linux/arch/um/os-Linux/skas/process.c

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/*
* Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
* Licensed under the GPL
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <sched.h>
#include "ptrace_user.h"
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <sys/time.h>
#include <sys/syscall.h>
#include <asm/types.h>
#include "user.h"
#include "sysdep/ptrace.h"
#include "user_util.h"
#include "kern_util.h"
#include "skas.h"
#include "stub-data.h"
#include "mm_id.h"
#include "sysdep/sigcontext.h"
#include "sysdep/stub.h"
#include "os.h"
#include "proc_mm.h"
#include "skas_ptrace.h"
#include "chan_user.h"
#include "registers.h"
#include "mem.h"
#include "uml-config.h"
#include "process.h"
[PATCH] uml: implement soft interrupts This patch implements soft interrupts. Interrupt enabling and disabling no longer map to sigprocmask. Rather, a flag is set indicating whether interrupts may be handled. If a signal comes in and interrupts are marked as OK, then it is handled normally. If interrupts are marked as off, then the signal handler simply returns after noting that a signal needs handling. When interrupts are enabled later on, this pending signals flag is checked, and the IRQ handlers are called at that point. The point of this is to reduce the cost of local_irq_save et al, since they are very much more common than the signals that they are enabling and disabling. Soft interrupts produce a speed-up of ~25% on a kernel build. Subtleties - UML uses sigsetjmp/siglongjmp to switch contexts. sigsetjmp has been wrapped in a save_flags-like macro which remembers the interrupt state at setjmp time, and restores it when it is longjmp-ed back to. The enable_signals function has to loop because the IRQ handler disables interrupts before returning. enable_signals has to return with signals enabled, and signals may come in between the disabling and the return to enable_signals. So, it loops for as long as there are pending signals, ensuring that signals are enabled when it finally returns, and that there are no pending signals that need to be dealt with. 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>
2006-01-19 01:42:49 +00:00
#include "longjmp.h"
int is_skas_winch(int pid, int fd, void *data)
{
if(pid != os_getpgrp())
return(0);
register_winch_irq(-1, fd, -1, data);
return(1);
}
void wait_stub_done(int pid, int sig, char * fname)
{
int n, status, err;
do {
if ( sig != -1 ) {
err = ptrace(PTRACE_CONT, pid, 0, sig);
if(err)
panic("%s : continue failed, errno = %d\n",
fname, errno);
}
sig = 0;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
} while((n >= 0) && WIFSTOPPED(status) &&
((WSTOPSIG(status) == SIGVTALRM) ||
/* running UML inside a detached screen can cause
* SIGWINCHes
*/
(WSTOPSIG(status) == SIGWINCH)));
if((n < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
unsigned long regs[HOST_FRAME_SIZE];
if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
printk("Failed to get registers from stub, "
"errno = %d\n", errno);
else {
int i;
printk("Stub registers -\n");
for(i = 0; i < HOST_FRAME_SIZE; i++)
printk("\t%d - %lx\n", i, regs[i]);
}
panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
"pid = %d, n = %d, errno = %d, status = 0x%x\n",
fname, pid, n, errno, status);
}
}
extern unsigned long current_stub_stack(void);
void get_skas_faultinfo(int pid, struct faultinfo * fi)
{
int err;
if(ptrace_faultinfo){
err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
if(err)
panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
"errno = %d\n", errno);
/* Special handling for i386, which has different structs */
if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
sizeof(struct faultinfo) -
sizeof(struct ptrace_faultinfo));
}
else {
wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
/* faultinfo is prepared by the stub-segv-handler at start of
* the stub stack page. We just have to copy it.
