kernel.git/arch/um/kernel, branch linux-2.6.25.y

uml: deal with inaccessible address space start

2008-08-20T18:15:37Z

commit 40fb16a360d9c6459afee91dc793c1e3374feb94 upstream This patch makes os_get_task_size locate the bottom of the address space, as well as the top. This is for systems which put a lower limit on mmap addresses. It works by manually scanning pages from zero onwards until a valid page is found. Because the bottom of the address space may not be zero, it's not sufficient to assume the top of the address space is the size of the address space. The size is the difference between the top address and bottom address. [jdike@addtoit.com: changed the name to reflect that this function is supposed to return the top of the process address space, not its size and changed the return value to reflect that. Also some minor formatting changes] Signed-off-by: Tom Spink Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

uml: physical memory shouldn't include initial stack

2008-08-20T18:15:33Z

commit 60a2988aea701a6424809a5432bf068667aac177 upstream The top of physical memory should be below the initial process stack, not the top of the address space, at least for as long as the stack isn't known to the kernel VM system and appropriately reserved. Cc: "Christopher S. Aker" Signed-off-by: Jeff Dike Cc: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

uml: fix bad NTP interaction with clock

2008-08-20T18:15:32Z

commit cfd28f6695d0fc047478480791a21bdd4967f98e upstream UML's supposed nanosecond clock interacts badly with NTP when NTP decides that the clock has drifted ahead and needs to be slowed down. Slowing down the clock is done by decrementing the cycle-to-nanosecond multiplier, which is 1. Decrementing that gives you 0 and time is stopped. This is fixed by switching to a microsecond clock, with a multiplier of 1000. Signed-off-by: Jeff Dike Cc: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

uml: fix build when SLOB is enabled

2008-08-20T18:15:32Z

commit 43f5b3085fdd27c4edf535d938b2cb0ccead4f75 upstream Reintroduce uml_kmalloc for the benefit of UML libc code. The previous tactic of declaring __kmalloc so it could be called directly from the libc side of the house turned out to be getting too intimate with slab, and it doesn't work with slob. So, the uml_kmalloc wrapper is back. It calls kmalloc or whatever that translates into, and libc code calls it. kfree is left alone since that still works, leaving a somewhat inconsistent API. Signed-off-by: Jeff Dike Cc: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sched: add declaration of sched_tail to sched.h

2008-02-25T15:34:17Z

Avoids sparse warnings: kernel/sched.c:2170:17: warning: symbol 'schedule_tail' was not declared. Should it be static? Avoids the need for an external declaration in arch/um/process.c Signed-off-by: Harvey Harrison Signed-off-by: Ingo Molnar

arch/um/kernel/mem.c: fix a shadowed variable

2008-02-24T01:12:13Z

Fix a shadowed variable in arch/um/kernel/mem.c, since there is a global variable has the same name. Cc: Jeff Dike Signed-off-by: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: fix initrd printk

2008-02-24T01:12:13Z

If the initrd file has zero-length, the error message should contain the filepath. Cc: WANG Cong Signed-off-by: Johann Felix Soden Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: fix mm_context memory leak

2008-02-08T17:22:43Z

[ Spotted by Miklos ] Fix a memory leak in init_new_context. The struct page ** buffer allocated for install_special_mapping was never recorded, and thus leaked when the mm_struct was freed. Fix it by saving the pointer in mm_context_t and freeing it in arch_exit_mmap. Signed-off-by: Jeff Dike Cc: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: runtime host VMSPLIT detection

2008-02-08T17:22:42Z

Calculate TASK_SIZE at run-time by figuring out the host's VMSPLIT - this is needed on i386 if UML is to run on hosts with varying VMSPLITs without recompilation. TASK_SIZE is now defined in terms of a variable, task_size. This gets rid of an include of pgtable.h from processor.h, which can cause include loops. On i386, task_size is calculated early in boot by probing the address space in a binary search to figure out where the boundary between usable and non-usable memory is. This tries to make sure that a page that is considered to be in userspace is, or can be made, read-write. I'm concerned about a system-global VDSO page in kernel memory being hit and considered to be a userspace page. On x86_64, task_size is just the old value of CONFIG_TOP_ADDR. A bunch of config variable are gone now. CONFIG_TOP_ADDR is directly replaced by TASK_SIZE. NEST_LEVEL is gone since the relocation of the stubs makes it irrelevant. All the HOST_VMSPLIT stuff is gone. All references to these in arch/um/Makefile are also gone. I noticed and fixed a missing extern in os.h when adding os_get_task_size. Note: This has been revised to fix the 32-bit UML on 64-bit host bug that Miklos ran into. Signed-off-by: Jeff Dike Cc: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

CONFIG_HIGHPTE vs. sub-page page tables.

2008-02-08T17:22:42Z

Background: I've implemented 1K/2K page tables for s390. These sub-page page tables are required to properly support the s390 virtualization instruction with KVM. The SIE instruction requires that the page tables have 256 page table entries (pte) followed by 256 page status table entries (pgste). The pgstes are only required if the process is using the SIE instruction. The pgstes are updated by the hardware and by the hypervisor for a number of reasons, one of them is dirty and reference bit tracking. To avoid wasting memory the standard pte table allocation should return 1K/2K (31/64 bit) and 2K/4K if the process is using SIE. Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means the s390 version for pte_alloc_one cannot return a pointer to a struct page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one cannot return a pointer to a pte either, since that would require more than 32 bit for the return value of pte_alloc_one (and the pte * would not be accessible since its not kmapped). Solution: The only solution I found to this dilemma is a new typedef: a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a later patch. For everybody else it will be a (struct page *). The additional problem with the initialization of the ptl lock and the NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and a destructor pgtable_page_dtor. The page table allocation and free functions need to call these two whenever a page table page is allocated or freed. pmd_populate will get a pgtable_t instead of a struct page pointer. To get the pgtable_t back from a pmd entry that has been installed with pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page call in free_pte_range and apply_to_pte_range. Signed-off-by: Martin Schwidefsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds