On Mon, May 02, 2016 at 02:32:14PM -0700, Dave Hansen wrote:
>
> I think we're off in the weeds here.
>
> Please just send an updated patch for what you want to do here.
>From 43134a773d23ae8bab9f158d143c5cfb76bc0e9c Mon Sep 17 00:00:00 2001
From: Yu-cheng Yu <yu-cheng...@intel.com>
Date: Sat, 14 Nov 2015 16:59:45 -0800
Subject: [PATCH] x86/xsaves: Introduce a new check that allows correct xstates
copy from kernel to user directly
XSAVES is a kernel instruction and uses a compacted format. When working with
user space, the kernel should provide
standard-format, non-supervisor state data. We cannot do __copy_to_user() from
a compacted- format kernel xstate area to a
signal frame.
Dave Hansen proposes this method to simplify copy xstate directly to user.
Signed-off-by: Fenghua Yu <fenghua...@intel.com>
Signed-off by: Yu-cheng Yu <yu-cheng...@intel.com>
---
arch/x86/include/asm/fpu/xstate.h | 1 +
arch/x86/kernel/fpu/signal.c | 3 ++-
arch/x86/kernel/fpu/xstate.c | 2 +-
3 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/fpu/xstate.h
b/arch/x86/include/asm/fpu/xstate.h
index 16df2c4..d812cf3 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -47,5 +47,6 @@ extern void update_regset_xstate_info(unsigned int size, u64
xstate_mask);
void fpu__xstate_clear_all_cpu_caps(void);
void *get_xsave_addr(struct xregs_state *xsave, int xstate);
const void *get_xsave_field_ptr(int xstate_field);
+int using_compacted_format(void);
#endif
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 0fbf60c..d7fdd8c 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -8,6 +8,7 @@
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
+#include <asm/fpu/xstate.h>
#include <asm/sigframe.h>
@@ -167,7 +168,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user
*buf_fx, int size)
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_32 __user *) buf) ? -1 : 1;
- if (fpregs_active()) {
+ if (fpregs_active() || using_compacted_format()) {
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 170c164..2b59bd7 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -415,7 +415,7 @@ static int xfeature_size(int xfeature_nr)
* that it is obvious which aspect of 'XSAVES' is being handled
* by the calling code.
*/
-static int using_compacted_format(void)
+int using_compacted_format(void)
{
return cpu_has_xsaves;
}
--
1.9.1
