[mirror_ubuntu-kernels.git] / arch / parisc / kernel / syscall.S

/* 
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 * 
 * System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
 * Licensed under the GNU GPL.
 * thanks to Philipp Rumpf, Mike Shaver and various others
 * sorry about the wall, puffin..
 */

#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#include <asm/errno.h>
#include <asm/psw.h>
#include <asm/thread_info.h>
#include <asm/assembly.h>
#include <asm/processor.h>

#include <linux/linkage.h>

	/* We fill the empty parts of the gateway page with
 	 * something that will kill the kernel or a
 	 * userspace application.
	 */
#define KILL_INSN	break	0,0

	.level          LEVEL

	.text

	.import syscall_exit,code
	.import syscall_exit_rfi,code

	/* Linux gateway page is aliased to virtual page 0 in the kernel
	 * address space. Since it is a gateway page it cannot be
	 * dereferenced, so null pointers will still fault. We start
	 * the actual entry point at 0x100. We put break instructions
	 * at the beginning of the page to trap null indirect function
	 * pointers.
	 */

	.align ASM_PAGE_SIZE
ENTRY(linux_gateway_page)

        /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
	.rept 44
	KILL_INSN
	.endr

	/* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */
	/* Light-weight-syscall entry must always be located at 0xb0 */
	/* WARNING: Keep this number updated with table size changes */
#define __NR_lws_entries (2)

lws_entry:
	/* Unconditional branch to lws_start, located on the 
	   same gateway page */
	b,n	lws_start

	/* Fill from 0xb4 to 0xe0 */
	.rept 11
	KILL_INSN
	.endr

	/* This function MUST be located at 0xe0 for glibc's threading 
	mechanism to work. DO NOT MOVE THIS CODE EVER! */
set_thread_pointer:
	gate	.+8, %r0		/* increase privilege */
	depi	3, 31, 2, %r31		/* Ensure we return into user mode. */
	be	0(%sr7,%r31)		/* return to user space */
	mtctl	%r26, %cr27		/* move arg0 to the control register */

	/* Increase the chance of trapping if random jumps occur to this
	address, fill from 0xf0 to 0x100 */
	.rept 4
	KILL_INSN
	.endr

/* This address must remain fixed at 0x100 for glibc's syscalls to work */
	.align 256
linux_gateway_entry:
	gate	.+8, %r0			/* become privileged */
	mtsp	%r0,%sr4			/* get kernel space into sr4 */
	mtsp	%r0,%sr5			/* get kernel space into sr5 */
	mtsp	%r0,%sr6			/* get kernel space into sr6 */
	mfsp    %sr7,%r1                        /* save user sr7 */
	mtsp    %r1,%sr3                        /* and store it in sr3 */

#ifdef CONFIG_64BIT
	/* for now we can *always* set the W bit on entry to the syscall
	 * since we don't support wide userland processes.  We could
	 * also save the current SM other than in r0 and restore it on
	 * exit from the syscall, and also use that value to know
	 * whether to do narrow or wide syscalls. -PB
	 */
	ssm	PSW_SM_W, %r1
	extrd,u	%r1,PSW_W_BIT,1,%r1
	/* sp must be aligned on 4, so deposit the W bit setting into
	 * the bottom of sp temporarily */
	or,ev	%r1,%r30,%r30
	b,n	1f
	/* The top halves of argument registers must be cleared on syscall
	 * entry from narrow executable.
	 */
	depdi	0, 31, 32, %r26
	depdi	0, 31, 32, %r25
	depdi	0, 31, 32, %r24
	depdi	0, 31, 32, %r23
	depdi	0, 31, 32, %r22
	depdi	0, 31, 32, %r21
1:	
#endif
	mfctl   %cr30,%r1
	xor     %r1,%r30,%r30                   /* ye olde xor trick */
	xor     %r1,%r30,%r1
	xor     %r1,%r30,%r30
	
	ldo     THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30  /* set up kernel stack */

	/* N.B.: It is critical that we don't set sr7 to 0 until r30
	 *       contains a valid kernel stack pointer. It is also
	 *       critical that we don't start using the kernel stack
	 *       until after sr7 has been set to 0.
	 */

	mtsp	%r0,%sr7			/* get kernel space into sr7 */
	STREGM	%r1,FRAME_SIZE(%r30)		/* save r1 (usp) here for now */
	mfctl	%cr30,%r1			/* get task ptr in %r1 */
	LDREG	TI_TASK(%r1),%r1

	/* Save some registers for sigcontext and potential task
	   switch (see entry.S for the details of which ones are
	   saved/restored).  TASK_PT_PSW is zeroed so we can see whether
	   a process is on a syscall or not.  For an interrupt the real
	   PSW value is stored.  This is needed for gdb and sys_ptrace. */
	STREG	%r0,  TASK_PT_PSW(%r1)
	STREG	%r2,  TASK_PT_GR2(%r1)		/* preserve rp */
	STREG	%r19, TASK_PT_GR19(%r1)

	LDREGM	-FRAME_SIZE(%r30), %r2		/* get users sp back */
#ifdef CONFIG_64BIT
	extrd,u	%r2,63,1,%r19			/* W hidden in bottom bit */
#if 0
	xor	%r19,%r2,%r2			/* clear bottom bit */
	depd,z	%r19,1,1,%r19
	std	%r19,TASK_PT_PSW(%r1)
#endif
#endif
	STREG	%r2,  TASK_PT_GR30(%r1)		/* ... and save it */
	
	STREG	%r20, TASK_PT_GR20(%r1)		/* Syscall number */
	STREG	%r21, TASK_PT_GR21(%r1)
	STREG	%r22, TASK_PT_GR22(%r1)
	STREG	%r23, TASK_PT_GR23(%r1)		/* 4th argument */
	STREG	%r24, TASK_PT_GR24(%r1)		/* 3rd argument */
	STREG	%r25, TASK_PT_GR25(%r1)		/* 2nd argument */
	STREG	%r26, TASK_PT_GR26(%r1)	 	/* 1st argument */
	STREG	%r27, TASK_PT_GR27(%r1)		/* user dp */
	STREG   %r28, TASK_PT_GR28(%r1)         /* return value 0 */
	STREG   %r28, TASK_PT_ORIG_R28(%r1)     /* return value 0 (saved for signals) */
	STREG	%r29, TASK_PT_GR29(%r1)		/* return value 1 */
	STREG	%r31, TASK_PT_GR31(%r1)		/* preserve syscall return ptr */
	
	ldo	TASK_PT_FR0(%r1), %r27		/* save fpregs from the kernel */
	save_fp	%r27				/* or potential task switch  */

	mfctl	%cr11, %r27			/* i.e. SAR */
	STREG	%r27, TASK_PT_SAR(%r1)

	loadgp

#ifdef CONFIG_64BIT
	ldo	-16(%r30),%r29			/* Reference param save area */
	copy	%r19,%r2			/* W bit back to r2 */
#else
	/* no need to save these on stack in wide mode because the first 8
	 * args are passed in registers */
	stw     %r22, -52(%r30)                 /* 5th argument */
	stw     %r21, -56(%r30)                 /* 6th argument */
#endif

