perf: Fix arch_perf_out_copy_user default

The arch_perf_output_copy_user() default of
__copy_from_user_inatomic() returns bytes not copied, while all other
argument functions given DEFINE_OUTPUT_COPY() return bytes copied.

Since copy_from_user_nmi() is the odd duck out by returning bytes
copied where all other *copy_{to,from}* functions return bytes not
copied, change it over and ammend DEFINE_OUTPUT_COPY() to expect bytes
not copied.

Oddly enough DEFINE_OUTPUT_COPY() already returned bytes not copied
while expecting its worker functions to return bytes copied.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: will.deacon@arm.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20131030201622.GR16117@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 7 insertions, 7 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 8a87a322412..8e132931614 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1989,7 +1989,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
 		frame.return_address = 0;
 
 		bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
-		if (bytes != sizeof(frame))
+		if (bytes != 0)
 			break;
 
 		if (!valid_user_frame(fp, sizeof(frame)))
@@ -2041,7 +2041,7 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 		frame.return_address = 0;
 
 		bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
-		if (bytes != sizeof(frame))
+		if (bytes != 0)
 			break;
 
 		if (!valid_user_frame(fp, sizeof(frame)))
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index c1760ff3c75..ae96cfa5edd 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -789,7 +789,7 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs)
 
 		size = ip - to; /* Must fit our buffer, see above */
 		bytes = copy_from_user_nmi(buf, (void __user *)to, size);
-		if (bytes != size)
+		if (bytes != 0)
 			return 0;
 
 		kaddr = buf;
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 90ee6c1d054..d82d155aca8 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -491,7 +491,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort)
 
 		/* may fail if text not present */
 		bytes = copy_from_user_nmi(buf, (void __user *)from, size);
-		if (bytes != size)
+		if (bytes != 0)
 			return X86_BR_NONE;
 
 		addr = buf;
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 5465b861394..ddf9ecb53cc 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -31,6 +31,6 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
 	ret = __copy_from_user_inatomic(to, from, n);
 	pagefault_enable();
 
-	return n - ret;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(copy_from_user_nmi);
diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index d6aa6e8315d..5d04be5efb6 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -47,7 +47,7 @@ dump_user_backtrace_32(struct stack_frame_ia32 *head)
 	unsigned long bytes;
 
 	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
-	if (bytes != sizeof(bufhead))
+	if (bytes != 0)
 		return NULL;
 
 	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
@@ -93,7 +93,7 @@ static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
 	unsigned long bytes;
 
 	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
-	if (bytes != sizeof(bufhead))
+	if (bytes != 0)
 		return NULL;
 
 	oprofile_add_trace(bufhead[0].return_address);