Commit c37b5efe authored by Suresh Siddha's avatar Suresh Siddha Committed by Ingo Molnar
Browse files

x86, xsave: save/restore the extended state context in sigframe 



On cpu's supporting xsave/xrstor, fpstate pointer in the sigcontext, will
include the extended state information along with fpstate information. Presence
of extended state information is indicated by the presence
of FP_XSTATE_MAGIC1 at fpstate.sw_reserved.magic1 and FP_XSTATE_MAGIC2
at fpstate + (fpstate.sw_reserved.extended_size - FP_XSTATE_MAGIC2_SIZE).

Extended feature bit mask that is saved in the memory layout is represented
by the fpstate.sw_reserved.xstate_bv

For RT signal frames, UC_FP_XSTATE in the uc_flags also indicate the
presence of extended state information in the sigcontext's fpstate
pointer.

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent bdd8caba

arch/x86/ia32/ia32_signal.c

+4 −1
Original line number Diff line number Diff line
@@ -544,6 +544,9 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
		goto give_sigsegv;



	/* Create the ucontext.  */

	if (cpu_has_xsave)

		err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);

	else

		err |= __put_user(0, &frame->uc.uc_flags);

	err |= __put_user(0, &frame->uc.uc_link);

	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);

arch/x86/kernel/i387.c

+76 −6
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
# define _fpstate_ia32		_fpstate

# define _xstate_ia32		_xstate

# define sig_xstate_ia32_size   sig_xstate_size

# define fx_sw_reserved_ia32	fx_sw_reserved

# define user_i387_ia32_struct	user_i387_struct

# define user32_fxsr_struct	user_fxsr_struct

#endif
@@ -447,12 +448,30 @@ static int save_i387_fxsave(struct _fpstate_ia32 __user *buf) 
	if (err)

		return -1;



	if (__copy_to_user(&buf->_fxsr_env[0], fx,

			   sizeof(struct i387_fxsave_struct)))

	if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))

		return -1;

	return 1;

}



static int save_i387_xsave(void __user *buf)

{

	struct _fpstate_ia32 __user *fx = buf;

	int err = 0;



	if (save_i387_fxsave(fx) < 0)

		return -1;



	err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,

			     sizeof(struct _fpx_sw_bytes));

	err |= __put_user(FP_XSTATE_MAGIC2,

			  (__u32 __user *) (buf + sig_xstate_ia32_size

					    - FP_XSTATE_MAGIC2_SIZE));

	if (err)

		return -1;



	return 1;

}



int save_i387_xstate_ia32(void __user *buf)

{

	struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
@@ -477,6 +496,8 @@ int save_i387_xstate_ia32(void __user *buf) 


	unlazy_fpu(tsk);



	if (cpu_has_xsave)

		return save_i387_xsave(fp);

	if (cpu_has_fxsr)

		return save_i387_fxsave(fp);

	else
@@ -491,14 +512,15 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf) 
				sizeof(struct i387_fsave_struct));

}



static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)

static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,

			       unsigned int size)

{

	struct task_struct *tsk = current;

	struct user_i387_ia32_struct env;

	int err;



	err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],

			       sizeof(struct i387_fxsave_struct));

			       size);

	/* mxcsr reserved bits must be masked to zero for security reasons */

	tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;

	if (err || __copy_from_user(&env, buf, sizeof(env)))
@@ -508,6 +530,51 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf) 
	return 0;

}



static int restore_i387_xsave(void __user *buf)

{

	struct _fpx_sw_bytes fx_sw_user;

	struct _fpstate_ia32 __user *fx_user =

			((struct _fpstate_ia32 __user *) buf);

	struct i387_fxsave_struct __user *fx =

		(struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];

	struct xsave_hdr_struct *xsave_hdr =

				&current->thread.xstate->xsave.xsave_hdr;

	unsigned int lmask, hmask;

	int err;



	if (check_for_xstate(fx, buf, &fx_sw_user))

		goto fx_only;



	lmask = fx_sw_user.xstate_bv;

	hmask = fx_sw_user.xstate_bv >> 32;



	err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);



	xsave_hdr->xstate_bv &=  (pcntxt_lmask | (((u64) pcntxt_hmask) << 32));

	/*

	 * These bits must be zero.

	 */

	xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;



	/*

	 * Init the state that is not present in the memory layout

	 * and enabled by the OS.

