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[Linuxconsole-commit]CVS: ruby/linux/arch/s390x/mm fault.c,1.3,1.4
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From: James S. <jsi...@us...> - 2002-06-15 19:17:12
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Update of /cvsroot/linuxconsole/ruby/linux/arch/s390x/mm
In directory usw-pr-cvs1:/tmp/cvs-serv22898/linux/arch/s390x/mm
Modified Files:
fault.c
Log Message:
Synced to 2.5.21
Index: fault.c
===================================================================
RCS file: /cvsroot/linuxconsole/ruby/linux/arch/s390x/mm/fault.c,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -d -r1.3 -r1.4
--- fault.c 26 Dec 2001 17:28:11 -0000 1.3
+++ fault.c 15 Jun 2002 19:17:09 -0000 1.4
@@ -34,7 +34,77 @@
#endif
extern void die(const char *,struct pt_regs *,long);
-static void force_sigsegv(struct task_struct *tsk, int code, void *address);
+
+/*
+ * Check which address space is addressed by the access
+ * register in S390_lowcore.exc_access_id.
+ * Returns 1 for user space and 0 for kernel space.
+ */
+static int __check_access_register(struct pt_regs *regs, int error_code)
+{
+ int areg = S390_lowcore.exc_access_id;
+
+ if (areg == 0)
+ /* Access via access register 0 -> kernel address */
+ return 0;
+ if (regs && areg < NUM_ACRS && regs->acrs[areg] <= 1)
+ /*
+ * access register contains 0 -> kernel address,
+ * access register contains 1 -> user space address
+ */
+ return regs->acrs[areg];
+
+ /* Something unhealthy was done with the access registers... */
+ die("page fault via unknown access register", regs, error_code);
+ do_exit(SIGKILL);
+ return 0;
+}
+
+/*
+ * Check which address space the address belongs to.
+ * Returns 1 for user space and 0 for kernel space.
+ */
+static inline int check_user_space(struct pt_regs *regs, int error_code)
+{
+ /*
+ * The lowest two bits of S390_lowcore.trans_exc_code indicate
+ * which paging table was used:
+ * 0: Primary Segment Table Descriptor
+ * 1: STD determined via access register
+ * 2: Secondary Segment Table Descriptor
+ * 3: Home Segment Table Descriptor
+ */
+ int descriptor = S390_lowcore.trans_exc_code & 3;
+ if (descriptor == 1)
+ return __check_access_register(regs, error_code);
+ return descriptor >> 1;
+}
+
+/*
+ * Send SIGSEGV to task. This is an external routine
+ * to keep the stack usage of do_page_fault small.
+ */
+static void force_sigsegv(struct pt_regs *regs, unsigned long error_code,
+ int si_code, unsigned long address)
+{
+ struct siginfo si;
+
+#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
+#if defined(CONFIG_SYSCTL)
+ if (sysctl_userprocess_debug)
+#endif
+ {
+ printk("User process fault: interruption code 0x%lX\n",
+ error_code);
+ printk("failing address: %lX\n", address);
+ show_regs(regs);
+ }
+#endif
+ si.si_signo = SIGSEGV;
+ si.si_code = si_code;
+ si.si_addr = (void *) address;
+ force_sig_info(SIGSEGV, &si, current);
+}
/*
* This routine handles page faults. It determines the address,
@@ -42,21 +112,20 @@
* routines.
*
* error_code:
- * ****0004 Protection -> Write-Protection (suprression)
- * ****0010 Segment translation -> Not present (nullification)
- * ****0011 Page translation -> Not present (nullification)
- * ****003B Region third exception -> Not present (nullification)
+ * 04 Protection -> Write-Protection (suprression)
+ * 10 Segment translation -> Not present (nullification)
+ * 11 Page translation -> Not present (nullification)
+ * 3b Region third trans. -> Not present (nullification)
*/
-asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
+extern inline void do_exception(struct pt_regs *regs, unsigned long error_code)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long address;
+ int user_address;
unsigned long fixup;
- int write;
int si_code = SEGV_MAPERR;
- int kernel_address = 0;
tsk = current;
mm = tsk->mm;
@@ -66,13 +135,13 @@
* 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)) {
+ if (error_code == 4 && !(S390_lowcore.trans_exc_code & 4)) {
/* 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;
+ user_address = 0;
goto no_context;
}
@@ -86,52 +155,15 @@
* more specific the segment and page table portion of
* the address
*/
-
- address = S390_lowcore.trans_exc_code&-4096L;
-
-
- /*
- * Check which address space the address belongs to
- */
- switch (S390_lowcore.trans_exc_code & 3)
- {
- case 0: /* Primary Segment Table Descriptor */
- kernel_address = 1;
- goto no_context;
-
- case 1: /* STD determined via access register */
- if (S390_lowcore.exc_access_id == 0)
- {
- kernel_address = 1;
- goto no_context;
- }
- if (regs && S390_lowcore.exc_access_id < NUM_ACRS)
- {
- if (regs->acrs[S390_lowcore.exc_access_id] == 0)
- {
- kernel_address = 1;
- goto no_context;
- }
- if (regs->acrs[S390_lowcore.exc_access_id] == 1)
- {
- /* user space address */
- break;
- }
- }
- die("page fault via unknown access register", regs, error_code);
- do_exit(SIGKILL);
- break;
-
- case 2: /* Secondary Segment Table Descriptor */
- case 3: /* Home Segment Table Descriptor */
- /* user space address */
- break;
- }
+ address = S390_lowcore.trans_exc_code & -4096L;
+ user_address = check_user_space(regs, error_code);
/*
- * Check whether we have a user MM in the first place.
+ * Verify that the fault happened in user space, that
+ * we are not in an interrupt and that there is a
+ * user context.
*/
- if (in_interrupt() || !mm || !(regs->psw.mask & _PSW_IO_MASK_BIT))
+ if (user_address == 0 || in_interrupt() || !mm)
goto no_context;
/*
@@ -139,7 +171,6 @@
* task's user address space, so we can switch on the
* interrupts again and then search the VMAs
*/
-
__sti();
down_read(&mm->mmap_sem);
@@ -158,31 +189,23 @@
* we can handle it..
*/
good_area:
- write = 0;
si_code = SEGV_ACCERR;
+ if (error_code != 4) {
+ /* page not present, check vm flags */
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+ goto bad_area;
+ } else {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ }
- switch (error_code & 0xFF) {
- case 0x04: /* write, present*/
- write = 1;
- break;
- case 0x10: /* not present*/
- case 0x11: /* not present*/
- case 0x3B: /* not present*/
- if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
- goto bad_area;
- break;
- default:
- printk("code should be 4, 10 or 11 (%lX) \n",error_code&0xFF);
- goto bad_area;
- }
-
- survive:
+survive:
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- switch (handle_mm_fault(mm, vma, address, write)) {
+ switch (handle_mm_fault(mm, vma, address, error_code == 4)) {
case 1:
tsk->min_flt++;
break;
@@ -209,22 +232,7 @@
if (regs->psw.mask & PSW_PROBLEM_STATE) {
tsk->thread.prot_addr = address;
tsk->thread.trap_no = error_code;
-#ifndef CONFIG_SYSCTL
-#ifdef CONFIG_PROCESS_DEBUG
- printk("User process fault: interruption code 0x%lX\n",error_code);
- printk("failing address: %lX\n",address);
- show_regs(regs);
-#endif
-#else
- if (sysctl_userprocess_debug) {
- printk("User process fault: interruption code 0x%lX\n",
- error_code);
- printk("failing address: %lX\n", address);
- show_regs(regs);
- }
-#endif
-
- force_sigsegv(tsk, si_code, (void *)address);
+ force_sigsegv(regs, error_code, si_code, address);
return;
}
@@ -239,8 +247,7 @@
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
-
- if (kernel_address)
+ if (user_address == 0)
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
" at virtual kernel address %016lx\n", address);
else
@@ -258,9 +265,7 @@
out_of_memory:
up_read(&mm->mmap_sem);
if (tsk->pid == 1) {
- tsk->policy |= SCHED_YIELD;
- schedule();
- down_read(&mm->mmap_sem);
+ yield();
goto survive;
}
printk("VM: killing process %s\n", tsk->comm);
@@ -284,19 +289,26 @@
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)
+void do_protection_exception(struct pt_regs *regs, unsigned long error_code)
{
- struct siginfo si;
- si.si_signo = SIGSEGV;
- si.si_code = code;
- si.si_addr = address;
- force_sig_info(SIGSEGV, &si, tsk);
+ regs->psw.addr -= (error_code >> 16);
+ do_exception(regs, 4);
}
+void do_segment_exception(struct pt_regs *regs, unsigned long error_code)
+{
+ do_exception(regs, 0x10);
+}
+
+void do_page_exception(struct pt_regs *regs, unsigned long error_code)
+{
+ do_exception(regs, 0x11);
+}
+
+void do_region_exception(struct pt_regs *regs, unsigned long error_code)
+{
+ do_exception(regs, 0x3b);
+}
#ifdef CONFIG_PFAULT
/*
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