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Managed to self-destruct pager.

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Issues:
- A page-faulting thread suspends if receives -1 from pager page fault ipc.
  This is fine if pager is about to delete the thread, but it is not if
  it is a buggy pager.
- Need to find a way to completely get rid of suspended pager.
- A method of deleting suspended tasks could remedy both cases above.
This commit is contained in:
Bahadir Balban
2009-10-19 00:33:10 +03:00
parent c3b0399485
commit 9177166817
10 changed files with 162 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
src/arch/arm/exception.c
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@@ -4,6 +4,8 @@
* Copyright (C) 2007, 2008 Bahadir Balban
*/
#include <l4/generic/scheduler.h>
#include <l4/generic/thread.h>
#include <l4/api/thread.h>
#include <l4/generic/space.h>
#include <l4/generic/tcb.h>
#include <l4/lib/printk.h>
@@ -62,9 +64,14 @@ void ipc_restore_state(struct ipc_state *state)
/* Send data fault ipc to the faulty task's pager */
void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
{
int err;
/* mr[0] has the fault tag. The rest is the fault structure */
u32 mr[MR_TOTAL] = { [MR_TAG] = L4_IPC_TAG_PFAULT,
[MR_SENDER] = current->tid };
u32 mr[MR_TOTAL] = {
[MR_TAG] = L4_IPC_TAG_PFAULT,
[MR_SENDER] = current->tid
};
fault_kdata_t *fault = (fault_kdata_t *)&mr[MR_UNUSED_START];
/* Fill in fault information to pass over during ipc */
@@ -94,16 +101,22 @@ void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
/* Set current flags to short ipc */
tcb_set_ipc_flags(current, IPC_FLAGS_SHORT);
/* Send ipc to the task's pager */
ipc_sendrecv(current->pagerid, current->pagerid, 0);
/* Detect if a pager is self-faulting */
if (current->tid == current->pagerid) {
printk("Pager (%d) self-faulting. Exiting.\n",
current->tid);
thread_destroy_self();
}
/*
* FIXME: CHECK TASK KILL REPLY !!!
* Here, pager has handled the request and sent us back a message.
* It is natural that a pager might want to kill the task due to
* illegal access. Here we ought to check this and kill it rather
* than return back to it.
*/
/* Send ipc to the task's pager */
if ((err = ipc_sendrecv(current->pagerid,
current->pagerid, 0)) < 0) {
//printk("Thread (%d) faulted in kernel and its pager "
// "returned error (%d). Suspending.\n",
// current->tid, err);
BUG_ON(current->nlocks);
sched_suspend_sync();
}
}
/*
@@ -226,11 +239,6 @@ void data_abort_handler(u32 faulted_pc, u32 fsr, u32 far)
{
set_abort_type(fsr, ARM_DABT);
/*
* FIXME: Find why if we use a clause like if tid == PAGER_TID
* this prints just the faulted_pc but not the text "Data abort @ PC:"
* Strange.
*/
dbg_abort("Data abort @ PC: ", faulted_pc);
/* Check for more details */
@@ -244,6 +252,11 @@ void data_abort_handler(u32 faulted_pc, u32 fsr, u32 far)
/* This notifies the pager */
fault_ipc_to_pager(faulted_pc, fsr, far);
if (current->flags & TASK_SUSPENDING) {
BUG_ON(current->nlocks);
sched_suspend_sync();
}
return;
error:
@@ -256,7 +269,6 @@ error:
while (1)
;
}
void prefetch_abort_handler(u32 faulted_pc, u32 fsr, u32 far, u32 lr)
{
set_abort_type(fsr, ARM_PABT);
@@ -268,6 +280,11 @@ void prefetch_abort_handler(u32 faulted_pc, u32 fsr, u32 far, u32 lr)
if (KERN_ADDR(lr))
goto error;
fault_ipc_to_pager(faulted_pc, fsr, far);
if (current->flags & TASK_SUSPENDING) {
BUG_ON(current->nlocks);
sched_suspend_sync();
}
return;
error: