From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: TASK_SIZE for !MMU Date: Tue, 29 Apr 2014 12:00:28 +0200 Message-ID: <20140429100028.GH28564@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Rabin Vincent , Will Deacon , linux-arm-kernel@lists.infradead.org Cc: David Howells , uclinux-dist-devel@blackfin.uclinux.org, linux-m68k@lists.linux-m68k.org, linux-c6x-dev@linux-c6x.org, linux-m32r@ml.linux-m32r.org, microblaze-uclinux@itee.uq.edu.au, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de Hello, I grepped through the kernel (v3.15-rc1) for usages of TASK_SIZE to check if/how it is used on !MMU ARM machines. Most open questions also affect the other !MMU platforms, so I put the blackfin, c6x, frv and m32r, m68k, microblaze and xtensa lists on Cc:. (Did I miss a platform that cares for !MMU ?) Most occurences are fine, see the list at the end of this mail. However some are not or are unclear to me. Here is the complete list[1] apart f= rom the definition of TASK_SIZE for !MMU in arch/arm/include/asm/memory.h: - Probably this should be explict s/TASK_SIZE/CONFIG_DRAM_SIZE/. This is generic code however while CONFIG_DRAM_SIZE is ARM only. mm/nommu.c: if (!rlen || rlen > TASK_SIZE) - The issue the patch by Rabin is addressing (Subject: [PATCH] ARM: fi= x string functions on !MMU), alternatively make TASK_SIZE ~0UL. arch/arm/include/asm/uaccess.h:#define user_addr_max() \ arch/arm/include/asm/uaccess.h: (segment_eq(get_fs(), USER_DS) = ? TASK_SIZE : ~0UL) - probably bearable if broken: drivers/misc/lkdtm.c: if (user_addr >=3D TASK_SIZE) { lib/test_user_copy.c: user_addr =3D vm_mmap(...) lib/test_user_copy.c: if (user_addr >=3D (unsigned long)(TASK= _SIZE)) { lib/test_user_copy.c: pr_warn("Failed to allocate use= r memory\n"); lib/test_user_copy.c: return -ENOMEM; - unclear to me: fs/exec.c: current->mm->task_size =3D TASK_SIZE; - depends on PERF_EVENTS kernel/events/core.c: if (!addr || addr >=3D TASK_SIZE) kernel/events/core.c: return TASK_SIZE - addr; kernel/events/uprobes.c: area->vaddr =3D get_unm= apped_area(NULL, TASK_SIZE - PAGE_SIZE, - depends on (PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)): arch/arm/kernel/hw_breakpoint.c: return (va >=3D TASK_SI= ZE) && ((va + len - 1) >=3D TASK_SIZE); - seems to cope with big TASK_SIZE fs/namespace.c: size =3D TASK_SIZE - (unsigned long)data= ; fs/namespace.c: if (size > PAGE_SIZE) fs/namespace.c: size =3D PAGE_SIZE; - depends on PLAT_S5P || ARCH_EXYNOS, this looks wrong drivers/media/platform/s5p-mfc/s5p_mfc_common.h:#define DST_QUE= UE_OFF_BASE (TASK_SIZE / 2) - used for prctl(PR_SET_MM, ...) kernel/sys.c: if (addr >=3D TASK_SIZE || addr < mmap_min_addr= ) Any help to judge if these are OK is appreciated (even from Will :-) I think it would be OK to define TASK_SIZE to 0xffffffff for !MMU. blackfin, frv and m68k also do this. c6x does define it to 0xFFFFF000 t= o leave space for error codes. Thoughts? Best regards Uwe [1] complete as in "skip everything below arch/ but arch/arm" :-) =3D=3D=3D=3D=3D=3D=3D These occurences are fine =3D=3D=3D=3D=3D=3D=3D mmu-only: arch/arm/include/asm/memory.h: * TASK_SIZE - the maximum size o= f a user space task. arch/arm/include/asm/memory.h:#define TASK_SIZE (UL(CON= =46IG_PAGE_OFFSET) - UL(SZ_16M)) arch/arm/include/asm/memory.h:#define TASK_UNMAPPED_BASE = ALIGN(TASK_SIZE / 3, SZ_16M) arch/arm/include/asm/memory.h:#define TASK_SIZE_26 = (UL(1) << 26) arch/arm/include/asm/memory.h: * The module space lives between= the addresses given by TASK_SIZE arch/arm/include/asm/memory.h:#if TASK_SIZE > MODULES_VADDR arch/arm/include/asm/pgtable-2level.h:#define