	/* Are we being ptraced? */
	mfctl	%cr30, %r1
	LDREG	TI_TASK(%r1),%r1
	ldw	TASK_PTRACE(%r1), %r1
	bb,<,n	%r1,31,.Ltracesys
	
	/* Note!  We cannot use the syscall table that is mapped
	nearby since the gateway page is mapped execute-only. */

#ifdef CONFIG_64BIT
	ldil	L%sys_call_table, %r1
	or,=	%r2,%r2,%r2
	addil	L%(sys_call_table64-sys_call_table), %r1
	ldo	R%sys_call_table(%r1), %r19
	or,=	%r2,%r2,%r2
	ldo	R%sys_call_table64(%r1), %r19
#else
	ldil	L%sys_call_table, %r1
	ldo     R%sys_call_table(%r1), %r19
#endif	
	comiclr,>>	__NR_Linux_syscalls, %r20, %r0
	b,n	.Lsyscall_nosys
	
	LDREGX  %r20(%r19), %r19

	/* If this is a sys_rt_sigreturn call, and the signal was received
	 * when not in_syscall, then we want to return via syscall_exit_rfi,
	 * not syscall_exit.  Signal no. in r20, in_syscall in r25 (see
	 * trampoline code in signal.c).
	 */
	ldi	__NR_rt_sigreturn,%r2
	comb,=	%r2,%r20,.Lrt_sigreturn
.Lin_syscall:
	ldil	L%syscall_exit,%r2
	be      0(%sr7,%r19)
	ldo	R%syscall_exit(%r2),%r2
.Lrt_sigreturn:
	comib,<> 0,%r25,.Lin_syscall
	ldil	L%syscall_exit_rfi,%r2
	be      0(%sr7,%r19)
	ldo	R%syscall_exit_rfi(%r2),%r2

	/* Note!  Because we are not running where we were linked, any
	calls to functions external to this file must be indirect.  To
	be safe, we apply the opposite rule to functions within this
	file, with local labels given to them to ensure correctness. */
	
.Lsyscall_nosys:
syscall_nosys:
	ldil	L%syscall_exit,%r1
	be	R%syscall_exit(%sr7,%r1)
	ldo	-ENOSYS(%r0),%r28		   /* set errno */


/* Warning! This trace code is a virtual duplicate of the code above so be
 * sure to maintain both! */
.Ltracesys:
tracesys:
	/* Need to save more registers so the debugger can see where we
	 * are.  This saves only the lower 8 bits of PSW, so that the C
	 * bit is still clear on syscalls, and the D bit is set if this
	 * full register save path has been executed.  We check the D
	 * bit on syscall_return_rfi to determine which registers to
	 * restore.  An interrupt results in a full PSW saved with the
	 * C bit set, a non-straced syscall entry results in C and D clear
	 * in the saved PSW.
	 */
	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
	LDREG	TI_TASK(%r1), %r1
	ssm	0,%r2
	STREG	%r2,TASK_PT_PSW(%r1)		/* Lower 8 bits only!! */
	mfsp	%sr0,%r2
	STREG	%r2,TASK_PT_SR0(%r1)
	mfsp	%sr1,%r2
	STREG	%r2,TASK_PT_SR1(%r1)
	mfsp	%sr2,%r2
	STREG	%r2,TASK_PT_SR2(%r1)
	mfsp	%sr3,%r2
	STREG	%r2,TASK_PT_SR3(%r1)
	STREG	%r2,TASK_PT_SR4(%r1)
	STREG	%r2,TASK_PT_SR5(%r1)
	STREG	%r2,TASK_PT_SR6(%r1)
	STREG	%r2,TASK_PT_SR7(%r1)
	STREG	%r2,TASK_PT_IASQ0(%r1)
	STREG	%r2,TASK_PT_IASQ1(%r1)
	LDREG	TASK_PT_GR31(%r1),%r2
	STREG	%r2,TASK_PT_IAOQ0(%r1)
	ldo	4(%r2),%r2
	STREG	%r2,TASK_PT_IAOQ1(%r1)
	ldo	TASK_REGS(%r1),%r2
	/* reg_save %r2 */
	STREG	%r3,PT_GR3(%r2)
	STREG	%r4,PT_GR4(%r2)
	STREG	%r5,PT_GR5(%r2)
	STREG	%r6,PT_GR6(%r2)
	STREG	%r7,PT_GR7(%r2)
	STREG	%r8,PT_GR8(%r2)
	STREG	%r9,PT_GR9(%r2)
	STREG	%r10,PT_GR10(%r2)
	STREG	%r11,PT_GR11(%r2)
	STREG	%r12,PT_GR12(%r2)
	STREG	%r13,PT_GR13(%r2)
	STREG	%r14,PT_GR14(%r2)
	STREG	%r15,PT_GR15(%r2)
	STREG	%r16,PT_GR16(%r2)
	STREG	%r17,PT_GR17(%r2)
	STREG	%r18,PT_GR18(%r2)
	/* Finished saving things for the debugger */

	ldil	L%syscall_trace,%r1
	ldil	L%tracesys_next,%r2
	be	R%syscall_trace(%sr7,%r1)
	ldo	R%tracesys_next(%r2),%r2
	
tracesys_next:	
	ldil	L%sys_call_table,%r1
	ldo     R%sys_call_table(%r1), %r19

	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
	LDREG	TI_TASK(%r1), %r1
	LDREG   TASK_PT_GR20(%r1), %r20
	LDREG   TASK_PT_GR26(%r1), %r26		/* Restore the users args */
	LDREG   TASK_PT_GR25(%r1), %r25
	LDREG   TASK_PT_GR24(%r1), %r24
	LDREG   TASK_PT_GR23(%r1), %r23
#ifdef CONFIG_64BIT
	LDREG   TASK_PT_GR22(%r1), %r22
	LDREG   TASK_PT_GR21(%r1), %r21
	ldo	-16(%r30),%r29			/* Reference param save area */
#endif

	comiclr,>>=	__NR_Linux_syscalls, %r20, %r0
	b,n	.Lsyscall_nosys

	LDREGX  %r20(%r19), %r19

	/* If this is a sys_rt_sigreturn call, and the signal was received
	 * when not in_syscall, then we want to return via syscall_exit_rfi,
	 * not syscall_exit.  Signal no. in r20, in_syscall in r25 (see
	 * trampoline code in signal.c).
	 */
	ldi	__NR_rt_sigreturn,%r2
	comb,=	%r2,%r20,.Ltrace_rt_sigreturn
.Ltrace_in_syscall:
	ldil	L%tracesys_exit,%r2
	be      0(%sr7,%r19)
	ldo	R%tracesys_exit(%r2),%r2

