syscall.s

内核linux2.4.20,可跟rtlinux3.2打补丁 组成实时linux系统,编译内核

/* 
 * Linux/PARISC Project (http://www.thepuffingroup.com/parisc)
 * 
 * System call entry code Copyright (c) Matthew Wilcox 1999 <[e-mail]>
 * Licensed under the GNU GPL.
 * thanks to Philipp Rumpf, Mike Shaver and various others
 * sorry about the wall, puffin..
 */

#include <asm/offset.h>
#include <asm/unistd.h>
#include <asm/errno.h>
#include <asm/psw.h>

#define __ASSEMBLY__
#include <asm/assembly.h>
#include <asm/processor.h>
#include <linux/version.h>

#ifdef __LP64__
	.level          2.0w
#else
	.level		1.1
#endif
	.text
	
	.import syscall_exit,code
	.import syscall_exit_rfi,code
	.export linux_gateway_page

	/* 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 4096
linux_gateway_page:

	break   0,0

	.align 256
linux_gateway_entry:
	mfsp	%sr7,%r1			/* we must set sr3 to the space */
	mtsp	%r1,%sr3			/* of the user before the gate */
	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 */
	mtsp	%r0,%sr7			/* get kernel space into sr7 */
#ifdef __LP64__
	/* 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, %r0
#endif
	mtctl	%r28,%cr27
	rsm	PSW_I, %r28			/* no ints for a bit  */
	mfctl	%cr30,%r1			/* get the kernel task ptr */
	mtctl	%r0,%cr30			/* zero it (flag) */

	/* Save some registers for sigcontext and potential task
	   switch (see entry.S for the details of which ones are
	   saved/restored) */
	STREG	%r2,  TASK_PT_GR2(%r1)		/* preserve rp */
	STREG	%r19, TASK_PT_GR19(%r1)
	STREG	%r20, TASK_PT_GR20(%r1)
	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 */
	mfctl	%cr27,%r19
	STREG	%r19, TASK_PT_GR28(%r1)		/* return value 0 */
	STREG	%r19, TASK_PT_ORIG_R28(%r1)	/* return value 0 (saved for signals) */
	STREG	%r29, TASK_PT_GR29(%r1)		/* return value 1 */
	STREG	%r30, TASK_PT_GR30(%r1)		/* preserve userspace sp */
	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

	ldo	TASK_SZ_ALGN+64(%r1),%r30	/* set up kernel stack */

#ifndef __LP64__
	/* no need to save these on stack because in wide mode the first 8
	 * args are passed in registers */
	stw     %r22, -52(%r30)                 /* 5th argument */
	stw     %r21, -56(%r30)                 /* 6th argument */
#endif

	/* for some unknown reason, task_struct.ptrace is an unsigned long so use LDREG */
	LDREG	TASK_PTRACE(%r1), %r19		/* Are we being ptraced? */
	mtsm	%r28				/* irqs back  */

	bb,<,n	%r19, 31, .Ltracesys		/* must match PT_PTRACE bit */
	
	/* Note!  We cannot use the syscall table that is mapped
	nearby since the gateway page is mapped execute-only. */

	ldil	L%sys_call_table, %r1
	ldo     R%sys_call_table(%r1), %r19
	LDIL_FIXUP(%r19)
	
	comiclr,>>=	__NR_Linux_syscalls, %r20, %r0
	b,n	.Lsyscall_nosys
	
#ifdef __LP64__
	ldd,s   %r20(%r19), %r19
#else
	ldwx,s  %r20(%r19), %r19
#endif
	/* 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
	LDIL_FIXUP(%r2)
	be      0(%sr7,%r19)
	ldo	R%syscall_exit(%r2),%r2
.Lrt_sigreturn:
	comib,<> 0,%r25,.Lin_syscall
	ldil	L%syscall_exit_rfi,%r2
	LDIL_FIXUP(%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
	LDIL_FIXUP(%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.
	 */
	ldo     -TASK_SZ_ALGN-64(%r30),%r1      /* get task ptr */
	ssm	0,%r2				/* Lower 8 bits only!! */
	STREG	%r2,TASK_PT_PSW(%r1)
	STREG	%r1,TASK_PT_CR30(%r1)
	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_FIXUP(%r1)
	ldil	L%tracesys_next,%r2
	LDIL_FIXUP(%r2)
	be	R%syscall_trace(%sr7,%r1)
	ldo	R%tracesys_next(%r2),%r2
	
tracesys_next:	
	ldil	L%sys_call_table,%r1
	LDIL_FIXUP(%r1)
	ldo     R%sys_call_table(%r1), %r19

	ldo     -TASK_SZ_ALGN-64(%r30),%r1      /* get task ptr */
	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 __LP64__
	LDREG   TASK_PT_GR22(%r1), %r22
	LDREG   TASK_PT_GR21(%r1), %r21
#endif

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

#ifdef __LP64__
	ldd,s   %r20(%r19), %r19
#else
	ldwx,s  %r20(%r19), %r19
#endif
	/* 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
	LDIL_FIXUP(%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     -TASK_SZ_ALGN-64(%r30),%r1      /* get task ptr */
	bl	syscall_trace, %r2
	STREG   %r28,TASK_PT_GR28(%r1)          /* save return value now */
	ldo     -TASK_SZ_ALGN-64(%r30),%r1      /* get task ptr */
	LDREG   TASK_PT_GR28(%r1), %r28		/* Restore return val. */

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

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

tracesys_sigexit:
	ldo     -TASK_SZ_ALGN-64(%r30),%r1      /* get task ptr */
	bl	syscall_trace, %r2
	nop

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

#ifdef __LP64__
/* Use ENTRY_SAME for 32-bit syscalls which are the same on wide and
 * narrow palinux.  Use ENTRY_DIFF for those where a 32-bit specific