diff options
Diffstat (limited to 'arch/x86/entry/entry_64_compat.S')
| -rw-r--r-- | arch/x86/entry/entry_64_compat.S | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S new file mode 100644 index 000000000000..bb187a6a877c --- /dev/null +++ b/arch/x86/entry/entry_64_compat.S @@ -0,0 +1,556 @@ +/* + * Compatibility mode system call entry point for x86-64. + * + * Copyright 2000-2002 Andi Kleen, SuSE Labs. + */ +#include "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" + +#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 */ + RESTORE_RSI_RDI + 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 + 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 + 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_with_check + .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) + RESTORE_RSI_RDI_RDX + 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: + ASM_CLAC + movq $-EFAULT, RAX(%rsp) +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) |