ia32entry.s

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/*
 * Compatibility mode system call entry point for x86-64. 
 * 		
 * Copyright 2000-2002 Andi Kleen, SuSE Labs.
 */		 

#include <asm/dwarf2.h>
#include <asm/calling.h>
#include <asm/offset.h>
#include <asm/current.h>
#include <asm/errno.h>
#include <asm/ia32_unistd.h>	
#include <asm/thread_info.h>	
#include <asm/segment.h>
#include <asm/vsyscall32.h>
#include <linux/linkage.h>

	.macro IA32_ARG_FIXUP noebp=0
	movl	%edi,%r8d
	.if \noebp
	.else
	movl	%ebp,%r9d
	.endif
	xchg	%ecx,%esi
	movl	%ebx,%edi
	movl	%edx,%edx	/* zero extension */
	.endm 

	/* clobbers %eax */	
	.macro  CLEAR_RREGS
	xorl 	%eax,%eax
	movq	%rax,R11(%rsp)
	movq	%rax,R10(%rsp)
	movq	%rax,R9(%rsp)
	movq	%rax,R8(%rsp)
	.endm

/*
 * 32bit SYSENTER instruction entry.
 *
 * Arguments:
 * %eax	System call number.
 * %ebx Arg1
 * %ecx Arg2
 * %edx Arg3
 * %esi Arg4
 * %edi Arg5
 * %ebp user stack
 * 0(%ebp) Arg6	
 * 	
 * Interrupts off.
 *	
 * This is purely a fast path. For anything complicated we use the int 0x80
 * path below.	Set up a complete hardware stack frame to share code
 * with the int 0x80 path.
 */ 	
ENTRY(ia32_sysenter_target)
	CFI_STARTPROC
	swapgs
	movq	%gs:pda_kernelstack, %rsp
	addq	$(PDA_STACKOFFSET),%rsp	
	sti	
 	movl	%ebp,%ebp		/* zero extension */
	pushq	$__USER32_DS
	pushq	%rbp
	pushfq
	movl	$VSYSCALL32_SYSEXIT, %r10d
	pushq	$__USER32_CS
	movl	%eax, %eax
	pushq	%r10
	pushq	%rax
	cld
	SAVE_ARGS 0,0,1
 	/* no need to do an access_ok check here because rbp has been
 	   32bit zero extended */ 
1:	movl	(%rbp),%r9d
 	.section __ex_table,"a"
 	.quad 1b,ia32_badarg
 	.previous	
	GET_THREAD_INFO(%r10)
	testl  $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%r10)
	jnz  sysenter_tracesys
sysenter_do_call:	
	cmpl	$(IA32_NR_syscalls),%eax
	jae	ia32_badsys
	IA32_ARG_FIXUP 1
	call	*ia32_sys_call_table(,%rax,8)
	movq	%rax,RAX-ARGOFFSET(%rsp)
	GET_THREAD_INFO(%r10)
	cli
	testl	$_TIF_ALLWORK_MASK,threadinfo_flags(%r10)
	jnz	int_ret_from_sys_call
	/* clear IF, that popfq doesn't enable interrupts early */
	andl  $~0x200,EFLAGS-R11(%rsp) 
	RESTORE_ARGS 1,24,1,1,1,1
	popfq
	popq	%rcx				/* User %esp */
	movl	$VSYSCALL32_SYSEXIT,%edx	/* User %eip */
	swapgs
	sti		/* sti only takes effect after the next instruction */
	/* sysexit */
	.byte	0xf, 0x35

sysenter_tracesys:
	SAVE_REST
	CLEAR_RREGS
	movq	$-ENOSYS,RAX(%rsp)	/* really needed? */
	movq	%rsp,%rdi        /* &pt_regs -> arg1 */
	call	syscall_trace_enter
	LOAD_ARGS ARGOFFSET  /* reload args from stack in case ptrace changed it */
	RESTORE_REST
	movl	%ebp, %ebp
	/* no need to do an access_ok check here because rbp has been
	   32bit zero extended */ 
1:	movl	(%rbp),%r9d
	.section __ex_table,"a"
	.quad 1b,ia32_badarg
	.previous
	jmp	sysenter_do_call
	CFI_ENDPROC

/*
 * 32bit SYSCALL instruction entry.
 *
 * Arguments:
 * %eax	System call number.
 * %ebx Arg1
 * %ecx return EIP 
 * %edx Arg3
 * %esi Arg4
 * %edi Arg5
 * %ebp Arg2    [note: not saved in the stack frame, should not be touched]
 * %esp user stack 
 * 0(%esp) Arg6
 * 	
 * Interrupts off.
 *	
 * This is purely a fast path. For anything complicated we use the int 0x80
 * path below.	Set up a complete hardware stack frame to share code
 * with the int 0x80 path.	
 */ 	
ENTRY(ia32_cstar_target)
	CFI_STARTPROC
	swapgs
	movl	%esp,%r8d
	movq	%gs:pda_kernelstack,%rsp
	sti
	SAVE_ARGS 8,1,1
	movl 	%eax,%eax	/* zero extension */
	movq	%rax,ORIG_RAX-ARGOFFSET(%rsp)
	movq	%rcx,RIP-ARGOFFSET(%rsp)
	movq	%rbp,RCX-ARGOFFSET(%rsp) /* this lies slightly to ptrace */
	movl	%ebp,%ecx
	movq	$__USER32_CS,CS-ARGOFFSET(%rsp)
	movq	$__USER32_DS,SS-ARGOFFSET(%rsp)
	movq	%r11,EFLAGS-ARGOFFSET(%rsp)
	movq	%r8,RSP-ARGOFFSET(%rsp)	
	/* no need to do an access_ok check here because r8 has been
	   32bit zero extended */ 
	/* hardware stack frame is complete now */	
1:	movl	(%r8),%r9d
	.section __ex_table,"a"
	.quad 1b,ia32_badarg
	.previous	
	GET_THREAD_INFO(%r10)
	testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%r10)
	jnz   cstar_tracesys
cstar_do_call:	
	cmpl $IA32_NR_syscalls,%eax
	jae  ia32_badsys
	IA32_ARG_FIXUP 1
	call *ia32_sys_call_table(,%rax,8)
	movq %rax,RAX-ARGOFFSET(%rsp)
	GET_THREAD_INFO(%r10)
	cli
	testl $_TIF_ALLWORK_MASK,threadinfo_flags(%r10)
	jnz  int_ret_from_sys_call
	RESTORE_ARGS 1,-ARG_SKIP,1,1,1
	movl RIP-ARGOFFSET(%rsp),%ecx
	movl EFLAGS-ARGOFFSET(%rsp),%r11d	
	movl RSP-ARGOFFSET(%rsp),%esp
	swapgs
	sysretl
	
