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linux-os.c

/*
 * the Linux incarnation of OS-dependent routines.  See also
 * $(sbcl_arch)-linux-os.c
 *
 * This file (along with os.h) exports an OS-independent interface to
 * the operating system VM facilities. Surprise surprise, this
 * interface looks a lot like the Mach interface (but simpler in some
 * places). For some operating systems, a subset of these functions
 * will have to be emulated.
 */

/*
 * This software is part of the SBCL system. See the README file for
 * more information.
 *
 * This software is derived from the CMU CL system, which was
 * written at Carnegie Mellon University and released into the
 * public domain. The software is in the public domain and is
 * provided with absolutely no warranty. See the COPYING and CREDITS
 * files for more information.
 */

#include <stdio.h>
#include <sys/param.h>
#include <sys/file.h>
#include "sbcl.h"
#include "./signal.h"
#include "os.h"
#include "arch.h"
#include "globals.h"
#include "sbcl.h"
#include "interrupt.h"
#include "interr.h"
#include "lispregs.h"
#include <sys/socket.h>
#include <sys/utsname.h>

#include <sys/types.h>
#include <signal.h>
/* #include <sys/sysinfo.h> */
#include <sys/time.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/version.h>

#include "validate.h"
#include "thread.h"
size_t os_vm_page_size;

#ifdef LISP_FEATURE_SB_FUTEX
#include <linux/unistd.h>
#include <errno.h>

/* values taken from the kernel's linux/futex.h.  This header file
   doesn't exist in userspace, which is our excuse for not grovelling
   them automatically */
#define FUTEX_WAIT (0)
#define FUTEX_WAKE (1)
#define FUTEX_FD (2)
#define FUTEX_REQUEUE (3)

#define __NR_sys_futex __NR_futex

_syscall4(int,sys_futex,
        int *, futex,
        int, op,
        int, val,
        struct timespec *, rel);
#endif

#include "gc.h"

int linux_sparc_siginfo_bug = 0;
int linux_supports_futex=0;

void os_init(void)
{
    /* Conduct various version checks: do we have enough mmap(), is
     * this a sparc running 2.2, can we do threads? */
    int *futex=0;
    struct utsname name;
    int major_version;
    int minor_version;
    char *p;
    uname(&name);
    p=name.release;  
    major_version = atoi(p);
    p=strchr(p,'.')+1;
    minor_version = atoi(p);
    if (major_version<2) {
      lose("linux kernel version too old: major version=%d (can't run in version < 2.0.0)",
           major_version);
    }
    if (!(major_version>2 || minor_version >= 4)) {
#ifdef LISP_FEATURE_SB_THREAD
      lose("linux kernel 2.4 required for thread-enabled SBCL");
#endif
#ifdef LISP_FEATURE_SPARC
      FSHOW((stderr,"linux kernel %d.%d predates 2.4;\n enabling workarounds for SPARC kernel bugs in signal handling.\n", major_version,minor_version));
      linux_sparc_siginfo_bug = 1;
#endif
    }
#ifdef LISP_FEATURE_SB_FUTEX
    futex_wait(futex,-1);
    if(errno!=ENOSYS) linux_supports_futex=1;
#endif
    os_vm_page_size = getpagesize();
}


#ifdef LISP_FEATURE_ALPHA
/* The Alpha is a 64 bit CPU.  SBCL is a 32 bit application.  Due to all
 * the places that assume we can get a pointer into a fixnum with no 
 * information loss, we have to make sure it allocates all its ram in the
 * 0-2Gb region.  */

static void * under_2gb_free_pointer=DYNAMIC_1_SPACE_END;
#endif

os_vm_address_t
os_validate(os_vm_address_t addr, os_vm_size_t len)
{
    int flags =  MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE;
    os_vm_address_t actual ;

    if (addr) 
      flags |= MAP_FIXED;
#ifdef LISP_FEATURE_ALPHA
    else {
      flags |= MAP_FIXED;
      addr=under_2gb_free_pointer;
    }
#endif      
    actual = mmap(addr, len, OS_VM_PROT_ALL, flags, -1, 0);
    if (actual == MAP_FAILED ||     (addr && (addr!=actual))) {
      perror("mmap");
      return 0;         /* caller should check this */
    }

#ifdef LISP_FEATURE_ALPHA

    len=(len+(os_vm_page_size-1))&(~(os_vm_page_size-1));
    under_2gb_free_pointer+=len;
#endif

    return actual;
}

void
os_invalidate(os_vm_address_t addr, os_vm_size_t len)
{
    if (munmap(addr,len) == -1) {
      perror("munmap");
    }
}

os_vm_address_t
os_map(int fd, int offset, os_vm_address_t addr, os_vm_size_t len)
{
    addr = mmap(addr, len,
            OS_VM_PROT_ALL,
            MAP_PRIVATE | MAP_FILE | MAP_FIXED,
            fd, (off_t) offset);

    if (addr == MAP_FAILED) {
      perror("mmap");
      lose("unexpected mmap(..) failure");
    }

    return addr;
}

void
os_protect(os_vm_address_t address, os_vm_size_t length, os_vm_prot_t prot)
{
    if (mprotect(address, length, prot) == -1) {
      perror("mprotect");
    }
}

/* FIXME: Now that FOO_END, rather than FOO_SIZE, is the fundamental
 * description of a space, we could probably punt this and just do
 * (FOO_START <= x && x < FOO_END) everywhere it's called. */
static boolean
in_range_p(os_vm_address_t a, lispobj sbeg, size_t slen)
{
    char* beg = (char*)((long)sbeg);
    char* end = (char*)((long)sbeg) + slen;
    char* adr = (char*)a;
    return (adr >= beg && adr < end);
}

boolean
is_valid_lisp_addr(os_vm_address_t addr)
{
    struct thread *th;
    if(in_range_p(addr, READ_ONLY_SPACE_START, READ_ONLY_SPACE_SIZE) ||
       in_range_p(addr, STATIC_SPACE_START   , STATIC_SPACE_SIZE) ||
       in_range_p(addr, DYNAMIC_SPACE_START  , DYNAMIC_SPACE_SIZE))
      return 1;
    for_each_thread(th) {
      if((th->control_stack_start <= addr) && (addr < th->control_stack_end))
          return 1;
      if(in_range_p(addr, th->binding_stack_start, BINDING_STACK_SIZE))
          return 1;
    }
    return 0;
}

/*
 * any OS-dependent special low-level handling for signals
 */


#if defined LISP_FEATURE_GENCGC

/*
 * The GENCGC needs to be hooked into whatever signal is raised for
 * page fault on this OS.
 */
void
sigsegv_handler(int signal, siginfo_t *info, void* void_context)
{
    os_context_t *context = arch_os_get_context(&void_context);
    void* fault_addr = (void*)info->si_addr;
    if (!gencgc_handle_wp_violation(fault_addr)) 
      if(!handle_control_stack_guard_triggered(context,fault_addr))
          interrupt_handle_now(signal, info, void_context);
}

#else

static void
sigsegv_handler(int signal, siginfo_t *info, void* void_context)
{
    os_context_t *context = arch_os_get_context(&void_context);
    os_vm_address_t addr;

    addr = arch_get_bad_addr(signal,info,context);
    if (addr != NULL && 
      *os_context_register_addr(context,reg_ALLOC) & (1L<<63)){
      
      /* Alpha stuff: This is the end of a pseudo-atomic section
       * during which a signal was received.  We must deal with the
       * pending interrupt (see also interrupt.c,
       * ../code/interrupt.lisp)
       */
      /* (how we got here: when interrupting, we set bit 63 in
       * reg_Alloc.  At the end of the atomic section we tried to
       * write to reg_ALLOC, got a SIGSEGV (there's nothing mapped
       * there) so ended up here
       */
      *os_context_register_addr(context,reg_ALLOC) -= (1L<<63);
      interrupt_handle_pending(context);
    } else {
      if(!interrupt_maybe_gc(signal, info, context))
          if(!handle_control_stack_guard_triggered(context,addr))
            interrupt_handle_now(signal, info, context);
    }
}
#endif

void sigcont_handler(int signal, siginfo_t *info, void *void_context)
{
    /* We need to have a handler installed for this signal so that
     * sigwaitinfo() for it actually returns at the appropriate time.
     * We don't need it to actually do anything.  This mkes it
     * possibly the only signal handler in SBCL that doesn't depend on
     * not-guaranteed-by-POSIX features 
     */    
}

void
os_install_interrupt_handlers(void)
{
    undoably_install_low_level_interrupt_handler(SIG_MEMORY_FAULT,
                                     sigsegv_handler);
#ifdef LISP_FEATURE_SB_THREAD
    undoably_install_low_level_interrupt_handler(SIG_INTERRUPT_THREAD,
                                     interrupt_thread_handler);
    undoably_install_low_level_interrupt_handler(SIG_STOP_FOR_GC,
                                     sig_stop_for_gc_handler);
    undoably_install_low_level_interrupt_handler(SIG_THREAD_EXIT,
                                     thread_exit_handler);
    if(!linux_supports_futex)
      undoably_install_low_level_interrupt_handler(SIG_DEQUEUE,
                                         sigcont_handler);
#endif
}

#ifdef LISP_FEATURE_SB_FUTEX
int futex_wait(int *lock_word, int oldval) {
    int t= sys_futex(lock_word,FUTEX_WAIT,oldval, 0);
    return t;
}
int futex_wake(int *lock_word, int n){
    return sys_futex(lock_word,FUTEX_WAKE,n,0);
}
#endif

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