	/* Do *not* call this function on the gateway page, because it
	makes a direct call to syscall_trace. */
	
tracesys_exit:
	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
	LDREG	TI_TASK(%r1), %r1
#ifdef CONFIG_64BIT
	ldo	-16(%r30),%r29			/* Reference param save area */
#endif
	bl	syscall_trace, %r2
	STREG   %r28,TASK_PT_GR28(%r1)          /* save return value now */
	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
	LDREG	TI_TASK(%r1), %r1
	LDREG   TASK_PT_GR28(%r1), %r28		/* Restore return val. */

	ldil	L%syscall_exit,%r1
	be,n	R%syscall_exit(%sr7,%r1)

.Ltrace_rt_sigreturn:
	comib,<> 0,%r25,.Ltrace_in_syscall
	ldil	L%tracesys_sigexit,%r2
	be      0(%sr7,%r19)
	ldo	R%tracesys_sigexit(%r2),%r2

tracesys_sigexit:
	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
	LDREG	0(%r1), %r1
#ifdef CONFIG_64BIT
	ldo	-16(%r30),%r29			/* Reference param save area */
#endif
	bl	syscall_trace, %r2
	nop

	ldil	L%syscall_exit_rfi,%r1
	be,n	R%syscall_exit_rfi(%sr7,%r1)


	/*********************************************************
		Light-weight-syscall code

		r20 - lws number
		r26,r25,r24,r23,r22 - Input registers
		r28 - Function return register
		r21 - Error code.

		Scracth: Any of the above that aren't being
		currently used, including r1. 

		Return pointer: r31 (Not usable)

		Error codes returned by entry path:

		ENOSYS - r20 was an invalid LWS number.

	*********************************************************/
lws_start:
	/* Gate and ensure we return to userspace */
	gate	.+8, %r0
	depi	3, 31, 2, %r31	/* Ensure we return to userspace */

#ifdef CONFIG_64BIT
	/* FIXME: If we are a 64-bit kernel just
	 *        turn this on unconditionally.
	 */
	ssm	PSW_SM_W, %r1
	extrd,u	%r1,PSW_W_BIT,1,%r1
	/* sp must be aligned on 4, so deposit the W bit setting into
	 * the bottom of sp temporarily */
	or,ev	%r1,%r30,%r30

	/* Clip LWS number to a 32-bit value always */
	depdi	0, 31, 32, %r20
#endif	

        /* Is the lws entry number valid? */
	comiclr,>>=	__NR_lws_entries, %r20, %r0
	b,n	lws_exit_nosys

	/* WARNING: Trashing sr2 and sr3 */
	mfsp	%sr7,%r1			/* get userspace into sr3 */
	mtsp	%r1,%sr3
	mtsp	%r0,%sr2			/* get kernel space into sr2 */

	/* Load table start */
	ldil	L%lws_table, %r1
	ldo	R%lws_table(%r1), %r28	/* Scratch use of r28 */
	LDREGX	%r20(%sr2,r28), %r21	/* Scratch use of r21 */

	/* Jump to lws, lws table pointers already relocated */
	be,n	0(%sr2,%r21)

lws_exit_nosys:
	ldo	-ENOSYS(%r0),%r21		   /* set errno */
	/* Fall through: Return to userspace */

lws_exit:
#ifdef CONFIG_64BIT
	/* decide whether to reset the wide mode bit
	 *
	 * For a syscall, the W bit is stored in the lowest bit
	 * of sp.  Extract it and reset W if it is zero */
	extrd,u,*<>	%r30,63,1,%r1
	rsm	PSW_SM_W, %r0
	/* now reset the lowest bit of sp if it was set */
	xor	%r30,%r1,%r30
#endif
	be,n	0(%sr3, %r31)


	/***************************************************
		Implementing CAS as an atomic operation:

		%r26 - Address to examine
		%r25 - Old value to check (old)
		%r24 - New value to set (new)
		%r28 - Return prev through this register.
		%r21 - Kernel error code

		If debugging is DISabled:

		%r21 has the following meanings:

		EAGAIN - CAS is busy, ldcw failed, try again.
		EFAULT - Read or write failed.		

		If debugging is enabled:

		EDEADLOCK - CAS called recursively.
		EAGAIN && r28 == 1 - CAS is busy. Lock contended.
		EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
		EFAULT - Read or write failed.

		Scratch: r20, r28, r1

	****************************************************/

	/* Do not enable LWS debugging */
#define ENABLE_LWS_DEBUG 0 

	/* ELF64 Process entry path */
lws_compare_and_swap64:
#ifdef CONFIG_64BIT
	b,n	lws_compare_and_swap
#else
	/* If we are not a 64-bit kernel, then we don't
	 * implement having 64-bit input registers
	 */
	b,n	lws_exit_nosys
#endif

	/* ELF32 Process entry path */
lws_compare_and_swap32:
#ifdef CONFIG_64BIT
	/* Clip all the input registers */
	depdi	0, 31, 32, %r26
	depdi	0, 31, 32, %r25
	depdi	0, 31, 32, %r24
#endif

lws_compare_and_swap:
#ifdef CONFIG_SMP
	/* Load start of lock table */
	ldil	L%lws_lock_start, %r20
	ldo	R%lws_lock_start(%r20), %r28

	/* Extract four bits from r26 and hash lock (Bits 4-7) */
	extru  %r26, 27, 4, %r20

	/* Find lock to use, the hash is either one of 0 to
	   15, multiplied by 16 (keep it 16-byte aligned)
	   and add to the lock table offset. */
	shlw	%r20, 4, %r20
	add	%r20, %r28, %r20

