forked from Minki/linux
c5f638ac90
These audit optimizations are messy and hard to maintain. We'll get a similar effect from opportunistic sysret when fast compat system calls are re-implemented. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/0bcca79ac7ff835d0e5a38725298865b01347a82.1444091584.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
538 lines
15 KiB
ArmAsm
538 lines
15 KiB
ArmAsm
/*
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* Compatibility mode system call entry point for x86-64.
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*
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* Copyright 2000-2002 Andi Kleen, SuSE Labs.
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*/
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#include "calling.h"
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#include <asm/asm-offsets.h>
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#include <asm/current.h>
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#include <asm/errno.h>
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#include <asm/ia32_unistd.h>
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#include <asm/thread_info.h>
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#include <asm/segment.h>
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#include <asm/irqflags.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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#include <linux/linkage.h>
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#include <linux/err.h>
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.section .entry.text, "ax"
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#ifdef CONFIG_PARAVIRT
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ENTRY(native_usergs_sysret32)
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swapgs
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sysretl
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ENDPROC(native_usergs_sysret32)
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#endif
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/*
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* 32-bit SYSENTER instruction entry.
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*
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* SYSENTER loads ss, rsp, cs, and rip from previously programmed MSRs.
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* IF and VM in rflags are cleared (IOW: interrupts are off).
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* SYSENTER does not save anything on the stack,
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* and does not save old rip (!!!) and rflags.
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*
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* Arguments:
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* eax system call number
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* ebx arg1
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* ecx arg2
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* edx arg3
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* esi arg4
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* edi arg5
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* ebp user stack
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* 0(%ebp) arg6
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*
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* This is purely a fast path. For anything complicated we use the int 0x80
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* path below. We set up a complete hardware stack frame to share code
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* with the int 0x80 path.
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*/
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ENTRY(entry_SYSENTER_compat)
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/* Interrupts are off on entry. */
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SWAPGS_UNSAFE_STACK
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movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
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/* Zero-extending 32-bit regs, do not remove */
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movl %ebp, %ebp
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movl %eax, %eax
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movl ASM_THREAD_INFO(TI_sysenter_return, %rsp, 0), %r10d
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/* Construct struct pt_regs on stack */
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pushq $__USER32_DS /* pt_regs->ss */
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pushq %rbp /* pt_regs->sp */
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/*
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* Push flags. This is nasty. First, interrupts are currently
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* off, but we need pt_regs->flags to have IF set. Second, even
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* if TF was set when SYSENTER started, it's clear by now. We fix
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* that later using TIF_SINGLESTEP.
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*/
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pushfq /* pt_regs->flags (except IF = 0) */
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orl $X86_EFLAGS_IF, (%rsp) /* Fix saved flags */
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pushq $__USER32_CS /* pt_regs->cs */
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pushq %r10 /* pt_regs->ip = thread_info->sysenter_return */
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pushq %rax /* pt_regs->orig_ax */
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pushq %rdi /* pt_regs->di */
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pushq %rsi /* pt_regs->si */
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pushq %rdx /* pt_regs->dx */
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pushq %rcx /* pt_regs->cx */
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pushq $-ENOSYS /* pt_regs->ax */
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cld
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sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */
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/*
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* Sysenter doesn't filter flags, so we need to clear NT
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* ourselves. To save a few cycles, we can check whether
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* NT was set instead of doing an unconditional popfq.
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* This needs to happen before enabling interrupts so that
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* we don't get preempted with NT set.
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*/
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testl $X86_EFLAGS_NT, EFLAGS(%rsp)
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jnz sysenter_fix_flags
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sysenter_flags_fixed:
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/* Temporary: SYSENTER is disabled. */
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#ifdef CONFIG_CONTEXT_TRACKING
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call enter_from_user_mode
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#endif
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ENABLE_INTERRUPTS(CLBR_NONE)
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movl $11, %edi
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call do_exit
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/*
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* Re-enable interrupts. IRQ tracing already thinks that IRQs are
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* on (since we treat user mode as having IRQs on), and the
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* prologue above is too short for it to be worth adding a
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* tracing round trip.
