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minix/kernel/arch/i386/exception.c
David van Moolenbroek b423d7b477 Merge of David's ptrace branch. Summary: 
o Support for ptrace T_ATTACH/T_DETACH and T_SYSCALL
o PM signal handling logic should now work properly, even with debuggers
  being present
o Asynchronous PM/VFS protocol, full IPC support for senda(), and
  AMF_NOREPLY senda() flag

DETAILS

Process stop and delay call handling of PM:
o Added sys_runctl() kernel call with sys_stop() and sys_resume()
  aliases, for PM to stop and resume a process
o Added exception for sending/syscall-traced processes to sys_runctl(),
  and matching SIGKREADY pseudo-signal to PM
o Fixed PM signal logic to deal with requests from a process after
  stopping it (so-called "delay calls"), using the SIGKREADY facility
o Fixed various PM panics due to race conditions with delay calls versus
  VFS calls
o Removed special PRIO_STOP priority value
o Added SYS_LOCK RTS kernel flag, to stop an individual process from
  running while modifying its process structure

Signal and debugger handling in PM:
o Fixed debugger signals being dropped if a second signal arrives when
  the debugger has not retrieved the first one
o Fixed debugger signals being sent to the debugger more than once
o Fixed debugger signals unpausing process in VFS; removed PM_UNPAUSE_TR
  protocol message
o Detached debugger signals from general signal logic and from being
  blocked on VFS calls, meaning that even VFS can now be traced
o Fixed debugger being unable to receive more than one pending signal in
  one process stop
o Fixed signal delivery being delayed needlessly when multiple signals
  are pending
o Fixed wait test for tracer, which was returning for children that were
  not waited for
o Removed second parallel pending call from PM to VFS for any process
o Fixed process becoming runnable between exec() and debugger trap
o Added support for notifying the debugger before the parent when a
  debugged child exits
o Fixed debugger death causing child to remain stopped forever
o Fixed consistently incorrect use of _NSIG

Extensions to ptrace():
o Added T_ATTACH and T_DETACH ptrace request, to attach and detach a
  debugger to and from a process
o Added T_SYSCALL ptrace request, to trace system calls
o Added T_SETOPT ptrace request, to set trace options
o Added TO_TRACEFORK trace option, to attach automatically to children
  of a traced process
o Added TO_ALTEXEC trace option, to send SIGSTOP instead of SIGTRAP upon
  a successful exec() of the tracee
o Extended T_GETUSER ptrace support to allow retrieving a process's priv
  structure
o Removed T_STOP ptrace request again, as it does not help implementing
  debuggers properly
o Added MINIX3-specific ptrace test (test42)
o Added proper manual page for ptrace(2)

Asynchronous PM/VFS interface:
o Fixed asynchronous messages not being checked when receive() is called
  with an endpoint other than ANY
o Added AMF_NOREPLY senda() flag, preventing such messages from
  satisfying the receive part of a sendrec()
o Added asynsend3() that takes optional flags; asynsend() is now a
  #define passing in 0 as third parameter
o Made PM/VFS protocol asynchronous; reintroduced tell_fs()
o Made PM_BASE request/reply number range unique
o Hacked in a horrible temporary workaround into RS to deal with newly
  revealed RS-PM-VFS race condition triangle until VFS is asynchronous

System signal handling:
o Fixed shutdown logic of device drivers; removed old SIGKSTOP signal
o Removed is-superuser check from PM's do_procstat() (aka getsigset())
o Added sigset macros to allow system processes to deal with the full
  signal set, rather than just the POSIX subset

Miscellaneous PM fixes:
o Split do_getset into do_get and do_set, merging common code and making
  structure clearer
o Fixed setpriority() being able to put to sleep processes using an
  invalid parameter, or revive zombie processes
o Made find_proc() global; removed obsolete proc_from_pid()
o Cleanup here and there

Also included:
o Fixed false-positive boot order kernel warning
o Removed last traces of old NOTIFY_FROM code

THINGS OF POSSIBLE INTEREST

o It should now be possible to run PM at any priority, even lower than
  user processes
o No assumptions are made about communication speed between PM and VFS,
  although communication must be FIFO
o A debugger will now receive incoming debuggee signals at kill time
  only; the process may not yet be fully stopped
o A first step has been made towards making the SYSTEM task preemptible
2009-09-30 09:57:22 +00:00

