1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 17 Oct 2018 16:10:45 +0200
Subject: [PATCH 02/27] x86/fpu: Remove fpu__restore()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.0/older/patches-5.0.7-rt5.tar.xz
There are no users of fpu__restore() so it is time to remove it.
The comment regarding fpu__restore() and TS bit is stale since commit
b3b0870ef3ffe ("i387: do not preload FPU state at task switch time")
and has no meaning since.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
Documentation/preempt-locking.txt | 1 -
arch/x86/include/asm/fpu/internal.h | 1 -
arch/x86/kernel/fpu/core.c | 24 ------------------------
arch/x86/kernel/process_32.c | 4 +---
arch/x86/kernel/process_64.c | 4 +---
5 files changed, 2 insertions(+), 32 deletions(-)
--- a/Documentation/preempt-locking.txt
+++ b/Documentation/preempt-locking.txt
@@ -52,7 +52,6 @@ preemption must be disabled around such
Note, some FPU functions are already explicitly preempt safe. For example,
kernel_fpu_begin and kernel_fpu_end will disable and enable preemption.
-However, fpu__restore() must be called with preemption disabled.
RULE #3: Lock acquire and release must be performed by same task
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -28,7 +28,6 @@ extern void fpu__initialize(struct fpu *
extern void fpu__prepare_read(struct fpu *fpu);
extern void fpu__prepare_write(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
-extern void fpu__restore(struct fpu *fpu);
extern int fpu__restore_sig(void __user *buf, int ia32_frame);
extern void fpu__drop(struct fpu *fpu);
extern int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu);
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -304,30 +304,6 @@ void fpu__prepare_write(struct fpu *fpu)
}
/*
- * 'fpu__restore()' is called to copy FPU registers from
- * the FPU fpstate to the live hw registers and to activate
- * access to the hardware registers, so that FPU instructions
- * can be used afterwards.
- *
- * Must be called with kernel preemption disabled (for example
- * with local interrupts disabled, as it is in the case of
- * do_device_not_available()).
- */
-void fpu__restore(struct fpu *fpu)
-{
- fpu__initialize(fpu);
-
- /* Avoid __kernel_fpu_begin() right after fpregs_activate() */
- kernel_fpu_disable();
- trace_x86_fpu_before_restore(fpu);
- fpregs_activate(fpu);
- copy_kernel_to_fpregs(&fpu->state);
- trace_x86_fpu_after_restore(fpu);
- kernel_fpu_enable();
-}
-EXPORT_SYMBOL_GPL(fpu__restore);
-
-/*
* Drops current FPU state: deactivates the fpregs and
* the fpstate. NOTE: it still leaves previous contents
* in the fpregs in the eager-FPU case.
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -267,9 +267,7 @@ EXPORT_SYMBOL_GPL(start_thread);
/*
* Leave lazy mode, flushing any hypercalls made here.
* This must be done before restoring TLS segments so
- * the GDT and LDT are properly updated, and must be
- * done before fpu__restore(), so the TS bit is up
- * to date.
+ * the GDT and LDT are properly updated.
*/
arch_end_context_switch(next_p);
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -538,9 +538,7 @@ void compat_start_thread(struct pt_regs
/*
* Leave lazy mode, flushing any hypercalls made here. This
* must be done after loading TLS entries in the GDT but before
- * loading segments that might reference them, and and it must
- * be done before fpu__restore(), so the TS bit is up to
- * date.
+ * loading segments that might reference them.
*/
arch_end_context_switch(next_p);
|