# if ENABLE_LWS_DEBUG
	/*	
		DEBUG, check for deadlock! 
		If the thread register values are the same
		then we were the one that locked it last and
		this is a recurisve call that will deadlock.
		We *must* giveup this call and fail.
	*/
	ldw	4(%sr2,%r20), %r28			/* Load thread register */
	/* WARNING: If cr27 cycles to the same value we have problems */
	mfctl	%cr27, %r21				/* Get current thread register */
	cmpb,<>,n	%r21, %r28, cas_lock		/* Called recursive? */
	b	lws_exit				/* Return error! */
	ldo	-EDEADLOCK(%r0), %r21
cas_lock:
	cmpb,=,n	%r0, %r28, cas_nocontend	/* Is nobody using it? */
	ldo	1(%r0), %r28				/* 1st case */
	b	lws_exit				/* Contended... */
	ldo	-EAGAIN(%r0), %r21			/* Spin in userspace */
cas_nocontend:
# endif
/* ENABLE_LWS_DEBUG */

	LDCW	0(%sr2,%r20), %r28			/* Try to acquire the lock */
	cmpb,<>,n	%r0, %r28, cas_action		/* Did we get it? */
cas_wouldblock:
	ldo	2(%r0), %r28				/* 2nd case */
	b	lws_exit				/* Contended... */
	ldo	-EAGAIN(%r0), %r21			/* Spin in userspace */
#endif
/* CONFIG_SMP */

	/*
		prev = *addr;
		if ( prev == old )
		  *addr = new;
		return prev;
	*/

	/* NOTES:
		This all works becuse intr_do_signal
		and schedule both check the return iasq
		and see that we are on the kernel page
		so this process is never scheduled off
		or is ever sent any signal of any sort,
		thus it is wholly atomic from usrspaces
		perspective
	*/
cas_action:
#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
	/* DEBUG */
	mfctl	%cr27, %r1
	stw	%r1, 4(%sr2,%r20)
#endif
	/* The load and store could fail */
1:	ldw	0(%sr3,%r26), %r28
	sub,<>	%r28, %r25, %r0
2:	stw	%r24, 0(%sr3,%r26)
#ifdef CONFIG_SMP
	/* Free lock */
	stw	%r20, 0(%sr2,%r20)
# if ENABLE_LWS_DEBUG
	/* Clear thread register indicator */
	stw	%r0, 4(%sr2,%r20)
# endif
#endif
	/* Return to userspace, set no error */
	b	lws_exit
	copy	%r0, %r21

3:		
	/* Error occured on load or store */
#ifdef CONFIG_SMP
	/* Free lock */
	stw	%r20, 0(%sr2,%r20)
# if ENABLE_LWS_DEBUG
	stw	%r0, 4(%sr2,%r20)
# endif
#endif
	b	lws_exit
	ldo	-EFAULT(%r0),%r21	/* set errno */
	nop
	nop
	nop
	nop

	/* Two exception table entries, one for the load,
	   the other for the store. Either return -EFAULT.
	   Each of the entries must be relocated. */
	.section __ex_table,"aw"
	ASM_ULONG_INSN (1b - linux_gateway_page), (3b - linux_gateway_page)
	ASM_ULONG_INSN (2b - linux_gateway_page), (3b - linux_gateway_page)
	.previous


	/* Make sure nothing else is placed on this page */
	.align ASM_PAGE_SIZE
END(linux_gateway_page)
ENTRY(end_linux_gateway_page)

	/* Relocate symbols assuming linux_gateway_page is mapped
	   to virtual address 0x0 */

#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)

	.section .rodata,"a"

	.align ASM_PAGE_SIZE
	/* Light-weight-syscall table */
	/* Start of lws table. */
ENTRY(lws_table)
	LWS_ENTRY(compare_and_swap32)	/* 0 - ELF32 Atomic compare and swap */
	LWS_ENTRY(compare_and_swap64)	/* 1 - ELF64 Atomic compare and swap */
END(lws_table)
	/* End of lws table */

	.align ASM_PAGE_SIZE
ENTRY(sys_call_table)
#include "syscall_table.S"
END(sys_call_table)

#ifdef CONFIG_64BIT
	.align ASM_PAGE_SIZE
ENTRY(sys_call_table64)
#define SYSCALL_TABLE_64BIT
#include "syscall_table.S"
END(sys_call_table64)
#endif

#ifdef CONFIG_SMP
	/*
		All light-weight-syscall atomic operations 
		will use this set of locks 
	*/
	.section .data
	.align 4096
ENTRY(lws_lock_start)
	/* lws locks */
	.align 16
	.rept 16
	/* Keep locks aligned at 16-bytes */
	.word 1
	.word 0 
	.word 0
	.word 0
	.endr
END(lws_lock_start)
	.previous
#endif
/* CONFIG_SMP for lws_lock_start */