USER_PTRS_PER_PGD= (TASK_SIZE / PGDIR_SIZE) arch/arm/include/asm/pgtable-3level.h: BUG_ON(addr >=3D TASK_S= IZE); arch/arm/include/asm/pgtable.h: * Use TASK_SIZE as the ceiling = argument for free_pgtables() and arch/arm/include/asm/pgtable.h:#define USER_PGTABLES_CEILING = TASK_SIZE arch/arm/include/asm/pgtable.h: if (addr < TASK_SIZE && pte_val= id_user(pteval)) { arch/arm/include/asm/tlb.h: tlb->range_start =3D TA= SK_SIZE; arch/arm/include/asm/tlb.h: tlb->range_start =3D TA= SK_SIZE; arch/arm/kernel/entry-armv.S: cmp r4, #TASK_SIZE arch/arm/mm/fault.c: if (addr < TASK_SIZE) arch/arm/mm/init.c: BUILD_BUG_ON(TASK_SIZE = > MODULES_VADDR); arch/arm/mm/init.c: BUG_ON(TASK_SIZE = > MODULES_VADDR); arch/arm/mm/mmap.c:#define MAX_GAP ((TASK_SIZE)/6*5) arch/arm/mm/mmap.c: return PAGE_ALIGN(TASK_SIZE - gap - rnd= ); arch/arm/mm/mmap.c: if (len > TASK_SIZE) arch/arm/mm/mmap.c: if (TASK_SIZE - len >=3D addr &= & arch/arm/mm/mmap.c: info.high_limit =3D TASK_SIZE; arch/arm/mm/mmap.c: if (len > TASK_SIZE) arch/arm/mm/mmap.c: if (TASK_SIZE - len >=3D addr &= & arch/arm/mm/mmap.c: info.high_limit =3D TASK_SIZE; arch/arm/mm/mmu.c: if (md->virtual !=3D vectors_base() && = md->virtual < TASK_SIZE) { arch/arm/include/asm/uaccess.h:#define USER_DS TASK_SI= ZE mm/memory.c: if (pg > TASK_SIZE) mm/mlock.c: mm_populate(0, TASK_SIZE); mm/mmap.c: if (len > TASK_SIZE - mmap_min_addr) mm/mmap.c: if (TASK_SIZE - len >=3D addr && addr >= =3D mmap_min_addr && mm/mmap.c: info.high_limit =3D TASK_SIZE; mm/mmap.c: if (len > TASK_SIZE - mmap_min_addr) mm/mmap.c: if (TASK_SIZE - len >=3D addr && addr >= =3D mmap_min_addr && mm/mmap.c: info.high_limit =3D TASK_SIZE; mm/mmap.c: if (len > TASK_SIZE) mm/mmap.c: if (addr > TASK_SIZE - len) mm/mmap.c: if ((start & ~PAGE_MASK) || start > TASK_SIZE |= | len > TASK_SIZE mm/mremap.c: if (new_len > TASK_SIZE || new_addr > TASK_SIZE= - new_len) enabled by CONFIG_NUMA, unavailable on ARM: mm/mempolicy.c: pvma.vm_end =3D TASK_SIZE; /* po= licy covers entire Only used in fs/exec.c in #ifdef CONFIG_MMU: arch/arm/include/asm/processor.h:#define STACK_TOP_MAX TASK_SI= ZE Used in: - fs/binfmt_aout.c (HAVE_AOUT=3Dn on ARM) - fs/binfmt_elf.c (depends on MMU) - fs/binfmt_som.c (BINFMT_SOM depends on PARISC && HPUX) - fs/exec.c (#ifdef CONFIG_MMU) arch/arm/include/asm/processor.h:#define STACK_TOP ((curr= ent->personality & ADDR_LIMIT_32BIT) ? \ arch/arm/include/asm/processor.h: TASK_S= IZE : TASK_SIZE_26) Only used in fs/{,compat_}binfmt_elf.c, depends on MMU arch/arm/include/asm/elf.h:#define ELF_ET_DYN_BASE (2 * TA= SK_SIZE / 3) fs/binfmt_aout.c (HAVE_AOUT=3Dn on ARM) fs/binfmt_aout.c:#define BAD_ADDR(x) ((unsigned long)(x) >=3D= TASK_SIZE) fs/binfmt_elf.c (depends on MMU) fs/binfmt_elf.c:#define BAD_ADDR(x) ((unsigned long)(x) >=3D TA= SK_SIZE) fs/binfmt_elf.c: eppnt->p_memsz > TA= SK_SIZE || fs/binfmt_elf.c: TASK_SIZE - eppnt->= p_memsz < k) { fs/binfmt_elf.c: elf_ppnt->p_memsz > TASK_SI= ZE || fs/binfmt_elf.c: TASK_SIZE - elf_ppnt->p_mem= sz < k) { HUGETLBFS depends on !ARM || ARM_LPAE || BROKEN, LPAE depends on MMU fs/hugetlbfs/inode.c: if (len > TASK_SIZE) fs/hugetlbfs/inode.c: if (TASK_SIZE - len >=3D addr &= & fs/hugetlbfs/inode.c: info.high_limit =3D TASK_SIZE; USER_DS is defined in arch/arm/include/asm/uaccess.h: include/asm-generic/uaccess.h:#ifndef USER_DS include/asm-generic/uaccess.h:#define USER_DS MAKE_MM= _SEG(TASK_SIZE - include/asm-generic/uaccess.h:#endif Only used in fs/proc/task_mmu.c, depends on CONFIG_MMU include/linux/sched.h:#define TASK_SIZE_OF(tsk) TASK_SIZE --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= |