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-rw-r--r--pkg/ring0/entry_impl_amd64.s151
1 files changed, 122 insertions, 29 deletions
diff --git a/pkg/ring0/entry_impl_amd64.s b/pkg/ring0/entry_impl_amd64.s
index 9a5d6c064..1d0262a18 100644
--- a/pkg/ring0/entry_impl_amd64.s
+++ b/pkg/ring0/entry_impl_amd64.s
@@ -66,8 +66,8 @@
#define PTRACE_FLAGS 0x90
#define PTRACE_RSP 0x98
#define PTRACE_SS 0xa0
-#define PTRACE_FS 0xa8
-#define PTRACE_GS 0xb0
+#define PTRACE_FS_BASE 0xa8
+#define PTRACE_GS_BASE 0xb0
// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
@@ -158,11 +158,33 @@
#define LOAD_KERNEL_STACK(entry) \
MOVQ ENTRY_STACK_TOP(entry), SP;
+// ADDR_OF_FUNC defines a function named 'name' that returns the address of
+// 'symbol'.
+#define ADDR_OF_FUNC(name, symbol) \
+TEXT name,$0-8; \
+ MOVQ $symbol, AX; \
+ MOVQ AX, ret+0(FP); \
+ RET
+
// See kernel.go.
TEXT ·Halt(SB),NOSPLIT,$0
HLT
RET
+// See kernel_amd64.go.
+TEXT ·HaltAndWriteFSBase(SB),NOSPLIT,$8-8
+ HLT
+
+ // Restore FS_BASE.
+ MOVQ regs+0(FP), AX
+ MOVQ PTRACE_FS_BASE(AX), AX
+
+ PUSHQ AX // First argument (FS_BASE)
+ CALL ·writeFS(SB)
+ POPQ AX
+
+ RET
+
// See entry_amd64.go.
TEXT ·swapgs(SB),NOSPLIT,$0
SWAP_GS()
@@ -177,8 +199,29 @@ TEXT ·jumpToKernel(SB),NOSPLIT,$0
MOVQ AX, 0(SP)
RET
+// jumpToUser changes execution to the user address space.
+//
+// This works by changing the return value to the user version.
+TEXT ·jumpToUser(SB),NOSPLIT,$0
+ // N.B. we can't access KernelStartAddress from the upper half (data
+ // pages not available), so just naively clear all the upper bits.
+ // We are assuming a 47-bit virtual address space.
+ MOVQ $0x00007fffffffffff, AX
+ MOVQ 0(SP), BX
+ ANDQ BX, AX // Future return value.
+ MOVQ AX, 0(SP)
+ RET
+
// See entry_amd64.go.
TEXT ·sysret(SB),NOSPLIT,$0-24
+ // Set application FS. We can't do this in Go because Go code needs FS.
+ MOVQ regs+8(FP), AX
+ MOVQ PTRACE_FS_BASE(AX), AX
+
+ PUSHQ AX
+ CALL ·writeFS(SB)
+ POPQ AX
+
CALL ·jumpToKernel(SB)
// Save original state and stack. sysenter() or exception()
// from APP(gr3) will switch to this stack, set the return
@@ -212,6 +255,14 @@ TEXT ·sysret(SB),NOSPLIT,$0-24
// See entry_amd64.go.
TEXT ·iret(SB),NOSPLIT,$0-24
+ // Set application FS. We can't do this in Go because Go code needs FS.
+ MOVQ regs+8(FP), AX
+ MOVQ PTRACE_FS_BASE(AX), AX
+
+ PUSHQ AX // First argument (FS_BASE)
+ CALL ·writeFS(SB)
+ POPQ AX
+
CALL ·jumpToKernel(SB)
// Save original state and stack. sysenter() or exception()
// from APP(gr3) will switch to this stack, set the return
@@ -254,13 +305,29 @@ TEXT ·resume(SB),NOSPLIT,$0
IRET()
// See entry_amd64.go.
-TEXT ·Start(SB),NOSPLIT,$0
+TEXT ·start(SB),NOSPLIT,$0
+ // N.B. This is the vCPU entrypoint. It is not called from Go code and
+ // thus pushes and pops values on the stack until calling into Go
+ // (startGo) because we aren't usually a typical Go assembly frame.
+
PUSHQ $0x0 // Previous frame pointer.
MOVQ SP, BP // Set frame pointer.
- PUSHQ AX // First argument (CPU).
- CALL ·start(SB) // Call Go hook.
+
+ PUSHQ AX // Save CPU.
