powerpc: Exception hooks for context tracking subsystem

[cascardo/linux.git] / arch / powerpc / mm / fault.c

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 229951f..8726779 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -32,6 +32,7 @@
 #include <linux/perf_event.h>
 #include <linux/magic.h>
 #include <linux/ratelimit.h>
+#include <linux/context_tracking.h>
 
 #include <asm/firmware.h>
 #include <asm/page.h>
@@ -196,6 +197,7 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)
 int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
                            unsigned long error_code)
 {
+       enum ctx_state prev_state = exception_enter();
        struct vm_area_struct * vma;
        struct mm_struct *mm = current->mm;
        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
@@ -204,6 +206,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
        int trap = TRAP(regs);
        int is_exec = trap == 0x400;
        int fault;
+       int rc = 0;
 
 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
        /*
@@ -230,28 +233,30 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
         * look at it
         */
        if (error_code & ICSWX_DSI_UCT) {
-               int rc = acop_handle_fault(regs, address, error_code);
+               rc = acop_handle_fault(regs, address, error_code);
                if (rc)
-                       return rc;
+                       goto bail;
        }
 #endif /* CONFIG_PPC_ICSWX */
 
        if (notify_page_fault(regs))
-               return 0;
+               goto bail;
 
        if (unlikely(debugger_fault_handler(regs)))
-               return 0;
+               goto bail;
 
        /* On a kernel SLB miss we can only check for a valid exception entry */
-       if (!user_mode(regs) && (address >= TASK_SIZE))
-               return SIGSEGV;
+       if (!user_mode(regs) && (address >= TASK_SIZE)) {
+               rc = SIGSEGV;
+               goto bail;
+       }
 
 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
                             defined(CONFIG_PPC_BOOK3S_64))
        if (error_code & DSISR_DABRMATCH) {
                /* breakpoint match */
                do_break(regs, address, error_code);
-               return 0;
+               goto bail;
        }
 #endif
 
@@ -260,8 +265,10 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
                local_irq_enable();
 
        if (in_atomic() || mm == NULL) {
-               if (!user_mode(regs))
-                       return SIGSEGV;
+               if (!user_mode(regs)) {
+                       rc = SIGSEGV;
+                       goto bail;
+               }
                /* in_atomic() in user mode is really bad,
                   as is current->mm == NULL. */
                printk(KERN_EMERG "Page fault in user mode with "
@@ -417,9 +424,11 @@ good_area:
         */
        fault = handle_mm_fault(mm, vma, address, flags);
        if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
-               int rc = mm_fault_error(regs, address, fault);
+               rc = mm_fault_error(regs, address, fault);
                if (rc >= MM_FAULT_RETURN)
-                       return rc;
+                       goto bail;
+               else
+                       rc = 0;
        }
 
        /*
@@ -454,7 +463,7 @@ good_area:
        }
 
        up_read(&mm->mmap_sem);
-       return 0;
+       goto bail;
 
 bad_area:
        up_read(&mm->mmap_sem);
@@ -463,7 +472,7 @@ bad_area_nosemaphore:
        /* User mode accesses cause a SIGSEGV */
        if (user_mode(regs)) {
                _exception(SIGSEGV, regs, code, address);
-               return 0;
+               goto bail;
        }
 
        if (is_exec && (error_code & DSISR_PROTFAULT))
@@ -471,7 +480,11 @@ bad_area_nosemaphore:
                                   " page (%lx) - exploit attempt? (uid: %d)\n",
                                   address, from_kuid(&init_user_ns, current_uid()));
 
-       return SIGSEGV;
+       rc = SIGSEGV;
+
+bail:
+       exception_exit(prev_state);
+       return rc;
 
 }