.end
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Linux/PA-RISC Project (http://www.parisc-linux.org/)
	3	*
	4	* System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
	5	* Licensed under the GNU GPL.
	6	* thanks to Philipp Rumpf, Mike Shaver and various others
	7	* sorry about the wall, puffin..
	8	*/
	9
0013a854	10	#include <asm/asm-offsets.h>
1da177e4 LT	11	#include <asm/unistd.h>
	12	#include <asm/errno.h>
	13	#include <asm/psw.h>
	14	#include <asm/thread_info.h>
1da177e4 LT	15	#include <asm/assembly.h>
	16	#include <asm/processor.h>
	17
8e9e9844 HD	18	#include <linux/linkage.h>
8e9e9844 HD	19
1da177e4 LT	20	/* We fill the empty parts of the gateway page with
	21	* something that will kill the kernel or a
	22	* userspace application.
	23	*/
	24	#define KILL_INSN break 0,0
	25
0b3d643f	26	.level LEVEL
8e9e9844	27
1da177e4 LT	28	.text
	29
	30	.import syscall_exit,code
	31	.import syscall_exit_rfi,code
1da177e4 LT	32
	33	/* Linux gateway page is aliased to virtual page 0 in the kernel
	34	* address space. Since it is a gateway page it cannot be
	35	* dereferenced, so null pointers will still fault. We start
	36	* the actual entry point at 0x100. We put break instructions
	37	* at the beginning of the page to trap null indirect function
	38	* pointers.
	39	*/
	40
2fd83038	41	.align ASM_PAGE_SIZE
8e9e9844	42	ENTRY(linux_gateway_page)
1da177e4 LT	43
	44	/* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */
	45	.rept 44
	46	KILL_INSN
	47	.endr
	48
	49	/* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */
	50	/* Light-weight-syscall entry must always be located at 0xb0 */
	51	/* WARNING: Keep this number updated with table size changes */
	52	#define __NR_lws_entries (2)
	53
	54	lws_entry:
	55	/* Unconditional branch to lws_start, located on the
	56	same gateway page */
	57	b,n lws_start
	58
	59	/* Fill from 0xb4 to 0xe0 */
	60	.rept 11
	61	KILL_INSN
	62	.endr
	63
	64	/* This function MUST be located at 0xe0 for glibc's threading
	65	mechanism to work. DO NOT MOVE THIS CODE EVER! */
	66	set_thread_pointer:
	67	gate .+8, %r0 /* increase privilege */
	68	depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
	69	be 0(%sr7,%r31) /* return to user space */
	70	mtctl %r26, %cr27 /* move arg0 to the control register */
	71
	72	/* Increase the chance of trapping if random jumps occur to this
	73	address, fill from 0xf0 to 0x100 */
	74	.rept 4
	75	KILL_INSN
	76	.endr
	77
	78	/* This address must remain fixed at 0x100 for glibc's syscalls to work */
	79	.align 256
	80	linux_gateway_entry:
	81	gate .+8, %r0 /* become privileged */
	82	mtsp %r0,%sr4 /* get kernel space into sr4 */
	83	mtsp %r0,%sr5 /* get kernel space into sr5 */
	84	mtsp %r0,%sr6 /* get kernel space into sr6 */
	85	mfsp %sr7,%r1 /* save user sr7 */
	86	mtsp %r1,%sr3 /* and store it in sr3 */
	87
413059f2	88	#ifdef CONFIG_64BIT
1da177e4 LT	89	/* for now we can always set the W bit on entry to the syscall
	90	* since we don't support wide userland processes. We could
	91	* also save the current SM other than in r0 and restore it on
	92	* exit from the syscall, and also use that value to know
	93	* whether to do narrow or wide syscalls. -PB
	94	*/
	95	ssm PSW_SM_W, %r1
	96	extrd,u %r1,PSW_W_BIT,1,%r1
	97	/* sp must be aligned on 4, so deposit the W bit setting into
	98	* the bottom of sp temporarily */
	99	or,ev %r1,%r30,%r30
	100	b,n 1f
	101	/* The top halves of argument registers must be cleared on syscall
	102	* entry from narrow executable.
	103	*/
	104	depdi 0, 31, 32, %r26
	105	depdi 0, 31, 32, %r25
	106	depdi 0, 31, 32, %r24
	107	depdi 0, 31, 32, %r23
	108	depdi 0, 31, 32, %r22
	109	depdi 0, 31, 32, %r21
	110	1:
	111	#endif
	112	mfctl %cr30,%r1
	113	xor %r1,%r30,%r30 /* ye olde xor trick */
	114	xor %r1,%r30,%r1
	115	xor %r1,%r30,%r30
	116
	117	ldo THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30 /* set up kernel stack */
	118
	119	/* N.B.: It is critical that we don't set sr7 to 0 until r30
	120	* contains a valid kernel stack pointer. It is also
	121	* critical that we don't start using the kernel stack
	122	* until after sr7 has been set to 0.
	123	*/
	124
	125	mtsp %r0,%sr7 /* get kernel space into sr7 */
	126	STREGM %r1,FRAME_SIZE(%r30) /* save r1 (usp) here for now */
	127	mfctl %cr30,%r1 /* get task ptr in %r1 */
	128	LDREG TI_TASK(%r1),%r1
	129
	130	/* Save some registers for sigcontext and potential task
	131	switch (see entry.S for the details of which ones are
	132	saved/restored). TASK_PT_PSW is zeroed so we can see whether
	133	a process is on a syscall or not. For an interrupt the real
	134	PSW value is stored. This is needed for gdb and sys_ptrace. */
	135	STREG %r0, TASK_PT_PSW(%r1)
	136	STREG %r2, TASK_PT_GR2(%r1) /* preserve rp */
	137	STREG %r19, TASK_PT_GR19(%r1)
	138
	139	LDREGM -FRAME_SIZE(%r30), %r2 /* get users sp back */
413059f2	140	#ifdef CONFIG_64BIT
1da177e4 LT	141	extrd,u %r2,63,1,%r19 /* W hidden in bottom bit */
	142	#if 0
	143	xor %r19,%r2,%r2 /* clear bottom bit */
	144	depd,z %r19,1,1,%r19
	145	std %r19,TASK_PT_PSW(%r1)
	146	#endif
	147	#endif
	148	STREG %r2, TASK_PT_GR30(%r1) /* ... and save it */
	149
aa0eecb0	150	STREG %r20, TASK_PT_GR20(%r1) /* Syscall number */
1da177e4 LT	151	STREG %r21, TASK_PT_GR21(%r1)
	152	STREG %r22, TASK_PT_GR22(%r1)
	153	STREG %r23, TASK_PT_GR23(%r1) /* 4th argument */
