------------------------- > 4 files changed, 2 insertions(+), 109 deletions(-) > delete mode 100644 arch/powerpc/mm/mmap.c > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index fb48823ccd62..20504a9901f2 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -122,7 +122,6 @@ config PPC > select ARCH_HAS_DEBUG_WX if STRICT_KERNEL_RWX > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_DMA_MAP_DIRECT if PPC_PSERIES > - select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_HUGEPD if HUGETLB_PAGE > @@ -158,6 +157,7 @@ config PPC > select ARCH_USE_MEMTEST > select ARCH_USE_QUEUED_RWLOCKS if PPC_QUEUED_SPINLOCKS > select ARCH_USE_QUEUED_SPINLOCKS if PPC_QUEUED_SPINLOCKS > + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT > select ARCH_WANT_IPC_PARSE_VERSION > select ARCH_WANT_IRQS_OFF_ACTIVATE_MM > select ARCH_WANT_LD_ORPHAN_WARN > diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h > index e39bd0ff69f3..d906b14dd599 100644 > --- a/arch/powerpc/include/asm/processor.h > +++ b/arch/powerpc/include/asm/processor.h > @@ -378,8 +378,6 @@ static inline void prefetchw(const void *x) > > #define spin_lock_prefetch(x) prefetchw(x) > > -#define HAVE_ARCH_PICK_MMAP_LAYOUT > - > /* asm stubs */ > extern unsigned long isa300_idle_stop_noloss(unsigned long psscr_val); > extern unsigned long isa300_idle_stop_mayloss(unsigned long psscr_val); > 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 5972d619d274..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; > - 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; > - } > -} > -- > 2.33.1 > > >
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index fb48823ccd62..20504a9901f2 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -122,7 +122,6 @@ config PPC select ARCH_HAS_DEBUG_WX if STRICT_KERNEL_RWX select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_DMA_MAP_DIRECT if PPC_PSERIES - select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FORTIFY_SOURCE select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_HUGEPD if HUGETLB_PAGE @@ -158,6 +157,7 @@ config PPC select ARCH_USE_MEMTEST select ARCH_USE_QUEUED_RWLOCKS if PPC_QUEUED_SPINLOCKS select ARCH_USE_QUEUED_SPINLOCKS if PPC_QUEUED_SPINLOCKS + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT select ARCH_WANT_IPC_PARSE_VERSION select ARCH_WANT_IRQS_OFF_ACTIVATE_MM select ARCH_WANT_LD_ORPHAN_WARN diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index e39bd0ff69f3..d906b14dd599 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -378,8 +378,6 @@ static inline void prefetchw(const void *x) #define spin_lock_prefetch(x) prefetchw(x) -#define HAVE_ARCH_PICK_MMAP_LAYOUT - /* asm stubs */ extern unsigned long isa300_idle_stop_noloss(unsigned long psscr_val); extern unsigned long isa300_idle_stop_mayloss(unsigned long psscr_val); 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 5972d619d274..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; - 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; - } -}
Select CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT and remove arch/powerpc/mm/mmap.c This change provides standard randomisation of mmaps. See commit 8b8addf891de ("x86/mm/32: Enable full randomization on i386 and X86_32") for all the benefits of mmap randomisation. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- v2: Also remove selection of ARCH_HAS_ELF_RANDOMIZE as it is already selected by CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT --- arch/powerpc/Kconfig | 2 +- arch/powerpc/include/asm/processor.h | 2 - arch/powerpc/mm/Makefile | 2 +- arch/powerpc/mm/mmap.c | 105 --------------------------- 4 files changed, 2 insertions(+), 109 deletions(-) delete mode 100644 arch/powerpc/mm/mmap.c