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[Linuxconsole-commit]CVS: ruby/linux/arch/s390x/mm fault.c,1.1,1.2
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From: James S. <jsi...@us...> - 2001-10-29 00:11:31
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Update of /cvsroot/linuxconsole/ruby/linux/arch/s390x/mm
In directory usw-pr-cvs1:/tmp/cvs-serv10630/arch/s390x/mm
Modified Files:
fault.c
Log Message:
Synced to 2.4.13
Index: fault.c
===================================================================
RCS file: /cvsroot/linuxconsole/ruby/linux/arch/s390x/mm/fault.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -d -r1.1 -r1.2
--- fault.c 2001/09/02 23:14:23 1.1
+++ fault.c 2001/10/29 00:10:58 1.2
@@ -4,6 +4,7 @@
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Hartmut Penner (hp...@de...)
+ * Ulrich Weigand (uwe...@de...)
*
* Derived from "arch/i386/mm/fault.c"
* Copyright (C) 1995 Linus Torvalds
@@ -21,6 +22,7 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
+#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -32,6 +34,7 @@
#endif
extern void die(const char *,struct pt_regs *,long);
+static void force_sigsegv(struct task_struct *tsk, int code, void *address);
/*
* This routine handles page faults. It determines the address,
@@ -52,19 +55,32 @@
unsigned long address;
unsigned long fixup;
int write;
- unsigned long psw_mask;
- unsigned long psw_addr;
int si_code = SEGV_MAPERR;
int kernel_address = 0;
- /*
- * get psw mask of Program old psw to find out,
- * if user or kernel mode
- */
+ tsk = current;
+ mm = tsk->mm;
+
+ /*
+ * Check for low-address protection. This needs to be treated
+ * as a special case because the translation exception code
+ * field is not guaranteed to contain valid data in this case.
+ */
+ if ((error_code & 0xff) == 4 && !(S390_lowcore.trans_exc_code & 4)) {
- psw_mask = S390_lowcore.program_old_psw.mask;
- psw_addr = S390_lowcore.program_old_psw.addr;
+ /* Low-address protection hit in kernel mode means
+ NULL pointer write access in kernel mode. */
+ if (!(regs->psw.mask & PSW_PROBLEM_STATE)) {
+ address = 0;
+ kernel_address = 1;
+ goto no_context;
+ }
+ /* Low-address protection hit in user mode 'cannot happen'. */
+ die ("Low-address protection", regs, error_code);
+ do_exit(SIGKILL);
+ }
+
/*
* get the failing address
* more specific the segment and page table portion of
@@ -73,11 +89,6 @@
address = S390_lowcore.trans_exc_code&-4096L;
- tsk = current;
- mm = tsk->mm;
-
- if (in_interrupt() || !mm)
- goto no_context;
/*
* Check which address space the address belongs to
@@ -108,6 +119,7 @@
}
}
die("page fault via unknown access register", regs, error_code);
+ do_exit(SIGKILL);
break;
case 2: /* Secondary Segment Table Descriptor */
@@ -116,6 +128,11 @@
break;
}
+ /*
+ * Check whether we have a user MM in the first place.
+ */
+ if (in_interrupt() || !mm)
+ goto no_context;
/*
* When we get here, the fault happened in the current
@@ -125,10 +142,8 @@
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
- if (!vma) {
- printk("no vma for address %lX\n",address);
+ if (!vma)
goto bad_area;
- }
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
@@ -158,6 +173,7 @@
goto bad_area;
}
+ survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
@@ -187,8 +203,7 @@
up_read(&mm->mmap_sem);
/* User mode accesses just cause a SIGSEGV */
- if (psw_mask & PSW_PROBLEM_STATE) {
- struct siginfo si;
+ if (regs->psw.mask & PSW_PROBLEM_STATE) {
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
#ifndef CONFIG_SYSCTL
@@ -205,10 +220,8 @@
show_regs(regs);
}
#endif
- si.si_signo = SIGSEGV;
- si.si_code = si_code;
- si.si_addr = (void*) address;
- force_sig_info(SIGSEGV, &si, tsk);
+
+ force_sigsegv(tsk, si_code, (void *)address);
return;
}
@@ -223,6 +236,7 @@
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
+
if (kernel_address)
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %016lx\n", address);
@@ -230,10 +244,6 @@
printk(KERN_ALERT "Unable to handle kernel paging request"
" at virtual user address %016lx\n", address);
-/*
- * need to define, which information is useful here
- */
-
die("Oops", regs, error_code);
do_exit(SIGKILL);
@@ -244,8 +254,14 @@
*/
out_of_memory:
up_read(&mm->mmap_sem);
+ if (tsk->pid == 1) {
+ tsk->policy |= SCHED_YIELD;
+ schedule();
+ down_read(&mm->mmap_sem);
+ goto survive;
+ }
printk("VM: killing process %s\n", tsk->comm);
- if (psw_mask & PSW_PROBLEM_STATE)
+ if (regs->psw.mask & PSW_PROBLEM_STATE)
do_exit(SIGKILL);
goto no_context;
@@ -261,6 +277,151 @@
force_sig(SIGBUS, tsk);
/* Kernel mode? Handle exceptions or die */
- if (!(psw_mask & PSW_PROBLEM_STATE))
+ if (!(regs->psw.mask & PSW_PROBLEM_STATE))
goto no_context;
}
+
+/*
+ * Send SIGSEGV to task. This is an external routine
+ * to keep the stack usage of do_page_fault small.