	 */

	lmask = ~(pcntxt_lmask & ~lmask);

	hmask = ~(pcntxt_hmask & ~hmask);

	xsave_hdr->xstate_bv &=  (lmask | (((u64) hmask) << 32));



	return err;

fx_only:

	/*

	 * Couldn't find the extended state information in the memory

	 * layout. Restore the FP/SSE and init the other extended state

	 * enabled by the OS.

	 */

	xsave_hdr->xstate_bv = XSTATE_FPSSE;

	return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));

}



int restore_i387_xstate_ia32(void __user *buf)

{

	int err;
@@ -535,8 +602,11 @@ int restore_i387_xstate_ia32(void __user *buf) 
	}



	if (HAVE_HWFP) {

		if (cpu_has_fxsr)

			err = restore_i387_fxsave(fp);

		if (cpu_has_xsave)

			err = restore_i387_xsave(buf);

		else if (cpu_has_fxsr)

			err = restore_i387_fxsave(fp, sizeof(struct

							   i387_fxsave_struct));

		else

			err = restore_i387_fsave(fp);

	} else {

arch/x86/kernel/signal_32.c

+4 −1
Original line number Diff line number Diff line
@@ -441,6 +441,9 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
		goto give_sigsegv;



	/* Create the ucontext.  */

	if (cpu_has_xsave)

		err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);

	else

		err |= __put_user(0, &frame->uc.uc_flags);

	err |= __put_user(0, &frame->uc.uc_link);

	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);

arch/x86/kernel/signal_64.c

+5 −2
Original line number Diff line number Diff line
@@ -192,7 +192,7 @@ get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) 
			sp = current->sas_ss_sp + current->sas_ss_size;

	}



	return (void __user *)round_down(sp - size, 16);

	return (void __user *)round_down(sp - size, 64);

}



static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
@@ -226,6 +226,9 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 
	}

		

	/* Create the ucontext.  */

	if (cpu_has_xsave)

		err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);

	else

		err |= __put_user(0, &frame->uc.uc_flags);

	err |= __put_user(0, &frame->uc.uc_link);

	err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);

arch/x86/kernel/xsave.c

+162 −10
Original line number Diff line number Diff line
@@ -6,12 +6,68 @@ 
#include <linux/bootmem.h>

#include <linux/compat.h>

#include <asm/i387.h>

#ifdef CONFIG_IA32_EMULATION

#include <asm/sigcontext32.h>

#endif



/*

 * Supported feature mask by the CPU and the kernel.

 */

unsigned int pcntxt_hmask, pcntxt_lmask;



struct _fpx_sw_bytes fx_sw_reserved;

#ifdef CONFIG_IA32_EMULATION

struct _fpx_sw_bytes fx_sw_reserved_ia32;

#endif



/*

 * Check for the presence of extended state information in the

 * user fpstate pointer in the sigcontext.

 */

int check_for_xstate(struct i387_fxsave_struct __user *buf,

		     void __user *fpstate,

		     struct _fpx_sw_bytes *fx_sw_user)

{

	int min_xstate_size = sizeof(struct i387_fxsave_struct) +

			      sizeof(struct xsave_hdr_struct);

	unsigned int magic2;

	int err;



	err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],

			       sizeof(struct _fpx_sw_bytes));



	if (err)

		return err;



	/*

	 * First Magic check failed.

	 */

	if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)

		return -1;



	/*

	 * Check for error scenarios.

	 */

	if (fx_sw_user->xstate_size < min_xstate_size ||

	    fx_sw_user->xstate_size > xstate_size ||

	    fx_sw_user->xstate_size > fx_sw_user->extended_size)

		return -1;



	err = __get_user(magic2, (__u32 *) (((void *)fpstate) +

					    fx_sw_user->extended_size -

					    FP_XSTATE_MAGIC2_SIZE));

	/*

	 * Check for the presence of second magic word at the end of memory

	 * layout. This detects the case where the user just copied the legacy

	 * fpstate layout with out copying the extended state information

	 * in the memory layout.

	 */

	if (err || magic2 != FP_XSTATE_MAGIC2)

		return -1;



	return 0;

}



#ifdef CONFIG_X86_64

/*

 * Signal frame handlers.
@@ -28,15 +84,18 @@ int save_i387_xstate(void __user *buf) 
	BUILD_BUG_ON(sizeof(struct user_i387_struct) !=

			sizeof(tsk->thread.xstate->fxsave));



	if ((unsigned long)buf % 16)

	if ((unsigned long)buf % 64)

		printk("save_i387_xstate: bad fpstate %p\n", buf);



	if (!used_math())

		return 0;

	clear_used_math(); /* trigger finit */

	if (task_thread_info(tsk)->status & TS_USEDFPU) {

		err = save_i387_checking((struct i387_fxsave_struct __user *)

					 buf);

		if (task_thread_info(tsk)->status & TS_XSAVE)

			err = xsave_user(buf);

		else

			err = fxsave_user(buf);



		if (err)

			return err;

		task_thread_info(tsk)->status &= ~TS_USEDFPU;
@@ -46,23 +105,77 @@ int save_i387_xstate(void __user *buf) 
				   xstate_size))

			return -1;