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*/
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ENABLE_INTERRUPTS(CLBR_NONE)
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/*
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* No need to do an access_ok() check here because RBP has been
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* 32-bit zero extended:
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*/
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ASM_STAC
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1: movl (%rbp), %ebp
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_ASM_EXTABLE(1b, ia32_badarg)
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ASM_CLAC
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orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
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testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
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jnz sysenter_tracesys
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sysenter_do_call:
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/* 32-bit syscall -> 64-bit C ABI argument conversion */
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movl %edi, %r8d /* arg5 */
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movl %ebp, %r9d /* arg6 */
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xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */
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movl %ebx, %edi /* arg1 */
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movl %edx, %edx /* arg3 (zero extension) */
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sysenter_dispatch:
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cmpq $(IA32_NR_syscalls-1), %rax
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ja 1f
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call *ia32_sys_call_table(, %rax, 8)
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movq %rax, RAX(%rsp)
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1:
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DISABLE_INTERRUPTS(CLBR_NONE)
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TRACE_IRQS_OFF
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testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
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jnz ia32_ret_from_sys_call_irqs_off
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sysexit_from_sys_call:
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/*
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* NB: SYSEXIT is not obviously safe for 64-bit kernels -- an
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* NMI between STI and SYSEXIT has poorly specified behavior,
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* and and NMI followed by an IRQ with usergs is fatal. So
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* we just pretend we're using SYSEXIT but we really use
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* SYSRETL instead.
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*
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* This code path is still called 'sysexit' because it pairs
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* with 'sysenter' and it uses the SYSENTER calling convention.
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*/
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andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
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movl RIP(%rsp), %ecx /* User %eip */
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movq RAX(%rsp), %rax
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movl RSI(%rsp), %esi
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movl RDI(%rsp), %edi
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xorl %edx, %edx /* Do not leak kernel information */
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xorq %r8, %r8
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xorq %r9, %r9
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xorq %r10, %r10
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movl EFLAGS(%rsp), %r11d /* User eflags */
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TRACE_IRQS_ON
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/*
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* SYSRETL works even on Intel CPUs. Use it in preference to SYSEXIT,
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* since it avoids a dicey window with interrupts enabled.
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*/
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movl RSP(%rsp), %esp
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/*
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* USERGS_SYSRET32 does:
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* gsbase = user's gs base
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* eip = ecx
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* rflags = r11
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* cs = __USER32_CS
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* ss = __USER_DS
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*
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* The prologue set RIP(%rsp) to VDSO32_SYSENTER_RETURN, which does:
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*
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* pop %ebp
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* pop %edx
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* pop %ecx
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*
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* Therefore, we invoke SYSRETL with EDX and R8-R10 zeroed to
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* avoid info leaks. R11 ends up with VDSO32_SYSENTER_RETURN's
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* address (already known to user code), and R12-R15 are
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* callee-saved and therefore don't contain any interesting
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* kernel data.
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*/
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USERGS_SYSRET32
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sysenter_fix_flags:
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pushq $X86_EFLAGS_FIXED
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popfq
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jmp sysenter_flags_fixed
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sysenter_tracesys:
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SAVE_EXTRA_REGS
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xorl %eax, %eax /* Do not leak kernel information */
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movq %rax, R11(%rsp)
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movq %rax, R10(%rsp)
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movq %rax, R9(%rsp)
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movq %rax, R8(%rsp)
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movq %rsp, %rdi /* &pt_regs -> arg1 */
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call syscall_trace_enter
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/* Reload arg registers from stack. (see sysenter_tracesys) */
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movl RCX(%rsp), %ecx
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movl RDX(%rsp), %edx
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movl RSI(%rsp), %esi
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movl RDI(%rsp), %edi
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movl %eax, %eax /* zero extension */
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RESTORE_EXTRA_REGS
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jmp sysenter_do_call
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ENDPROC(entry_SYSENTER_compat)
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/*
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* 32-bit SYSCALL instruction entry.
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*
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* 32-bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11,
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* then loads new ss, cs, and rip from previously programmed MSRs.