*/
memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
}
}
static void handle_segv(int pid, union uml_pt_regs * regs)
{
get_skas_faultinfo(pid, &regs->skas.faultinfo);
segv(regs->skas.faultinfo, 0, 1, NULL);
}
/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
{
int err, status;
/* Mark this as a syscall */
UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
if (!local_using_sysemu)
{
err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
__NR_getpid);
if(err < 0)
panic("handle_trap - nullifying syscall failed errno = %d\n",
errno);
err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
if(err < 0)
panic("handle_trap - continuing to end of syscall failed, "
"errno = %d\n", errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if((err < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGTRAP + 0x80))
panic("handle_trap - failed to wait at end of syscall, "
"errno = %d, status = %d\n", errno, status);
}
handle_syscall(regs);
}
extern int __syscall_stub_start;
static int userspace_tramp(void *stack)
{
void *addr;
int err;
ptrace(PTRACE_TRACEME, 0, 0, 0);
init_new_thread_signals();
err = set_interval(1);
if(err)
panic("userspace_tramp - setting timer failed, errno = %d\n",
err);
if(!proc_mm){
/* This has a pte, but it can't be mapped in with the usual
* tlb_flush mechanism because this is part of that mechanism
*/
int fd;
__u64 offset;
fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
if(addr == MAP_FAILED){
printk("mapping mmap stub failed, errno = %d\n",
errno);
exit(1);
}
if(stack != NULL){
fd = phys_mapping(to_phys(stack), &offset);
addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, fd, offset);
if(addr == MAP_FAILED){
printk("mapping segfault stack failed, "
"errno = %d\n", errno);
exit(1);
}
}
}
if(!ptrace_faultinfo && (stack != NULL)){
struct sigaction sa;
unsigned long v = UML_CONFIG_STUB_CODE +
(unsigned long) stub_segv_handler -
(unsigned long) &__syscall_stub_start;
set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
sigemptyset(&sa.sa_mask);
sigaddset(&sa.sa_mask, SIGIO);
sigaddset(&sa.sa_mask, SIGWINCH);
sigaddset(&sa.sa_mask, SIGALRM);
sigaddset(&sa.sa_mask, SIGVTALRM);
sigaddset(&sa.sa_mask, SIGUSR1);
sa.sa_flags = SA_ONSTACK;
sa.sa_handler = (void *) v;
sa.sa_restorer = NULL;
if(sigaction(SIGSEGV, &sa, NULL) < 0)
panic("userspace_tramp - setting SIGSEGV handler "
"failed - errno = %d\n", errno);
}
os_stop_process(os_getpid());
return(0);
}
/* Each element set once, and only accessed by a single processor anyway */
#undef NR_CPUS
#define NR_CPUS 1
int userspace_pid[NR_CPUS];
int start_userspace(unsigned long stub_stack)
{
void *stack;
unsigned long sp;
int pid, status, n, flags;
stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if(stack == MAP_FAILED)
panic("start_userspace : mmap failed, errno = %d", errno);
sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
flags = CLONE_FILES | SIGCHLD;
if(proc_mm) flags |= CLONE_VM;
pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
if(pid < 0)
panic("start_userspace : clone failed, errno = %d", errno);
do {
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("start_userspace : wait failed, errno = %d",
errno);
} while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
panic("start_userspace : expected SIGSTOP, got status = %d",
status);
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("start_userspace : PTRACE_OLDSETOPTIONS failed, errno=%d\n",
errno);
if(munmap(stack, PAGE_SIZE) < 0)
panic("start_userspace : munmap failed, errno = %d\n", errno);
return(pid);
}
void userspace(union uml_pt_regs *regs)
{
int err, status, op, pid = userspace_pid[0];
int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
while(1){
restore_registers(pid, regs);
/* Now we set local_using_sysemu to be used for one loop */
local_using_sysemu = get_using_sysemu();
op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
err = ptrace(op, pid, 0, 0);
if(err)
panic("userspace - could not resume userspace process, "
"pid=%d, ptrace operation = %d, errno = %d\n",
pid, op, errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if(err < 0)
panic("userspace - waitpid failed, errno = %d\n",
errno);
regs->skas.is_user = 1;
save_registers(pid, regs);
UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
if(WIFSTOPPED(status)){
switch(WSTOPSIG(status)){
case SIGSEGV:
if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
user_signal(SIGSEGV, regs, pid);
else handle_segv(pid, regs);
break;
case SIGTRAP + 0x80:
handle_trap(pid, regs, local_using_sysemu);
break;
case SIGTRAP:
relay_signal(SIGTRAP, regs);
break;
case SIGIO:
case SIGVTALRM:
case SIGILL:
case SIGBUS:
case SIGFPE:
case SIGWINCH:
user_signal(WSTOPSIG(status), regs, pid);
break;
default:
printk("userspace - child stopped with signal "
"%d\n", WSTOPSIG(status));
}
pid = userspace_pid[0];
interrupt_end();
/* Avoid -ERESTARTSYS handling in host */
if(PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
PT_SYSCALL_NR(regs->skas.regs) = -1;
}
}
}
int copy_context_skas0(unsigned long new_stack, int pid)
{
int err;
unsigned long regs[HOST_FRAME_SIZE];
unsigned long fp_regs[HOST_FP_SIZE];
unsigned long current_stack = current_stub_stack();
struct stub_data *data = (struct stub_data *) current_stack;
struct stub_data *child_data = (struct stub_data *) new_stack;
__u64 new_offset;
int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
/* prepare offset and fd of child's stack as argument for parent's
* and child's mmap2 calls
*/
*data = ((struct stub_data) { .offset = MMAP_OFFSET(new_offset),
.fd = new_fd,
.timer = ((struct itimerval)
{ { 0, 1000000 / hz() },
{ 0, 1000000 / hz() }})});
get_safe_registers(regs, fp_regs);
/* Set parent's instruction pointer to start of clone-stub */
regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
(unsigned long) stub_clone_handler -
(unsigned long) &__syscall_stub_start;
regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
sizeof(void *);
#ifdef __SIGNAL_FRAMESIZE
regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
#endif
err = ptrace_setregs(pid, regs);
if(err < 0)
panic("copy_context_skas0 : PTRACE_SETREGS failed, "
"pid = %d, errno = %d\n", pid, -err);
err = ptrace_setfpregs(pid, fp_regs);
if(err < 0)
panic("copy_context_skas0 : PTRACE_SETFPREGS failed, "
"pid = %d, errno = %d\n", pid, -err);
/* set a well known return code for detection of child write failure */
child_data->err = 12345678;
/* Wait, until parent has finished its work: read child's pid from
* parent's stack, and check, if bad result.
