linux-kernel - [PATCH v3 51/51] x86/mm: convert arch_within_stack

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Date:	Fri, 12 Aug 2016 09:29:10 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	"H . Peter Anvin" <hpa@...or.com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Brian Gerst <brgerst@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Byungchul Park <byungchul.park@....com>,
	Nilay Vaish <nilayvaish@...il.com>
Subject: [PATCH v3 51/51] x86/mm: convert arch_within_stack_frames() to use the new unwinder

Convert arch_within_stack_frames() to use the new unwinder.

Boot tested with CONFIG_HARDENED_USERCOPY.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/lib/usercopy.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 96ce151..9d0913c 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -50,12 +50,21 @@ int arch_within_stack_frames(const void * const stack,
 			     const void * const stackend,
 			     const void *obj, unsigned long len)
 {
-	const void *frame = NULL;
-	const void *oldframe;
+	struct unwind_state state;
+	const void *frame, *oldframe;
+
+	unwind_start(&state, current, NULL, NULL);
+
+	if (!unwind_next_frame(&state))
+		return 0;
+
+	oldframe = unwind_get_stack_ptr(&state);
+
+	if (!unwind_next_frame(&state))
+		return 0;
+
+	frame = unwind_get_stack_ptr(&state);
 
-	oldframe = __builtin_frame_address(2);
-	if (oldframe)
-		frame = __builtin_frame_address(3);
 	/*
 	 * low ----------------------------------------------> high
 	 * [saved bp][saved ip][args][local vars][saved bp][saved ip]
@@ -71,8 +80,12 @@ int arch_within_stack_frames(const void * const stack,
 		 */
 		if (obj + len <= frame)
 			return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
+
+		if (!unwind_next_frame(&state))
+			return 0;
+
 		oldframe = frame;
-		frame = *(const void * const *)frame;
+		frame = unwind_get_stack_ptr(&state);
 	}
 	return -1;
 }
-- 
2.7.4