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* rflags gets masked by a value from another MSR (so CLD and CLAC
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* are not needed). SYSCALL does not save anything on the stack
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* and does not change rsp.
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*
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* Note: rflags saving+masking-with-MSR happens only in Long mode
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* (in legacy 32-bit mode, IF, RF and VM bits are cleared and that's it).
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* Don't get confused: rflags saving+masking depends on Long Mode Active bit
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* (EFER.LMA=1), NOT on bitness of userspace where SYSCALL executes
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* or target CS descriptor's L bit (SYSCALL does not read segment descriptors).
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*
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* Arguments:
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* eax system call number
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* ecx return address
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* ebx arg1
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* ebp arg2 (note: not saved in the stack frame, should not be touched)
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* edx arg3
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* esi arg4
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* edi arg5
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* esp user stack
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* 0(%esp) arg6
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*
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* This is purely a fast path. For anything complicated we use the int 0x80
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* path below. We set up a complete hardware stack frame to share code
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* with the int 0x80 path.
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*/
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ENTRY(entry_SYSCALL_compat)
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/*
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* Interrupts are off on entry.
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* We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
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* it is too small to ever cause noticeable irq latency.
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*/
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SWAPGS_UNSAFE_STACK
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/* Temporary: SYSCALL32 is disabled. */
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movl $-ENOSYS, %eax
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USERGS_SYSRET32
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movl %esp, %r8d
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movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
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ENABLE_INTERRUPTS(CLBR_NONE)
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/* Zero-extending 32-bit regs, do not remove */
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movl %eax, %eax
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/* Construct struct pt_regs on stack */
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pushq $__USER32_DS /* pt_regs->ss */
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pushq %r8 /* pt_regs->sp */
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pushq %r11 /* pt_regs->flags */
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pushq $__USER32_CS /* pt_regs->cs */
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pushq %rcx /* pt_regs->ip */
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pushq %rax /* pt_regs->orig_ax */
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pushq %rdi /* pt_regs->di */
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pushq %rsi /* pt_regs->si */
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pushq %rdx /* pt_regs->dx */
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pushq %rbp /* pt_regs->cx */
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movl %ebp, %ecx
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pushq $-ENOSYS /* pt_regs->ax */
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sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */
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/*
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* No need to do an access_ok check here because r8 has been
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* 32-bit zero extended:
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*/
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ASM_STAC
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1: movl (%r8), %r9d
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_ASM_EXTABLE(1b, ia32_badarg)
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ASM_CLAC
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orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
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testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
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jnz cstar_tracesys
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cstar_do_call:
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/* 32-bit syscall -> 64-bit C ABI argument conversion */
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movl %edi, %r8d /* arg5 */
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/* r9 already loaded */ /* arg6 */
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xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */
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movl %ebx, %edi /* arg1 */
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movl %edx, %edx /* arg3 (zero extension) */
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cstar_dispatch:
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cmpq $(IA32_NR_syscalls-1), %rax
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ja 1f
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call *ia32_sys_call_table(, %rax, 8)
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movq %rax, RAX(%rsp)
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1:
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DISABLE_INTERRUPTS(CLBR_NONE)
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TRACE_IRQS_OFF
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testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
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jnz ia32_ret_from_sys_call_irqs_off
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sysretl_from_sys_call:
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andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
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movl RDX(%rsp), %edx
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movl RSI(%rsp), %esi
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movl RDI(%rsp), %edi
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movl RIP(%rsp), %ecx
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movl EFLAGS(%rsp), %r11d
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movq RAX(%rsp), %rax
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xorq %r10, %r10
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xorq %r9, %r9
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xorq %r8, %r8
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TRACE_IRQS_ON
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movl RSP(%rsp), %esp
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/*
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* 64-bit->32-bit SYSRET restores eip from ecx,
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* eflags from r11 (but RF and VM bits are forced to 0),
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* cs and ss are loaded from MSRs.
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* (Note: 32-bit->32-bit SYSRET is different: since r11
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* does not exist, it merely sets eflags.IF=1).
