/* * Compatibility mode system call entry point for x86-64. * * Copyright 2000-2002 Andi Kleen, SuSE Labs. */ #include "calling.h" #include #include #include #include #include #include #include #include #include #include #include /* Avoid __ASSEMBLER__'ifying just for this. */ #include #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_irqs_off # define sysretl_audit ia32_ret_from_sys_call_irqs_off #endif .section .entry.text, "ax" #ifdef CONFIG_PARAVIRT ENTRY(native_usergs_sysret32) swapgs sysretl ENDPROC(native_usergs_sysret32) #endif /* * 32-bit 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(entry_SYSENTER_compat) /* * 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 /* Construct struct pt_regs on stack */ pushq $__USER32_DS /* pt_regs->ss */ pushq %rbp /* pt_regs->sp */ pushfq /* pt_regs->flags */ pushq $__USER32_CS /* pt_regs->cs */ pushq %r10 /* pt_regs->ip = thread_info->sysenter_return */ pushq %rax /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ pushq %rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */ cld sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */ /* * no need to do an access_ok check here because rbp has been * 32-bit 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) jnz sysenter_tracesys sysenter_do_call: /* 32-bit syscall -> 64-bit 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 */ movl RSI(%rsp), %esi movl RDI(%rsp), %edi xorl %edx, %edx /* Do not leak kernel information */ xorq %r8, %r8 xorq %r9, %r9 xorq %r10, %r10 movl EFLAGS(%rsp), %r11d /* User eflags */ 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 #ifdef CONFIG_AUDITSYSCALL .macro auditsys_entry_common /* * At this point, registers hold syscall args in the 32-bit syscall ABI: * EAX is syscall number, the 6 args are in EBX,ECX,EDX,ESI,EDI,EBP. * * We want to pass them to __audit_syscall_entry(), which is a 64-bit * C function with 5 parameters, so shuffle them to match what * the function expects: RDI,RSI,RDX,RCX,R8. */ movl %esi, %r8d /* arg5 (R8 ) <= 4th syscall arg (ESI) */ xchg %ecx, %edx /* arg4 (RCX) <= 3rd syscall arg (EDX) */ /* arg3 (RDX) <= 2nd syscall arg (ECX) */ movl %ebx, %esi /* arg2 (RSI) <= 1st syscall arg (EBX) */ movl %eax, %edi /* arg1 (RDI) <= syscall number (EAX) */ call __audit_syscall_entry /* * We are going to jump back to the syscall dispatch code. * Prepare syscall args as required by the 64-bit C ABI. * Registers clobbered by __audit_syscall_entry() are * loaded from pt_regs on stack: */ movl ORIG_RAX(%rsp), %eax /* syscall number */ movl %ebx, %edi /* arg1 */ movl RCX(%rsp), %esi /* arg2 */ movl RDX(%rsp), %edx /* arg3 */ movl RSI(%rsp), %ecx /* arg4 */ movl RDI(%rsp), %r8d /* arg5 */ movl %ebp, %r9d /* arg6 */ .endm .macro auditsys_exit exit TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jnz ia32_ret_from_sys_call 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 xorl %eax, %eax /* Do not leak kernel information */ movq %rax, R11(%rsp) movq %rax, R10(%rsp) movq %rax, R9(%rsp) movq %rax, R8(%rsp) jmp int_ret_from_sys_call_irqs_off .endm sysenter_auditsys: auditsys_entry_common jmp sysenter_dispatch sysexit_audit: auditsys_exit sysexit_from_sys_call #endif sysenter_fix_flags: pushq $(X86_EFLAGS_IF|X86_EFLAGS_FIXED) popfq 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 xorl %eax, %eax /* Do not leak kernel information */ movq %rax, R11(%rsp) movq %rax, R10(%rsp) movq %rax, R9(%rsp) movq %rax, R8(%rsp) movq %rsp, %rdi /* &pt_regs -> arg1 */ call syscall_trace_enter /* Reload arg registers from stack. (see sysenter_tracesys) */ movl RCX(%rsp), %ecx movl RDX(%rsp), %edx movl RSI(%rsp), %esi movl RDI(%rsp), %edi movl %eax, %eax /* zero extension */ RESTORE_EXTRA_REGS jmp sysenter_do_call ENDPROC(entry_SYSENTER_compat) /* * 32-bit SYSCALL instruction entry. * * 32-bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11, * then loads new ss, cs, and rip from previously programmed MSRs. * rflags gets masked by a value from another MSR (so CLD and CLAC * are not needed). SYSCALL does not save anything on the stack * and does not change rsp. * * Note: rflags saving+masking-with-MSR happens only in Long mode * (in legacy 32-bit mode, IF, RF and VM bits are cleared and that's it). * Don't get confused: rflags saving+masking depends on Long Mode Active bit * (EFER.LMA=1), NOT on bitness of userspace where SYSCALL executes * or target CS descriptor's L bit (SYSCALL does not read segment descriptors). * * Arguments: * eax system call number * ecx return address * ebx arg1 * ebp arg2 (note: not saved in the stack frame, should not be touched) * edx arg3 * esi arg4 * edi arg5 * esp user stack * 0(%esp) 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(entry_SYSCALL_compat) /* * 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 movl %esp, %r8d movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp ENABLE_INTERRUPTS(CLBR_NONE) /* Zero-extending 32-bit regs, do not remove */ movl %eax, %eax /* Construct struct pt_regs on stack */ pushq $__USER32_DS /* pt_regs->ss */ pushq %r8 /* pt_regs->sp */ pushq %r11 /* pt_regs->flags */ pushq $__USER32_CS /* pt_regs->cs */ pushq %rcx /* pt_regs->ip */ pushq %rax /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ pushq %rdx /* pt_regs->dx */ pushq %rbp /* pt_regs->cx */ movl %ebp, %ecx pushq $-ENOSYS /* pt_regs->ax */ sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */ /* * No need to do an access_ok check here because r8 has been * 32-bit zero extended: */ ASM_STAC 1: movl (%r8), %ebp _ASM_EXTABLE(1b, ia32_badarg) ASM_CLAC orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jnz cstar_tracesys cstar_do_call: /* 32-bit syscall -> 64-bit 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) */ cstar_dispatch: cmpq $(IA32_NR_syscalls-1), %rax ja 1f call *ia32_sys_call_table(, %rax, 8) movq %rax, RAX(%rsp) 1: movl RCX(%rsp), %ebp DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jnz sysretl_audit sysretl_from_sys_call: andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) movl RDX(%rsp), %edx movl RSI(%rsp), %esi movl RDI(%rsp), %edi movl RIP(%rsp), %ecx movl EFLAGS(%rsp), %r11d xorq %r10, %r10 xorq %r9, %r9 xorq %r8, %r8 TRACE_IRQS_ON movl RSP(%rsp), %esp /* * 64-bit->32-bit SYSRET restores eip from ecx, * eflags from r11 (but RF and VM bits are forced to 0), * cs and ss are loaded from MSRs. * (Note: 32-bit->32-bit SYSRET is different: since r11 * does not exist, it merely sets eflags.IF=1). * * NB: On AMD CPUs with the X86_BUG_SYSRET_SS_ATTRS bug, the ss * descriptor is not reinitialized. This means that we must * avoid SYSRET with SS == NULL, which could happen if we schedule, * exit the kernel, and re-enter using an interrupt vector. (All * interrupt entries on x86_64 set SS to NULL.) We prevent that * from happening by reloading SS in __switch_to. */ USERGS_SYSRET32 #ifdef CONFIG_AUDITSYSCALL cstar_auditsys: auditsys_entry_common jmp cstar_dispatch sysretl_audit: auditsys_exit sysretl_from_sys_call #endif cstar_tracesys: #ifdef CONFIG_AUDITSYSCALL testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jz cstar_auditsys #endif SAVE_EXTRA_REGS xorl %eax, %eax /* Do not leak kernel information */ movq %rax, R11(%rsp) movq %rax, R10(%rsp) movq %rax, R9(%rsp) movq %rax, R8(%rsp) movq %rsp, %rdi /* &pt_regs -> arg1 */ call syscall_trace_enter /* Reload arg registers from stack. (see sysenter_tracesys) */ movl RCX(%rsp), %ecx movl RDX(%rsp), %edx movl RSI(%rsp), %esi movl RDI(%rsp), %edi movl %eax, %eax /* zero extension */ RESTORE_EXTRA_REGS jmp cstar_do_call END(entry_SYSCALL_compat) ia32_badarg: /* * So far, we've entered kernel mode, set AC, turned on IRQs, and * saved C regs except r8-r11. We haven't done any of the other * standard entry work, though. We want to bail, but we shouldn't * treat this as a syscall entry since we don't even know what the * args are. Instead, treat this as a non-syscall entry, finish * the entry work, and immediately exit after setting AX = -EFAULT. * * We're really just being polite here. Killing the task outright * would be a reasonable action, too. Given that the only valid * way to have gotten here is through the vDSO, and we already know * that the stack pointer is bad, the task isn't going to survive * for long no matter what we do. */ ASM_CLAC /* undo STAC */ movq $-EFAULT, RAX(%rsp) /* return -EFAULT if possible */ /* Fill in the rest of pt_regs */ xorl %eax, %eax movq %rax, R11(%rsp) movq %rax, R10(%rsp) movq %rax, R9(%rsp) movq %rax, R8(%rsp) SAVE_EXTRA_REGS /* Turn IRQs back off. */ DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF /* Now finish entering normal kernel mode. */ #ifdef CONFIG_CONTEXT_TRACKING call enter_from_user_mode #endif /* And exit again. */ jmp retint_user ia32_ret_from_sys_call_irqs_off: TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) ia32_ret_from_sys_call: xorl %eax, %eax /* Do not leak kernel information */ movq %rax, R11(%rsp) movq %rax, R10(%rsp) movq %rax, R9(%rsp) movq %rax, R8(%rsp) jmp int_ret_from_sys_call /* * 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(entry_INT80_compat) /* * 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. */ PARAVIRT_ADJUST_EXCEPTION_FRAME SWAPGS ENABLE_INTERRUPTS(CLBR_NONE) /* Zero-extending 32-bit regs, do not remove */ movl %eax, %eax /* Construct struct pt_regs on stack (iret frame is already on stack) */ pushq %rax /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ pushq %rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */ pushq $0 /* pt_regs->r8 */ pushq $0 /* pt_regs->r9 */ pushq $0 /* pt_regs->r10 */ pushq $0 /* pt_regs->r11 */ cld sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) jnz ia32_tracesys ia32_do_call: /* 32-bit syscall -> 64-bit 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) */ cmpq $(IA32_NR_syscalls-1), %rax ja 1f call *ia32_sys_call_table(, %rax, 8) movq %rax, RAX(%rsp) 1: jmp int_ret_from_sys_call ia32_tracesys: SAVE_EXTRA_REGS movq %rsp, %rdi /* &pt_regs -> arg1 */ call syscall_trace_enter /* * Reload arg registers from stack in case ptrace changed them. * Don't reload %eax because syscall_trace_enter() returned * the %rax value we should see. But do truncate it to 32 bits. * If it's -1 to make us punt the syscall, then (u32)-1 is still * an appropriately invalid value. */ movl RCX(%rsp), %ecx movl RDX(%rsp), %edx movl RSI(%rsp), %esi movl RDI(%rsp), %edi movl %eax, %eax /* zero extension */ RESTORE_EXTRA_REGS jmp ia32_do_call END(entry_INT80_compat) .macro PTREGSCALL label, func ALIGN GLOBAL(\label) leaq \func(%rip), %rax jmp ia32_ptregs_common .endm PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn PTREGSCALL stub32_sigreturn, sys32_sigreturn PTREGSCALL stub32_fork, sys_fork PTREGSCALL stub32_vfork, sys_vfork ALIGN GLOBAL(stub32_clone) leaq sys_clone(%rip), %rax /* * The 32-bit clone ABI is: clone(..., int tls_val, int *child_tidptr). * The 64-bit clone ABI is: clone(..., int *child_tidptr, int tls_val). * * The native 64-bit kernel's sys_clone() implements the latter, * so we need to swap arguments here before calling it: */ xchg %r8, %rcx jmp ia32_ptregs_common ALIGN ia32_ptregs_common: SAVE_EXTRA_REGS 8 call *%rax RESTORE_EXTRA_REGS 8 ret END(ia32_ptregs_common)