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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/asm-offsets.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/irqflags.h>
#include <asm/asm.h>
#include <asm/smap.h>
#include <linux/linkage.h>
#include <linux/err.h>
/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
#include <linux/elf-em.h>
#define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE)
#define __AUDIT_ARCH_LE 0x40000000
#ifndef CONFIG_AUDITSYSCALL
#define sysexit_audit ia32_ret_from_sys_call
#define sysretl_audit ia32_ret_from_sys_call
#endif
.section .entry.text, "ax"
/* clobbers %rax */
.macro CLEAR_RREGS _r9=rax
xorl %eax,%eax
movq %rax,R11(%rsp)
movq %rax,R10(%rsp)
movq %\_r9,R9(%rsp)
movq %rax,R8(%rsp)
.endm
/*
* Reload arg registers from stack in case ptrace changed them.
* We don't reload %eax because syscall_trace_enter() returned
* the %rax value we should see. Instead, we just truncate that
* value to 32 bits again as we did on entry from user mode.
* If it's a new value set by user_regset during entry tracing,
* this matches the normal truncation of the user-mode value.
* If it's -1 to make us punt the syscall, then (u32)-1 is still
* an appropriately invalid value.
*/
.macro LOAD_ARGS32 _r9=0
.if \_r9
movl R9(%rsp),%r9d
.endif
movl RCX(%rsp),%ecx
movl RDX(%rsp),%edx
movl RSI(%rsp),%esi
movl RDI(%rsp),%edi
movl %eax,%eax /* zero extension */
.endm
.macro CFI_STARTPROC32 simple
CFI_STARTPROC \simple
CFI_UNDEFINED r8
CFI_UNDEFINED r9
CFI_UNDEFINED r10
CFI_UNDEFINED r11
CFI_UNDEFINED r12
CFI_UNDEFINED r13
CFI_UNDEFINED r14
CFI_UNDEFINED r15
.endm
#ifdef CONFIG_PARAVIRT
ENTRY(native_usergs_sysret32)
swapgs
sysretl
ENDPROC(native_usergs_sysret32)
#endif
/*
* 32bit SYSENTER instruction entry.
*
* SYSENTER loads ss, rsp, cs, and rip from previously programmed MSRs.
* IF and VM in rflags are cleared (IOW: interrupts are off).
* SYSENTER does not save anything on the stack,
* and does not save old rip (!!!) and rflags.
*
* Arguments:
* eax system call number
* ebx arg1
* ecx arg2
* edx arg3
* esi arg4
* edi arg5
* ebp user stack
* 0(%ebp) arg6
*
* This is purely a fast path. For anything complicated we use the int 0x80
* path below. We set up a complete hardware stack frame to share code
* with the int 0x80 path.
*/
ENTRY(ia32_sysenter_target)
CFI_STARTPROC32 simple
CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,0
CFI_REGISTER rsp,rbp
/*
* Interrupts are off on entry.
* We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
* it is too small to ever cause noticeable irq latency.
*/
SWAPGS_UNSAFE_STACK
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
ENABLE_INTERRUPTS(CLBR_NONE)
/* Zero-extending 32-bit regs, do not remove */
movl %ebp, %ebp
movl %eax, %eax
movl ASM_THREAD_INFO(TI_sysenter_return, %rsp, 0), %r10d
CFI_REGISTER rip,r10
/* Construct struct pt_regs on stack */
pushq_cfi $__USER32_DS /* pt_regs->ss */
pushq_cfi %rbp /* pt_regs->sp */
CFI_REL_OFFSET rsp,0
pushfq_cfi /* pt_regs->flags */
pushq_cfi $__USER32_CS /* pt_regs->cs */
pushq_cfi %r10 /* pt_regs->ip = thread_info->sysenter_return */
CFI_REL_OFFSET rip,0
pushq_cfi_reg rax /* pt_regs->orig_ax */
pushq_cfi_reg rdi /* pt_regs->di */
pushq_cfi_reg rsi /* pt_regs->si */
pushq_cfi_reg rdx /* pt_regs->dx */
pushq_cfi_reg rcx /* pt_regs->cx */
pushq_cfi $-ENOSYS /* pt_regs->ax */
cld
sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */
CFI_ADJUST_CFA_OFFSET 10*8
/*
* no need to do an access_ok check here because rbp has been
* 32bit zero extended
*/
ASM_STAC
1: movl (%rbp),%ebp
_ASM_EXTABLE(1b,ia32_badarg)
ASM_CLAC
/*
* Sysenter doesn't filter flags, so we need to clear NT
* ourselves. To save a few cycles, we can check whether
* NT was set instead of doing an unconditional popfq.