252 lines
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/* This file contains a simple exception handler. Exceptions in user
* processes are converted to signals. Exceptions in a kernel task cause
* a panic.
*/
#include "../../kernel.h"
#include "proto.h"
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <minix/sysutil.h>
#include "../../proc.h"
#include "../../proto.h"
#include "../../vm.h"
extern int vm_copy_in_progress, catch_pagefaults;
extern struct proc *vm_copy_from, *vm_copy_to;
void pagefault(vir_bytes old_eip, struct proc *pr, int trap_errno,
u32_t *old_eipptr, u32_t *old_eaxptr, u32_t pagefaultcr2)
{
int s;
vir_bytes ph;
u32_t pte;
int procok = 0, pcok = 0, rangeok = 0;
int in_physcopy = 0;
vir_bytes test_eip;
vmassert(old_eipptr);
vmassert(old_eaxptr);
vmassert(*old_eipptr == old_eip);
vmassert(old_eipptr != &old_eip);
#if 0
printf("kernel: pagefault in pr %d, addr 0x%lx, his cr3 0x%lx, actual cr3 0x%lx\n",
pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
#endif
if(pr->p_seg.p_cr3) {
vmassert(pr->p_seg.p_cr3 == read_cr3());
}
test_eip = k_reenter ? old_eip : pr->p_reg.pc;
in_physcopy = (test_eip > (vir_bytes) phys_copy) &&
(test_eip < (vir_bytes) phys_copy_fault);
if((k_reenter || iskernelp(pr)) &&
catch_pagefaults && in_physcopy) {
#if 0
printf("pf caught! addr 0x%lx\n", pagefaultcr2);
#endif
*old_eipptr = (u32_t) phys_copy_fault;
*old_eaxptr = pagefaultcr2;
return;
}
/* System processes that don't have their own page table can't
* have page faults. VM does have its own page table but also
* can't have page faults (because VM has to handle them).
*/
if(k_reenter || (pr->p_endpoint <= INIT_PROC_NR &&
!(pr->p_misc_flags & MF_FULLVM)) || pr->p_endpoint == VM_PROC_NR) {
/* Page fault we can't / don't want to
* handle.
*/
kprintf("pagefault for process %d ('%s'), pc = 0x%x, addr = 0x%x, flags = 0x%x, k_reenter %d\n",
pr->p_endpoint, pr->p_name, pr->p_reg.pc,
pagefaultcr2, trap_errno, k_reenter);
proc_stacktrace(pr);
minix_panic("page fault in system process", pr->p_endpoint);
return;
}
/* Don't schedule this process until pagefault is handled. */
vmassert(pr->p_seg.p_cr3 == read_cr3());
vmassert(!RTS_ISSET(pr, PAGEFAULT));
RTS_LOCK_SET(pr, PAGEFAULT);
/* Save pagefault details, suspend process,
* add process to pagefault chain,
* and tell VM there is a pagefault to be
* handled.
*/
pr->p_pagefault.pf_virtual = pagefaultcr2;
pr->p_pagefault.pf_flags = trap_errno;
pr->p_nextpagefault = pagefaults;
pagefaults = pr;
mini_notify(proc_addr(HARDWARE), VM_PROC_NR);
return;
}
/*===========================================================================*
* exception *
*===========================================================================*/
PUBLIC void exception(vec_nr, trap_errno, old_eip, old_cs, old_eflags,
old_eipptr, old_eaxptr, pagefaultcr2)
unsigned vec_nr;
u32_t trap_errno;
u32_t old_eip;
U16_t old_cs;
u32_t old_eflags;
u32_t *old_eipptr;
u32_t *old_eaxptr;
u32_t pagefaultcr2;
{
/* An exception or unexpected interrupt has occurred. */
struct proc *t;
struct ex_s {
char *msg;
int signum;
int minprocessor;
};
static struct ex_s ex_data[] = {
{ "Divide error", SIGFPE, 86 },
{ "Debug exception", SIGTRAP, 86 },
{ "Nonmaskable interrupt", SIGBUS, 86 },
{ "Breakpoint", SIGEMT, 86 },
{ "Overflow", SIGFPE, 86 },
{ "Bounds check", SIGFPE, 186 },
{ "Invalid opcode", SIGILL, 186 },
{ "Coprocessor not available", SIGFPE, 186 },
{ "Double fault", SIGBUS, 286 },
