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

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'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>
This commit is contained in:
Ingo Molnar
2015-04-24 10:19:47 +02:00
parent 3a54450b5e
commit 400e4b2091
7 changed files with 39 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/kernel/fpu/core.c
View File

@@ -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;
}

52
arch/x86/kernel/fpu/xsave.c
View File

@@ -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;
}
/*