3 files changed, 16 insertions, 53 deletions

diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index bd3507da39f0..2836de390f95 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -58,28 +58,6 @@ static void cpuid_smp_cpuid(void *cmd_block)
 		    &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx);
 }
 
-static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
-{
-	loff_t ret;
-	struct inode *inode = file->f_mapping->host;
-
-	mutex_lock(&inode->i_mutex);
-	switch (orig) {
-	case 0:
-		file->f_pos = offset;
-		ret = file->f_pos;
-		break;
-	case 1:
-		file->f_pos += offset;
-		ret = file->f_pos;
-		break;
-	default:
-		ret = -EINVAL;
-	}
-	mutex_unlock(&inode->i_mutex);
-	return ret;
-}
-
 static ssize_t cpuid_read(struct file *file, char __user *buf,
 			  size_t count, loff_t *ppos)
 {
@@ -132,7 +110,7 @@ static int cpuid_open(struct inode *inode, struct file *file)
  */
 static const struct file_operations cpuid_fops = {
 	.owner = THIS_MODULE,
-	.llseek = cpuid_seek,
+	.llseek = no_seek_end_llseek,
 	.read = cpuid_read,
 	.open = cpuid_open,
 };
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 311bcf338f07..29408d6d6626 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -105,14 +105,14 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
 {
 	unsigned char replaced[MCOUNT_INSN_SIZE];
 
+	ftrace_expected = old_code;
+
 	/*
-	 * Note: Due to modules and __init, code can
-	 *  disappear and change, we need to protect against faulting
-	 *  as well as code changing. We do this by using the
-	 *  probe_kernel_* functions.
-	 *
-	 * No real locking needed, this code is run through
-	 * kstop_machine, or before SMP starts.
+	 * Note:
+	 * We are paranoid about modifying text, as if a bug was to happen, it
+	 * could cause us to read or write to someplace that could cause harm.
+	 * Carefully read and modify the code with probe_kernel_*(), and make
+	 * sure what we read is what we expected it to be before modifying it.
 	 */
 
 	/* read the text we want to modify */
@@ -154,6 +154,8 @@ int ftrace_make_nop(struct module *mod,
 	if (addr == MCOUNT_ADDR)
 		return ftrace_modify_code_direct(rec->ip, old, new);
 
+	ftrace_expected = NULL;
+
 	/* Normal cases use add_brk_on_nop */
 	WARN_ONCE(1, "invalid use of ftrace_make_nop");
 	return -EINVAL;
@@ -220,6 +222,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 				 unsigned long addr)
 {
 	WARN_ON(1);
+	ftrace_expected = NULL;
 	return -EINVAL;
 }
 
@@ -314,6 +317,8 @@ static int add_break(unsigned long ip, const char *old)
 	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
+	ftrace_expected = old;
+
 	/* Make sure it is what we expect it to be */
 	if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
 		return -EINVAL;
@@ -413,6 +418,8 @@ static int remove_breakpoint(struct dyn_ftrace *rec)
 		ftrace_addr = ftrace_get_addr_curr(rec);
 		nop = ftrace_call_replace(ip, ftrace_addr);
 
+		ftrace_expected = nop;
+
 		if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
 			return -EINVAL;
 	}
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 113e70784854..64f9616f93f1 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -45,28 +45,6 @@
 
 static struct class *msr_class;
 
-static loff_t msr_seek(struct file *file, loff_t offset, int orig)
-{
-	loff_t ret;
-	struct inode *inode = file_inode(file);
-
-	mutex_lock(&inode->i_mutex);
-	switch (orig) {
-	case SEEK_SET:
-		file->f_pos = offset;
-		ret = file->f_pos;
-		break;
-	case SEEK_CUR:
-		file->f_pos += offset;
-		ret = file->f_pos;
-		break;
-	default:
-		ret = -EINVAL;
-	}
-	mutex_unlock(&inode->i_mutex);
-	return ret;
-}
-
 static ssize_t msr_read(struct file *file, char __user *buf,
 			size_t count, loff_t *ppos)
 {
@@ -194,7 +172,7 @@ static int msr_open(struct inode *inode, struct file *file)
  */
 static const struct file_operations msr_fops = {
 	.owner = THIS_MODULE,
-	.llseek = msr_seek,
+	.llseek = no_seek_end_llseek,
 	.read = msr_read,
 	.write = msr_write,
 	.open = msr_open,