/* * 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 .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. */ SWAPGS_UNSAFE_STACK movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp /* 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 */ /* * Push flags. This is nasty. First, interrupts are currently * off, but we need pt_regs->flags to have IF set. Second, even * if TF was set when SYSENTER started, it's clear by now. We fix * that later using TIF_SINGLESTEP. */ pushfq /* pt_regs->flags (except IF = 0) */ orl $X86_EFLAGS_IF, (%rsp) /* Fix saved 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 */ /* * 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. * This needs to happen before enabling interrupts so that * we don't get preempted with NT set. */ testl $X86_EFLAGS_NT, EFLAGS(%rsp) jnz sysenter_fix_flags sysenter_flags_fixed: /* Temporary: SYSENTER is disabled. */ #ifdef CONFIG_CONTEXT_TRACKING call enter_from_user_mode #endif ENABLE_INTERRUPTS(CLBR_NONE) movl $11, %edi call do_exit /* Unreachable. */ ud2 sysenter_fix_flags: pushq $X86_EFLAGS_FIXED popfq jmp sysenter_flags_fixed 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 /* Temporary: SYSCALL32 is disabled. */ movl $-ENOSYS, %eax USERGS_SYSRET32 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 */ /* Unreachable. */ ud2 END(entry_SYSCALL_compat) /* * 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)