From: "zhengdbu@gmail.com" <zhengdbu@gmail.com>
To: alex <alex@ghiti.fr>, paul.walmsley <paul.walmsley@sifive.com>
Cc: palmer <palmer@dabbelt.com>, aou <aou@eecs.berkeley.edu>,
anup.patel <anup.patel@wdc.com>,
sunnanyong <sunnanyong@huawei.com>, jszhang <jszhang@kernel.org>,
penberg <penberg@kernel.org>, guoren <guoren@linux.alibaba.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Re: [PATCH v1 1/1] Add support for mm->mmap_legacy_base in legacy layout
Date: Wed, 13 Oct 2021 00:03:49 +0800 [thread overview]
Message-ID: <2021101300034741790513@gmail.com> (raw)
In-Reply-To: ca177872-8ce8-0cb7-4dbf-2debcb1ce76f@ghiti.fr
Hi Alex,
Do you think map_legacy_base should not be used? Or is
the kernel about to delete it? I think it's weird not to use it
because it's already defined.
Thanks,
Jinli Zheng
--------------
zhengdbu@gmail.com
>Hi Jinli,
>
>Le 27/09/2021 à 13:11, Jinli Zheng a écrit :
>> Add support for mm->mmap_legacy_base in the legacy layout
>> of the process memory space for the riscv architecture
>>
>
>Can you elaborate a bit more? What value does it bring? I remember I had
>spent some time to factorize this code with arm64 to offer
>ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT config and I had another patchset
>to get rid of mmap_legacy_base entirely at
>https://lkml.org/lkml/2019/6/19/18 (which never got merged though).
>
>Thanks,
>
>Alex
>
>> Signed-off-by: Jinli Zheng <zhengdbu@gmail.com>
>> ---
>> arch/riscv/Kconfig | 2 +-
>> arch/riscv/include/asm/pgtable.h | 3 +
>> arch/riscv/include/asm/processor.h | 1 +
>> arch/riscv/mm/Makefile | 2 +-
>> arch/riscv/mm/mmap.c | 165 +++++++++++++++++++++++++++++
>> 5 files changed, 171 insertions(+), 2 deletions(-)
>> create mode 100644 arch/riscv/mm/mmap.c
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 301a54233c7e..e64231592227 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -37,7 +37,7 @@ config RISCV
>> select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
>> select ARCH_SUPPORTS_HUGETLBFS if MMU
>> select ARCH_USE_MEMTEST
>> - select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
>> + select ARCH_HAS_ELF_RANDOMIZE
>> select ARCH_WANT_FRAME_POINTERS
>> select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
>> select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 39b550310ec6..107d61371272 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -700,6 +700,9 @@ void misc_mem_init(void);
>> extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
>> #define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
>>
>> +#define HAVE_ARCH_UNMAPPED_AREA
>> +#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
>> +
>> #endif /* !__ASSEMBLY__ */
>>
>> #endif /* _ASM_RISCV_PGTABLE_H */
>> diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
>> index 46b492c78cbb..e7dc7c1f820a 100644
>> --- a/arch/riscv/include/asm/processor.h
>> +++ b/arch/riscv/include/asm/processor.h
>> @@ -56,6 +56,7 @@ static inline void arch_thread_struct_whitelist(unsigned long *offset,
>> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->epc)
>> #define KSTK_ESP(tsk) (task_pt_regs(tsk)->sp)
>>
>> +#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
>>
>> /* Do necessary setup to start up a newly executed thread. */
>> extern void start_thread(struct pt_regs *regs,
>> diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
>> index 7ebaef10ea1b..123c67a2c24a 100644
>> --- a/arch/riscv/mm/Makefile
>> +++ b/arch/riscv/mm/Makefile
>> @@ -10,7 +10,7 @@ KCOV_INSTRUMENT_init.o := n
>>
>> obj-y += init.o
>> obj-y += extable.o
>> -obj-$(CONFIG_MMU) += fault.o pageattr.o
>> +obj-$(CONFIG_MMU) += fault.o pageattr.o mmap.o
>> obj-y += cacheflush.o
>> obj-y += context.o
>>
>> diff --git a/arch/riscv/mm/mmap.c b/arch/riscv/mm/mmap.c
>> new file mode 100644
>> index 000000000000..6c5818db5a65
>> --- /dev/null
>> +++ b/arch/riscv/mm/mmap.c
>> @@ -0,0 +1,165 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Legacy and flexible mmap layout support
>> + *
>> + * Copyright (C) 2021 Jinli Zheng <zhengdbu@gmail.com>
>> + */
>> +
>> +#include <linux/personality.h>
>> +#include <linux/mm.h>
>> +#include <linux/mman.h>
>> +#include <linux/random.h>
>> +#include <linux/limits.h>
>> +#include <linux/security.h>
>> +#include <linux/compat.h>
>> +#include <linux/sched/mm.h>
>> +#include <linux/sched.h>
