OpenCloudOS-Kernel/arch/um/kernel/skas/process.c

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/*
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <as-layout.h>
#include <kern.h>
#include <os.h>
#include <skas.h>
int new_mm(unsigned long stack)
{
uml: kill processes instead of panicing kernel 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 <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 14:30:58 +08:00
int fd, err;
fd = os_open_file("/proc/mm", of_cloexec(of_write(OPENFLAGS())), 0);
if (fd < 0)
return fd;
uml: kill processes instead of panicing kernel 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 <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 14:30:58 +08:00
if (skas_needs_stub) {
err = map_stub_pages(fd, STUB_CODE, STUB_DATA, stack);
if (err) {
os_close_file(fd);
return err;
}
}
return fd;
}
extern void start_kernel(void);
static int __init start_kernel_proc(void *unused)
{
int pid;
block_signals();
pid = os_getpid();
cpu_tasks[0].pid = pid;
cpu_tasks[0].task = current;
#ifdef CONFIG_SMP
init_cpu_online(get_cpu_mask(0));
#endif
start_kernel();
return 0;
}
extern int userspace_pid[];
uml: iRQ stacks Add a separate IRQ stack. This differs from i386 in having the entire interrupt run on a separate stack rather than starting on the normal kernel stack and switching over once some preparation has been done. The underlying mechanism, is of course, sigaltstack. Another difference is that interrupts that happen in userspace are handled on the normal kernel stack. These cause a wait wakeup instead of a signal delivery so there is no point in trying to switch stacks for these. There's no other stuff on the stack, so there is no extra stack consumption. This quirk makes it possible to have the entire interrupt run on a separate stack - process preemption (and calls to schedule()) happens on a normal kernel stack. If we enable CONFIG_PREEMPT, this will need to be rethought. The IRQ stack for CPU 0 is declared in the same way as the initial kernel stack. IRQ stacks for other CPUs will be allocated dynamically. An extra field was added to the thread_info structure. When the active thread_info is copied to the IRQ stack, the real_thread field points back to the original stack. This makes it easy to tell where to copy the thread_info struct back to when the interrupt is finished. It also serves as a marker of a nested interrupt. It is NULL for the first interrupt on the stack, and non-NULL for any nested interrupts. Care is taken to behave correctly if a second interrupt comes in when the thread_info structure is being set up or taken down. I could just disable interrupts here, but I don't feel like giving up any of the performance gained by not flipping signals on and off. If an interrupt comes in during these critical periods, the handler can't run because it has no idea what shape the stack is in. So, it sets a bit for its signal in a global mask and returns. The outer handler will deal with this signal itself. Atomicity is had with xchg. A nested interrupt that needs to bail out will xchg its signal mask into pending_mask and repeat in case yet another interrupt hit at the same time, until the mask stabilizes. The outermost interrupt will set up the thread_info and xchg a zero into pending_mask when it is done. At this point, nested interrupts will look at ->real_thread and see that no setup needs to be done. They can just continue normally. Similar care needs to be taken when exiting the outer handler. If another interrupt comes in while it is copying the thread_info, it will drop a bit into pending_mask. The outer handler will check this and if it is non-zero, will loop, set up the stack again, and handle the interrupt. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11 13:22:34 +08:00
extern char cpu0_irqstack[];
int __init start_uml(void)
{
uml: iRQ stacks Add a separate IRQ stack. This differs from i386 in having the entire interrupt run on a separate stack rather than starting on the normal kernel stack and switching over once some preparation has been done. The underlying mechanism, is of course, sigaltstack. Another difference is that interrupts that happen in userspace are handled on the normal kernel stack. These cause a wait wakeup instead of a signal delivery so there is no point in trying to switch stacks for these. There's no other stuff on the stack, so there is no extra stack consumption. This quirk makes it possible to have the entire interrupt run on a separate stack - process preemption (and calls to schedule()) happens on a normal kernel stack. If we enable CONFIG_PREEMPT, this will need to be rethought. The IRQ stack for CPU 0 is declared in the same way as the initial kernel stack. IRQ stacks for other CPUs will be allocated dynamically. An extra field was added to the thread_info structure. When the active thread_info is copied to the IRQ stack, the real_thread field points back to the original stack. This makes it easy to tell where to copy the thread_info struct back to when the interrupt is finished. It also serves as a marker of a nested interrupt. It is NULL for the first interrupt on the stack, and non-NULL for any nested interrupts. Care is taken to behave correctly if a second interrupt comes in when the thread_info structure is being set up or taken down. I could just disable interrupts here, but I don't feel like giving up any of the performance gained by not flipping signals on and off. If an interrupt comes in during these critical periods, the handler can't run because it has no idea what shape the stack is in. So, it sets a bit for its signal in a global mask and returns. The outer handler will deal with this signal itself. Atomicity is had with xchg. A nested interrupt that needs to bail out will xchg its signal mask into pending_mask and repeat in case yet another interrupt hit at the same time, until the mask stabilizes. The outermost interrupt will set up the thread_info and xchg a zero into pending_mask when it is done. At this point, nested interrupts will look at ->real_thread and see that no setup needs to be done. They can just continue normally. Similar care needs to be taken when exiting the outer handler. If another interrupt comes in while it is copying the thread_info, it will drop a bit into pending_mask. The outer handler will check this and if it is non-zero, will loop, set up the stack again, and handle the interrupt. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11 13:22:34 +08:00
stack_protections((unsigned long) &cpu0_irqstack);
set_sigstack(cpu0_irqstack, THREAD_SIZE);
uml: kill processes instead of panicing kernel 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 <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 14:30:58 +08:00
if (proc_mm) {
userspace_pid[0] = start_userspace(0);
uml: kill processes instead of panicing kernel 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 <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 14:30:58 +08:00
if (userspace_pid[0] < 0) {
printf("start_uml - start_userspace returned %d\n",
userspace_pid[0]);
exit(1);
}
}
init_new_thread_signals();
init_task.thread.request.u.thread.proc = start_kernel_proc;
init_task.thread.request.u.thread.arg = NULL;
return start_idle_thread(task_stack_page(&init_task),
&init_task.thread.switch_buf);
}
unsigned long current_stub_stack(void)
{
if (current->mm == NULL)
return 0;
return current->mm->context.id.stack;
}