[patch V2 16/52] x86/fpu: Use copy_uabi_xstate_to_membuf() in fpregs_get()

Thomas Gleixner
2021-06-14T16:38:43Z

Use the new functionality of copy_uabi_xstate_to_membuf() to retrieve the
FX state when XSAVE* is in use. This avoids to overwrite the FPU state
buffer with fpstate_sanitize_xstate() which is error prone and duplicated
code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: New patch
---
arch/x86/kernel/fpu/regset.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)

--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -211,10 +211,10 @@ static inline u32 twd_fxsr_to_i387(struc
* FXSR floating point environment conversions.
*/

-void
-convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
+static void __convert_from_fxsr(struct user_i387_ia32_struct *env,
+ struct task_struct *tsk,
+ struct fxregs_state *fxsave)
{
- struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
int i;
@@ -248,6 +248,12 @@ convert_from_fxsr(struct user_i387_ia32_
memcpy(&to[i], &from[i], sizeof(to[0]));
}

+void
+convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
+{
+ __convert_from_fxsr(env, tsk, &tsk->thread.fpu.state.fxsave);
+}
+
void convert_to_fxsr(struct fxregs_state *fxsave,
const struct user_i387_ia32_struct *env)

@@ -280,25 +286,29 @@ int fpregs_get(struct task_struct *targe
{
struct fpu *fpu = &target->thread.fpu;
struct user_i387_ia32_struct env;
+ struct fxregs_state fxsave, *fx;

fpu__prepare_read(fpu);

- if (!boot_cpu_has(X86_FEATURE_FPU))
+ if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, to);

- if (!boot_cpu_has(X86_FEATURE_FXSR)) {
+ if (!static_cpu_has(X86_FEATURE_FXSR)) {
return membuf_write(&to, &fpu->state.fsave,
sizeof(struct fregs_state));
}

- fpstate_sanitize_xstate(fpu);
+ if (use_xsave()) {
+ struct membuf mb = { .p = &fxsave, .left = sizeof(fxsave) };

- if (to.left == sizeof(env)) {
- convert_from_fxsr(to.p, target);
- return 0;
+ /* Handle init state optimized xstate correctly */
+ copy_uabi_xstate_to_membuf(mb, &fpu->state.xsave, XSTATE_COPY_FP);
+ fx = &fxsave;
+ } else {
+ fx = &fpu->state.fxsave;
}

- convert_from_fxsr(&env, target);
+ __convert_from_fxsr(&env, target, fx);
return membuf_write(&to, &env, sizeof(env));
}