*/
wait_stub_done(pid, 0, "copy_context_skas0");
pid = data->err;
if(pid < 0)
panic("copy_context_skas0 - stub-parent reports error %d\n",
-pid);
/* Wait, until child has finished too: read child's result from
* child's stack and check it.
*/
wait_stub_done(pid, -1, "copy_context_skas0");
if (child_data->err != UML_CONFIG_STUB_DATA)
panic("copy_context_skas0 - stub-child reports error %ld\n",
child_data->err);
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
(void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
"errno = %d\n", errno);
return pid;
}
/*
* This is used only, if stub pages are needed, while proc_mm is
* availabl. Opening /proc/mm creates a new mm_context, which lacks
* the stub-pages. Thus, we map them using /proc/mm-fd
*/
void map_stub_pages(int fd, unsigned long code,
unsigned long data, unsigned long stack)
{
struct proc_mm_op mmop;
int n;
__u64 code_offset;
int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
&code_offset);
mmop = ((struct proc_mm_op) { .op = MM_MMAP,
.u =
{ .mmap =
{ .addr = code,
.len = PAGE_SIZE,
.prot = PROT_EXEC,
.flags = MAP_FIXED | MAP_PRIVATE,
.fd = code_fd,
.offset = code_offset
} } });
n = os_write_file(fd, &mmop, sizeof(mmop));
if(n != sizeof(mmop)){
printk("mmap args - addr = 0x%lx, fd = %d, offset = %llx\n",
code, code_fd, (unsigned long long) code_offset);
panic("map_stub_pages : /proc/mm map for code failed, "
"err = %d\n", -n);
}
if ( stack ) {
__u64 map_offset;
int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
mmop = ((struct proc_mm_op)
{ .op = MM_MMAP,
.u =
{ .mmap =
{ .addr = data,
.len = PAGE_SIZE,
.prot = PROT_READ | PROT_WRITE,
.flags = MAP_FIXED | MAP_SHARED,
.fd = map_fd,
.offset = map_offset
} } });
n = os_write_file(fd, &mmop, sizeof(mmop));
if(n != sizeof(mmop))
panic("map_stub_pages : /proc/mm map for data failed, "
"err = %d\n", -n);
}
}
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
{
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
(*buf)[0].JB_IP = (unsigned long) handler;
(*buf)[0].JB_SP = (unsigned long) stack +
(PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) - sizeof(void *);
}
#define INIT_JMP_NEW_THREAD 0
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
#define INIT_JMP_CALLBACK 1
#define INIT_JMP_HALT 2
#define INIT_JMP_REBOOT 3
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
void switch_threads(jmp_buf *me, jmp_buf *you)
{
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
if(UML_SETJMP(me) == 0)
UML_LONGJMP(you, 1);
}
static jmp_buf initial_jmpbuf;
/* XXX Make these percpu */
static void (*cb_proc)(void *arg);
static void *cb_arg;
static jmp_buf *cb_back;
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
int start_idle_thread(void *stack, jmp_buf *switch_buf)
{
int n;
set_handler(SIGWINCH, (__sighandler_t) sig_handler,
SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
SIGVTALRM, -1);
n = UML_SETJMP(&initial_jmpbuf);
switch(n){
case INIT_JMP_NEW_THREAD:
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
(*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
(*switch_buf)[0].JB_SP = (unsigned long) stack +
(PAGE_SIZE << UML_CONFIG_KERNEL_STACK_ORDER) -
sizeof(void *);
break;
case INIT_JMP_CALLBACK:
(*cb_proc)(cb_arg);
UML_LONGJMP(cb_back, 1);
break;
case INIT_JMP_HALT:
kmalloc_ok = 0;
return(0);
case INIT_JMP_REBOOT:
kmalloc_ok = 0;
return(1);
default:
panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
}
[PATCH] uml: thread creation tidying 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>
2006-09-27 08:50:40 +00:00
UML_LONGJMP(switch_buf, 1);
}
void initial_thread_cb_skas(void (*proc)(void *), void *arg)
{
jmp_buf here;
cb_proc = proc;
cb_arg = arg;
cb_back = &here;
block_signals();
if(UML_SETJMP(&here) == 0)
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
unblock_signals();
cb_proc = NULL;
cb_arg = NULL;
cb_back = NULL;
}
void halt_skas(void)
{
block_signals();
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
}
void reboot_skas(void)
{
block_signals();
UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
}
void switch_mm_skas(struct mm_id *mm_idp)
{
int err;
#warning need cpu pid in switch_mm_skas
if(proc_mm){
err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
mm_idp->u.mm_fd);
if(err)
panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
"errno = %d\n", errno);
}
else userspace_pid[0] = mm_idp->u.pid;
}