>> +#include <linux/elf-randomize.h>
>> +#include <asm/pgtable.h>
>> +#include <asm/processor.h>
>> +
>> +#define SIZE_128M (128*1024*1024UL)
>> +
>> +/*gap between MMAP and STACK*/
>> +#define GAP_MIN SIZE_128M
>> +#define GAP_MAX (((TASK_SIZE)/6)*5)
>> +
>> +static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
>> +{
>> + unsigned long gap = rlim_stack->rlim_cur;
>> +
>> + if (gap < GAP_MIN)
>> + gap = GAP_MIN;
>> + else if (gap > GAP_MAX)
>> + gap = GAP_MAX;
>> +
>> + return PAGE_ALIGN(TASK_SIZE - gap - rnd);
>> +}
>> +
>> +unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>> + unsigned long len, unsigned long pgoff, unsigned long flags)
>> +{
>> + struct mm_struct *mm = current->mm;
>> + struct vm_area_struct *vma, *prev;
>> + struct vm_unmapped_area_info info;
>> +
>> + if (len > TASK_SIZE)
>> + return -ENOMEM;
>> +
>> + if (flags & MAP_FIXED)
>> + return addr;
>> +
>> + if (addr) {
>> + addr = PAGE_ALIGN(addr);
>> + vma = find_vma_prev(mm, addr, &prev);
>> + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
>> + (!vma || addr + len <= vm_start_gap(vma)) &&
>> + (!prev || addr >= vm_end_gap(prev)))
>> + return addr;
>> + }
>> +
>> + info.flags = 0;
>> + info.length = len;
>> + info.low_limit = mm->mmap_legacy_base;
>> + info.high_limit = TASK_SIZE;
>> + info.align_mask = 0;
>> + info.align_offset = 0;
>> + return vm_unmapped_area(&info);
>> +}
>> +
>> +unsigned long arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
>> + unsigned long len, unsigned long pgoff, unsigned long flags)
>> +{
>> + struct mm_struct *mm = current->mm;
>> + struct vm_area_struct *vma, *prev;
>> + struct vm_unmapped_area_info info;
>> +
>> + if (len > TASK_SIZE)
>> + return -ENOMEM;
>> +
>> + if (flags & MAP_FIXED)
>> + return addr;
>> +
>> + if (addr) {
>> + addr = PAGE_ALIGN(addr);
>> + vma = find_vma_prev(mm, addr, &prev);
>> + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
>> + (!vma || addr + len <= vm_start_gap(vma)) &&
>> + (!prev || addr >= vm_end_gap(prev)))
>> + return addr;
>> + }
>> +
>> + info.flags = VM_UNMAPPED_AREA_TOPDOWN;
>> + info.length = len;
>> + info.low_limit = max(PAGE_SIZE, mmap_min_addr);
>> + info.high_limit = mm->mmap_base;
>> + info.align_mask = 0;
>> + info.align_offset = 0;
>> + addr = vm_unmapped_area(&info);
>> +
>> + if (offset_in_page(addr)) {
>> + VM_BUG_ON(addr != -ENOMEM);
>> + info.flags = 0;
>> + info.low_limit = TASK_UNMAPPED_BASE;
>> + info.high_limit = TASK_SIZE;
>> + addr = vm_unmapped_area(&info);
>> + }
>> +
>> + return addr;
>> +}
>> +
>> +unsigned long arch_mmap_rnd(void)
>> +{
>> + unsigned long rnd;
>> +
>> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
>> + if (is_compat_task())
>> + rnd = get_random_int() & ((1UL << mmap_rnd_compat_bits) - 1);
>> + else
>> +#endif /*CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS*/
>> + rnd = get_random_int() & ((1UL << mmap_rnd_bits) - 1);
>> +
>> + return rnd << PAGE_SHIFT;
>> +}
>> +
>> +static 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;
>> +}
>> +
>> +static void arch_pick_mmap_base(struct mm_struct *mm, struct rlimit *rlim_stack)
>> +{
>> + unsigned long random;
>> +
>> + random = (current->flags & PF_RANDOMIZE) ?
>> + arch_mmap_rnd() : 0UL;
>> +
>> + if (mmap_is_legacy(rlim_stack))
>> + mm->mmap_legacy_base = TASK_UNMAPPED_BASE + random;
>> + else
>> + mm->mmap_base = mmap_base(random, rlim_stack);
>> +}
>> +
>> +void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>> +{
>> + if (mmap_is_legacy(rlim_stack))
>> + mm->get_unmapped_area = arch_get_unmapped_area;
>> + else
>> + mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>> +
>> + arch_pick_mmap_base(mm, rlim_stack);
>> +}
>> +
>> +unsigned long arch_randomize_brk(struct mm_struct *mm)
>> +{
>> + if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
>> + return randomize_page(mm->brk, SZ_32M);
>> +
>> + return randomize_page(mm->brk, SZ_1G);
>> +}
>>
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next prev parent reply other threads:[~2021-10-12 16:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 11:11 [PATCH v1 1/1] Add support for mm->mmap_legacy_base in legacy layout Jinli Zheng
2021-10-10 15:33 ` Alex Ghiti
2021-10-12 16:03 ` zhengdbu [this message]
2021-10-13 14:30 ` Alexandre ghiti
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