kernel.git/arch/um/kernel/skas, branch linux-2.6.28.y

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: redo the calculation of NR_syscalls

2008-02-05T17:44:32Z

Redo the calculation of NR_syscalls since that disappeared from i386 and use a similar mechanism on x86_64. We now figure out the size of the system call table in arch code and stick that in syscall_table_size. arch/um/kernel/skas/syscall.c defines NR_syscalls in terms of that since its the only thing that needs to know how many system calls there are. The old mechananism that was used on x86_64 is gone. arch/um/include/sysdep-i386/syscalls.h got some formatting since I was looking at it. Signed-off-by: Jeff Dike Cc: WANG Cong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: get rid of syscall counters

2008-02-05T17:44:30Z

Get rid of some syscall counters which haven't been useful in ages. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: don't kill pid 0

2008-02-05T17:44:30Z

A bit of defensive programming - during development, it ocassionally happens that a call to init_new_context is missed, resulting in context holding a host pid of zero. When that address space is torn down, destroy_context does a kill(0), which instantly kills the whole UML without any errors whatsoever. This patch add a check for pids less than 2, to also catch 1 and negative pids. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: eliminate setjmp_wrapper

2008-02-05T17:44:29Z

setjmp_wrapper existed to provide setjmp to kernel code when UML used libc's setjmp and longjmp. Now that UML has its own implementation, this isn't needed and kernel code can invoke setjmp directly. do_buffer_op is massively cleaned up since it is no longer a callback from setjmp_wrapper and given a va_list from which it must extract its arguments. The actual setjmp is moved from buffer_op to do_op_one_page because the copy operation is inside an atomic section (kmap_atomic to kunmap_atomic) and it shouldn't be longjmp-ed out of. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: cover stubs with a VMA

2008-02-05T17:44:29Z

Give the stubs a VMA. This allows the removal of a truly nasty kludge to make sure that mm->nr_ptes was correct in exit_mmap. The underlying problem was always that the stubs, which have ptes, and thus allocated a page table, weren't covered by a VMA. This patch fixes that by using install_special_mapping in arch_dup_mmap and activate_context to create the VMA. The stubs have to be moved, since shift_arg_pages seems to assume that the stack is the only VMA present at that point during exec, and uses vma_adjust to fiddle its VMA. However, that extends the stub VMA by the amount removed from the stack VMA. To avoid this problem, the stubs were moved to a different fixed location at the start of the address space. The init_stub_pte calls were moved from init_new_context to arch_dup_mmap because I was occasionally seeing arch_dup_mmap not being called, causing exit_mmap to die. Rather than figure out what was really happening, I decided it was cleaner to just move the calls so that there's no doubt that both the pte and VMA creation happen, no matter what. arch_exit_mmap is used to clear the stub ptes at exit time. The STUB_* constants in as-layout.h no longer depend on UM_TASK_SIZE, that that definition is removed, along with the comments complaining about gcc. Because the stubs are no longer at the top of the address space, some care is needed while flushing TLBs. update_pte_range checks for addresses in the stub range and skips them. flush_thread now issues two unmaps, one for the range before STUB_START and one for the range after STUB_END. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: kill processes instead of panicing kernel

2008-02-05T17:44:28Z

UML was panicing in the case of failures of libc calls which shouldn't happen. This is an overreaction since a failure from libc doesn't normally mean that kernel data structures are in an unknown state. Instead, the current process should just be killed if there is no way to recover. The case that prompted this was a failure of PTRACE_SETREGS restoring the same state that was read by PTRACE_GETREGS. It appears that when a process tries to load a bogus value into a segment register, it segfaults (as expected) and the value is actually loaded and is seen by PTRACE_GETREGS (not expected). This case is fixed by forcing a fatal SIGSEGV on the process so that it immediately dies. fatal_sigsegv was added for this purpose. It was declared as noreturn, so in order to pursuade gcc that it actually does not return, I added a call to os_dump_core (and declared it noreturn) so that I get a core file if somehow the process survives. All other calls in arch/um/os-Linux/skas/process.c got the same treatment, with failures causing the process to die instead of a kernel panic, with some exceptions. userspace_tramp exits with status 1 if anything goes wrong there. That will cause start_userspace to return an error. copy_context_skas0 and map_stub_pages also now return errors instead of panicing. Callers of thes functions were changed to check for errors and do something appropriate. Usually that's to return an error to their callers. check_skas3_ptrace_faultinfo just exits since that's too early to do anything else. save_registers, restore_registers, and init_registers now return status instead of panicing on failure, with their callers doing something appropriate. There were also duplicate declarations of save_registers and restore_registers in os.h - these are gone. I noticed and fixed up some whitespace damage. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: add virt_to_pte

2008-02-05T17:44:28Z

Turn um_virt_to_phys into virt_to_pte, cleaning up a horrid interface. It's also made non-static and declared in pgtable.h because it'll be needed when the stubs get a vma. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: header untangling

2008-02-05T17:44:28Z

Untangle UML headers somewhat and add some includes where they were needed explicitly, but gotten accidentally via some other header. arch/um/include/um_uaccess.h loses asm/fixmap.h because it uses no fixmap stuff and gains elf.h, because it needs FIXADDR_USER_*, and archsetjmp.h, because it needs jmp_buf. pmd_alloc_one is uninlined because it needs mm_struct, and that's inconvenient to provide in asm-um/pgtable-3level.h. elf_core_copy_fpregs is also uninlined from elf-i386.h and elf-x86_64.h, which duplicated the code anyway, to arch/um/kernel/process.c, so that the reference to current_thread doesn't pull sched.h or anything related into asm/elf.h. arch/um/sys-i386/ldt.c, arch/um/kernel/tlb.c and arch/um/kernel/skas/uaccess.c got sched.h because they dereference task_structs. Its includes of linux and asm headers got turned from "" to <>. arch/um/sys-i386/bug.c gets asm/errno.h because it needs errno constants. asm/elf-i386 gets asm/user.h because it needs user_regs_struct. asm/fixmap.h gets page.h because it needs PAGE_SIZE and PAGE_MASK and system.h for BUG_ON. asm/pgtable doesn't need sched.h. asm/processor-generic.h defined mm_segment_t, but didn't use it. So, that definition is moved to uaccess.h, which defines a bunch of mm_segment_t-related stuff. thread_info.h uses mm_segment_t, and includes uaccess.h, which causes a recursion. So, the definition is placed above the include of thread_info. in uaccess.h. thread_info.h also gets page.h because it needs PAGE_SIZE. ObCheckpatchViolationJustification - I'm not adding a typedef; I'm moving mm_segment_t from one place to another. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uml: move um_virt_to_phys

2008-02-05T17:44:28Z

This patchset makes UML build and run with three-level page tables on 32-bit hosts. This is an uncommon use case, but the code here needed fixing and cleaning up, so 32-bit three-level pages tables were tested to make sure the changes are good. Patch 1 - code movement Patch 2 - header untangling Patch 3 - style fixups in files affected so far Patch 4 - clean up use of current.h Patch 5 - fix sizes of types that are different between 2 and 3-level page tables - three-level page table support should build at this point Patch 6 - tidy (i.e. eliminate much of) the code that figures out how big the address space is Patch 7 - change um_virt_to_phys into virt_to_pte, clean its interface, and clean its (so far) one caller Patch 8 - the stub pages are covered with a VMA, allowing some nasty code to be thrown out - three-level page tables now work This patch: um_virt_to_phys only has one user, so it can be moved to the same file and made static. Its declarations in pgtable.h and ksyms.c are also gone. current_cmd was another apparent user, but it itself isn't used, so it is deleted. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds