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* x86, um: take arch/um/include/* out of the wayAl Viro2008-10-23
| | | | | | | | | We can't just plop asm/* into it - userland helpers are built with it in search path and seeing asm/* show up there suddenly would be a bad idea. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* uml: tidy ptrace interfaceJeff Dike2008-05-13
| | | | | | | | | | Tidy the ptrace interface code. Removed a bunch of unused macros. Started converting register sets from arrays of longs to structures. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: style fixesJeff Dike2008-05-13
| | | | | | | | | A few random style fixes. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: fix FP register corruptionJeff Dike2008-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit ee3d9bd4de1ed93d2a7ee41c331ed30a1c7b8acd ("uml: simplify SIGSEGV handling"), while greatly simplifying the kernel SIGSEGV handler that runs in the process address space, introduced a bug which corrupts FP state in the process. Previously, the SIGSEGV handler called the sigreturn system call by hand - it couldn't return through the restorer provided to it because that could try to call the libc restorer which likely wouldn't exist in the process address space. So, it blocked off some signals, including SIGUSR1, on entry to the SIGSEGV handler, queued a SIGUSR1 to itself, and invoked sigreturn. The SIGUSR1 was delivered, and was visible to the UML kernel after sigreturn finished. The commit eliminated the signal masking and the call to sigreturn. The handler simply hits itself with a SIGTRAP to let the UML kernel know that it is finished. UML then restores the process registers, which effectively longjmps the process out of the signal handler, skipping sigreturn's restoring of register state and the signal mask. The bug is that the host apparently sets used_fp to 0 when it saves the process FP state in the sigcontext on the process signal stack. Thus, when the process is longjmped out of the handler, its FP state is corrupt because it wasn't saved on the context switch to the UML kernel. This manifested itself as sleep hanging. For some reason, sleep uses floating point in order to calculate the sleep interval. When a page fault corrupts its FP state, it is faked into essentially sleeping forever. This patch saves the FP state before entering the SIGSEGV handler and restores it afterwards. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: redo the calculation of NR_syscallsJeff Dike2008-02-05
| | | | | | | | | | | | | | | | | | | | 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 <jdike@linux.intel.com> Cc: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: fix stub address calculationsJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The calculation of CONFIG_STUB_CODE and CONFIG_STUB_DATA didn't take into account anything but 3G/1G and 2G/2G, leaving the other vmsplits out in the cold. I'd rather not duplicate the four known host vmsplit cases for each of these symbols. I'd also like to calculate them based on the highest userspace address. The Kconfig language seems not to allow calculation of hex constants, so I moved this to as-layout.h. CONFIG_STUB_CODE, CONFIG_STUB_DATA, and CONFIG_STUB_START are now gone. In their place are STUB_CODE, STUB_DATA, and STUB_START in as-layout.h. i386 and x86_64 seem to differ as to whether an unadorned constant is an int or a long, so I cast them to unsigned long so they can be printed consistently. However, they are also used in stub.S, where C types don't work so well. So, there are ASM_ versions of these constants for use in stub.S. I also ifdef-ed the non-asm-friendly portion of as-layout.h. With this in place, most of the rest of this patch is changing CONFIG_STUB_* to STUB_*, except in stub.S, where they are changed to ASM_STUB_*. defconfig has the old symbols deleted. I also print these addresses out in case there is any problem mapping them on the host. The two stub.S files had some trailing whitespace, so that is cleaned up here. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: eliminate floating point state from register fileJeff Dike2007-10-16
| | | | | | | | | The floating point fields in the pt_regs register file aren't used, so they are deleted. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: style fixes in FP codeJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | Tidy the code affected by the floating point fixes. A bunch of unused stuff is gone, including two sigcontext.c files, which turned out to be entirely unneeded. There are the usual fixes - whitespace and style cleanups copyright updates emacs formatting comments gone include cleanups adding severities to printks Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: floating point signal delivery fixesJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | Handle floating point state in across signals correctly. UML/i386 needs to know whether the host does PTRACE_[GS]ETFPXREGS, so an arch_init_registers hook is added, which on x86_64 does nothing. UML doesn't save and restore floating point registers on kernel entry and exit, so they need to be copied between the host process and the sigcontext. save_fpx_registers and restore_fpx_registers are added for this purpose. save_fp_registers and restore_fp_registers already exist. There was a bunch of floating point state conversion code in arch/um/sys-i386/ptrace.c which isn't needed there, but is needed in signal.c, so it is moved over. The i386 code now distinguishes between fp and fpx state and handles them correctly. The x86_64 code just needs to copy state as-is between the host process and the stack. There are also some fixes there to pass the correct address of the floating point state around. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: remove os_* usage from userspace filesJeff Dike2007-10-16
| | | | | | | | | | | | | | This patch fixes some userspace files which were calling libc through the os_* wrappers. It turns out that there was only one user of os_new_tty_pgrp, so it can be deleted. There are also some style and whitespace fixes in here. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: rename pt_regs general-purpose register fileJeff Dike2007-10-16
| | | | | | | | | | | | Before the removal of tt mode, access to a register on the skas-mode side of a pt_regs struct looked like pt_regs.regs.skas.regs.regs[FOO]. This was bad enough, but it became pt_regs.regs.regs.regs[FOO] with the removal of the union from the middle. To get rid of the run of three "regs", the last field is renamed to "gp". Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: style fixes pass 3Jeff Dike2007-10-16
| | | | | | | | | | | | | | | Formatting changes in the files which have been changed in the course of folding foo_skas functions into their callers. These include: copyright updates header file trimming style fixes adding severity to printks These changes should be entirely non-functional. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: remove code made redundant by CHOOSE_MODE removalJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | | | | | This patch makes a number of simplifications enabled by the removal of CHOOSE_MODE. There were lots of functions that looked like int foo(args){ foo_skas(args); } The bodies of foo_skas are now folded into foo, and their declarations (and sometimes entire header files) are deleted. In addition, the union uml_pt_regs, which was a union between the tt and skas register formats, is now a struct, with the tt-mode arm of the union being removed. It turns out that usr2_handler was unused, so it is gone. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: throw out CHOOSE_MODEJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | The next stage after removing code which depends on CONFIG_MODE_TT is removing the CHOOSE_MODE abstraction, which provided both compile-time and run-time branching to either tt-mode or skas-mode code. This patch removes choose-mode.h and all inclusions of it, and replaces all CHOOSE_MODE invocations with the skas branch. This leaves a number of trivial functions which will be dealt with in a later patch. There are some changes in the uaccess and tls support which go somewhat beyond this and eliminate some of the now-redundant functions. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: style fixes pass 1Jeff Dike2007-10-16
| | | | | | | | | | | | | | | | Formatting changes in the files which have been changed in the tt-removal patchset so far. These include: copyright updates header file trimming style fixes adding severity to printks indenting Kconfig help according to the predominant kernel style These changes should be entirely non-functional. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: remove sysdep/thread.hJeff Dike2007-10-16
| | | | | | | | This patch removes thread.h, which turns out not to be needed any more. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: throw out CONFIG_MODE_TTJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patchset throws out tt mode, which has been non-functional for a while. This is done in phases, interspersed with code cleanups on the affected files. The removal is done as follows: remove all code, config options, and files which depend on CONFIG_MODE_TT get rid of the CHOOSE_MODE macro, which decided whether to call tt-mode or skas-mode code, and replace invocations with their skas portions replace all now-trivial procedures with their skas equivalents There are now a bunch of now-redundant pieces of data structures, including mode-specific pieces of the thread structure, pt_regs, and mm_context. These are all replaced with their skas-specific contents. As part of the ongoing style compliance project, I made a style pass over all files that were changed. There are three such patches, one for each phase, covering the files affected by that phase but no later ones. I noticed that we weren't freeing the LDT state associated with a process when it exited, so that's fixed in one of the later patches. The last patch is a tidying patch which I've had for a while, but which caused inexplicable crashes under tt mode. Since that is no longer a problem, this can now go in. This patch: Start getting rid of tt mode support. This patch throws out CONFIG_MODE_TT and all config options, code, and files which depend on it. CONFIG_MODE_SKAS is gone and everything that depends on it is included unconditionally. The few changed lines are in re-written Kconfig help, lines which needed something skas-related removed from them, and a few more which weren't strictly deletions. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: stop saving process FP stateJeff Dike2007-10-16
| | | | | | | | | | | | | | | | | | | | | | | | | Throw out a lot of code dealing with saving and restoring floating-point state. In skas mode, where processes run in a restoring floating-point state on kernel entry and exit is pointless. This eliminates most of arch/um/os-Linux/sys-{i386,x86_64}/registers.c. Most of what remained is now arch-indpendent, and can be moved up to arch/um/os-Linux/registers.c. Both arches need the jmp_buf accessor get_thread_reg, and i386 needs {save,restore}_fp_regs because it cheats during sigreturn by getting the fp state using ptrace rather than copying it out of the process sigcontext. After this, it turns out that arch/um/include/skas/mode-skas.h is almost completely unneeded. The declarations in it are variables which either don't exist or which don't have global scope. The one exception is kill_off_processes_skas. If that's removed, this header can be deleted. This uncovered a bug in user.h, which wasn't correctly making sure that a size_t definition was available to both userspace and kernelspace files. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* uml: stop using libc asm/page.hJeff Dike2007-10-16
| | | | | | | | | | | | Remove includes of asm/page.h from libc code. This header seems to be disappearing, and UML doesn't make much use of it anyway. The one use, PAGE_SHIFT in stub.h, is handled by copying the constant from the kernel side of the house in common_offsets.h. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix file specification in commentsUwe Kleine-König2007-05-09
| | | | | | | Many files include the filename at the beginning, serveral used a wrong one. Signed-off-by: Uwe Kleine-König <ukleinek@informatik.uni-freiburg.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] uml: size register files correctlyJeff Dike2006-12-07
| | | | | | | | | We were using the wrong symbol to size register files. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: include asm/page.h in order to get PAGE_SHIFTJeff Dike2006-12-07
| | | | | | | | | Include the proper header to get a definition of PAGE_SHIFT. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [NET]: UML checksum annotations and cleanups.Al Viro2006-12-03
| | | | | | | | | | * sanitize prototypes, annotate * kill csum_partial_copy_fromuser * kill shift-by-16 in checksum calculations * ntohs->shift in checksum calculations Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
* [PATCH] uml: fix I/O hangJeff Dike2006-11-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix a UML hang in which everything would just stop until some I/O happened - a ping, someone whacking the keyboard - at which point everything would start up again as though nothing had happened. The cause was gcc reordering some code which absolutely needed to be executed in the order in the source. When unblock_signals switches signals from off to on, it needs to see if any interrupts had happened in the critical section. The interrupt handlers check signals_enabled - if it is zero, then the handler adds a bit to the "pending" bitmask and returns. unblock_signals checks this mask to see if any signals need to be delivered. The crucial part is this: signals_enabled = 1; save_pending = pending; if(save_pending == 0) return; pending = 0; In order to avoid an interrupt arriving between reading pending and setting it to zero, in which case, the record of the interrupt would be erased, signals are enabled. What happened was that gcc reordered this so that 'save_pending = pending' came before 'signals_enabled = 1', creating a one-instruction window within which an interrupt could arrive, set its bit in pending, and have it be immediately erased. When the I/O workload is purely disk-based, the loss of a block device interrupt stops the entire I/O system because the next block request will wait for the current one to finish. Thus the system hangs until something else causes some I/O to arrive, such as a network packet or console input. The fix to this particular problem is a memory barrier between enabling signals and reading the pending signal mask. An xchg would also probably work. Looking over this code for similar problems led me to do a few more things: - make signals_enabled and pending volatile so that they don't get cached in registers - add an mb() to the return paths of block_signals and unblock_signals so that the modification of signals_enabled doesn't get shuffled into the caller in the event that these are inlined in the future. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: asm offsets duplication removalPaolo 'Blaisorblade' Giarrusso2006-10-11
| | | | | | | | | Unify macros common to x86 and x86_64 kernel-offsets.h files. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: allow using again x86/x86_64 crypto codePaolo 'Blaisorblade' Giarrusso2006-10-11
| | | | | | | | | | | | Enable compilation of x86_64 crypto code;, and add the needed constant to make the code compile again (that macro was added to i386 asm-offsets between 2.6.17 and 2.6.18, in 6c2bb98bc33ae33c7a33a133a4cd5a06395fece5). Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: thread creation tidyingJeff Dike2006-09-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fork on UML has always somewhat subtle. The underlying cause has been the need to initialize a stack for the new process. The only portable way to initialize a new stack is to set it as the alternate signal stack and take a signal. The signal handler does whatever initialization is needed and jumps back to the original stack, where the fork processing is finished. The basic context switching mechanism is a jmp_buf for each process. You switch to a new process by longjmping to its jmp_buf. Now that UML has its own implementation of setjmp and longjmp, and I can poke around inside a jmp_buf without fear that libc will change the structure, a much simpler mechanism is possible. The jmpbuf can simply be initialized by hand. This eliminates - the need to set up and remove the alternate signal stack sending and handling a signal the signal blocking needed around the stack switching, since there is no stack switching setting up the jmp_buf needed to jump back to the original stack after the new one is set up In addition, since jmp_buf is now defined by UML, and not by libc, it can be embedded in the thread struct. This makes it unnecessary to have it exist on the stack, where it used to be. It also simplifies interfaces, since the switch jmp_buf used to be a void * inside the thread struct, and functions which took it as an argument needed to define a jmp_buf variable and assign it from the void *. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Move signal handlers to arch codeJeff Dike2006-09-26
| | | | | | | | | | | | | | | | | Have most signals go through an arch-provided handler which recovers the sigcontext and then calls a generic handler. This replaces the ARCH_GET_SIGCONTEXT macro, which was somewhat fragile. On x86_64, recovering %rdx (which holds the sigcontext pointer) must be the first thing that happens. sig_handler duly invokes that first, but there is no guarantee that I can see that instructions won't be reordered such that %rdx is used before that. Having the arch provide the handler seems much more robust. Some signals in some parts of UML require their own handlers - these places don't call set_handler any more. They call sigaction or signal themselves. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Use klibc setjmp/longjmpJeff Dike2006-09-26
| | | | | | | | | | | | | | | | | | | This patch adds an implementation of setjmp and longjmp to UML, allowing access to the inside of a jmpbuf without needing the access macros formerly provided by libc. The implementation is stolen from klibc. I copy the relevant files into arch/um. I have another patch which avoids the copying, but requires klibc be in the tree. setjmp and longjmp users required some tweaking. Includes of <setjmp.h> were removed and includes of the UML longjmp.h were added where necessary. There are also replacements of siglongjmp with UML_LONGJMP which I somehow missed earlier. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: MADV_REMOVE fixesJeff Dike2006-04-19
| | | | | | | | | | | | | MADV_REMOVE fixes - change the test mapping to be MAP_SHARED instead of MAP_PRIVATE, as MADV_REMOVE on MAP_PRIVATE maps won't work. Also, use the kernel's definition of MADV_REMOVE instead of hardcoding it if there isn't a libc definition. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: check for differences in host supportPaolo 'Blaisorblade' Giarrusso2006-03-31
| | | | | | | | | | | | | | | | | | If running on a host not supporting TLS (for instance 2.4) we should report that cleanly to the user, instead of printing not comprehensible "error 5" for that. Additionally, i386 and x86_64 support different ranges for user_desc->entry_number, and we must account for that; we couldn't pass ourselves -1 because we need to override previously existing TLS descriptors which glibc has possibly set, so test at startup the range to use. x86 and x86_64 existing ranges are hardcoded. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: tls support: hack to make it compile on any hostPaolo 'Blaisorblade' Giarrusso2006-03-31
| | | | | | | | | | | Copy the definition of struct user_desc (with another name) for use by userspace sources (where we use the host headers, and we can't be sure about their content) to make sure UML compiles. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: clean arch_switch usagePaolo 'Blaisorblade' Giarrusso2006-03-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Call arch_switch also in switch_to_skas, even if it's, for now, a no-op for that case (and mark this in the comment); this will change soon. Also, arch_switch for TT mode is actually useless when the PT proxy (a complicate debugging instrumentation for TT mode) is not enabled. In fact, it only calls update_debugregs, which checks debugregs_seq against seq (to check if the registers are up-to-date - seq here means a "version number" of the registers). If the ptrace proxy is not enabled, debugregs_seq always stays 0 and update_debugregs will be a no-op. So, optimize this out (the compiler can't do it). Also, I've been disappointed by the fact that it would make a lot of sense if, after calling a successful update_debugregs(current->thread.arch.debugregs_seq), current->thread.arch.debugregs_seq were updated with the new debugregs_seq. But this is not done. Is this a bug or a feature? For all purposes, it seems a bug (otherwise the whole mechanism does not make sense, which is also a possibility to check), which causes some performance only problems (not correctness), since we write_debugregs when not needed. Also, as suggested by Jeff, remove a redundant enabling of SIGVTALRM, comprised in the subsequent local_irq_enable(). I'm just a bit dubious if ordering matters there... Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: sparse cleanupsAl Viro2006-03-31
| | | | | | | | | | misc sparse annotations Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* return statement cleanup - kill pointless parenthesesJesper Juhl2006-01-14
| | | | | | | This patch removes pointless parentheses from return statements. Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] uml: fix missing KBUILD_BASENAMEJeff Dike2006-01-11
| | | | | | | | | | | | | | | | | | | | | | | | | | 2.6.15-mm1 caused kernel-offsets.c to stop compiling with a syntax error in a header. The problem was with KBUILD_BASENAME, which didn't get a definition with the by-hand compilation in the main UML Makefile. This was OK before since the expansion was syntactically the same as the KBUILD_BASENAME token. With -mm1, the expansion is now a quote-delimited string, so there needs to be a definition of it. Since kernel-offsets.c is basically the same as other arches' asm-offsets.c, and those seem to build OK, this patch turns kernel-offsets.c into asm-offsets.c. kernel-offsets.c is in arch/um/sys-$(SUBARCH), i.e. sys-i386 and sys-x86_64, while kbuild expects it to be in arch/um/kernel. kernel-offsets.c is moved to arch/um/include/sysdep-$(SUBARCH)/kernel-offsets.h, which is included by arch/um/kernel/asm-offsets.c. With that, include/asm-um/asm-offsets.h is generated automatically. kernel-offsets.h continues to exist because it needs to be accessible to userspace UML code, and include/asm-um isn't. So, a symlink is made from arch/um/include/kernel-offsets.h to include/asm-um/asm-offsets.h. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml skas0: stop gcc's insanityJeff Dike2005-12-18
| | | | | | | | | | | | | | | | With Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> UML skas0 stub has been miscompiling for many people (incidentally not the authors), depending on the used GCC versions. I think (and testing on some GCC versions shows) this patch avoids the fundamental issue which is behind this, namely gcc using the stack when we have just replaced it, behind gcc's back. The remapping and storage of the return value is hidden in a blob of asm, hopefully giving gcc no room for creativity. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: properly invoke x86_64 system callsJeff Dike2005-11-22
| | | | | | | | | | | | | | This patch makes stub_segv use the stub_syscall macros. This was needed anyway, but the bug that prompted this was the discovery that gcc was storing stuff in RCX, which is trashed across a system call. This is exactly the sort of problem that the new macros fix. There is a stub_syscall0 for getpid. stub_segv was changed to be a libc file, and that caused some include changes. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix syscall stubsPaolo 'Blaisorblade' Giarrusso2005-11-07
| | | | | | | | | | | | | | | | | | | | | | Jeff Dike noted that the assembly code for syscall stubs is misassembled with GCC 3.2.3: the values copied in registers weren't preserved between one asm() and the following one. So I fixed the thing by rewriting the __asm__ constraints more like unistd.h ones. Note: in syscall6 case I had to add one more instruction (i.e. moving arg6 in eax and shuffling things around) - it's needed for the function to be valid in general (we can't load the value from the stack, relative to ebp, because we change it), but could be avoided since we actually use a constant as param 6. The only fix would be to turn stub_syscall6 to a macro and use a "i" constraint for arg6 (i.e., specify it's a constant value). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] unify sys_ptrace prototypeChristoph Hellwig2005-10-30
| | | | | | | | | | Make sure we always return, as all syscalls should. Also move the common prototype to <linux/syscalls.h> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix compile failure for TT modeMiklos Szeredi2005-10-24
| | | | | | | | | | | | | Without this patch, uml compile fails with: LD .tmp_vmlinux1 arch/um/kernel/built-in.o: In function `config_gdb_cb': arch/um/kernel/tt/gdb.c:129: undefined reference to `TASK_EXTERN_PID' Tested on i386, but fix needed on x86_64 too AFAICS. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: fix page faults in SKAS3 mode.Paolo 'Blaisorblade' Giarrusso2005-09-30
| | | | | | | | | | | | I hadn't been running a SKAS3 host when testing the "uml: fix hang in TT mode on fault" patch (commit 546fe1cbf91d4d62e3849517c31a2327c992e5c5), and I didn't think enough to the missing trap_no in SKAS3 mode. In fact, the resulting kernel doesn't work at all in SKAS3 mode. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml makefiles sanitizedAl Viro2005-09-29
| | | | | | | | | | | | | | | UML makefiles sanitized: - number of generated headers reduced to 2 (from user-offsets.c and kernel-offsets.c resp.). The rest is made constant and simply includes those two. - mk_... helpers are gone now that we don't need to generate these headers - arch/um/include2 removed since everything under arch/um/include/sysdep is constant now and symlink can point straight to source tree. - dependencies seriously simplified. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: system call path cleanupJeff Dike2005-09-05
| | | | | | | | | This merges two sets of files which had no business being split apart in the first place. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: Proper clone support for skas0Bodo Stroesser2005-07-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch implements the clone-stub mechanism, which allows skas0 to run with proc_mm==0, even if the clib in UML uses modify_ldt. Note: There is a bug in skas3.v7 host patch, that avoids UML-skas from running properly on a SMP-box. In full skas3, I never really saw problems, but in skas0 they showed up. More commentary by jdike - What this patch does is makes sure that the host parent of each new host process matches the UML parent of the corresponding UML process. This ensures that any changed LDTs are inherited. This is done by having clone actually called by the UML process from its stub, rather than by the kernel. We have special syscall stubs that are loaded onto the stub code page because that code must be completely self-contained. These stubs are given C interfaces, and used like normal C functions, but there are subtleties. Principally, we have to be careful about stack variables in stub_clone_handler after the clone. The code is written so that there aren't any - everything boils down to a fixed address. If there were any locals, references to them after the clone would be wrong because the stack just changed. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: skas0 - separate kernel address space on stock hostsJeff Dike2005-07-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | UML has had two modes of operation - an insecure, slow mode (tt mode) in which the kernel is mapped into every process address space which requires no host kernel modifications, and a secure, faster mode (skas mode) in which the UML kernel is in a separate host address space, which requires a patch to the host kernel. This patch implements something very close to skas mode for hosts which don't support skas - I'm calling this skas0. It provides the security of the skas host patch, and some of the performance gains. The two main things that are provided by the skas patch, /proc/mm and PTRACE_FAULTINFO, are implemented in a way that require no host patch. For the remote address space changing stuff (mmap, munmap, and mprotect), we set aside two pages in the process above its stack, one of which contains a little bit of code which can call mmap et al. To update the address space, the system call information (system call number and arguments) are written to the stub page above the code. The %esp is set to the beginning of the data, the %eip is set the the start of the stub, and it repeatedly pops the information into its registers and makes the system call until it sees a system call number of zero. This is to amortize the cost of the context switch across multiple address space updates. When the updates are done, it SIGSTOPs itself, and the kernel process continues what it was doing. For a PTRACE_FAULTINFO replacement, we set up a SIGSEGV handler in the child, and let it handle segfaults rather than nullifying them. The handler is in the same page as the mmap stub. The second page is used as the stack. The handler reads cr2 and err from the sigcontext, sticks them at the base of the stack in a faultinfo struct, and SIGSTOPs itself. The kernel then reads the faultinfo and handles the fault. A complication on x86_64 is that this involves resetting the registers to the segfault values when the process is inside the kill system call. This breaks on x86_64 because %rcx will contain %rip because you tell SYSRET where to return to by putting the value in %rcx. So, this corrupts $rcx on return from the segfault. To work around this, I added an arch_finish_segv, which on x86 does nothing, but which on x86_64 ptraces the child back through the sigreturn. This causes %rcx to be restored by sigreturn and avoids the corruption. Ultimately, I think I will replace this with the trick of having it send itself a blocked signal which will be unblocked by the sigreturn. This will allow it to be stopped just after the sigreturn, and PTRACE_SYSCALLed without all the back-and-forth of PTRACE_SYSCALLing it through sigreturn. This runs on a stock host, so theoretically (and hopefully), tt mode isn't needed any more. We need to make sure that this is better in every way than tt mode, though. I'm concerned about the speed of address space updates and page fault handling, since they involve extra round-trips to the child. We can amortize the round-trip cost for large address space updates by writing all of the operations to the data page and having the child execute them all at the same time. This will help fork and exec, but not page faults, since they involve only one page. I can't think of any way to help page faults, except to add something like PTRACE_FAULTINFO to the host. There is PTRACE_SIGINFO, but UML doesn't use siginfo for SIGSEGV (or anything else) because there isn't enough information in the siginfo struct to handle page faults (the faulting operation type is missing). Adding that would make PTRACE_SIGINFO a usable equivalent to PTRACE_FAULTINFO. As for the code itself: - The system call stub is in arch/um/kernel/sys-$(SUBARCH)/stub.S. It is put in its own section of the binary along with stub_segv_handler in arch/um/kernel/skas/process.c. This is manipulated with run_syscall_stub in arch/um/kernel/skas/mem_user.c. syscall_stub will execute any system call at all, but it's only used for mmap, munmap, and mprotect. - The x86_64 stub calls sigreturn by hand rather than allowing the normal sigreturn to happen, because the normal sigreturn is a SA_RESTORER in UML's address space provided by libc. Needless to say, this is not available in the child's address space. Also, it does a couple of odd pops before that which restore the stack to the state it was in at the time the signal handler was called. - There is a new field in the arch mmu_context, which is now a union. This is the pid to be manipulated rather than the /proc/mm file descriptor. Code which deals with this now checks proc_mm to see whether it should use