+
+ // Set up environment required by Go before calling startGo: Go needs
+ // FS_BASE and floating point initialized.
+ MOVQ CPU_REGISTERS+PTRACE_FS_BASE(AX), BX
+ PUSHQ BX // First argument (FS_BASE)
+ CALL ·writeFS(SB)
+ POPQ BX
+
+ // First argument (CPU) already at bottom of stack.
+ CALL ·startGo(SB) // Call Go hook.
JMP ·resume(SB) // Restore to registers.
+ADDR_OF_FUNC(·AddrOfStart(SB), ·start(SB));
+
// See entry_amd64.go.
TEXT ·sysenter(SB),NOSPLIT,$0
// _RFLAGS_IOPL0 is always set in the user mode and it is never set in
@@ -288,6 +355,18 @@ user:
MOVQ $0, CPU_ERROR_CODE(AX) // Clear error code.
MOVQ $1, CPU_ERROR_TYPE(AX) // Set error type to user.
+ CALL ·jumpToUser(SB)
+
+ // Restore kernel FS_BASE.
+ MOVQ ENTRY_CPU_SELF(GS), AX // Load vCPU.
+ MOVQ CPU_REGISTERS+PTRACE_FS_BASE(AX), BX
+
+ PUSHQ BX // First argument (FS_BASE)
+ CALL ·writeFS(SB)
+ POPQ BX
+
+ MOVQ ENTRY_CPU_SELF(GS), AX // Load vCPU.
+
// Return to the kernel, where the frame is:
//
// vector (sp+32)
@@ -322,6 +401,8 @@ kernel:
POPQ AX // Pop vCPU.
JMP ·resume(SB)
+ADDR_OF_FUNC(·addrOfSysenter(SB), ·sysenter(SB));
+
// exception is a generic exception handler.
//
// There are two cases handled:
@@ -368,6 +449,16 @@ user:
MOVQ 40(SP), DI; MOVQ DI, PTRACE_RSP(AX)
MOVQ 48(SP), SI; MOVQ SI, PTRACE_SS(AX)
+ CALL ·jumpToUser(SB)
+
+ // Restore kernel FS_BASE.
+ MOVQ ENTRY_CPU_SELF(GS), AX // Load vCPU.
+ MOVQ CPU_REGISTERS+PTRACE_FS_BASE(AX), BX
+
+ PUSHQ BX // First argument (FS_BASE)
+ CALL ·writeFS(SB)
+ POPQ BX
+
// Copy out and return.
MOVQ ENTRY_CPU_SELF(GS), AX // Load vCPU.
MOVQ 0(SP), BX // Load vector.
@@ -406,36 +497,38 @@ kernel:
POPQ AX // Pop vCPU.
JMP ·resume(SB)
-#define EXCEPTION_WITH_ERROR(value, symbol) \
+#define EXCEPTION_WITH_ERROR(value, symbol, addr) \
+ADDR_OF_FUNC(addr, symbol); \
TEXT symbol,NOSPLIT,$0; \
PUSHQ $value; \
JMP ·exception(SB);
-#define EXCEPTION_WITHOUT_ERROR(value, symbol) \
+#define EXCEPTION_WITHOUT_ERROR(value, symbol, addr) \
+ADDR_OF_FUNC(addr, symbol); \
TEXT symbol,NOSPLIT,$0; \
PUSHQ $0x0; \
PUSHQ $value; \
JMP ·exception(SB);
-EXCEPTION_WITHOUT_ERROR(DivideByZero, ·divideByZero(SB))
-EXCEPTION_WITHOUT_ERROR(Debug, ·debug(SB))
-EXCEPTION_WITHOUT_ERROR(NMI, ·nmi(SB))
-EXCEPTION_WITHOUT_ERROR(Breakpoint, ·breakpoint(SB))
-EXCEPTION_WITHOUT_ERROR(Overflow, ·overflow(SB))
-EXCEPTION_WITHOUT_ERROR(BoundRangeExceeded, ·boundRangeExceeded(SB))
-EXCEPTION_WITHOUT_ERROR(InvalidOpcode, ·invalidOpcode(SB))
-EXCEPTION_WITHOUT_ERROR(DeviceNotAvailable, ·deviceNotAvailable(SB))
-EXCEPTION_WITH_ERROR(DoubleFault, ·doubleFault(SB))
-EXCEPTION_WITHOUT_ERROR(CoprocessorSegmentOverrun, ·coprocessorSegmentOverrun(SB))
-EXCEPTION_WITH_ERROR(InvalidTSS, ·invalidTSS(SB))
-EXCEPTION_WITH_ERROR(SegmentNotPresent, ·segmentNotPresent(SB))
