x86/fpu: Rename xsave.header::xstate_bv to 'xfeatures'

'xsave.header::xstate_bv' is a misnomer - what does 'bv' stand for?

It probably comes from the 'XGETBV' instruction name, but I could
not find in the Intel documentation where that abbreviation comes
from. It could mean 'bit vector' - or something else?

But how about - instead of guessing about a weird name - we named
the field in an obvious and descriptive way that tells us exactly
what it does?

So rename it to 'xfeatures', which is a bitmask of the
xfeatures that are fpstate_active in that context structure.

Eyesore like:

           fpu->state->xsave.xsave_hdr.xstate_bv |= XSTATE_FP;

is now much more readable:

           fpu->state->xsave.header.xfeatures |= XSTATE_FP;

Which form is not just infinitely more readable, but is also
shorter as well.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 3007df9..07c6adc 100644 (file)
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -261,7 +261,7 @@ static inline int fpu_save_init(struct fpu *fpu)
                /*
                 * xsave header may indicate the init state of the FP.
                 */
-               if (!(fpu->state->xsave.header.xstate_bv & XSTATE_FP))
+               if (!(fpu->state->xsave.header.xfeatures & XSTATE_FP))
                        return 1;
        } else if (use_fxsr()) {
                fpu_fxsave(fpu);

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 33c0c7b..9bd2cd1 100644 (file)
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -100,7 +100,7 @@ struct bndcsr {
 } __packed;
 
 struct xstate_header {
-       u64                             xstate_bv;
+       u64                             xfeatures;
        u64                             xcomp_bv;
        u64                             reserved[6];
 } __attribute__((packed));

diff --git a/arch/x86/include/asm/user.h b/arch/x86/include/asm/user.h
index fa04241..59a54e8 100644 (file)
--- a/arch/x86/include/asm/user.h
+++ b/arch/x86/include/asm/user.h
@@ -15,7 +15,7 @@ struct user_ymmh_regs {
 };
 
 struct user_xstate_header {
-       __u64 xstate_bv;
+       __u64 xfeatures;
        __u64 reserved1[2];
        __u64 reserved2[5];
 };
@@ -41,11 +41,11 @@ struct user_xstate_header {
  * particular process/thread.
  *
  * Also when the user modifies certain state FP/SSE/etc through the
- * ptrace interface, they must ensure that the header.xstate_bv
+ * ptrace interface, they must ensure that the header.xfeatures
  * bytes[512..519] of the memory layout are updated correspondingly.
  * i.e., for example when FP state is modified to a non-init state,
- * header.xstate_bv's bit 0 must be set to '1', when SSE is modified to
- * non-init state, header.xstate_bv's bit 1 must to be set to '1', etc.
+ * header.xfeatures's bit 0 must be set to '1', when SSE is modified to
+ * non-init state, header.xfeatures's bit 1 must to be set to '1', etc.
  */
 #define USER_XSTATE_FX_SW_WORDS 6
 #define USER_XSTATE_XCR0_WORD  0

diff --git a/arch/x86/include/uapi/asm/sigcontext.h b/arch/x86/include/uapi/asm/sigcontext.h
index 7f850f7..0e8a973 100644 (file)
--- a/arch/x86/include/uapi/asm/sigcontext.h
+++ b/arch/x86/include/uapi/asm/sigcontext.h
@@ -25,7 +25,7 @@ struct _fpx_sw_bytes {
        __u32 extended_size;    /* total size of the layout referred by
                                 * fpstate pointer in the sigcontext.
                                 */
-       __u64 xstate_bv;
+       __u64 xfeatures;
                                /* feature bit mask (including fp/sse/extended
                                 * state) that is present in the memory
                                 * layout.
@@ -210,7 +210,7 @@ struct sigcontext {
 #endif /* !__i386__ */
 
 struct _header {
-       __u64 xstate_bv;
+       __u64 xfeatures;
        __u64 reserved1[2];
        __u64 reserved2[5];
 };

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 74189f3..ae8f26b 100644 (file)
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -470,7 +470,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
         * presence of FP and SSE state.
         */
        if (cpu_has_xsave)
-               fpu->state->xsave.header.xstate_bv |= XSTATE_FPSSE;
+               fpu->state->xsave.header.xfeatures |= XSTATE_FPSSE;
 
        return ret;
 }
@@ -528,7 +528,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
         * mxcsr reserved bits must be masked to zero for security reasons.
         */
        xsave->i387.mxcsr &= mxcsr_feature_mask;
-       xsave->header.xstate_bv &= xfeatures_mask;
+       xsave->header.xfeatures &= xfeatures_mask;
        /*
         * These bits must be zero.
         */
@@ -740,7 +740,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
         * presence of FP.
         */
        if (cpu_has_xsave)
-               fpu->state->xsave.header.xstate_bv |= XSTATE_FP;
+               fpu->state->xsave.header.xfeatures |= XSTATE_FP;
        return ret;
 }
 

diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index 03639fa..467e463 100644 (file)
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -32,7 +32,7 @@ static unsigned int xfeatures_nr;
 /*
  * If a processor implementation discern that a processor state component is
  * in its initialized state it may modify the corresponding bit in the
- * header.xstate_bv as '0', with out modifying the corresponding memory
+ * header.xfeatures as '0', with out modifying the corresponding memory
  * layout in the case of xsaveopt. While presenting the xstate information to
  * the user, we always ensure that the memory layout of a feature will be in
  * the init state if the corresponding header bit is zero. This is to ensure
@@ -43,24 +43,24 @@ void __sanitize_i387_state(struct task_struct *tsk)
 {
        struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
        int feature_bit = 0x2;
-       u64 xstate_bv;
+       u64 xfeatures;
 
        if (!fx)
                return;
 
-       xstate_bv = tsk->thread.fpu.state->xsave.header.xstate_bv;
+       xfeatures = tsk->thread.fpu.state->xsave.header.xfeatures;
 
        /*
         * None of the feature bits are in init state. So nothing else
         * to do for us, as the memory layout is up to date.
         */
-       if ((xstate_bv & xfeatures_mask) == xfeatures_mask)
+       if ((xfeatures & xfeatures_mask) == xfeatures_mask)
                return;
 
        /*
         * FP is in init state
         */
-       if (!(xstate_bv & XSTATE_FP)) {
+       if (!(xfeatures & XSTATE_FP)) {
                fx->cwd = 0x37f;
                fx->swd = 0;
                fx->twd = 0;
@@ -73,17 +73,17 @@ void __sanitize_i387_state(struct task_struct *tsk)
        /*
         * SSE is in init state
         */
-       if (!(xstate_bv & XSTATE_SSE))
+       if (!(xfeatures & XSTATE_SSE))
                memset(&fx->xmm_space[0], 0, 256);
 
-       xstate_bv = (xfeatures_mask & ~xstate_bv) >> 2;
+       xfeatures = (xfeatures_mask & ~xfeatures) >> 2;
 
        /*
         * Update all the other memory layouts for which the corresponding
         * header bit is in the init state.
         */
-       while (xstate_bv) {
-               if (xstate_bv & 0x1) {
+       while (xfeatures) {
+               if (xfeatures & 0x1) {
                        int offset = xstate_offsets[feature_bit];
                        int size = xstate_sizes[feature_bit];
 
@@ -92,7 +92,7 @@ void __sanitize_i387_state(struct task_struct *tsk)
                               size);
                }
 
-               xstate_bv >>= 1;
+               xfeatures >>= 1;
                feature_bit++;
        }
 }
@@ -162,7 +162,7 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
 {
        struct xsave_struct __user *x = buf;
        struct _fpx_sw_bytes *sw_bytes;
-       u32 xstate_bv;
+       u32 xfeatures;
        int err;
 
        /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
@@ -175,25 +175,25 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
        err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
 
        /*
-        * Read the xstate_bv which we copied (directly from the cpu or
+        * Read the xfeatures which we copied (directly from the cpu or
         * from the state in task struct) to the user buffers.
         */
-       err |= __get_user(xstate_bv, (__u32 *)&x->header.xstate_bv);
+       err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
 
        /*
         * For legacy compatible, we always set FP/SSE bits in the bit
         * vector while saving the state to the user context. This will
         * enable us capturing any changes(during sigreturn) to
         * the FP/SSE bits by the legacy applications which don't touch
-        * xstate_bv in the xsave header.
+        * xfeatures in the xsave header.
         *
-        * xsave aware apps can change the xstate_bv in the xsave
+        * xsave aware apps can change the xfeatures in the xsave
         * header as well as change any contents in the memory layout.
         * xrestore as part of sigreturn will capture all the changes.
         */
-       xstate_bv |= XSTATE_FPSSE;
+       xfeatures |= XSTATE_FPSSE;
 
-       err |= __put_user(xstate_bv, (__u32 *)&x->header.xstate_bv);
+       err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
 
        return err;
 }
@@ -277,7 +277,7 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
 static inline void
 sanitize_restored_xstate(struct task_struct *tsk,
                         struct user_i387_ia32_struct *ia32_env,
-                        u64 xstate_bv, int fx_only)
+                        u64 xfeatures, int fx_only)
 {
        struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
        struct xstate_header *header = &xsave->header;
@@ -291,9 +291,9 @@ sanitize_restored_xstate(struct task_struct *tsk,
                 * layout and not enabled by the OS.
                 */
                if (fx_only)
-                       header->xstate_bv = XSTATE_FPSSE;
+                       header->xfeatures = XSTATE_FPSSE;
                else
-                       header->xstate_bv &= (xfeatures_mask & xstate_bv);
+                       header->xfeatures &= (xfeatures_mask & xfeatures);
        }
 
        if (use_fxsr()) {
@@ -335,7 +335,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
        struct task_struct *tsk = current;
        struct fpu *fpu = &tsk->thread.fpu;
        int state_size = xstate_size;
-       u64 xstate_bv = 0;
+       u64 xfeatures = 0;
        int fx_only = 0;
 
        ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
@@ -369,7 +369,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
                        fx_only = 1;
                } else {
                        state_size = fx_sw_user.xstate_size;
-                       xstate_bv = fx_sw_user.xstate_bv;
+                       xfeatures = fx_sw_user.xfeatures;
                }
        }
 
@@ -398,7 +398,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
                        fpstate_init(fpu);
                        err = -1;
                } else {
-                       sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
+                       sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
                }
 
                fpu->fpstate_active = 1;
@@ -415,7 +415,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
                 * state to the registers directly (with exceptions handled).
                 */
                user_fpu_begin();
-               if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
+               if (restore_user_xstate(buf_fx, xfeatures, fx_only)) {
                        fpu_reset_state(fpu);
                        return -1;
                }
@@ -441,7 +441,7 @@ static void prepare_fx_sw_frame(void)
 
        fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
        fx_sw_reserved.extended_size = size;
-       fx_sw_reserved.xstate_bv = xfeatures_mask;
+       fx_sw_reserved.xfeatures = xfeatures_mask;
        fx_sw_reserved.xstate_size = xstate_size;
 
        if (config_enabled(CONFIG_IA32_EMULATION)) {
@@ -576,7 +576,7 @@ static void __init setup_init_fpu_buf(void)
        if (cpu_has_xsaves) {
                init_xstate_buf->header.xcomp_bv =
                                                (u64)1 << 63 | xfeatures_mask;
-               init_xstate_buf->header.xstate_bv = xfeatures_mask;
+               init_xstate_buf->header.xfeatures = xfeatures_mask;
        }
 
        /*

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac24889..0b58b93 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3197,7 +3197,7 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
 static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
 {
        struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave;
-       u64 xstate_bv = xsave->header.xstate_bv;
+       u64 xstate_bv = xsave->header.xfeatures;
        u64 valid;
 
        /*
@@ -3243,7 +3243,7 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
        memcpy(xsave, src, XSAVE_HDR_OFFSET);
 
        /* Set XSTATE_BV and possibly XCOMP_BV.  */
-       xsave->header.xstate_bv = xstate_bv;
+       xsave->header.xfeatures = xstate_bv;
        if (cpu_has_xsaves)
                xsave->header.xcomp_bv = host_xcr0 | XSTATE_COMPACTION_ENABLED;