Commit 0a319ef7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-fpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 FPU updates from Ingo Molnar:
 "Most of the changes here related to 'XSAVES supervisor state' support,
  which is a feature that allows kernel-only data to be automatically
  saved/restored by the FPU context switching code.

  CPU features that can be supported this way are Intel PT, 'PASID' and
  CET features"

* tag 'x86-fpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu/xstate: Restore supervisor states for signal return
  x86/fpu/xstate: Preserve supervisor states for the slow path in __fpu__restore_sig()
  x86/fpu: Introduce copy_supervisor_to_kernel()
  x86/fpu/xstate: Update copy_kernel_to_xregs_err() for supervisor states
  x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates
  x86/fpu/xstate: Define new functions for clearing fpregs and xstates
  x86/fpu/xstate: Introduce XSAVES supervisor states
  x86/fpu/xstate: Separate user and supervisor xfeatures mask
  x86/fpu/xstate: Define new macros for supervisor and user xstates
  x86/fpu/xstate: Rename validate_xstate_header() to validate_user_xstate_header()
parents eff5ddad 55e00fb6

arch/x86/include/asm/fpu/internal.h

+7 −3
Original line number Diff line number Diff line
@@ -31,7 +31,8 @@ extern void fpu__save(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 task_struct *dst, struct task_struct *src);

extern void fpu__clear(struct fpu *fpu);

extern void fpu__clear_user_states(struct fpu *fpu);

extern void fpu__clear_all(struct fpu *fpu);

extern int  fpu__exception_code(struct fpu *fpu, int trap_nr);

extern int  dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate);
@@ -92,7 +93,7 @@ static inline void fpstate_init_xstate(struct xregs_state *xsave) 
	 * XRSTORS requires these bits set in xcomp_bv, or it will

	 * trigger #GP:

	 */

	xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask;

	xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;

}



static inline void fpstate_init_fxstate(struct fxregs_state *fx)
@@ -399,6 +400,9 @@ static inline int copy_kernel_to_xregs_err(struct xregs_state *xstate, u64 mask) 
	u32 hmask = mask >> 32;

	int err;



	if (static_cpu_has(X86_FEATURE_XSAVES))

		XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);

	else

		XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);



	return err;

arch/x86/include/asm/fpu/xstate.h

+37 −15
Original line number Diff line number Diff line
@@ -21,11 +21,8 @@ 
#define XSAVE_YMM_SIZE	    256

#define XSAVE_YMM_OFFSET    (XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET)



/* Supervisor features */

#define XFEATURE_MASK_SUPERVISOR (XFEATURE_MASK_PT)



/* All currently supported features */

#define XCNTXT_MASK		(XFEATURE_MASK_FP | \

/* All currently supported user features */

#define XFEATURE_MASK_USER_SUPPORTED (XFEATURE_MASK_FP | \

				      XFEATURE_MASK_SSE | \

				      XFEATURE_MASK_YMM | \

				      XFEATURE_MASK_OPMASK | \
@@ -35,13 +32,37 @@ 
				      XFEATURE_MASK_BNDREGS | \

				      XFEATURE_MASK_BNDCSR)



/* All currently supported supervisor features */

#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (0)



/*

 * Unsupported supervisor features. When a supervisor feature in this mask is

 * supported in the future, move it to the supported supervisor feature mask.

 */

#define XFEATURE_MASK_SUPERVISOR_UNSUPPORTED (XFEATURE_MASK_PT)



/* All supervisor states including supported and unsupported states. */

#define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \

				      XFEATURE_MASK_SUPERVISOR_UNSUPPORTED)



#ifdef CONFIG_X86_64

#define REX_PREFIX	"0x48, "

#else

#define REX_PREFIX

#endif



extern u64 xfeatures_mask;

extern u64 xfeatures_mask_all;



static inline u64 xfeatures_mask_supervisor(void)

{

	return xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_SUPPORTED;

