[PATCH 04/14] x86/fpu: Remove 'kbuf' parameter from the copy_xstate_to_user() APIs

[Ingo Molnar]

The 'kbuf' parameter is unused in the _user() side of the API, remove it.

This simplifies the code and makes it easier to think about.

Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/fpu/xstate.h |  2 +-
 arch/x86/kernel/fpu/regset.c      |  2 +-
 arch/x86/kernel/fpu/xstate.c      | 25 +++++++------------------
 3 files changed, 9 insertions(+), 20 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index c762574a245f..65bd68c30cd0 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -49,7 +49,7 @@ void *get_xsave_addr(struct xregs_state *xsave, int xstate);
 const void *get_xsave_field_ptr(int xstate_field);
 int using_compacted_format(void);
 int copy_xstate_to_kernel(unsigned int pos, unsigned int count, void *kbuf, struct xregs_state *xsave);
-int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf, struct xregs_state *xsave);
+int copy_xstate_to_user(unsigned int pos, unsigned int count, void __user *ubuf, struct xregs_state *xsave);
 int copy_user_to_xstate(const void *kbuf, const void __user *ubuf,
 		     struct xregs_state *xsave);
 #endif
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index a5f2b38a47dc..62a2d1154e45 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -94,7 +94,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 		if (kbuf)
 			ret = copy_xstate_to_kernel(pos, count, kbuf, xsave);
 		else
-			ret = copy_xstate_to_user(pos, count, kbuf, ubuf, xsave);
+			ret = copy_xstate_to_user(pos, count, ubuf, xsave);
 	} else {
 		fpstate_sanitize_xstate(fpu);
 		/*
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 6ac8e4a759ff..1ac3d2ae73e6 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1010,10 +1010,7 @@ int copy_xstate_to_kernel(unsigned int pos, unsigned int count, void *kbuf, stru
 }
 
 static inline int
-__copy_xstate_to_user(unsigned int pos, unsigned int count,
-		      void *kbuf, void __user *ubuf,
-		      const void *data, const int start_pos,
-		      const int end_pos)
+__copy_xstate_to_user(unsigned int pos, unsigned int count, void __user *ubuf, const void *data, const int start_pos, const int end_pos)
 {
 	if ((count == 0) || (pos < start_pos))
 		return 0;
@@ -1021,12 +1018,8 @@ __copy_xstate_to_user(unsigned int pos, unsigned int count,
 	if (end_pos < 0 || pos < end_pos) {
 		unsigned int copy = (end_pos < 0 ? count : min(count, end_pos - pos));
 
-		if (kbuf) {
-			memcpy(kbuf + pos, data, copy);
-		} else {
-			if (__copy_to_user(ubuf + pos, data, copy))
-				return -EFAULT;
-		}
+		if (__copy_to_user(ubuf + pos, data, copy))
+			return -EFAULT;
 	}
 	return 0;
 }
@@ -1037,8 +1030,7 @@ __copy_xstate_to_user(unsigned int pos, unsigned int count,
  * zero. This is called from xstateregs_get() and there we check the CPU
  * has XSAVES.
  */
-int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
-			void __user *ubuf, struct xregs_state *xsave)
+int copy_xstate_to_user(unsigned int pos, unsigned int count, void __user *ubuf, struct xregs_state *xsave)
 {
 	unsigned int offset, size;
 	int ret, i;
@@ -1063,8 +1055,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
 	offset = offsetof(struct xregs_state, header);
 	size = sizeof(header);
 
-	ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, &header, 0, count);
-
+	ret = __copy_xstate_to_user(offset, size, ubuf, &header, 0, count);
 	if (ret)
 		return ret;
 
@@ -1078,8 +1069,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
 			offset = xstate_offsets[i];
 			size = xstate_sizes[i];
 
-			ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, src, 0, count);
-
+			ret = __copy_xstate_to_user(offset, size, ubuf, src, 0, count);
 			if (ret)
 				return ret;
 
@@ -1095,8 +1085,7 @@ int copy_xstate_to_user(unsigned int pos, unsigned int count, void *kbuf,
 	offset = offsetof(struct fxregs_state, sw_reserved);
 	size = sizeof(xstate_fx_sw_bytes);
 
-	ret = __copy_xstate_to_user(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count);
-
+	ret = __copy_xstate_to_user(offset, size, ubuf, xstate_fx_sw_bytes, 0, count);
 	if (ret)
 		return ret;
 
-- 
2.7.4