{ "Copressor segment overrun", SIGSEGV, 286 },
{ "Invalid TSS", SIGSEGV, 286 },
{ "Segment not present", SIGSEGV, 286 },
{ "Stack exception", SIGSEGV, 286 }, /* STACK_FAULT already used */
{ "General protection", SIGSEGV, 286 },
{ "Page fault", SIGSEGV, 386 }, /* not close */
{ NIL_PTR, SIGILL, 0 }, /* probably software trap */
{ "Coprocessor error", SIGFPE, 386 },
};
register struct ex_s *ep;
struct proc *saved_proc;
if(k_reenter > 2) {
/* This can't end well. */
minix_panic("exception: k_reenter too high", k_reenter);
}
/* Save proc_ptr, because it may be changed by debug statements. */
saved_proc = proc_ptr;
ep = &ex_data[vec_nr];
if (vec_nr == 2) { /* spurious NMI on some machines */
kprintf("got spurious NMI\n");
return;
}
if(vec_nr == PAGE_FAULT_VECTOR) {
pagefault(old_eip, saved_proc, trap_errno,
old_eipptr, old_eaxptr, pagefaultcr2);
return;
}
/* If an exception occurs while running a process, the k_reenter variable
* will be zero. Exceptions in interrupt handlers or system traps will make
* k_reenter larger than zero.
*/
if (k_reenter == 0 && ! iskernelp(saved_proc)) {
#if 0
{
kprintf(
"vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
vec_nr, (unsigned long)trap_errno,
(unsigned long)old_eip, old_cs,
(unsigned long)old_eflags);
printseg("cs: ", 1, saved_proc, old_cs);
printseg("ds: ", 0, saved_proc, saved_proc->p_reg.ds);
if(saved_proc->p_reg.ds != saved_proc->p_reg.ss) {
printseg("ss: ", 0, saved_proc, saved_proc->p_reg.ss);
}
proc_stacktrace(saved_proc);
}
#endif
cause_sig(proc_nr(saved_proc), ep->signum);
return;
}
/* Exception in system code. This is not supposed to happen. */
if (ep->msg == NIL_PTR || machine.processor < ep->minprocessor)
kprintf("\nIntel-reserved exception %d\n", vec_nr);
else
kprintf("\n%s\n", ep->msg);
kprintf("k_reenter = %d ", k_reenter);
kprintf("vec_nr= %d, trap_errno= 0x%x, eip= 0x%x, cs= 0x%x, eflags= 0x%x\n",
vec_nr, trap_errno, old_eip, old_cs, old_eflags);
/* TODO should we enable this only when compiled for some debug mode? */
if (saved_proc) {
kprintf("scheduled was: process %d (%s), ", proc_nr(saved_proc), saved_proc->p_name);
kprintf("pc = %u:0x%x\n", (unsigned) saved_proc->p_reg.cs,
(unsigned) saved_proc->p_reg.pc);
proc_stacktrace(saved_proc);
minix_panic("exception in a kernel task", saved_proc->p_endpoint);
}
else {
/* in an early stage of boot process we don't have processes yet */
minix_panic("exception in kernel while booting", NO_NUM);
}
}
/*===========================================================================*
* stacktrace *
*===========================================================================*/
PUBLIC void proc_stacktrace(struct proc *whichproc)
{
reg_t bp, v_bp, v_pc, v_hbp;
int iskernel;
v_bp = whichproc->p_reg.fp;
iskernel = iskernelp(whichproc);
kprintf("%-8.8s %6d 0x%lx ",
whichproc->p_name, whichproc->p_endpoint, whichproc->p_reg.pc);
while(v_bp) {
#define PRCOPY(pr, pv, v, n) \
(iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
data_copy(pr->p_endpoint, pv, SYSTEM, (vir_bytes) (v), n))
if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
kprintf("(v_bp 0x%lx ?)", v_bp);
break;
}
if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
kprintf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
break;
}
kprintf("0x%lx ", (unsigned long) v_pc);
if(v_hbp != 0 && v_hbp <= v_bp) {
kprintf("(hbp %lx ?)", v_hbp);
break;
}
v_bp = v_hbp;
}
kprintf("\n");
}
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