the usual skas code or the new code. - userspace_tramp is now used to create a new host process for every UML process, rather than one per UML processor. It checks proc_mm and ptrace_faultinfo to decide whether to map in the pages above its stack. - start_userspace now makes CLONE_VM conditional on proc_mm since we need separate address spaces now. - switch_mm_skas now just sets userspace_pid[0] to the new pid rather than PTRACE_SWITCH_MM. There is an addition to userspace which updates its idea of the pid being manipulated each time around the loop. This is important on exec, when the pid will change underneath userspace(). - The stub page has a pte, but it can't be mapped in using tlb_flush because it is part of tlb_flush. This is why it's required for it to be mapped in by userspace_tramp. Other random things: - The stub section in uml.lds.S is page aligned. This page is written out to the backing vm file in setup_physmem because it is mapped from there into user processes. - There's some confusion with TASK_SIZE now that there are a couple of extra pages that the process can't use. TASK_SIZE is considered by the elf code to be the usable process memory, which is reasonable, so it is decreased by two pages. This confuses the definition of USER_PGDS_IN_LAST_PML4, making it too small because of the rounding down of the uneven division. So we round it to the nearest PGDIR_SIZE rather than the lower one. - I added a missing PT_SYSCALL_ARG6_OFFSET macro. - um_mmu.h was made into a userspace-usable file. - proc_mm and ptrace_faultinfo are globals which say whether the host supports these features. - There is a bad interaction between the mm.nr_ptes check at the end of exit_mmap, stack randomization, and skas0. exit_mmap will stop freeing pages at the PGDIR_SIZE boundary after the last vma. If the stack isn't on the last page table page, the last pte page won't be freed, as it should be since the stub ptes are there, and exit_mmap will BUG because there is an unfreed page. To get around this, TASK_SIZE is set to the next lowest PGDIR_SIZE boundary and mm->nr_ptes is decremented after the calls to init_stub_pte. This ensures that we know the process stack (and all other process mappings) will be below the top page table page, and thus we know that mm->nr_ptes will be one too many, and can be decremented. Things that need fixing: - We may need better assurrences that the stub code is PIC. - The stub pte is set up in init_new_context_skas. - alloc_pgdir is probably the right place. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: build cleanupsJeff Dike2005-06-13
| | | | | | | | | Fix a build failure when CONFIG_MODE_SKAS is disabled and make a Makefile comment fit in 80 columns. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: small fixes left over from rc4Jeff Dike2005-05-20
| | | | | | | | | | | | | | | | | | Some changes that I sent in didn't make 2.6.12-rc4 for some reason. This adds them back. We have an x86_64 definition of TOP_ADDR a reimplementation of the x86_64 csum_partial_copy_from_user some syntax fixes in arch/um/kernel/ptrace.c removal of a CFLAGS definition in the x86_64 Makefile some include changes in the x86_64 ptrace.c and user-offsets.h a syntax fix in elf-x86_64.h Also moved an include in the i386 and x86_64 Makefiles to make the symlinks work, and some small fixes from Al Viro. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: s390 preparation, sighandler interface abstractionBodo Stroesser2005-05-05
| | | | | | | | | | | | | | s390 passes parameters in registers. So the only safe way to find out the address of signal context, error-address and error-type (trap_no), which are passed to signal handlers as parameters, is to declare these parameters. So I inserted an subarch-specific macro which holds the declaration of parameters for signal handlers. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] uml: s390 preparation, checksumming done in arch codeBodo Stroesser2005-05-05
| | | | | | | | | | | | | | | | | | | | Checksum handling largely depends on the subarch. Thus, I renamed i386 arch_csum_partial in arch/um/sys-i386/checksum.S back to csum_partial, removed csum_partial from arch/um/kernel/checksum.c and shifted EXPORT_SYMBOL(csum_partial) to arch/um/sys-i386/ksyms.c. Then, csum_partial_copy_to and csum_partial_copy_from were shifted from arch/um/kernel/checksum.c to arch/um/include/sysdep-i386/checksum.h and inserted in the calling functions csum_partial_copy_from_user() and csum_and_copy_to_user(). Now, arch/um/kernel/checksum.c is empty and removed. Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com> Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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