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Subject[PATCH 15/33] x86/fpu: Simplify fpu->fpregs_active use
Date
The fpregs_active() inline function is pretty pointless - in almost
all the callsites it can be replaced with a direct fpu->fpregs_active
access.

Do so and eliminate the extra layer of obfuscation.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
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: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/fpu/internal.h | 17 +----------------
arch/x86/kernel/fpu/core.c | 2 +-
arch/x86/kernel/fpu/signal.c | 9 +++++----
arch/x86/mm/pkeys.c | 2 +-
4 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 554cdb205d17..b223c57dd5dc 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -543,21 +543,6 @@ static inline void fpregs_activate(struct fpu *fpu)
}

/*
- * The question "does this thread have fpu access?"
- * is slightly racy, since preemption could come in
- * and revoke it immediately after the test.
- *
- * However, even in that very unlikely scenario,
- * we can just assume we have FPU access - typically
- * to save the FP state - we'll just take a #NM
- * fault and get the FPU access back.
- */
-static inline int fpregs_active(void)
-{
- return current->thread.fpu.fpregs_active;
-}
-
-/*
* FPU state switching for scheduling.
*
* This is a two-stage process:
@@ -617,7 +602,7 @@ static inline void user_fpu_begin(void)
struct fpu *fpu = &current->thread.fpu;

preempt_disable();
- if (!fpregs_active())
+ if (!fpu->fpregs_active)
fpregs_activate(fpu);
preempt_enable();
}
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index e1114f070c2d..bad57248e5a0 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -367,7 +367,7 @@ void fpu__current_fpstate_write_end(void)
* registers may still be out of date. Update them with
* an XRSTOR if they are active.
*/
- if (fpregs_active())
+ if (fpu->fpregs_active)
copy_kernel_to_fpregs(&fpu->state);

/*
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 2d682dac35d4..684025654d0c 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -155,7 +155,8 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
- struct xregs_state *xsave = &current->thread.fpu.state.xsave;
+ struct fpu *fpu = &current->thread.fpu;
+ struct xregs_state *xsave = &fpu->state.xsave;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);

@@ -170,13 +171,13 @@ 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() || using_compacted_format()) {
+ if (fpu->fpregs_active || using_compacted_format()) {
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
/* Update the thread's fxstate to save the fsave header. */
if (ia32_fxstate)
- copy_fxregs_to_kernel(&tsk->thread.fpu);
+ copy_fxregs_to_kernel(fpu);
} else {
/*
* It is a *bug* if kernel uses compacted-format for xsave
@@ -189,7 +190,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
return -1;
}

- fpstate_sanitize_xstate(&tsk->thread.fpu);
+ fpstate_sanitize_xstate(fpu);
if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
return -1;
}
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index 2dab69a706ec..e2c23472233e 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -45,7 +45,7 @@ int __execute_only_pkey(struct mm_struct *mm)
*/
preempt_disable();
if (!need_to_set_mm_pkey &&
- fpregs_active() &&
+ current->thread.fpu.fpregs_active &&
!__pkru_allows_read(read_pkru(), execute_only_pkey)) {
preempt_enable();
return execute_only_pkey;
--
2.11.0
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