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*
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* NB: On AMD CPUs with the X86_BUG_SYSRET_SS_ATTRS bug, the ss
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* descriptor is not reinitialized. This means that we must
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* avoid SYSRET with SS == NULL, which could happen if we schedule,
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* exit the kernel, and re-enter using an interrupt vector. (All
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* interrupt entries on x86_64 set SS to NULL.) We prevent that
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* from happening by reloading SS in __switch_to.
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*/
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USERGS_SYSRET32
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cstar_tracesys:
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xchgl %r9d, %ebp
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SAVE_EXTRA_REGS
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xorl %eax, %eax /* Do not leak kernel information */
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movq %rax, R11(%rsp)
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movq %rax, R10(%rsp)
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movq %r9, R9(%rsp)
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movq %rax, R8(%rsp)
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movq %rsp, %rdi /* &pt_regs -> arg1 */
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call syscall_trace_enter
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movl R9(%rsp), %r9d
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/* Reload arg registers from stack. (see sysenter_tracesys) */
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movl RCX(%rsp), %ecx
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movl RDX(%rsp), %edx
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movl RSI(%rsp), %esi
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movl RDI(%rsp), %edi
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movl %eax, %eax /* zero extension */
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RESTORE_EXTRA_REGS
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xchgl %ebp, %r9d
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jmp cstar_do_call
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END(entry_SYSCALL_compat)
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ia32_badarg:
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/*
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* So far, we've entered kernel mode, set AC, turned on IRQs, and
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* saved C regs except r8-r11. We haven't done any of the other
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* standard entry work, though. We want to bail, but we shouldn't
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* treat this as a syscall entry since we don't even know what the
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* args are. Instead, treat this as a non-syscall entry, finish
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* the entry work, and immediately exit after setting AX = -EFAULT.
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*
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* We're really just being polite here. Killing the task outright
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* would be a reasonable action, too. Given that the only valid
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* way to have gotten here is through the vDSO, and we already know
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* that the stack pointer is bad, the task isn't going to survive
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* for long no matter what we do.
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*/
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ASM_CLAC /* undo STAC */
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movq $-EFAULT, RAX(%rsp) /* return -EFAULT if possible */
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/* Fill in the rest of pt_regs */
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xorl %eax, %eax
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movq %rax, R11(%rsp)
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movq %rax, R10(%rsp)
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movq %rax, R9(%rsp)
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movq %rax, R8(%rsp)
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SAVE_EXTRA_REGS
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/* Turn IRQs back off. */
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DISABLE_INTERRUPTS(CLBR_NONE)
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TRACE_IRQS_OFF
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/* Now finish entering normal kernel mode. */
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#ifdef CONFIG_CONTEXT_TRACKING
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call enter_from_user_mode
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#endif
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/* And exit again. */
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jmp retint_user
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ia32_ret_from_sys_call_irqs_off:
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TRACE_IRQS_ON
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ENABLE_INTERRUPTS(CLBR_NONE)
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ia32_ret_from_sys_call:
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xorl %eax, %eax /* Do not leak kernel information */
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movq %rax, R11(%rsp)
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movq %rax, R10(%rsp)
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movq %rax, R9(%rsp)
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movq %rax, R8(%rsp)
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jmp int_ret_from_sys_call
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/*
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* Emulated IA32 system calls via int 0x80.
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*
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* Arguments:
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* eax system call number
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* ebx arg1
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* ecx arg2
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* edx arg3
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* esi arg4
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* edi arg5
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* ebp arg6 (note: not saved in the stack frame, should not be touched)
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*
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* Notes:
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* Uses the same stack frame as the x86-64 version.
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* All registers except eax must be saved (but ptrace may violate that).
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* Arguments are zero extended. For system calls that want sign extension and
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* take long arguments a wrapper is needed. Most calls can just be called
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* directly.
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* Assumes it is only called from user space and entered with interrupts off.
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*/
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ENTRY(entry_INT80_compat)
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/*
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* Interrupts are off on entry.
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* We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
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* it is too small to ever cause noticeable irq latency.
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*/
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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SWAPGS
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ENABLE_INTERRUPTS(CLBR_NONE)
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/* Zero-extending 32-bit regs, do not remove */
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movl %eax, %eax
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/* 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)
|