7 files changed, 91 insertions, 42 deletions

diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 4e547296831d..52312cb5dbe2 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -47,9 +47,6 @@ struct thread_struct {
 /* Forward declaration, a strange C thing */
 struct task_struct;
 
-/* Return saved PC of a blocked thread  */
-unsigned long thread_saved_pc(struct task_struct *t);
-
 #define task_pt_regs(p) \
         ((struct pt_regs *)(THREAD_SIZE + (void *)task_stack_page(p)) - 1)
 
@@ -72,18 +69,21 @@ unsigned long thread_saved_pc(struct task_struct *t);
 #define release_segments(mm)        do { } while (0)
 
 #define KSTK_EIP(tsk)   (task_pt_regs(tsk)->ret)
+#define KSTK_ESP(tsk)   (task_pt_regs(tsk)->sp)
 
 /*
  * Where abouts of Task's sp, fp, blink when it was last seen in kernel mode.
  * Look in process.c for details of kernel stack layout
  */
-#define KSTK_ESP(tsk)   (tsk->thread.ksp)
+#define TSK_K_ESP(tsk)          (tsk->thread.ksp)
 
-#define KSTK_REG(tsk, off)      (*((unsigned int *)(KSTK_ESP(tsk) + \
+#define TSK_K_REG(tsk, off)     (*((unsigned int *)(TSK_K_ESP(tsk) + \
                                         sizeof(struct callee_regs) + off)))
 
-#define KSTK_BLINK(tsk) KSTK_REG(tsk, 4)
-#define KSTK_FP(tsk)    KSTK_REG(tsk, 0)
+#define TSK_K_BLINK(tsk)        TSK_K_REG(tsk, 4)
+#define TSK_K_FP(tsk)           TSK_K_REG(tsk, 0)
+
+#define thread_saved_pc(tsk)    TSK_K_BLINK(tsk)
 
 extern void start_thread(struct pt_regs * regs, unsigned long pc,
                          unsigned long usp);
diff --git a/arch/arc/include/asm/stacktrace.h b/arch/arc/include/asm/stacktrace.h
new file mode 100644
index 000000000000..b29b6064ea14
--- /dev/null
+++ b/arch/arc/include/asm/stacktrace.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com)
+ * Copyright (C) 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ASM_STACKTRACE_H
+#define __ASM_STACKTRACE_H
+
+#include <linux/sched.h>
+
+/**
+ * arc_unwind_core - Unwind the kernel mode stack for an execution context
+ * @tsk:                NULL for current task, specific task otherwise
+ * @regs:               pt_regs used to seed the unwinder {SP, FP, BLINK, PC}
+ *                      If NULL, use pt_regs of @tsk (if !NULL) otherwise
+ *                      use the current values of {SP, FP, BLINK, PC}
+ * @consumer_fn:        Callback invoked for each frame unwound
+ *                      Returns 0 to continue unwinding, -1 to stop
+ * @arg:                Arg to callback
+ *
+ * Returns the address of first function in stack
+ *
+ * Semantics:
+ *  - synchronous unwinding (e.g. dump_stack): @tsk  NULL, @regs  NULL
+ *  - Asynchronous unwinding of sleeping task: @tsk !NULL, @regs  NULL
+ *  - Asynchronous unwinding of intr/excp etc: @tsk !NULL, @regs !NULL
+ */
+notrace noinline unsigned int arc_unwind_core(
+        struct task_struct *tsk, struct pt_regs *regs,
+        int (*consumer_fn) (unsigned int, void *),
+        void *arg);
+
+#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index fdd89715d2d3..98c00a2d4dd9 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -192,29 +192,6 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
         return 0;
 }
 
-/*
- * API: expected by schedular Code: If thread is sleeping where is that.
- * What is this good for? it will be always the scheduler or ret_from_fork.
- * So we hard code that anyways.
- */
-unsigned long thread_saved_pc(struct task_struct *t)
-{
-        struct pt_regs *regs = task_pt_regs(t);
-        unsigned long blink = 0;
-
-        /*
-         * If the thread being queried for in not itself calling this, then it
-         * implies it is not executing, which in turn implies it is sleeping,
-         * which in turn implies it got switched OUT by the schedular.
-         * In that case, it's kernel mode blink can reliably retrieved as per
-         * the picture above (right above pt_regs).
-         */
-        if (t != current && t->state != TASK_RUNNING)
-                blink = *((unsigned int *)regs - 1);
-
-        return blink;
-}
-
 int elf_check_arch(const struct elf32_hdr *x)
 {
         unsigned int eflags;
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 114234e83caa..edda76fae83f 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -67,7 +67,7 @@ stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
                sigset_t *set)
 {
         int err;
-        err = __copy_to_user(&(sf->uc.uc_mcontext.regs), regs,
+        err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), regs,
                              sizeof(sf->uc.uc_mcontext.regs.scratch));
         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
 
@@ -83,7 +83,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
         if (!err)
                 set_current_blocked(&set);
 
