Messages in this thread Patch in this message | | | From | Yu-cheng Yu <> | Subject | [PATCH v5 04/13] x86/xsaves: Introduce a new check that allows correct xstates copy from kernel to user directly | Date | Mon, 9 May 2016 13:46:01 -0700 |
| |
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.yu@intel.com> Signed-off by: Yu-cheng Yu <yu-cheng.yu@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
| |