[patch 02/21] x86/fpu: Convert fpstate_init() to struct fpstate

Thomas Gleixner
2021-10-13T14:55:34Z

Convert fpstate_init() and related code to the new register storage
mechanism in preparation for dynamically sized buffers.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/fpu/core.c | 44 ++++++++++++++++++++---------------------
arch/x86/kernel/fpu/internal.h | 4 +--
arch/x86/kernel/fpu/signal.c | 2 -
arch/x86/kernel/fpu/xstate.c | 12 +++++------
4 files changed, 31 insertions(+), 31 deletions(-)

--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -29,7 +29,7 @@
* Represents the initial FPU state. It's mostly (but not completely) zeroes,
* depending on the FPU hardware format:
*/
-union fpregs_state init_fpstate __ro_after_init;
+struct fpstate init_fpstate __ro_after_init;

/*
* Track whether the kernel is using the FPU state
@@ -157,7 +157,7 @@ void restore_fpregs_from_fpstate(union f

void fpu_reset_from_exception_fixup(void)
{
- restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());
+ restore_fpregs_from_fpstate(&init_fpstate.regs, xfeatures_mask_fpstate());
}

#if IS_ENABLED(CONFIG_KVM)
@@ -297,24 +297,24 @@ static inline unsigned int init_fpstate_
return fpu_kernel_xstate_size;

/* XSAVE(S) just needs the legacy and the xstate header part */
- return sizeof(init_fpstate.xsave);
+ return sizeof(init_fpstate.regs.xsave);
}

-static inline void fpstate_init_fxstate(struct fxregs_state *fx)
+static inline void fpstate_init_fxstate(struct fpstate *fpstate)
{
- fx->cwd = 0x37f;
- fx->mxcsr = MXCSR_DEFAULT;
+ fpstate->regs.fxsave.cwd = 0x37f;
+ fpstate->regs.fxsave.mxcsr = MXCSR_DEFAULT;
}

/*
* Legacy x87 fpstate state init:
*/
-static inline void fpstate_init_fstate(struct fregs_state *fp)
+static inline void fpstate_init_fstate(struct fpstate *fpstate)
{
- fp->cwd = 0xffff037fu;
- fp->swd = 0xffff0000u;
- fp->twd = 0xffffffffu;
- fp->fos = 0xffff0000u;
+ fpstate->regs.fsave.cwd = 0xffff037fu;
+ fpstate->regs.fsave.swd = 0xffff0000u;
+ fpstate->regs.fsave.twd = 0xffffffffu;
+ fpstate->regs.fsave.fos = 0xffff0000u;
}

/*
@@ -322,19 +322,19 @@ static inline void fpstate_init_fstate(s
* 1) Early boot to setup init_fpstate for non XSAVE systems
* 2) fpu_init_fpstate_user() which is invoked from KVM
*/
-void fpstate_init_user(union fpregs_state *state)
+void fpstate_init_user(struct fpstate *fpstate)
{
if (!cpu_feature_enabled(X86_FEATURE_FPU)) {
- fpstate_init_soft(&state->soft);
+ fpstate_init_soft(&fpstate->regs.soft);
return;
}

- xstate_init_xcomp_bv(&state->xsave, xfeatures_mask_uabi());
+ xstate_init_xcomp_bv(&fpstate->regs.xsave, xfeatures_mask_uabi());

if (cpu_feature_enabled(X86_FEATURE_FXSR))
- fpstate_init_fxstate(&state->fxsave);
+ fpstate_init_fxstate(fpstate);
else
- fpstate_init_fstate(&state->fsave);
+ fpstate_init_fstate(fpstate);
}

