/* * 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) ENTRY(native_irq_enable_sysexit) swapgs sti sysexit ENDPROC(native_irq_enable_sysexit) #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_tss + TSS_sp0), %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_reg rax /* 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 cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys 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: call *ia32_sys_call_table(,%rax,8) movq %rax,RAX(%rsp) 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 RAX(%rsp),%eax /* reload syscall number */ cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys 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 $-ENOSYS,RAX(%rsp)/* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */ jmp sysenter_do_call CFI_ENDPROC ENDPROC(ia32_sysenter_target) /* * 32bit SYSCALL instruction entry. * * 32bit 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 32bit 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(ia32_cstar_target) CFI_STARTPROC32 simple CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,0 CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ /* * 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 CFI_REGISTER rsp,r8 movq PER_CPU_VAR(kernel_stack),%rsp ENABLE_INTERRUPTS(CLBR_NONE) /* Zero-extending 32-bit regs, do not remove */ movl %eax,%eax /* Construct struct pt_regs on stack */ pushq_cfi $__USER32_DS /* pt_regs->ss */ pushq_cfi %r8 /* pt_regs->sp */ CFI_REL_OFFSET rsp,0 pushq_cfi %r11 /* pt_regs->flags */ pushq_cfi $__USER32_CS /* pt_regs->cs */ pushq_cfi %rcx /* pt_regs->ip */ 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 rbp /* pt_regs->cx */ movl %ebp,%ecx pushq_cfi_reg rax /* pt_regs->ax */ 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 r8 has been * 32bit zero extended */ ASM_STAC 1: movl (%r8),%r9d _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) CFI_REMEMBER_STATE jnz cstar_tracesys cmpq $IA32_NR_syscalls-1,%rax ja ia32_badsys cstar_do_call: /* 32bit syscall -> 64bit C ABI argument conversion */ movl %edi,%r8d /* arg5 */ /* r9 already loaded */ /* arg6 */ xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */ movl %ebx,%edi /* arg1 */ movl %edx,%edx /* arg3 (zero extension) */ cstar_dispatch: call *ia32_sys_call_table(,%rax,8) movq %rax,RAX(%rsp) 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) RESTORE_RSI_RDI_RDX movl RIP(%rsp),%ecx CFI_REGISTER rip,rcx movl EFLAGS(%rsp),%r11d /*CFI_REGISTER rflags,r11*/ xorq %r10,%r10 xorq %r9,%r9 xorq %r8,%r8 TRACE_IRQS_ON movl RSP(%rsp),%esp CFI_RESTORE rsp /* * 64bit->32bit 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: 32bit->32bit 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: CFI_RESTORE_STATE movl %r9d,R9(%rsp) /* register to be clobbered by call */ auditsys_entry_common movl R9(%rsp),%r9d /* reload 6th syscall arg */ 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 xchgl %r9d,%ebp SAVE_EXTRA_REGS CLEAR_RREGS r9 movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 1 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS xchgl %ebp,%r9d cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */ jmp cstar_do_call END(ia32_cstar_target) ia32_badarg: ASM_CLAC 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_STARTPROC32 simple CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,5*8 /*CFI_REL_OFFSET ss,4*8 */ CFI_REL_OFFSET rsp,3*8 /*CFI_REL_OFFSET rflags,2*8 */ /*CFI_REL_OFFSET cs,1*8 */ CFI_REL_OFFSET rip,0*8 /* * 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_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_reg rax /* pt_regs->ax */ cld sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ CFI_ADJUST_CFA_OFFSET 10*8 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 cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys ia32_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) */ call *ia32_sys_call_table(,%rax,8) # xxx: rip relative ia32_sysret: movq %rax,RAX(%rsp) ia32_ret_from_sys_call: CLEAR_RREGS jmp int_ret_from_sys_call ia32_tracesys: SAVE_EXTRA_REGS CLEAR_RREGS movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */ jmp ia32_do_call END(ia32_syscall) ia32_badsys: movq $0,ORIG_RAX(%rsp) movq $-ENOSYS,%rax jmp ia32_sysret CFI_ENDPROC .macro PTREGSCALL label, func ALIGN GLOBAL(\label) leaq \func(%rip),%rax jmp ia32_ptregs_common .endm CFI_STARTPROC32 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 mov %r8, %rcx jmp ia32_ptregs_common ALIGN ia32_ptregs_common: CFI_ENDPROC CFI_STARTPROC32 simple CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,SIZEOF_PTREGS CFI_REL_OFFSET rax,RAX CFI_REL_OFFSET rcx,RCX CFI_REL_OFFSET rdx,RDX CFI_REL_OFFSET rsi,RSI CFI_REL_OFFSET rdi,RDI CFI_REL_OFFSET rip,RIP /* CFI_REL_OFFSET cs,CS*/ /* CFI_REL_OFFSET rflags,EFLAGS*/ CFI_REL_OFFSET rsp,RSP /* CFI_REL_OFFSET ss,SS*/ SAVE_EXTRA_REGS 8 call *%rax RESTORE_EXTRA_REGS 8 ret CFI_ENDPROC END(ia32_ptregs_common)