}



static inline u64 xfeatures_mask_user(void)

{

	return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED;

}



extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];



extern void __init update_regset_xstate_info(unsigned int size,
@@ -54,8 +75,9 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of 
int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);

int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);

int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);

void copy_supervisor_to_kernel(struct xregs_state *xsave);



/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */

extern int validate_xstate_header(const struct xstate_header *hdr);

int validate_user_xstate_header(const struct xstate_header *hdr);



#endif

arch/x86/kernel/fpu/core.c

+35 −18
Original line number Diff line number Diff line
@@ -291,15 +291,13 @@ void fpu__drop(struct fpu *fpu) 
}



/*

 * Clear FPU registers by setting them up from

 * the init fpstate:

 * Clear FPU registers by setting them up from the init fpstate.

 * Caller must do fpregs_[un]lock() around it.

 */

static inline void copy_init_fpstate_to_fpregs(void)

static inline void copy_init_fpstate_to_fpregs(u64 features_mask)

{

	fpregs_lock();



	if (use_xsave())

		copy_kernel_to_xregs(&init_fpstate.xsave, -1);

		copy_kernel_to_xregs(&init_fpstate.xsave, features_mask);

	else if (static_cpu_has(X86_FEATURE_FXSR))

		copy_kernel_to_fxregs(&init_fpstate.fxsave);

	else
@@ -307,9 +305,6 @@ static inline void copy_init_fpstate_to_fpregs(void) 


	if (boot_cpu_has(X86_FEATURE_OSPKE))

		copy_init_pkru_to_fpregs();



	fpregs_mark_activate();

	fpregs_unlock();

}



/*
@@ -318,18 +313,40 @@ static inline void copy_init_fpstate_to_fpregs(void) 
 * Called by sys_execve(), by the signal handler code and by various

 * error paths.

 */

void fpu__clear(struct fpu *fpu)

static void fpu__clear(struct fpu *fpu, bool user_only)

{

	WARN_ON_FPU(fpu != &current->thread.fpu); /* Almost certainly an anomaly */

	WARN_ON_FPU(fpu != &current->thread.fpu);



	if (!static_cpu_has(X86_FEATURE_FPU)) {

		fpu__drop(fpu);



	/*

	 * Make sure fpstate is cleared and initialized.

	 */

		fpu__initialize(fpu);

	if (static_cpu_has(X86_FEATURE_FPU))

		copy_init_fpstate_to_fpregs();

		return;

	}



	fpregs_lock();



	if (user_only) {

		if (!fpregs_state_valid(fpu, smp_processor_id()) &&

		    xfeatures_mask_supervisor())

			copy_kernel_to_xregs(&fpu->state.xsave,

					     xfeatures_mask_supervisor());

		copy_init_fpstate_to_fpregs(xfeatures_mask_user());

	} else {

		copy_init_fpstate_to_fpregs(xfeatures_mask_all);

	}



	fpregs_mark_activate();

	fpregs_unlock();

}



void fpu__clear_user_states(struct fpu *fpu)

{

	fpu__clear(fpu, true);

}



void fpu__clear_all(struct fpu *fpu)

{

	fpu__clear(fpu, false);

}



/*

arch/x86/kernel/fpu/init.c

+2 −1
Original line number Diff line number Diff line
@@ -224,7 +224,8 @@ static void __init fpu__init_system_xstate_size_legacy(void) 
 */

u64 __init fpu__get_supported_xfeatures_mask(void)

{

	return XCNTXT_MASK;

	return XFEATURE_MASK_USER_SUPPORTED |

	       XFEATURE_MASK_SUPERVISOR_SUPPORTED;

}



/* Legacy code to initialize eager fpu mode. */

arch/x86/kernel/fpu/regset.c

+1 −1
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, 
	} else {

		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);

		if (!ret)

			ret = validate_xstate_header(&xsave->header);

			ret = validate_user_xstate_header(&xsave->header);

	}



	/*

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