void fpstate_reset(struct fpu *fpu)
@@ -347,7 +347,7 @@ void fpstate_reset(struct fpu *fpu)
void fpu_init_fpstate_user(struct fpu *fpu)
{
fpstate_reset(fpu);
- fpstate_init_user(&fpu->fpstate->regs);
+ fpstate_init_user(fpu->fpstate);
}
EXPORT_SYMBOL_GPL(fpu_init_fpstate_user);
#endif
@@ -378,7 +378,7 @@ int fpu_clone(struct task_struct *dst)
*/
if (dst->flags & (PF_KTHREAD | PF_IO_WORKER)) {
/* Clear out the minimal state */
- memcpy(&dst_fpu->state, &init_fpstate,
+ memcpy(&dst_fpu->state, &init_fpstate.regs,
init_fpstate_copy_size());
return 0;
}
@@ -435,11 +435,11 @@ void fpu__drop(struct fpu *fpu)
static inline void restore_fpregs_from_init_fpstate(u64 features_mask)
{
if (use_xsave())
- os_xrstor(&init_fpstate.xsave, features_mask);
+ os_xrstor(&init_fpstate.regs.xsave, features_mask);
else if (use_fxsr())
- fxrstor(&init_fpstate.fxsave);
+ fxrstor(&init_fpstate.regs.fxsave);
else
- frstor(&init_fpstate.fsave);
+ frstor(&init_fpstate.regs.fsave);

pkru_write_default();
}
@@ -466,7 +466,7 @@ static void fpu_reset_fpstate(void)
* user space as PKRU is eagerly written in switch_to() and
* flush_thread().
*/
- memcpy(&fpu->state, &init_fpstate, init_fpstate_copy_size());
+ memcpy(&fpu->state, &init_fpstate.regs, init_fpstate_copy_size());
set_thread_flag(TIF_NEED_FPU_LOAD);
fpregs_unlock();
}
--- a/arch/x86/kernel/fpu/internal.h
+++ b/arch/x86/kernel/fpu/internal.h
@@ -2,7 +2,7 @@
#ifndef __X86_KERNEL_FPU_INTERNAL_H
#define __X86_KERNEL_FPU_INTERNAL_H

-extern union fpregs_state init_fpstate;
+extern struct fpstate init_fpstate;

/* CPU feature check wrappers */
static __always_inline __pure bool use_xsave(void)
@@ -25,7 +25,7 @@ static __always_inline __pure bool use_f
extern void fpu__init_prepare_fx_sw_frame(void);

/* Used in init.c */
-extern void fpstate_init_user(union fpregs_state *state);
+extern void fpstate_init_user(struct fpstate *fpstate);
extern void fpstate_reset(struct fpu *fpu);

#endif
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -243,7 +243,7 @@ static int __restore_fpregs_from_user(vo
ret = fxrstor_from_user_sigframe(buf);

if (!ret && unlikely(init_bv))
- os_xrstor(&init_fpstate.xsave, init_bv);
+ os_xrstor(&init_fpstate.regs.xsave, init_bv);
return ret;
} else if (use_fxsr()) {
return fxrstor_from_user_sigframe(buf);
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -408,12 +408,12 @@ static void __init setup_init_fpu_buf(vo
setup_xstate_features();
print_xstate_features();

- xstate_init_xcomp_bv(&init_fpstate.xsave, xfeatures_mask_all);
+ xstate_init_xcomp_bv(&init_fpstate.regs.xsave, xfeatures_mask_all);

/*
* Init all the features state with header.xfeatures being 0x0
*/
- os_xrstor_booting(&init_fpstate.xsave);
+ os_xrstor_booting(&init_fpstate.regs.xsave);

/*
* All components are now in init state. Read the state back so
@@ -431,7 +431,7 @@ static void __init setup_init_fpu_buf(vo
* state is all zeroes or if not to add the necessary handling
* here.
*/
- fxsave(&init_fpstate.fxsave);
+ fxsave(&init_fpstate.regs.fxsave);
}

static int xfeature_uncompacted_offset(int xfeature_nr)
@@ -672,11 +672,11 @@ static unsigned int __init get_xsave_siz
*/
static bool __init is_supported_xstate_size(unsigned int test_xstate_size)
{
- if (test_xstate_size <= sizeof(union fpregs_state))
+ if (test_xstate_size <= sizeof(init_fpstate.regs))
return true;

pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
- sizeof(union fpregs_state), test_xstate_size);
+ sizeof(init_fpstate.regs), test_xstate_size);
return false;
}

@@ -981,7 +981,7 @@ void __copy_xstate_to_uabi_buf(struct me
u32 pkru_val, enum xstate_copy_mode copy_mode)
{
const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
- struct xregs_state *xinit = &init_fpstate.xsave;
+ struct xregs_state *xinit = &init_fpstate.regs.xsave;
struct xstate_header header;
unsigned int zerofrom;
u64 mask;