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    Subject[PATCH 1/2] UML - Clean up TASK_SIZE usage
    Clean up the calculation and use of the usable address space size on
    the host.

    task_size is gone, replaced with TASK_SIZE, which is calculated from
    CONFIG_TOP_ADDR. get_kmem_end and set_task_sizes_skas are also gone.

    host_task_size, which refers to the entire address space usable by the
    UML kernel and which may be larger than the address space usable by a
    UML process, since that has to end on a pgdir boundary, is replaced by
    CONFIG_TOP_ADDR.

    STACK_TOP is now TASK_SIZE minus the two stub pages.

    Signed-off-by: Jeff Dike <jdike@linux.intel.com>
    ---
    arch/um/include/as-layout.h | 15 +++++++++++++--
    arch/um/include/common-offsets.h | 3 +++
    arch/um/include/mem_user.h | 4 ----
    arch/um/kernel/exec.c | 2 +-
    arch/um/kernel/ksyms.c | 3 ---
    arch/um/kernel/physmem.c | 10 ----------
    arch/um/kernel/tlb.c | 2 +-
    arch/um/kernel/um_arch.c | 22 ++--------------------
    include/asm-um/fixmap.h | 3 +--
    include/asm-um/processor-generic.h | 7 +++----
    10 files changed, 24 insertions(+), 47 deletions(-)

    Index: linux-2.6.22/arch/um/include/as-layout.h
    ===================================================================
    --- linux-2.6.22.orig/arch/um/include/as-layout.h 2007-11-21 11:49:33.000000000 -0500
    +++ linux-2.6.22/arch/um/include/as-layout.h 2007-11-21 11:53:02.000000000 -0500
    @@ -29,9 +29,20 @@
    #define _AC(X, Y) __AC(X, Y)
    #endif

    +/*
    + * The "- 1"'s are to avoid gcc complaining about integer overflows
    + * and unrepresentable decimal constants. With 3-level page tables,
    + * TASK_SIZE is 0x80000000, which gets turned into its signed decimal
    + * equivalent in asm-offsets.s. gcc then complains about that being
    + * unsigned only in C90. To avoid that, UM_TASK_SIZE is defined as
    + * TASK_SIZE - 1. To compensate, we need to add the 1 back here.
    + * However, adding it back to UM_TASK_SIZE produces more gcc
    + * complaints. So, I adjust the thing being subtracted from
    + * UM_TASK_SIZE instead. Bah.
    + */
    #define STUB_CODE _AC((unsigned long), \
    - UML_CONFIG_TOP_ADDR - 2 * UM_KERN_PAGE_SIZE)
    -#define STUB_DATA _AC((unsigned long), UML_CONFIG_TOP_ADDR - UM_KERN_PAGE_SIZE)
    + UM_TASK_SIZE - (2 * UM_KERN_PAGE_SIZE - 1))
    +#define STUB_DATA _AC((unsigned long), UM_TASK_SIZE - (UM_KERN_PAGE_SIZE - 1))
    #define STUB_START _AC(, STUB_CODE)

    #ifndef __ASSEMBLY__
    Index: linux-2.6.22/arch/um/include/common-offsets.h
    ===================================================================
    --- linux-2.6.22.orig/arch/um/include/common-offsets.h 2007-11-21 11:49:33.000000000 -0500
    +++ linux-2.6.22/arch/um/include/common-offsets.h 2007-11-21 11:53:02.000000000 -0500
    @@ -39,3 +39,6 @@ DEFINE(UM_HZ, HZ);
    DEFINE(UM_USEC_PER_SEC, USEC_PER_SEC);
    DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
    DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
    +
    +/* See as-layout.h for an explanation of the "- 1". Bah. */
    +DEFINE(UM_TASK_SIZE, TASK_SIZE - 1);
    Index: linux-2.6.22/arch/um/include/mem_user.h
    ===================================================================
    --- linux-2.6.22.orig/arch/um/include/mem_user.h 2007-11-21 11:43:52.000000000 -0500
    +++ linux-2.6.22/arch/um/include/mem_user.h 2007-11-21 11:53:02.000000000 -0500
    @@ -46,9 +46,6 @@ extern int iomem_size;

    #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))

    -extern unsigned long host_task_size;
    -extern unsigned long task_size;
    -
    extern int init_mem_user(void);
    extern void setup_memory(void *entry);
    extern unsigned long find_iomem(char *driver, unsigned long *len_out);
    @@ -62,6 +59,5 @@ extern unsigned long phys_offset(unsigne
    extern void unmap_physmem(void);
    extern void map_memory(unsigned long virt, unsigned long phys,
    unsigned long len, int r, int w, int x);
    -extern unsigned long get_kmem_end(void);

    #endif
    Index: linux-2.6.22/arch/um/kernel/exec.c
    ===================================================================
    --- linux-2.6.22.orig/arch/um/kernel/exec.c 2007-11-21 11:43:52.000000000 -0500
    +++ linux-2.6.22/arch/um/kernel/exec.c 2007-11-21 11:53:02.000000000 -0500
    @@ -19,7 +19,7 @@
    void flush_thread(void)
    {
    void *data = NULL;
    - unsigned long end = proc_mm ? task_size : STUB_START;
    + unsigned long end = proc_mm ? TASK_SIZE : STUB_START;
    int ret;

    arch_flush_thread(&current->thread.arch);
    Index: linux-2.6.22/arch/um/kernel/ksyms.c
    ===================================================================
    --- linux-2.6.22.orig/arch/um/kernel/ksyms.c 2007-11-21 11:49:33.000000000 -0500
    +++ linux-2.6.22/arch/um/kernel/ksyms.c 2007-11-21 11:53:02.000000000 -0500
    @@ -18,11 +18,8 @@ EXPORT_SYMBOL(set_signals);
    EXPORT_SYMBOL(get_signals);
    EXPORT_SYMBOL(kernel_thread);
    EXPORT_SYMBOL(sys_waitpid);
    -EXPORT_SYMBOL(task_size);
    EXPORT_SYMBOL(flush_tlb_range);
    -EXPORT_SYMBOL(host_task_size);
    EXPORT_SYMBOL(arch_validate);
    -EXPORT_SYMBOL(get_kmem_end);

    EXPORT_SYMBOL(high_physmem);
    EXPORT_SYMBOL(empty_zero_page);
    Index: linux-2.6.22/arch/um/kernel/physmem.c
    ===================================================================
    --- linux-2.6.22.orig/arch/um/kernel/physmem.c 2007-11-21 11:43:52.000000000 -0500
    +++ linux-2.6.22/arch/um/kernel/physmem.c 2007-11-21 11:53:02.000000000 -0500
    @@ -55,16 +55,6 @@ int __init init_maps(unsigned long physm
    return 0;
    }

    -/* Changed during early boot */
    -static unsigned long kmem_top = 0;
    -
    -unsigned long get_kmem_end(void)
    -{
    - if (kmem_top == 0)
    - kmem_top = host_task_size - 1024 * 1024;
    - return kmem_top;
    -}
    -
    void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
    int r, int w, int x)
    {
    Index: linux-2.6.22/arch/um/kernel/tlb.c
    ===================================================================
    --- linux-2.6.22.orig/arch/um/kernel/tlb.c 2007-11-21 11:49:33.000000000 -0500
    +++ linux-2.6.22/arch/um/kernel/tlb.c 2007-11-21 11:53:02.000000000 -0500
    @@ -511,7 +511,7 @@ void flush_tlb_mm(struct mm_struct *mm)
    if (atomic_read(&mm->mm_users) == 0)
    return;

    - end = proc_mm ? task_size : STUB_START;
    + end = proc_mm ? TASK_SIZE : STUB_START;
    fix_range(mm, 0, end, 0);
    }

    Index: linux-2.6.22/arch/um/kernel/um_arch.c
    ===================================================================
    --- linux-2.6.22.orig/arch/um/kernel/um_arch.c 2007-11-21 11:51:11.000000000 -0500
    +++ linux-2.6.22/arch/um/kernel/um_arch.c 2007-11-21 11:53:02.000000000 -0500
    @@ -101,8 +101,6 @@ const struct seq_operations cpuinfo_op =
    };

    /* Set in linux_main */
    -unsigned long host_task_size;
    -unsigned long task_size;
    unsigned long uml_physmem;
    unsigned long uml_reserved; /* Also modified in mem_init */
    unsigned long start_vm;
    @@ -234,20 +232,6 @@ EXPORT_SYMBOL(end_iomem);

    extern char __binary_start;

    -static unsigned long set_task_sizes_skas(unsigned long *task_size_out)
    -{
    - /* Round up to the nearest 4M */
    - unsigned long host_task_size = ROUND_4M((unsigned long)
    - &host_task_size);
    -
    - if (!skas_needs_stub)
    - *task_size_out = host_task_size;
    - else
    - *task_size_out = STUB_START & PGDIR_MASK;
    -
    - return host_task_size;
    -}
    -
    int __init linux_main(int argc, char **argv)
    {
    unsigned long avail, diff;
    @@ -278,8 +262,6 @@ int __init linux_main(int argc, char **a

    printf("UML running in %s mode\n", mode);

    - host_task_size = set_task_sizes_skas(&task_size);
    -
    brk_start = (unsigned long) sbrk(0);

    /*
    @@ -304,7 +286,7 @@ int __init linux_main(int argc, char **a

    highmem = 0;
    iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
    - max_physmem = get_kmem_end() - uml_physmem - iomem_size - MIN_VMALLOC;
    + max_physmem = CONFIG_TOP_ADDR - uml_physmem - iomem_size - MIN_VMALLOC;

    /*
    * Zones have to begin on a 1 << MAX_ORDER page boundary,
    @@ -336,7 +318,7 @@ int __init linux_main(int argc, char **a
    }

    virtmem_size = physmem_size;
    - avail = get_kmem_end() - start_vm;
    + avail = CONFIG_TOP_ADDR - start_vm;
    if (physmem_size > avail)
    virtmem_size = avail;
    end_vm = start_vm + virtmem_size;
    Index: linux-2.6.22/include/asm-um/fixmap.h
    ===================================================================
    --- linux-2.6.22.orig/include/asm-um/fixmap.h 2007-11-21 11:49:53.000000000 -0500
    +++ linux-2.6.22/include/asm-um/fixmap.h 2007-11-21 11:53:02.000000000 -0500
    @@ -56,9 +56,8 @@ extern void __set_fixmap (enum fixed_add
    * the start of the fixmap, and leave one page empty
    * at the top of mem..
    */
    -extern unsigned long get_kmem_end(void);

    -#define FIXADDR_TOP (get_kmem_end() - 0x2000)
    +#define FIXADDR_TOP (CONFIG_TOP_ADDR - 2 * PAGE_SIZE)
    #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
    #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)

    Index: linux-2.6.22/include/asm-um/processor-generic.h
    ===================================================================
    --- linux-2.6.22.orig/include/asm-um/processor-generic.h 2007-11-21 11:49:53.000000000 -0500
    +++ linux-2.6.22/include/asm-um/processor-generic.h 2007-11-21 11:53:45.000000000 -0500
    @@ -94,9 +94,7 @@ static inline void mm_copy_segments(stru
    /*
    * User space process size: 3GB (default).
    */
    -extern unsigned long task_size;
    -
    -#define TASK_SIZE (task_size)
    +#define TASK_SIZE (CONFIG_TOP_ADDR & PGDIR_MASK)

    /* This decides where the kernel will search for a free chunk of vm
    * space during mmap's.
    Index: linux-2.6.22/include/asm-um/a.out.h
    ===================================================================
    --- linux-2.6.22.orig/include/asm-um/a.out.h 2007-11-21 11:44:49.000000000 -0500
    +++ linux-2.6.22/include/asm-um/a.out.h 2007-11-21 11:54:30.000000000 -0500
    @@ -13,11 +13,9 @@

    extern unsigned long stacksizelim;

    -extern unsigned long host_task_size;
    -
    #define STACK_ROOM (stacksizelim)

    -#define STACK_TOP task_size
    +#define STACK_TOP (TASK_SIZE - 2 * PAGE_SIZE)

    #define STACK_TOP_MAX STACK_TOP

    -
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