Commit 3ac8d757 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Use fpstate in __copy_xstate_to_uabi_buf() 



With dynamically enabled features the copy function must know the features
and the size which is valid for the task. Retrieve them from fpstate.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145323.181495492@linutronix.de
parent ad6ede40

arch/x86/kernel/fpu/core.c

+4 −4
Original line number Diff line number Diff line
@@ -187,15 +187,15 @@ EXPORT_SYMBOL_GPL(fpu_swap_kvm_fpu); 
void fpu_copy_fpstate_to_kvm_uabi(struct fpu *fpu, void *buf,

			       unsigned int size, u32 pkru)

{

	union fpregs_state *kstate = &fpu->fpstate->regs;

	struct fpstate *kstate = fpu->fpstate;

	union fpregs_state *ustate = buf;

	struct membuf mb = { .p = buf, .left = size };



	if (cpu_feature_enabled(X86_FEATURE_XSAVE)) {

		__copy_xstate_to_uabi_buf(mb, &kstate->xsave, pkru,

					  XSTATE_COPY_XSAVE);

		__copy_xstate_to_uabi_buf(mb, kstate, pkru, XSTATE_COPY_XSAVE);

	} else {

		memcpy(&ustate->fxsave, &kstate->fxsave, sizeof(ustate->fxsave));

		memcpy(&ustate->fxsave, &kstate->regs.fxsave,

		       sizeof(ustate->fxsave));

		/* Make it restorable on a XSAVE enabled host */

		ustate->xsave.header.xfeatures = XFEATURE_MASK_FPSSE;

	}

arch/x86/kernel/fpu/xstate.c

+6 −5
Original line number Diff line number Diff line
@@ -969,7 +969,7 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate, 
/**

 * __copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer

 * @to:		membuf descriptor

 * @xsave:	The xsave from which to copy

 * @fpstate:	The fpstate buffer from which to copy

 * @pkru_val:	The PKRU value to store in the PKRU component

 * @copy_mode:	The requested copy mode

 *
@@ -979,11 +979,12 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate, 
 *

 * It supports partial copy but @to.pos always starts from zero.

 */

void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,

void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,

			       u32 pkru_val, enum xstate_copy_mode copy_mode)

{

	const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);

	struct xregs_state *xinit = &init_fpstate.regs.xsave;

	struct xregs_state *xsave = &fpstate->regs.xsave;

	struct xstate_header header;

	unsigned int zerofrom;

	u64 mask;
@@ -1003,7 +1004,7 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave, 
		break;



	case XSTATE_COPY_XSAVE:

		header.xfeatures &= xfeatures_mask_uabi();

		header.xfeatures &= fpstate->user_xfeatures;

		break;

	}
@@ -1046,7 +1047,7 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave, 
	 * but there is no state to copy from in the compacted

	 * init_fpstate. The gap tracking will zero these states.

	 */

	mask = xfeatures_mask_uabi();

	mask = fpstate->user_xfeatures;



	for_each_extended_xfeature(i, mask) {

		/*
@@ -1097,7 +1098,7 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave, 
void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,

			     enum xstate_copy_mode copy_mode)

{

	__copy_xstate_to_uabi_buf(to, &tsk->thread.fpu.fpstate->regs.xsave,

	__copy_xstate_to_uabi_buf(to, tsk->thread.fpu.fpstate,

				  tsk->thread.pkru, copy_mode);

}

arch/x86/kernel/fpu/xstate.h

+1 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask) 
		xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT;

}



extern void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave,

extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,

				      u32 pkru_val, enum xstate_copy_mode copy_mode);



extern void fpu__init_cpu_xstate(void);