+ */
+static void force_sigsegv(struct task_struct *tsk, int code, void *address)
+{
+ struct siginfo si;
+ si.si_signo = SIGSEGV;
+ si.si_code = code;
+ si.si_addr = address;
+ force_sig_info(SIGSEGV, &si, tsk);
+}
+
+
+#ifdef CONFIG_PFAULT
+/*
+ * 'pfault' pseudo page faults routines.
+ */
+static int pfault_disable = 0;
+
+static int __init nopfault(char *str)
+{
+ pfault_disable = 1;
+ return 1;
+}
+
+__setup("nopfault", nopfault);
+
+typedef struct {
+ __u16 refdiagc;
+ __u16 reffcode;
+ __u16 refdwlen;
+ __u16 refversn;
+ __u64 refgaddr;
+ __u64 refselmk;
+ __u64 refcmpmk;
+ __u64 reserved;
+} __attribute__ ((packed)) pfault_refbk_t;
+
+typedef struct _pseudo_wait_t {
+ struct _pseudo_wait_t *next;
+ wait_queue_head_t queue;
+ unsigned long address;
+ int resolved;
+} pseudo_wait_t;
+
+int pfault_init(void)
+{
+ pfault_refbk_t refbk =
+ { 0x258, 0, 5, 2, __LC_KERNEL_STACK, 1ULL << 48, 1ULL << 48,
+ 0x8000000000000000ULL };
+ int rc;
+
+ if (pfault_disable)
+ return -1;
+ __asm__ __volatile__(
+ " diag %1,%0,0x258\n"
+ "0: j 2f\n"
+ "1: la %0,8\n"
+ "2:\n"
+ ".section __ex_table,\"a\"\n"
+ " .align 4\n"
+ " .quad 0b,1b\n"
+ ".previous"
+ : "=d" (rc) : "a" (&refbk) : "cc" );
+ __ctl_set_bit(0, 9);
+ return rc;
+}
+
+void pfault_fini(void)
+{
+ pfault_refbk_t refbk =
+ { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
+
+ if (pfault_disable)
+ return;
+ __ctl_clear_bit(0, 9);
+ __asm__ __volatile__(
+ " diag %0,0,0x258\n"
+ "0:\n"
+ ".section __ex_table,\"a\"\n"
+ " .align 4\n"
+ " .quad 0b,0b\n"
+ ".previous"
+ : : "a" (&refbk) : "cc" );
+}
+
+asmlinkage void
+pfault_interrupt(struct pt_regs *regs, __u16 error_code)
+{
+ struct task_struct *tsk;
+ wait_queue_head_t queue;
+ wait_queue_head_t *qp;
+ __u16 subcode;
+
+ /*
+ * Get the external interruption subcode & pfault
+ * initial/completion signal bit. VM stores this
+ * in the 'cpu address' field associated with the
+ * external interrupt.
+ */
+ subcode = S390_lowcore.cpu_addr;
+ if ((subcode & 0xff00) != 0x0600)
+ return;
+
+ /*
+ * Get the token (= address of kernel stack of affected task).
+ */
+ tsk = (struct task_struct *)
+ (*((unsigned long *) __LC_PFAULT_INTPARM) - THREAD_SIZE);
+
+ if (subcode & 0x0080) {
+ /* signal bit is set -> a page has been swapped in by VM */
+ qp = (wait_queue_head_t *)
+ xchg(&tsk->thread.pfault_wait, -1);
+ if (qp != NULL) {
+ /* Initial interrupt was faster than the completion
+ * interrupt. pfault_wait is valid. Set pfault_wait
+ * back to zero and wake up the process. This can
+ * safely be done because the task is still sleeping
+ * and can't procude new pfaults. */
+ tsk->thread.pfault_wait = 0ULL;
+ wake_up(qp);
+ }
+ } else {
+ /* signal bit not set -> a real page is missing. */
+ init_waitqueue_head (&queue);
+ qp = (wait_queue_head_t *)
+ xchg(&tsk->thread.pfault_wait, (addr_t) &queue);
+ if (qp != NULL) {
+ /* Completion interrupt was faster than the initial
+ * interrupt (swapped in a -1 for pfault_wait). Set
+ * pfault_wait back to zero and exit. This can be
+ * done safely because tsk is running in kernel
+ * mode and can't produce new pfaults. */
+ tsk->thread.pfault_wait = 0ULL;
+ }
+
+ /* go to sleep */
+ wait_event(queue, tsk->thread.pfault_wait == 0ULL);
+ }
+}
+#endif
+
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