From 4a740604d94b6420d074e0b2229e8f6a96c10c16 Mon Sep 17 00:00:00 2001
From: Dan Pasanen <dan.pasanen@gmail.com>
Date: Wed, 26 Aug 2015 09:18:42 -0500
Subject: [PATCH] Revert "Revert "CHROMIUM: arch/arm: move secure_computing
 into trace; respect return code""

This reverts commit a25e94221e7b9023a3c1ee606897f2d5ee20a3db.

Change-Id: Ic0f0e2a217656f5500058760cbde35277f50c09c
---
 arch/arm/kernel/entry-common.S |  7 +------
 arch/arm/kernel/ptrace.c       | 13 +++++++++++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 5b52787419e..c314304f77e 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -452,12 +452,7 @@ ENTRY(vector_swi)
 
 #ifdef CONFIG_SECCOMP
 	tst	r10, #_TIF_SECCOMP
-	beq	1f
-	mov	r0, scno
-	bl	__secure_computing	
-	add	r0, sp, #S_R0 + S_OFF		@ pointer to regs
-	ldmia	r0, {r0 - r3}			@ have to reload r0 - r3
-1:
+	bne	__sys_trace
 #endif
 
 	tst	r10, #_TIF_SYSCALL_WORK		@ are we tracing syscalls?
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index d407ebf4180..282a99e1be1 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -910,12 +910,16 @@ long arch_ptrace(struct task_struct *child, long request,
 asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 {
 	unsigned long ip;
+	current_thread_info()->syscall = scno;
 
 	if (why)
 		audit_syscall_exit(regs);
-	else
+	else {
+		if (secure_computing(scno) == -1)
+			return -1;
 		audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0,
 				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
+	}
 
 	if (why == 0 && test_and_clear_thread_flag(TIF_SYSCALL_RESTARTSYS))
 		scno = __NR_restart_syscall - __NR_SYSCALL_BASE;
@@ -924,7 +928,12 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
 	if (!(current->ptrace & PT_PTRACED))
 		return scno;
 
-	current_thread_info()->syscall = scno;
+	/*
+	 * IP is used to denote syscall entry/exit:
+	 * IP = 0 -> entry, =1 -> exit
+	 */
+	ip = regs->ARM_ip;
+	regs->ARM_ip = why;
 
 	/*
 	 * IP is used to denote syscall entry/exit: