github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/pkg/sentry/platform/kvm/bluepill_arm64.s (about)

     1  // Copyright 2019 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  #include "textflag.h"
    16  
    17  // VCPU_CPU is the location of the CPU in the vCPU struct.
    18  //
    19  // This is guaranteed to be zero.
    20  #define VCPU_CPU 0x0
    21  
    22  // CPU_SELF is the self reference in ring0's percpu.
    23  //
    24  // This is guaranteed to be zero.
    25  #define CPU_SELF 0x0
    26  
    27  // Context offsets.
    28  //
    29  // Only limited use of the context is done in the assembly stub below, most is
    30  // done in the Go handlers.
    31  #define SIGINFO_SIGNO 0x0
    32  #define SIGINFO_CODE 0x8
    33  #define CONTEXT_PC  0x1B8
    34  #define CONTEXT_R0 0xB8
    35  
    36  #define SYS_MMAP 222
    37  
    38  // getTLS returns the value of TPIDR_EL0 register.
    39  TEXT ·getTLS(SB),NOSPLIT,$0-8
    40  	MRS TPIDR_EL0, R1
    41  	MOVD R1, value+0(FP)
    42  	RET
    43  
    44  // setTLS writes the TPIDR_EL0 value.
    45  TEXT ·setTLS(SB),NOSPLIT,$0-8
    46  	MOVD value+0(FP), R1
    47  	MSR R1, TPIDR_EL0
    48  	RET
    49  
    50  // See bluepill.go.
    51  TEXT ·bluepill(SB),NOSPLIT,$0
    52  begin:
    53  	MOVD	arg+0(FP), R8
    54  	MOVD	$VCPU_CPU(R8), R9
    55  	ORR	$0xffff000000000000, R9, R9
    56  	// Trigger sigill.
    57  	// In ring0.Start(), the value of R8 will be stored into tpidr_el1.
    58  	// When the context was loaded into vcpu successfully,
    59  	// we will check if the value of R10 and R9 are the same.
    60  	WORD	$0xd538d08a // MRS TPIDR_EL1, R10
    61  check_vcpu:
    62  	CMP	R10, R9
    63  	BEQ	right_vCPU
    64  wrong_vcpu:
    65  	CALL	·redpill(SB)
    66  	B	begin
    67  right_vCPU:
    68  	RET
    69  
    70  // sighandler: see bluepill.go for documentation.
    71  //
    72  // The arguments are the following:
    73  //
    74  // 	R0 - The signal number.
    75  // 	R1 - Pointer to siginfo_t structure.
    76  // 	R2 - Pointer to ucontext structure.
    77  //
    78  TEXT ·sighandler(SB),NOSPLIT,$0
    79  	// si_signo should be sigill.
    80  	MOVD	SIGINFO_SIGNO(R1), R7
    81  	CMPW	$4, R7
    82  	BNE	fallback
    83  
    84  	MOVD	CONTEXT_PC(R2), R7
    85  	CMPW	$0, R7
    86  	BEQ	fallback
    87  
    88  	MOVD	R2, 8(RSP)
    89  	BL	·bluepillHandler(SB)   // Call the handler.
    90  
    91  	RET
    92  
    93  fallback:
    94  	// Jump to the previous signal handler.
    95  	MOVD	·savedHandler(SB), R7
    96  	B	(R7)
    97  
    98  // func addrOfSighandler() uintptr
    99  TEXT ·addrOfSighandler(SB), $0-8
   100  	MOVD	$·sighandler(SB), R0
   101  	MOVD	R0, ret+0(FP)
   102  	RET
   103  
   104  // The arguments are the following:
   105  //
   106  // 	R0 - The signal number.
   107  // 	R1 - Pointer to siginfo_t structure.
   108  // 	R2 - Pointer to ucontext structure.
   109  //
   110  TEXT ·sigsysHandler(SB),NOSPLIT,$0
   111  	// si_code should be SYS_SECCOMP.
   112  	MOVD	SIGINFO_CODE(R1), R7
   113  	CMPW	$1, R7
   114  	BNE	fallback
   115  
   116  	CMPW	$SYS_MMAP, R8
   117  	BNE	fallback
   118  
   119  	MOVD	R2, 8(RSP)
   120  	BL	·seccompMmapHandler(SB)   // Call the handler.
   121  
   122  	RET
   123  
   124  fallback:
   125  	// Jump to the previous signal handler.
   126  	MOVD	·savedHandler(SB), R7
   127  	B	(R7)
   128  
   129  // func addrOfSighandler() uintptr
   130  TEXT ·addrOfSigsysHandler(SB), $0-8
   131  	MOVD	$·sigsysHandler(SB), R0
   132  	MOVD	R0, ret+0(FP)
   133  	RET
   134  
   135  // dieTrampoline: see bluepill.go, bluepill_arm64_unsafe.go for documentation.
   136  TEXT ·dieTrampoline(SB),NOSPLIT,$0
   137  	// R0: Fake the old PC as caller
   138  	// R1: First argument (vCPU)
   139  	MOVD.P R1, 8(RSP) // R1: First argument (vCPU)
   140  	MOVD.P R0, 8(RSP) // R0: Fake the old PC as caller
   141  	B ·dieHandler(SB)
   142  
   143  // func addrOfDieTrampoline() uintptr
   144  TEXT ·addrOfDieTrampoline(SB), $0-8
   145  	MOVD	$·dieTrampoline(SB), R0
   146  	MOVD	R0, ret+0(FP)
   147  	RET