[PATCH 2/4] x86/kprobes: Fix frame pointer annotations

From: Peter Zijlstra <peterz@infradead.org>
To: linux-kernel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolai Stange <nstange@suse.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Shuah Khan <shuah@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Mimi Zohar <zohar@linux.ibm.com>, Juergen Gross <jgross@suse.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nayna Jain <nayna@linux.ibm.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Joerg Roedel <jroedel@suse.de>,
	linux-kselftest@vger.kernel.org,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: [PATCH 2/4] x86/kprobes: Fix frame pointer annotations
Date: Wed, 08 May 2019 09:49:03 +0200	[thread overview]
Message-ID: <20190508080612.721269814@infradead.org> (raw)
In-Reply-To: 20190508074901.982470324@infradead.org

The kprobe trampolines have a FRAME_POINTER annotation that makes no
sense. It marks the frame in the middle of pt_regs, at the place of
saving BP.

Change it to mark the pt_regs frame as per the ENCODE_FRAME_POINTER
from the respective entry_*.S.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/kernel/kprobes/common.h |   32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

--- a/arch/x86/kernel/kprobes/common.h
+++ b/arch/x86/kernel/kprobes/common.h
@@ -6,14 +6,15 @@
 
 #include <asm/asm.h>
 
+#ifdef CONFIG_X86_64
+
 #ifdef CONFIG_FRAME_POINTER
-# define SAVE_RBP_STRING "	push %" _ASM_BP "\n" \
-			 "	mov  %" _ASM_SP ", %" _ASM_BP "\n"
+#define ENCODE_FRAME_POINTER			\
+	"	leaq 1(%rsp), %rbp\n"
 #else
-# define SAVE_RBP_STRING "	push %" _ASM_BP "\n"
+#define ENCODE_FRAME_POINTER
 #endif
 
-#ifdef CONFIG_X86_64
 #define SAVE_REGS_STRING			\
 	/* Skip cs, ip, orig_ax. */		\
 	"	subq $24, %rsp\n"		\
@@ -27,11 +28,13 @@
 	"	pushq %r10\n"			\
 	"	pushq %r11\n"			\
 	"	pushq %rbx\n"			\
-	SAVE_RBP_STRING				\
+	"	pushq %rbp\n"			\
 	"	pushq %r12\n"			\
 	"	pushq %r13\n"			\
 	"	pushq %r14\n"			\
-	"	pushq %r15\n"
+	"	pushq %r15\n"			\
+	ENCODE_FRAME_POINTER
+
 #define RESTORE_REGS_STRING			\
 	"	popq %r15\n"			\
 	"	popq %r14\n"			\
@@ -51,19 +54,30 @@
 	/* Skip orig_ax, ip, cs */		\
 	"	addq $24, %rsp\n"
 #else
+
+#ifdef CONFIG_FRAME_POINTER
+#define ENCODE_FRAME_POINTER			\
+	"	movl %esp, %ebp\n"		\
+	"	andl $0x7fffffff, %ebp\n"
+#else
+#define ENCODE_FRAME_POINTER
+#endif
+
 #define SAVE_REGS_STRING			\
 	/* Skip cs, ip, orig_ax and gs. */	\
-	"	subl $16, %esp\n"		\
+	"	subl $4*4, %esp\n"		\
 	"	pushl %fs\n"			\
 	"	pushl %es\n"			\
 	"	pushl %ds\n"			\
 	"	pushl %eax\n"			\
-	SAVE_RBP_STRING				\
+	"	pushl %ebp\n"			\
 	"	pushl %edi\n"			\
 	"	pushl %esi\n"			\
 	"	pushl %edx\n"			\
 	"	pushl %ecx\n"			\
-	"	pushl %ebx\n"
+	"	pushl %ebx\n"			\
+	ENCODE_FRAME_POINTER
+
 #define RESTORE_REGS_STRING			\
 	"	popl %ebx\n"			\
 	"	popl %ecx\n"			\


