From: Kris Van Hees <kris.van.hees@oracle.com>
Date: Wed, 24 May 2017 03:34:53 +0000 (-0400)
Subject: dtrace: ensure limit is enforced even when pcs is NULL
X-Git-Tag: v4.1.12-102.0.20170529_2200~57^2~12
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=984f2b7ff4e5bf92c285cdb75075942d73d5d52b;p=users%2Fjedix%2Flinux-maple.git

dtrace: ensure limit is enforced even when pcs is NULL

The dtrace_user_stacktrace() functions for x86_64 and sparc64 were
not handling the specified limit (st->limit correctly if the buffer
for PC values (st->pcs) was NULL.  This commit ensures that we
decrement the limit whenever we encounter a PC, whether it gets
stored or not.

Orabug: 25949692
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Acked-by: Nick Alcock <nick.alcock@oracle.com>
---

diff --git a/arch/sparc/kernel/dtrace_util.c b/arch/sparc/kernel/dtrace_util.c
index 9e6629068225c..47e19175cd7b7 100644
--- a/arch/sparc/kernel/dtrace_util.c
+++ b/arch/sparc/kernel/dtrace_util.c
@@ -141,10 +141,9 @@ void dtrace_user_stacktrace(stacktrace_state_t *st)
 	flush_user_windows();
 
 	st->depth = 1;
-	if (pcs) {
+	if (pcs)
 		*pcs++ = (uint64_t)instruction_pointer(regs);
-		limit--;
-	}
+	limit--;
 
 	if (!limit)
 		goto out;
@@ -168,10 +167,9 @@ void dtrace_user_stacktrace(stacktrace_state_t *st)
 			addr = ((struct reg_window32 *)(&t->reg_window[window]))->ins[7];
 		}
 
-		if (pcs) {
+		if (pcs)
 			*pcs++ = addr;
-			limit--;
-		}
+		limit--;
 		st->depth++;
 
 		if (!limit)
@@ -206,10 +204,9 @@ void dtrace_user_stacktrace(stacktrace_state_t *st)
 		if (ret)
 			break;
 
-		if (pcs) {
+		if (pcs)
 			*pcs++ = addr;
-			limit--;
-		}
+		limit--;
 		st->depth++;
 
 		pagefault_disable();
diff --git a/arch/x86/kernel/dtrace_util.c b/arch/x86/kernel/dtrace_util.c
index edd5fdf05290e..53d3c121aaa62 100644
--- a/arch/x86/kernel/dtrace_util.c
+++ b/arch/x86/kernel/dtrace_util.c
@@ -373,10 +373,9 @@ void dtrace_user_stacktrace(stacktrace_state_t *st)
 	bos = current->dtrace_psinfo->ustack;
 
 	st->depth = 1;
-	if (pcs) {
+	if (pcs)
 		*pcs++ = (uint64_t)instruction_pointer(regs);
-		limit--;
-	}
+	limit--;
 
 	if (!limit)
 		goto out;
@@ -391,11 +390,12 @@ void dtrace_user_stacktrace(stacktrace_state_t *st)
 		if (ret)
 			break;
 
-		if (dtrace_user_addr_is_exec(pc) && pcs) {
-			*pcs++ = pc;
+		if (dtrace_user_addr_is_exec(pc)) {
+			if (pcs)
+				*pcs++ = pc;
 			limit--;
+			st->depth++;
 		}
-		st->depth++;
 
 		sp++;
 	}