	154	STREG %r24, TASK_PT_GR24(%r1) /* 3rd argument */
	155	STREG %r25, TASK_PT_GR25(%r1) /* 2nd argument */
	156	STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
	157	STREG %r27, TASK_PT_GR27(%r1) /* user dp */
	158	STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
	159	STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */
	160	STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
	161	STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
	162
	163	ldo TASK_PT_FR0(%r1), %r27 /* save fpregs from the kernel */
	164	save_fp %r27 /* or potential task switch */
	165
	166	mfctl %cr11, %r27 /* i.e. SAR */
	167	STREG %r27, TASK_PT_SAR(%r1)
	168
	169	loadgp
	170
413059f2	171	#ifdef CONFIG_64BIT
1da177e4 LT	172	ldo -16(%r30),%r29 /* Reference param save area */
	173	copy %r19,%r2 /* W bit back to r2 */
	174	#else
	175	/* no need to save these on stack in wide mode because the first 8
	176	* args are passed in registers */
	177	stw %r22, -52(%r30) /* 5th argument */
	178	stw %r21, -56(%r30) /* 6th argument */
	179	#endif
	180
	181	/* Are we being ptraced? */
	182	mfctl %cr30, %r1
	183	LDREG TI_TASK(%r1),%r1
376e210b	184	ldw TASK_PTRACE(%r1), %r1
1da177e4 LT	185	bb,<,n %r1,31,.Ltracesys
	186
	187	/* Note! We cannot use the syscall table that is mapped
	188	nearby since the gateway page is mapped execute-only. */
	189
413059f2	190	#ifdef CONFIG_64BIT
1da177e4 LT	191	ldil L%sys_call_table, %r1
	192	or,= %r2,%r2,%r2
	193	addil L%(sys_call_table64-sys_call_table), %r1
	194	ldo R%sys_call_table(%r1), %r19
	195	or,= %r2,%r2,%r2
	196	ldo R%sys_call_table64(%r1), %r19
	197	#else
	198	ldil L%sys_call_table, %r1
	199	ldo R%sys_call_table(%r1), %r19
	200	#endif
3bb457af	201	comiclr,>> __NR_Linux_syscalls, %r20, %r0
1da177e4 LT	202	b,n .Lsyscall_nosys
	203
	204	LDREGX %r20(%r19), %r19
	205
	206	/* If this is a sys_rt_sigreturn call, and the signal was received
	207	* when not in_syscall, then we want to return via syscall_exit_rfi,
	208	* not syscall_exit. Signal no. in r20, in_syscall in r25 (see
	209	* trampoline code in signal.c).
	210	*/
	211	ldi __NR_rt_sigreturn,%r2
	212	comb,= %r2,%r20,.Lrt_sigreturn
	213	.Lin_syscall:
	214	ldil L%syscall_exit,%r2
	215	be 0(%sr7,%r19)
	216	ldo R%syscall_exit(%r2),%r2
	217	.Lrt_sigreturn:
	218	comib,<> 0,%r25,.Lin_syscall
	219	ldil L%syscall_exit_rfi,%r2
	220	be 0(%sr7,%r19)
	221	ldo R%syscall_exit_rfi(%r2),%r2
	222
	223	/* Note! Because we are not running where we were linked, any
	224	calls to functions external to this file must be indirect. To
	225	be safe, we apply the opposite rule to functions within this
	226	file, with local labels given to them to ensure correctness. */
	227
	228	.Lsyscall_nosys:
	229	syscall_nosys:
	230	ldil L%syscall_exit,%r1
	231	be R%syscall_exit(%sr7,%r1)
	232	ldo -ENOSYS(%r0),%r28 /* set errno */
	233
	234
	235	/* Warning! This trace code is a virtual duplicate of the code above so be
	236	* sure to maintain both! */
	237	.Ltracesys:
	238	tracesys:
	239	/* Need to save more registers so the debugger can see where we
	240	* are. This saves only the lower 8 bits of PSW, so that the C
	241	* bit is still clear on syscalls, and the D bit is set if this
	242	* full register save path has been executed. We check the D
	243	* bit on syscall_return_rfi to determine which registers to
	244	* restore. An interrupt results in a full PSW saved with the
	245	* C bit set, a non-straced syscall entry results in C and D clear
	246	* in the saved PSW.
	247	*/
	248	ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
	249	LDREG TI_TASK(%r1), %r1
	250	ssm 0,%r2
	251	STREG %r2,TASK_PT_PSW(%r1) /* Lower 8 bits only!! */
	252	mfsp %sr0,%r2
	253	STREG %r2,TASK_PT_SR0(%r1)
	254	mfsp %sr1,%r2
	255	STREG %r2,TASK_PT_SR1(%r1)
	256	mfsp %sr2,%r2
	257	STREG %r2,TASK_PT_SR2(%r1)
	258	mfsp %sr3,%r2
	259	STREG %r2,TASK_PT_SR3(%r1)
	260	STREG %r2,TASK_PT_SR4(%r1)
	261	STREG %r2,TASK_PT_SR5(%r1)
	262	STREG %r2,TASK_PT_SR6(%r1)
	263	STREG %r2,TASK_PT_SR7(%r1)
	264	STREG %r2,TASK_PT_IASQ0(%r1)
	265	STREG %r2,TASK_PT_IASQ1(%r1)
266	LDREG TASK_PT_GR31(%r1),%r2
267	STREG %r2,TASK_PT_IAOQ0(%r1)
268	ldo 4(%r2),%r2
269	STREG %r2,TASK_PT_IAOQ1(%r1)
270	ldo TASK_REGS(%r1),%r2
271	/* reg_save %r2 */
272	STREG %r3,PT_GR3(%r2)
273	STREG %r4,PT_GR4(%r2)
274	STREG %r5,PT_GR5(%r2)
275	STREG %r6,PT_GR6(%r2)
276	STREG %r7,PT_GR7(%r2)
277	STREG %r8,PT_GR8(%r2)
278	STREG %r9,PT_GR9(%r2)
279	STREG %r10,PT_GR10(%r2)
280	STREG %r11,PT_GR11(%r2)
281	STREG %r12,PT_GR12(%r2)
282	STREG %r13,PT_GR13(%r2)
283	STREG %r14,PT_GR14(%r2)
284	STREG %r15,PT_GR15(%r2)
285	STREG %r16,PT_GR16(%r2)
286	STREG %r17,PT_GR17(%r2)
287	STREG %r18,PT_GR18(%r2)
288	/* Finished saving things for the debugger */
289
290	ldil L%syscall_trace,%r1
291	ldil L%tracesys_next,%r2
292	be R%syscall_trace(%sr7,%r1)
293	ldo R%tracesys_next(%r2),%r2
294
295	tracesys_next:
296	ldil L%sys_call_table,%r1
297	ldo R%sys_call_table(%r1), %r19
298
299	ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
300	LDREG TI_TASK(%r1), %r1
301	LDREG TASK_PT_GR20(%r1), %r20
302	LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
303	LDREG TASK_PT_GR25(%r1), %r25
304	LDREG TASK_PT_GR24(%r1), %r24
305	LDREG TASK_PT_GR23(%r1), %r23
413059f2	306	#ifdef CONFIG_64BIT
1da177e4 LT	307	LDREG TASK_PT_GR22(%r1), %r22
