MIPS: kprobe: Add support.

This patch is based on previous work by Sony and Himanshu Chauhan.

I have done some cleanup and implemented JProbes and KRETPROBES.  The
KRETPROBES part is pretty much copied verbatim from powerpc.  A possible
future enhance might be to factor out the common code.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: Himanshu Chauhan <hschauhan@nulltrace.org>
To: linux-mips@linux-mips.org
To: ananth@in.ibm.com,
To: anil.s.keshavamurthy@intel.com
To: davem@davemloft.net
To: masami.hiramatsu.pt@hitachi.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1525/
Patchwork: https://patchwork.linux-mips.org/patch/1530/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index b4aac424b2e9..783ad0065fdf 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -17,6 +17,7 @@
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/module.h>
+#include <linux/kprobes.h>
 
 #include <asm/branch.h>
 #include <asm/mmu_context.h>
@@ -24,13 +25,14 @@
 #include <asm/uaccess.h>
 #include <asm/ptrace.h>
 #include <asm/highmem.h>                /* For VMALLOC_END */
+#include <linux/kdebug.h>
 
 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  */
-asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
                               unsigned long address)
 {
         struct vm_area_struct * vma = NULL;
@@ -46,6 +48,17 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
                field, regs->cp0_epc);
 #endif
 
+#ifdef CONFIG_KPROBES
+        /*
+         * This is to notify the fault handler of the kprobes.  The
+         * exception code is redundant as it is also carried in REGS,
+         * but we pass it anyhow.
+         */
+        if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
+                       (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
+                return;
+#endif
+
         info.si_code = SEGV_MAPERR;
 
         /*