*/
testl $X86_EFLAGS_NT,EFLAGS(%rsp)
jnz sysenter_fix_flags
sysenter_flags_fixed:
orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
CFI_REMEMBER_STATE
jnz sysenter_tracesys
sysenter_do_call:
/* 32bit syscall -> 64bit C ABI argument conversion */
movl %edi,%r8d /* arg5 */
movl %ebp,%r9d /* arg6 */
xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */
movl %ebx,%edi /* arg1 */
movl %edx,%edx /* arg3 (zero extension) */
sysenter_dispatch:
cmpq $(IA32_NR_syscalls-1),%rax
ja 1f
call *ia32_sys_call_table(,%rax,8)
movq %rax,RAX(%rsp)
1:
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jnz sysexit_audit
sysexit_from_sys_call:
/*
* NB: SYSEXIT is not obviously safe for 64-bit kernels -- an
* NMI between STI and SYSEXIT has poorly specified behavior,
* and and NMI followed by an IRQ with usergs is fatal. So
* we just pretend we're using SYSEXIT but we really use
* SYSRETL instead.
*
* This code path is still called 'sysexit' because it pairs
* with 'sysenter' and it uses the SYSENTER calling convention.
*/
andl $~TS_COMPAT,ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
movl RIP(%rsp),%ecx /* User %eip */
CFI_REGISTER rip,rcx
RESTORE_RSI_RDI
xorl %edx,%edx /* avoid info leaks */
xorq %r8,%r8
xorq %r9,%r9
xorq %r10,%r10
movl EFLAGS(%rsp),%r11d /* User eflags */
/*CFI_RESTORE rflags*/
TRACE_IRQS_ON
/*
* SYSRETL works even on Intel CPUs. Use it in preference to SYSEXIT,
* since it avoids a dicey window with interrupts enabled.
*/
movl RSP(%rsp),%esp
/*
* USERGS_SYSRET32 does:
* gsbase = user's gs base
* eip = ecx
* rflags = r11
* cs = __USER32_CS
* ss = __USER_DS
*
* The prologue set RIP(%rsp) to VDSO32_SYSENTER_RETURN, which does:
*
* pop %ebp
* pop %edx
* pop %ecx
*
* Therefore, we invoke SYSRETL with EDX and R8-R10 zeroed to
* avoid info leaks. R11 ends up with VDSO32_SYSENTER_RETURN's
* address (already known to user code), and R12-R15 are
* callee-saved and therefore don't contain any interesting
* kernel data.
*/
USERGS_SYSRET32
CFI_RESTORE_STATE
#ifdef CONFIG_AUDITSYSCALL
.macro auditsys_entry_common
movl %esi,%r8d /* 5th arg: 4th syscall arg */
movl %ecx,%r9d /*swap with edx*/
movl %edx,%ecx /* 4th arg: 3rd syscall arg */
movl %r9d,%edx /* 3rd arg: 2nd syscall arg */
movl %ebx,%esi /* 2nd arg: 1st syscall arg */
movl %eax,%edi /* 1st arg: syscall number */
call __audit_syscall_entry
movl ORIG_RAX(%rsp),%eax /* reload syscall number */
movl %ebx,%edi /* reload 1st syscall arg */
movl RCX(%rsp),%esi /* reload 2nd syscall arg */
movl RDX(%rsp),%edx /* reload 3rd syscall arg */
movl RSI(%rsp),%ecx /* reload 4th syscall arg */
movl RDI(%rsp),%r8d /* reload 5th syscall arg */
.endm
.macro auditsys_exit exit
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jnz ia32_ret_from_sys_call
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
movl %eax,%esi /* second arg, syscall return value */
cmpl $-MAX_ERRNO,%eax /* is it an error ? */
jbe 1f
movslq %eax, %rsi /* if error sign extend to 64 bits */
1: setbe %al /* 1 if error, 0 if not */
movzbl %al,%edi /* zero-extend that into %edi */
call __audit_syscall_exit
movq RAX(%rsp),%rax /* reload syscall return value */
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl %edi, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jz \exit
CLEAR_RREGS
jmp int_with_check
.endm
sysenter_auditsys:
auditsys_entry_common
movl %ebp,%r9d /* reload 6th syscall arg */
jmp sysenter_dispatch
sysexit_audit:
auditsys_exit sysexit_from_sys_call
#endif
sysenter_fix_flags:
pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_FIXED)
popfq_cfi
jmp sysenter_flags_fixed
sysenter_tracesys:
#ifdef CONFIG_AUDITSYSCALL
testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
jz sysenter_auditsys
#endif
SAVE_EXTRA_REGS
CLEAR_RREGS
movq %rsp
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