	308	LDREG TASK_PT_GR21(%r1), %r21
	309	ldo -16(%r30),%r29 /* Reference param save area */
	310	#endif
	311
	312	comiclr,>>= __NR_Linux_syscalls, %r20, %r0
	313	b,n .Lsyscall_nosys
	314
	315	LDREGX %r20(%r19), %r19
	316
	317	/* If this is a sys_rt_sigreturn call, and the signal was received
	318	* when not in_syscall, then we want to return via syscall_exit_rfi,
	319	* not syscall_exit. Signal no. in r20, in_syscall in r25 (see
	320	* trampoline code in signal.c).
	321	*/
	322	ldi __NR_rt_sigreturn,%r2
	323	comb,= %r2,%r20,.Ltrace_rt_sigreturn
	324	.Ltrace_in_syscall:
	325	ldil L%tracesys_exit,%r2
	326	be 0(%sr7,%r19)
	327	ldo R%tracesys_exit(%r2),%r2
	328
	329	/* Do not call this function on the gateway page, because it
	330	makes a direct call to syscall_trace. */
	331
	332	tracesys_exit:
	333	ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
	334	LDREG TI_TASK(%r1), %r1
413059f2	335	#ifdef CONFIG_64BIT
1da177e4 LT	336	ldo -16(%r30),%r29 /* Reference param save area */
	337	#endif
	338	bl syscall_trace, %r2
	339	STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
	340	ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
	341	LDREG TI_TASK(%r1), %r1
	342	LDREG TASK_PT_GR28(%r1), %r28 /* Restore return val. */
	343
	344	ldil L%syscall_exit,%r1
	345	be,n R%syscall_exit(%sr7,%r1)
	346
	347	.Ltrace_rt_sigreturn:
	348	comib,<> 0,%r25,.Ltrace_in_syscall
	349	ldil L%tracesys_sigexit,%r2
	350	be 0(%sr7,%r19)
	351	ldo R%tracesys_sigexit(%r2),%r2
	352
	353	tracesys_sigexit:
	354	ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
	355	LDREG 0(%r1), %r1
413059f2	356	#ifdef CONFIG_64BIT
1da177e4 LT	357	ldo -16(%r30),%r29 /* Reference param save area */
	358	#endif
	359	bl syscall_trace, %r2
	360	nop
	361
	362	ldil L%syscall_exit_rfi,%r1
	363	be,n R%syscall_exit_rfi(%sr7,%r1)
	364
	365
	366	/*********************************************************
	367	Light-weight-syscall code
	368
	369	r20 - lws number
	370	r26,r25,r24,r23,r22 - Input registers
	371	r28 - Function return register
	372	r21 - Error code.
	373
	374	Scracth: Any of the above that aren't being
	375	currently used, including r1.
	376
	377	Return pointer: r31 (Not usable)
	378
	379	Error codes returned by entry path:
	380
	381	ENOSYS - r20 was an invalid LWS number.
	382
	383	*********************************************************/
	384	lws_start:
	385	/* Gate and ensure we return to userspace */
	386	gate .+8, %r0
	387	depi 3, 31, 2, %r31 /* Ensure we return to userspace */
	388
413059f2	389	#ifdef CONFIG_64BIT
1da177e4 LT	390	/* FIXME: If we are a 64-bit kernel just
	391	* turn this on unconditionally.
	392	*/
	393	ssm PSW_SM_W, %r1
	394	extrd,u %r1,PSW_W_BIT,1,%r1
	395	/* sp must be aligned on 4, so deposit the W bit setting into
	396	* the bottom of sp temporarily */
	397	or,ev %r1,%r30,%r30
	398
	399	/* Clip LWS number to a 32-bit value always */
	400	depdi 0, 31, 32, %r20
	401	#endif
	402
	403	/* Is the lws entry number valid? */
	404	comiclr,>>= __NR_lws_entries, %r20, %r0
	405	b,n lws_exit_nosys
	406
	407	/* WARNING: Trashing sr2 and sr3 */
	408	mfsp %sr7,%r1 /* get userspace into sr3 */
	409	mtsp %r1,%sr3
	410	mtsp %r0,%sr2 /* get kernel space into sr2 */
	411
	412	/* Load table start */
	413	ldil L%lws_table, %r1
	414	ldo R%lws_table(%r1), %r28 /* Scratch use of r28 */
	415	LDREGX %r20(%sr2,r28), %r21 /* Scratch use of r21 */
	416
	417	/* Jump to lws, lws table pointers already relocated */
	418	be,n 0(%sr2,%r21)
	419
	420	lws_exit_nosys:
	421	ldo -ENOSYS(%r0),%r21 /* set errno */
	422	/* Fall through: Return to userspace */
	423
	424	lws_exit:
413059f2	425	#ifdef CONFIG_64BIT
1da177e4 LT	426	/* decide whether to reset the wide mode bit
	427	*
	428	* For a syscall, the W bit is stored in the lowest bit
	429	* of sp. Extract it and reset W if it is zero */
	430	extrd,u,*<> %r30,63,1,%r1
	431	rsm PSW_SM_W, %r0
	432	/* now reset the lowest bit of sp if it was set */
	433	xor %r30,%r1,%r30
	434	#endif
	435	be,n 0(%sr3, %r31)
	436
	437
	438
	439	/***************************************************
	440	Implementing CAS as an atomic operation:
	441
	442	%r26 - Address to examine
	443	%r25 - Old value to check (old)
	444	%r24 - New value to set (new)
	445	%r28 - Return prev through this register.
	446	%r21 - Kernel error code
	447
	448	If debugging is DISabled:
	449
	450	%r21 has the following meanings:
	451
	452	EAGAIN - CAS is busy, ldcw failed, try again.
	453	EFAULT - Read or write failed.
	454
	455	If debugging is enabled:
	456
	457	EDEADLOCK - CAS called recursively.
	458	EAGAIN && r28 == 1 - CAS is busy. Lock contended.
	459	EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
	460	EFAULT - Read or write failed.
	461
	462	Scratch: r20, r28, r1
	463
	464	****************************************************/
	465
	466	/* Do not enable LWS debugging */
	467	#define ENABLE_LWS_DEBUG 0
	468
	469	/* ELF64 Process entry path */
	470	lws_compare_and_swap64:
413059f2	471	#ifdef CONFIG_64BIT
1da177e4 LT	472	b,n lws_compare_and_swap
	473	#else
	474	/* If we are not a 64-bit kernel, then we don't
	475	* implement having 64-bit input registers
	476	*/
	477	b,n lws_exit_nosys
	478	#endif
	479
	480	/* ELF32 Process entry path */
	481	lws_compare_and_swap32:
413059f2	482	#ifdef CONFIG_64BIT
1da177e4 LT	483	/* Clip all the input registers */
