Commit-ID:  e7f180dcd8ab48f18b20d7e8a7e9b39192bdf8e0
Gitweb:     http://git.kernel.org/tip/e7f180dcd8ab48f18b20d7e8a7e9b39192bdf8e0
Author:     Oleg Nesterov <[email protected]>
AuthorDate: Tue, 10 Mar 2015 07:06:24 +0100
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 10 Mar 2015 07:14:31 +0100

x86/fpu: Change xstateregs_get()/set() to use ->xsave.i387 rather than ->fxsave

This is a cosmetic change: xstateregs_get() and xstateregs_set()
abuse ->fxsave to access xsave->i387.sw_reserved.

This practice is correct, ->fxsave and xsave->i387 share the same memory,
but IMHO this looks confusing.

And we can make this code more readable if we add a
"struct xsave_struct *" local variable as well.

Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Tavis Ormandy <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/kernel/i387.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 8416b5f..03cc0ad 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -339,6 +339,7 @@ int xstateregs_get(struct task_struct *target, const struct 
user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)
 {
+       struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
        int ret;
 
        if (!cpu_has_xsave)
@@ -353,14 +354,12 @@ int xstateregs_get(struct task_struct *target, const 
struct user_regset *regset,
         * memory layout in the thread struct, so that we can copy the entire
         * xstateregs to the user using one user_regset_copyout().
         */
-       memcpy(&target->thread.fpu.state->fxsave.sw_reserved,
-              xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
-
+       memcpy(&xsave->i387.sw_reserved,
+               xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
        /*
         * Copy the xstate memory layout.
         */
-       ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-                                 &target->thread.fpu.state->xsave, 0, -1);
+       ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
        return ret;
 }
 
@@ -368,8 +367,8 @@ int xstateregs_set(struct task_struct *target, const struct 
user_regset *regset,
                  unsigned int pos, unsigned int count,
                  const void *kbuf, const void __user *ubuf)
 {
+       struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
        int ret;
-       struct xsave_hdr_struct *xsave_hdr;
 
        if (!cpu_has_xsave)
                return -ENODEV;
@@ -378,22 +377,16 @@ int xstateregs_set(struct task_struct *target, const 
struct user_regset *regset,
        if (ret)
                return ret;
 
-       ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-                                &target->thread.fpu.state->xsave, 0, -1);
-
+       ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
        /*
         * mxcsr reserved bits must be masked to zero for security reasons.
         */
-       target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
-
-       xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr;
-
-       xsave_hdr->xstate_bv &= pcntxt_mask;
+       xsave->i387.mxcsr &= mxcsr_feature_mask;
+       xsave->xsave_hdr.xstate_bv &= pcntxt_mask;
        /*
         * These bits must be zero.
         */
-       memset(xsave_hdr->reserved, 0, 48);
-
+       memset(&xsave->xsave_hdr.reserved, 0, 48);
        return ret;
 }
 
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