diff options
Diffstat (limited to 'arch/x86/entry')
-rw-r--r-- | arch/x86/entry/Makefile | 5 | ||||
-rw-r--r-- | arch/x86/entry/ia32entry.S | 522 |
2 files changed, 526 insertions, 1 deletions
diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile index fa7e0cf6d3c4..4a626594fa79 100644 --- a/arch/x86/entry/Makefile +++ b/arch/x86/entry/Makefile @@ -1,4 +1,7 @@ # # Makefile for the x86 low level entry code # -obj-y := entry_$(BITS).o +obj-y := entry_$(BITS).o + +obj-$(CONFIG_IA32_EMULATION) += ia32entry.o + diff --git a/arch/x86/entry/ia32entry.S b/arch/x86/entry/ia32entry.S new file mode 100644 index 000000000000..2be23c734db5 --- /dev/null +++ b/arch/x86/entry/ia32entry.S @@ -0,0 +1,522 @@ +/* + * Compatibility mode system call entry point for x86-64. + * + * Copyright 2000-2002 Andi Kleen, SuSE Labs. + */ + +#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 + + +#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) + /* + * 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 + * 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) + 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 */ + RESTORE_RSI_RDI + xorl %edx,%edx /* avoid info leaks */ + 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 + 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 $(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 + CLEAR_RREGS + movq %rsp,%rdi /* &pt_regs -> arg1 */ + call syscall_trace_enter + LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ + RESTORE_EXTRA_REGS + jmp sysenter_do_call +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) + /* + * 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 + * 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) + jnz cstar_tracesys + +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: + 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 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 + /* + * 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: + 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 %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 + jmp cstar_do_call +END(ia32_cstar_target) + +ia32_badarg: + ASM_CLAC + movq $-EFAULT,%rax + jmp ia32_sysret + +/* + * 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) + /* + * 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 */ + cld + sub $(10*8),%rsp /* pt_regs->r8-11,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: + /* 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) */ + cmpq $(IA32_NR_syscalls-1),%rax + ja 1f + call *ia32_sys_call_table(,%rax,8) # xxx: rip relative +ia32_sysret: + movq %rax,RAX(%rsp) +1: +ia32_ret_from_sys_call: + CLEAR_RREGS + jmp int_ret_from_sys_call + +ia32_tracesys: + SAVE_EXTRA_REGS + CLEAR_RREGS + movq %rsp,%rdi /* &pt_regs -> arg1 */ + call syscall_trace_enter + LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ + RESTORE_EXTRA_REGS + jmp ia32_do_call +END(ia32_syscall) + + .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 + mov %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) |