	484	depdi 0, 31, 32, %r26
	485	depdi 0, 31, 32, %r25
	486	depdi 0, 31, 32, %r24
	487	#endif
	488
	489	lws_compare_and_swap:
	490	#ifdef CONFIG_SMP
	491	/* Load start of lock table */
	492	ldil L%lws_lock_start, %r20
	493	ldo R%lws_lock_start(%r20), %r28
	494
	495	/* Extract four bits from r26 and hash lock (Bits 4-7) */
	496	extru %r26, 27, 4, %r20
	497
	498	/* Find lock to use, the hash is either one of 0 to
	499	15, multiplied by 16 (keep it 16-byte aligned)
	500	and add to the lock table offset. */
	501	shlw %r20, 4, %r20
	502	add %r20, %r28, %r20
	503
b5e8b733	504	# if ENABLE_LWS_DEBUG
1da177e4 LT	505	/*
	506	DEBUG, check for deadlock!
	507	If the thread register values are the same
	508	then we were the one that locked it last and
	509	this is a recurisve call that will deadlock.
	510	We must giveup this call and fail.
	511	*/
	512	ldw 4(%sr2,%r20), %r28 /* Load thread register */
aa0eecb0	513	/* WARNING: If cr27 cycles to the same value we have problems */
1da177e4 LT	514	mfctl %cr27, %r21 /* Get current thread register */
	515	cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
	516	b lws_exit /* Return error! */
	517	ldo -EDEADLOCK(%r0), %r21
	518	cas_lock:
	519	cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
	520	ldo 1(%r0), %r28 /* 1st case */
	521	b lws_exit /* Contended... */
	522	ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
	523	cas_nocontend:
	524	# endif
	525	/* ENABLE_LWS_DEBUG */
	526
64f49532	527	LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
1da177e4 LT	528	cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
	529	cas_wouldblock:
	530	ldo 2(%r0), %r28 /* 2nd case */
	531	b lws_exit /* Contended... */
	532	ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
	533	#endif
	534	/* CONFIG_SMP */
	535
	536	/*
	537	prev = *addr;
	538	if ( prev == old )
	539	*addr = new;
	540	return prev;
	541	*/
	542
	543	/* NOTES:
	544	This all works becuse intr_do_signal
	545	and schedule both check the return iasq
	546	and see that we are on the kernel page
	547	so this process is never scheduled off
	548	or is ever sent any signal of any sort,
	549	thus it is wholly atomic from usrspaces
	550	perspective
	551	*/
	552	cas_action:
b5e8b733	553	#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
1da177e4 LT	554	/* DEBUG */
	555	mfctl %cr27, %r1
	556	stw %r1, 4(%sr2,%r20)
	557	#endif
	558	/* The load and store could fail */
	559	1: ldw 0(%sr3,%r26), %r28
	560	sub,<> %r28, %r25, %r0
	561	2: stw %r24, 0(%sr3,%r26)
	562	#ifdef CONFIG_SMP
	563	/* Free lock */
	564	stw %r20, 0(%sr2,%r20)
b5e8b733	565	# if ENABLE_LWS_DEBUG
1da177e4 LT	566	/* Clear thread register indicator */
	567	stw %r0, 4(%sr2,%r20)
	568	# endif
	569	#endif
	570	/* Return to userspace, set no error */
	571	b lws_exit
	572	copy %r0, %r21
	573
	574	3:
	575	/* Error occured on load or store */
	576	#ifdef CONFIG_SMP
	577	/* Free lock */
	578	stw %r20, 0(%sr2,%r20)
b5e8b733	579	# if ENABLE_LWS_DEBUG
1da177e4 LT	580	stw %r0, 4(%sr2,%r20)
	581	# endif
	582	#endif
	583	b lws_exit
	584	ldo -EFAULT(%r0),%r21 /* set errno */
	585	nop
	586	nop
	587	nop
	588	nop
	589
	590	/* Two exception table entries, one for the load,
	591	the other for the store. Either return -EFAULT.
	592	Each of the entries must be relocated. */
	593	.section __ex_table,"aw"
0b3d643f HD	594	ASM_ULONG_INSN (1b - linux_gateway_page), (3b - linux_gateway_page)
0b3d643f HD	595	ASM_ULONG_INSN (2b - linux_gateway_page), (3b - linux_gateway_page)
1da177e4 LT	596	.previous
1da177e4 LT	597
1da177e4 LT	598
1da177e4 LT	599	/* Make sure nothing else is placed on this page */
2fd83038	600	.align ASM_PAGE_SIZE
8e9e9844 HD	601	END(linux_gateway_page)
8e9e9844 HD	602	ENTRY(end_linux_gateway_page)
1da177e4 LT	603
	604	/* Relocate symbols assuming linux_gateway_page is mapped
	605	to virtual address 0x0 */
8e9e9844	606
0b3d643f	607	#define LWS_ENTRY(_name_) ASM_ULONG_INSN (lws_##_name_ - linux_gateway_page)
1da177e4	608
1bcdd854 HD	609	.section .rodata,"a"
1bcdd854 HD	610
2fd83038	611	.align ASM_PAGE_SIZE
1da177e4 LT	612	/* Light-weight-syscall table */
1da177e4 LT	613	/* Start of lws table. */
8e9e9844	614	ENTRY(lws_table)
1da177e4 LT	615	LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic compare and swap */
1da177e4 LT	616	LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic compare and swap */
8e9e9844	617	END(lws_table)
1da177e4 LT	618	/* End of lws table */
1da177e4 LT	619
2fd83038	620	.align ASM_PAGE_SIZE
8e9e9844	621	ENTRY(sys_call_table)
1da177e4	622	#include "syscall_table.S"
8e9e9844	623	END(sys_call_table)
1da177e4	624
413059f2	625	#ifdef CONFIG_64BIT
2fd83038	626	.align ASM_PAGE_SIZE
8e9e9844	627	ENTRY(sys_call_table64)
1da177e4 LT	628	#define SYSCALL_TABLE_64BIT
1da177e4 LT	629	#include "syscall_table.S"
8e9e9844	630	END(sys_call_table64)
1da177e4 LT	631	#endif
	632
	633	#ifdef CONFIG_SMP
	634	/*
	635	All light-weight-syscall atomic operations
	636	will use this set of locks
	637	*/
	638	.section .data
	639	.align 4096
8e9e9844	640	ENTRY(lws_lock_start)
1da177e4 LT	641	/* lws locks */
	642	.align 16
	643	.rept 16
	644	/* Keep locks aligned at 16-bytes */
	645	.word 1
	646	.word 0
	647	.word 0
	648	.word 0
	649	.endr
8e9e9844	650	END(lws_lock_start)
1da177e4 LT	651	.previous
	652	#endif
	653	/* CONFIG_SMP for lws_lock_start */
	654
	655	.end
	656
	657