arch/tile: support signal "exception-trace" hook

This change adds support for /proc/sys/debug/exception-trace to tile.
Like x86 and sparc, by default it is set to "1", generating a one-line
printk whenever a user process crashes.  By setting it to "2", we get
a much more complete userspace diagnostic at crash time, including
a user-space backtrace, register dump, and memory dump around the
address of the crash.

Some vestiges of the Tilera-internal version of this support are
removed with this patch (the show_crashinfo variable and the
arch_coredump_signal function).  We retain a "crashinfo" boot parameter
which allows you to set the boot-time value of exception-trace.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 15 insertions, 9 deletions

diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 24ca54a0703..25b7b90fd62 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -43,8 +43,11 @@
 
 #include <arch/interrupts.h>
 
-static noinline void force_sig_info_fault(int si_signo, int si_code,
-	unsigned long address, int fault_num, struct task_struct *tsk)
+static noinline void force_sig_info_fault(const char *type, int si_signo,
+					  int si_code, unsigned long address,
+					  int fault_num,
+					  struct task_struct *tsk,
+					  struct pt_regs *regs)
 {
 	siginfo_t info;
 
@@ -59,6 +62,7 @@ static noinline void force_sig_info_fault(int si_signo, int si_code,
 	info.si_code = si_code;
 	info.si_addr = (void __user *)address;
 	info.si_trapno = fault_num;
+	trace_unhandled_signal(type, regs, address, si_signo);
 	force_sig_info(si_signo, &info, tsk);
 }
 
@@ -71,11 +75,12 @@ SYSCALL_DEFINE2(cmpxchg_badaddr, unsigned long, address,
 		struct pt_regs *, regs)
 {
 	if (address >= PAGE_OFFSET)
-		force_sig_info_fault(SIGSEGV, SEGV_MAPERR, address,
-				     INT_DTLB_MISS, current);
+		force_sig_info_fault("atomic segfault", SIGSEGV, SEGV_MAPERR,
+				     address, INT_DTLB_MISS, current, regs);
 	else
-		force_sig_info_fault(SIGBUS, BUS_ADRALN, address,
-				     INT_UNALIGN_DATA, current);
+		force_sig_info_fault("atomic alignment fault", SIGBUS,
+				     BUS_ADRALN, address,
+				     INT_UNALIGN_DATA, current, regs);
 
 	/*
 	 * Adjust pc to point at the actual instruction, which is unusual
@@ -471,8 +476,8 @@ bad_area_nosemaphore:
 		 */
 		local_irq_enable();
 
-		force_sig_info_fault(SIGSEGV, si_code, address,
-				     fault_num, tsk);
+		force_sig_info_fault("segfault", SIGSEGV, si_code, address,
+				     fault_num, tsk, regs);
 		return 0;
 	}
 
@@ -547,7 +552,8 @@ do_sigbus:
 	if (is_kernel_mode)
 		goto no_context;
 
-	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, fault_num, tsk);
+	force_sig_info_fault("bus error", SIGBUS, BUS_ADRERR, address,
+			     fault_num, tsk, regs);
 	return 0;
 }