Commit-ID: 0560281266b313400b622c5ddfafb0ee8e59c702
Gitweb: http://git.kernel.org/tip/0560281266b313400b622c5ddfafb0ee8e59c702
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Wed, 27 May 2015 12:22:29 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 27 May 2015 14:11:24 +0200
x86/fpu: Split out the fpu__activate_fpstate_read() method
Currently fpu__activate_fpstate() is used for two distinct purposes:
- read access by ptrace and core dumping, where in the core dumping
case the current task's FPU state may be examined as well.
- write access by ptrace, which modifies FPU registers and expects
the modified registers to be reloaded on the next context switch.
Split out the reading side into fpu__activate_fpstate_read().
( Note that this is just a pure duplication of fpu__activate_fpstate()
for the time being, we'll optimize the new function in the next patch. )
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Bobby Powers <bobbypowers@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/fpu/internal.h | 1 +
arch/x86/kernel/fpu/core.c | 29 +++++++++++++++++++++++++++++
arch/x86/kernel/fpu/regset.c | 6 +++---
3 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 62d13d5..3cc2086 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -22,6 +22,7 @@
* High level FPU state handling functions:
*/
extern void fpu__activate_curr(struct fpu *fpu);
+extern void fpu__activate_fpstate_read(struct fpu *fpu);
extern void fpu__activate_fpstate(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
extern void fpu__restore(struct fpu *fpu);
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index b410492..174add3 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -296,6 +296,35 @@ void fpu__activate_curr(struct fpu *fpu)
EXPORT_SYMBOL_GPL(fpu__activate_curr);
/*
+ * This function must be called before we read a task's fpstate.
+ *
+ * If the task has not used the FPU before then initialize its
+ * fpstate.
+ *
+ * If the task has used the FPU before then save it.
+ */
+void fpu__activate_fpstate_read(struct fpu *fpu)
+{
+ /*
+ * If fpregs are active (in the current CPU), then
+ * copy them to the fpstate:
+ */
+ if (fpu->fpregs_active) {
+ fpu__save(fpu);
+ } else {
+ if (fpu->fpstate_active) {
+ /* Invalidate any lazy state: */
+ fpu->last_cpu = -1;
+ } else {
+ fpstate_init(&fpu->state);
+
+ /* Safe to do for current and for stopped child tasks: */
+ fpu->fpstate_active = 1;
+ }
+ }
+}
+
+/*
* This function must be called before we read or write a task's fpstate.
*
* If the task has not used the FPU before then initialize its
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index a1f97d9..4e40585 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -33,7 +33,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_fxsr)
return -ENODEV;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
fpstate_sanitize_xstate(fpu);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@@ -82,7 +82,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_has_xsave)
return -ENODEV;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
xsave = &fpu->state.xsave;
@@ -273,7 +273,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct fpu *fpu = &target->thread.fpu;
struct user_i387_ia32_struct env;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
--
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