	}



	if (task_thread_info(tsk)->status & TS_XSAVE) {

		struct _fpstate __user *fx = buf;



		err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,

				     sizeof(struct _fpx_sw_bytes));



		err |= __put_user(FP_XSTATE_MAGIC2,

				  (__u32 __user *) (buf + sig_xstate_size

						    - FP_XSTATE_MAGIC2_SIZE));

	}



	return 1;

}



/*

 * Restore the extended state if present. Otherwise, restore the FP/SSE

 * state.

 */

int restore_user_xstate(void __user *buf)

{

	struct _fpx_sw_bytes fx_sw_user;

	unsigned int lmask, hmask;

	int err;



	if (((unsigned long)buf % 64) ||

	     check_for_xstate(buf, buf, &fx_sw_user))

		goto fx_only;



	lmask = fx_sw_user.xstate_bv;

	hmask = fx_sw_user.xstate_bv >> 32;



	/*

	 * restore the state passed by the user.

	 */

	err = xrestore_user(buf, lmask, hmask);

	if (err)

		return err;



	/*

	 * init the state skipped by the user.

	 */

	lmask = pcntxt_lmask & ~lmask;

	hmask = pcntxt_hmask & ~hmask;



	xrstor_state(init_xstate_buf, lmask, hmask);



	return 0;



fx_only:

	/*

	 * couldn't find the extended state information in the

	 * memory layout. Restore just the FP/SSE and init all

	 * the other extended state.

	 */

	xrstor_state(init_xstate_buf, pcntxt_lmask & ~XSTATE_FPSSE,

		     pcntxt_hmask);

	return fxrstor_checking((__force struct i387_fxsave_struct *)buf);

}



/*

 * This restores directly out of user space. Exceptions are handled.

 */

int restore_i387_xstate(void __user *buf)

{

	struct task_struct *tsk = current;

	int err;

	int err = 0;



	if (!buf) {

		if (used_math()) {

			clear_fpu(tsk);

			clear_used_math();

		}



		if (used_math())

			goto clear;

		return 0;

	} else

		if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
@@ -78,12 +191,17 @@ int restore_i387_xstate(void __user *buf) 
		clts();

		task_thread_info(current)->status |= TS_USEDFPU;

	}

	err = fxrstor_checking((__force struct i387_fxsave_struct *)buf);

	if (task_thread_info(tsk)->status & TS_XSAVE)

		err = restore_user_xstate(buf);

	else

		err = fxrstor_checking((__force struct i387_fxsave_struct *)

				       buf);

	if (unlikely(err)) {

		/*

		 * Encountered an error while doing the restore from the

		 * user buffer, clear the fpu state.

		 */

clear:

		clear_fpu(tsk);

		clear_used_math();

	}
@@ -91,6 +209,38 @@ int restore_i387_xstate(void __user *buf) 
}

#endif



/*

 * Prepare the SW reserved portion of the fxsave memory layout, indicating

 * the presence of the extended state information in the memory layout

 * pointed by the fpstate pointer in the sigcontext.

 * This will be saved when ever the FP and extended state context is

 * saved on the user stack during the signal handler delivery to the user.

 */

void prepare_fx_sw_frame(void)

{

	int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +

			     FP_XSTATE_MAGIC2_SIZE;



	sig_xstate_size = sizeof(struct _fpstate) + size_extended;



#ifdef CONFIG_IA32_EMULATION

	sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;

#endif



	memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));



	fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;

	fx_sw_reserved.extended_size = sig_xstate_size;

	fx_sw_reserved.xstate_bv = pcntxt_lmask |

					 (((u64) (pcntxt_hmask)) << 32);

	fx_sw_reserved.xstate_size = xstate_size;

#ifdef CONFIG_IA32_EMULATION

	memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,

	       sizeof(struct _fpx_sw_bytes));

	fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;

#endif

}



/*

 * Represents init state for the supported extended state.

 */
@@ -162,6 +312,8 @@ void __init xsave_cntxt_init(void) 


	xstate_size = ebx;



	prepare_fx_sw_frame();



	setup_xstate_init();



	printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%Lx, "

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