cstar_tracesys:	
	SAVE_REST
	CLEAR_RREGS
	movq $-ENOSYS,RAX(%rsp)	/* really needed? */
	movq %rsp,%rdi        /* &pt_regs -> arg1 */
	call syscall_trace_enter
	LOAD_ARGS ARGOFFSET  /* reload args from stack in case ptrace changed it */
	RESTORE_REST
	movl RSP-ARGOFFSET(%rsp), %r8d
	/* no need to do an access_ok check here because r8 has been
	   32bit zero extended */ 
1:	movl	(%r8),%r9d
	.section __ex_table,"a"
	.quad 1b,ia32_badarg
	.previous
	jmp cstar_do_call
				
ia32_badarg:
	movq $-EFAULT,%rax
	jmp ia32_sysret
	CFI_ENDPROC

/* 
 * Emulated IA32 system calls via int 0x80. 
 *
 * Arguments:	 
 * %eax	System call number.
 * %ebx Arg1
 * %ecx Arg2
 * %edx Arg3
 * %esi Arg4
 * %edi Arg5
 * %ebp Arg6    [note: not saved in the stack frame, should not be touched]
 *
 * Notes:
 * Uses the same stack frame as the x86-64 version.	
 * All registers except %eax must be saved (but ptrace may violate that)
 * Arguments are zero extended. For system calls that want sign extension and
 * take long arguments a wrapper is needed. Most calls can just be called
 * directly.
 * Assumes it is only called from user space and entered with interrupts off.	
 */ 				

ENTRY(ia32_syscall)
	CFI_STARTPROC
	swapgs	
	sti
	movl %eax,%eax
	pushq %rax
	cld
	/* note the registers are not zero extended to the sf.
	   this could be a problem. */
	SAVE_ARGS 0,0,1
	GET_THREAD_INFO(%r10)
	testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%r10)
	jnz ia32_tracesys
ia32_do_syscall:	
	cmpl $(IA32_NR_syscalls),%eax
	jae  ia32_badsys
	IA32_ARG_FIXUP
	call *ia32_sys_call_table(,%rax,8) # xxx: rip relative
ia32_sysret:
	movq %rax,RAX-ARGOFFSET(%rsp)
	jmp int_ret_from_sys_call 

ia32_tracesys:			 
	SAVE_REST
	movq $-ENOSYS,RAX(%rsp)	/* really needed? */
	movq %rsp,%rdi        /* &pt_regs -> arg1 */
	call syscall_trace_enter
	LOAD_ARGS ARGOFFSET  /* reload args from stack in case ptrace changed it */
	RESTORE_REST
	jmp ia32_do_syscall

ia32_badsys:
	movq $0,ORIG_RAX-ARGOFFSET(%rsp)
	movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
	jmp int_ret_from_sys_call

ni_syscall:
	movq %rax,%rdi
	jmp  sys32_ni_syscall			

quiet_ni_syscall:
	movq $-ENOSYS,%rax
	ret
	CFI_ENDPROC
	
	.macro PTREGSCALL label, func, arg
	.globl \label
\label:
	leaq \func(%rip),%rax
	leaq -ARGOFFSET+8(%rsp),\arg	/* 8 for return address */
	jmp  ia32_ptregs_common	
	.endm

	PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn, %rdi
	PTREGSCALL stub32_sigreturn, sys32_sigreturn, %rdi
	PTREGSCALL stub32_sigaltstack, sys32_sigaltstack, %rdx
	PTREGSCALL stub32_sigsuspend, sys32_sigsuspend, %rcx
	PTREGSCALL stub32_execve, sys32_execve, %rcx
	PTREGSCALL stub32_fork, sys_fork, %rdi
	PTREGSCALL stub32_clone, sys32_clone, %rdx
	PTREGSCALL stub32_vfork, sys_vfork, %rdi
	PTREGSCALL stub32_iopl, sys_iopl, %rsi
	PTREGSCALL stub32_rt_sigsuspend, sys_rt_sigsuspend, %rdx

ENTRY(ia32_ptregs_common)
	CFI_STARTPROC
	popq %r11
	SAVE_REST
	call *%rax
	RESTORE_REST
	jmp  ia32_sysret	/* misbalances the return cache */
	CFI_ENDPROC

	.data
	.align 8