-EXCEPTION_WITH_ERROR(StackSegmentFault, ·stackSegmentFault(SB))
-EXCEPTION_WITH_ERROR(GeneralProtectionFault, ·generalProtectionFault(SB))
-EXCEPTION_WITH_ERROR(PageFault, ·pageFault(SB))
-EXCEPTION_WITHOUT_ERROR(X87FloatingPointException, ·x87FloatingPointException(SB))
-EXCEPTION_WITH_ERROR(AlignmentCheck, ·alignmentCheck(SB))
-EXCEPTION_WITHOUT_ERROR(MachineCheck, ·machineCheck(SB))
-EXCEPTION_WITHOUT_ERROR(SIMDFloatingPointException, ·simdFloatingPointException(SB))
-EXCEPTION_WITHOUT_ERROR(VirtualizationException, ·virtualizationException(SB))
-EXCEPTION_WITH_ERROR(SecurityException, ·securityException(SB))
-EXCEPTION_WITHOUT_ERROR(SyscallInt80, ·syscallInt80(SB))
+EXCEPTION_WITHOUT_ERROR(DivideByZero, ·divideByZero(SB), ·addrOfDivideByZero(SB))
+EXCEPTION_WITHOUT_ERROR(Debug, ·debug(SB), ·addrOfDebug(SB))
+EXCEPTION_WITHOUT_ERROR(NMI, ·nmi(SB), ·addrOfNMI(SB))
+EXCEPTION_WITHOUT_ERROR(Breakpoint, ·breakpoint(SB), ·addrOfBreakpoint(SB))
+EXCEPTION_WITHOUT_ERROR(Overflow, ·overflow(SB), ·addrOfOverflow(SB))
+EXCEPTION_WITHOUT_ERROR(BoundRangeExceeded, ·boundRangeExceeded(SB), ·addrOfBoundRangeExceeded(SB))
+EXCEPTION_WITHOUT_ERROR(InvalidOpcode, ·invalidOpcode(SB), ·addrOfInvalidOpcode(SB))
+EXCEPTION_WITHOUT_ERROR(DeviceNotAvailable, ·deviceNotAvailable(SB), ·addrOfDeviceNotAvailable(SB))
+EXCEPTION_WITH_ERROR(DoubleFault, ·doubleFault(SB), ·addrOfDoubleFault(SB))
+EXCEPTION_WITHOUT_ERROR(CoprocessorSegmentOverrun, ·coprocessorSegmentOverrun(SB), ·addrOfCoprocessorSegmentOverrun(SB))
+EXCEPTION_WITH_ERROR(InvalidTSS, ·invalidTSS(SB), ·addrOfInvalidTSS(SB))
+EXCEPTION_WITH_ERROR(SegmentNotPresent, ·segmentNotPresent(SB), ·addrOfSegmentNotPresent(SB))
+EXCEPTION_WITH_ERROR(StackSegmentFault, ·stackSegmentFault(SB), ·addrOfStackSegmentFault(SB))
+EXCEPTION_WITH_ERROR(GeneralProtectionFault, ·generalProtectionFault(SB), ·addrOfGeneralProtectionFault(SB))
+EXCEPTION_WITH_ERROR(PageFault, ·pageFault(SB), ·addrOfPageFault(SB))
+EXCEPTION_WITHOUT_ERROR(X87FloatingPointException, ·x87FloatingPointException(SB), ·addrOfX87FloatingPointException(SB))
+EXCEPTION_WITH_ERROR(AlignmentCheck, ·alignmentCheck(SB), ·addrOfAlignmentCheck(SB))
+EXCEPTION_WITHOUT_ERROR(MachineCheck, ·machineCheck(SB), ·addrOfMachineCheck(SB))
+EXCEPTION_WITHOUT_ERROR(SIMDFloatingPointException, ·simdFloatingPointException(SB), ·addrOfSimdFloatingPointException(SB))
+EXCEPTION_WITHOUT_ERROR(VirtualizationException, ·virtualizationException(SB), ·addrOfVirtualizationException(SB))
+EXCEPTION_WITH_ERROR(SecurityException, ·securityException(SB), ·addrOfSecurityException(SB))
+EXCEPTION_WITHOUT_ERROR(SyscallInt80, ·syscallInt80(SB), ·addrOfSyscallInt80(SB))
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 20:49:20 +0000