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x86/fpu/regset: Move fpu__read_begin() into regset 

The function can only be used from the regset get() callbacks safely. So
there is no reason to have it globally exposed.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.234942936@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-06-23 14:01:46 +02:00 committed by Borislav Petkov
parent afac9e8943
commit 5a32fac8db
3 changed files with 19 additions and 24 deletions
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1
arch/x86/include/asm/fpu/internal.h
View File

@ -26,7 +26,6 @@
/*
* High level FPU state handling functions:
*/
extern void fpu__prepare_read(struct fpu *fpu);
extern void fpu__prepare_write(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
extern int fpu__restore_sig(void __user *buf, int ia32_frame);

20
arch/x86/kernel/fpu/core.c
View File

@ -281,26 +281,6 @@ static void fpu__initialize(struct fpu *fpu)
trace_x86_fpu_init_state(fpu);
}
/*
* This function must be called before we read a task's fpstate.
*
* There's two cases where this gets called:
*
* - for the current task (when coredumping), in which case we have
* to save the latest FPU registers into the fpstate,
*
* - or it's called for stopped tasks (ptrace), in which case the
* registers were already saved by the context-switch code when
* the task scheduled out.
*
* If the task has used the FPU before then save it.
*/
void fpu__prepare_read(struct fpu *fpu)
{
if (fpu == &current->thread.fpu)
fpu__save(fpu);
}
/*
* This function must be called before we write a task's fpstate.
*

22
arch/x86/kernel/fpu/regset.c
View File

@ -28,6 +28,22 @@ int regset_xregset_fpregs_active(struct task_struct *target, const struct user_r
return 0;
}
/*
* The regset get() functions are invoked from:
*
* - coredump to dump the current task's fpstate. If the current task
* owns the FPU then the memory state has to be synchronized and the
* FPU register state preserved. Otherwise fpstate is already in sync.
*
* - ptrace to dump fpstate of a stopped task, in which case the registers
* have already been saved to fpstate on context switch.
*/
static void sync_fpstate(struct fpu *fpu)
{
if (fpu == &current->thread.fpu)
fpu__save(fpu);
}
int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
struct membuf to)
{
@ -36,7 +52,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_feature_enabled(X86_FEATURE_FXSR))
return -ENODEV;
fpu__prepare_read(fpu);
sync_fpstate(fpu);
if (!use_xsave()) {
return membuf_write(&to, &fpu->state.fxsave,
@ -96,7 +112,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
return -ENODEV;
fpu__prepare_read(fpu);
sync_fpstate(fpu);
copy_xstate_to_uabi_buf(to, &fpu->state.xsave, XSTATE_COPY_XSAVE);
return 0;
@ -287,7 +303,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
struct user_i387_ia32_struct env;
struct fxregs_state fxsave, *fx;
fpu__prepare_read(fpu);
sync_fpstate(fpu);
if (!cpu_feature_enabled(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, to);