-        err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs),
+        err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs.scratch),
                                 sizeof(sf->uc.uc_mcontext.regs.scratch));
 
         return err;
@@ -131,6 +131,15 @@ SYSCALL_DEFINE0(rt_sigreturn)
         /* Don't restart from sigreturn */
         syscall_wont_restart(regs);
 
+        /*
+         * Ensure that sigreturn always returns to user mode (in case the
+         * regs saved on user stack got fudged between save and sigreturn)
+         * Otherwise it is easy to panic the kernel with a custom
+         * signal handler and/or restorer which clobberes the status32/ret
+         * to return to a bogus location in kernel mode.
+         */
+        regs->status32 |= STATUS_U_MASK;
+
         return regs->r0;
 
 badframe:
@@ -229,8 +238,11 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 
         /*
          * handler returns using sigreturn stub provided already by userpsace
+         * If not, nuke the process right away
          */
-        BUG_ON(!(ksig->ka.sa.sa_flags & SA_RESTORER));
+        if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
+                return 1;
+
         regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
 
         /* User Stack for signal handler will be above the frame just carved */
@@ -296,12 +308,12 @@ static void
 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 {
         sigset_t *oldset = sigmask_to_save();
-        int ret;
+        int failed;
 
         /* Set up the stack frame */
-        ret = setup_rt_frame(ksig, oldset, regs);
+        failed = setup_rt_frame(ksig, oldset, regs);
 
-        signal_setup_done(ret, ksig, 0);
+        signal_setup_done(failed, ksig, 0);
 }
 
 void do_signal(struct pt_regs *regs)
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index 9ce47cfe2303..92320d6f737c 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -43,6 +43,10 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                                    struct pt_regs *regs,
                                    struct unwind_frame_info *frame_info)
 {
+        /*
+         * synchronous unwinding (e.g. dump_stack)
+         *  - uses current values of SP and friends
+         */
         if (tsk == NULL && regs == NULL) {
                 unsigned long fp, sp, blink, ret;
                 frame_info->task = current;
@@ -61,12 +65,17 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                 frame_info->regs.r63 = ret;
                 frame_info->call_frame = 0;
         } else if (regs == NULL) {
+                /*
+                 * Asynchronous unwinding of sleeping task
+                 *  - Gets SP etc from task's pt_regs (saved bottom of kernel
+                 *    mode stack of task)
+                 */
 
                 frame_info->task = tsk;
 
-                frame_info->regs.r27 = KSTK_FP(tsk);
-                frame_info->regs.r28 = KSTK_ESP(tsk);
-                frame_info->regs.r31 = KSTK_BLINK(tsk);
+                frame_info->regs.r27 = TSK_K_FP(tsk);
+                frame_info->regs.r28 = TSK_K_ESP(tsk);
+                frame_info->regs.r31 = TSK_K_BLINK(tsk);
                 frame_info->regs.r63 = (unsigned int)__switch_to;
 
                 /* In the prologue of __switch_to, first FP is saved on stack
@@ -83,6 +92,10 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
                 frame_info->call_frame = 0;
 
         } else {
+                /*
+                 * Asynchronous unwinding of intr/exception
+                 *  - Just uses the pt_regs passed
+                 */
                 frame_info->task = tsk;
 
                 frame_info->regs.r27 = regs->fp;
@@ -95,7 +108,7 @@ static void seed_unwind_frame_info(struct task_struct *tsk,
 
 #endif
 
-static noinline unsigned int
+notrace noinline unsigned int
 arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
                 int (*consumer_fn) (unsigned int, void *), void *arg)
 {
diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
index 7ff5b5c183bb..74db59b6f392 100644
--- a/arch/arc/kernel/unaligned.c
+++ b/arch/arc/kernel/unaligned.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/types.h>
+#include <linux/perf_event.h>
 #include <linux/ptrace.h>
 #include <linux/uaccess.h>
 #include <asm/disasm.h>
@@ -253,6 +254,7 @@ int misaligned_fixup(unsigned long address, struct pt_regs *regs,
                 }
         }
 
+        perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, address);
         return 0;
 
 fault:
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 563cb27e37f5..6a2e006cbcce 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -14,6 +14,7 @@
 #include <linux/ptrace.h>
 #include <linux/uaccess.h>
 #include <linux/kdebug.h>
+#include <linux/perf_event.h>
 #include <asm/pgalloc.h>
 #include <asm/mmu.h>
 
@@ -139,13 +140,20 @@ good_area:
                         return;
         }
 
+        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+
         if (likely(!(fault & VM_FAULT_ERROR))) {
                 if (flags & FAULT_FLAG_ALLOW_RETRY) {
                         /* To avoid updating stats twice for retry case */
-                        if (fault & VM_FAULT_MAJOR)
+                        if (fault & VM_FAULT_MAJOR) {
                                 tsk->maj_flt++;
-                        else
+                                perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+                                              regs, address);
+                        } else {
                                 tsk->min_flt++;
+                                perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+                                              regs, address);
+                        }
 
                         if (fault & VM_FAULT_RETRY) {
                                 flags &= ~FAULT_FLAG_ALLOW_RETRY;