3 files changed, 9 insertions, 2 deletions
diff --git a/pkg/sentry/platform/ring0/entry_arm64.s b/pkg/sentry/platform/ring0/entry_arm64.s
index f3d934996..253f54e49 100644
--- a/pkg/sentry/platform/ring0/entry_arm64.s
+++ b/pkg/sentry/platform/ring0/entry_arm64.s
@@ -342,6 +342,8 @@
 	ADD $16, RSP, RSP; \
 	MOVD RSV_REG, PTRACE_R18(R20); \
 	MOVD RSV_REG_APP, PTRACE_R9(R20); \
+	MRS TPIDR_EL0, R3; \
+	MOVD R3, PTRACE_TLS(R20); \
 	WORD $0xd5384003; \      //  MRS SPSR_EL1, R3
 	MOVD R3, PTRACE_PSTATE(R20); \
 	MRS ELR_EL1, R3; \
@@ -354,6 +356,8 @@
 	WORD $0xd538d092; \   //MRS   TPIDR_EL1, R18
 	REGISTERS_SAVE(RSV_REG, CPU_REGISTERS); \	// Save sentry context.
 	MOVD RSV_REG_APP, CPU_REGISTERS+PTRACE_R9(RSV_REG); \
+	MRS TPIDR_EL0, R4; \
+	MOVD R4, CPU_REGISTERS+PTRACE_TLS(RSV_REG); \
 	WORD $0xd5384004; \    //    MRS SPSR_EL1, R4
 	MOVD R4, CPU_REGISTERS+PTRACE_PSTATE(RSV_REG); \
 	MRS ELR_EL1, R4; \
@@ -435,6 +439,8 @@ TEXT ·kernelExitToEl0(SB),NOSPLIT,$0
 	MRS TPIDR_EL1, RSV_REG
 	REGISTERS_SAVE(RSV_REG, CPU_REGISTERS)
 	MOVD RSV_REG_APP, CPU_REGISTERS+PTRACE_R9(RSV_REG)
+	MRS TPIDR_EL0, R3
+	MOVD R3, CPU_REGISTERS+PTRACE_TLS(RSV_REG)
 
 	WORD $0xd5384003    //    MRS SPSR_EL1, R3
 	MOVD R3, CPU_REGISTERS+PTRACE_PSTATE(RSV_REG)
@@ -471,6 +477,8 @@ TEXT ·kernelExitToEl0(SB),NOSPLIT,$0
 do_exit_to_el0:
 	// RSV_REG & RSV_REG_APP will be loaded at the end.
 	REGISTERS_LOAD(RSV_REG_APP, 0)
+	MOVD PTRACE_TLS(RSV_REG_APP), RSV_REG
+	MSR RSV_REG, TPIDR_EL0
 
 	// switch to user pagetable.
 	MOVD PTRACE_R18(RSV_REG_APP), RSV_REG
diff --git a/pkg/sentry/platform/ring0/kernel_arm64.go b/pkg/sentry/platform/ring0/kernel_arm64.go
index 0ca98a7c7..b294ccc7c 100644
--- a/pkg/sentry/platform/ring0/kernel_arm64.go
+++ b/pkg/sentry/platform/ring0/kernel_arm64.go
@@ -64,11 +64,9 @@ func (c *CPU) SwitchToUser(switchOpts SwitchOpts) (vector Vector) {
 	regs.Pstate |= UserFlagsSet
 
 	LoadFloatingPoint(switchOpts.FloatingPointState)
-	SetTLS(regs.TPIDR_EL0)
 
 	kernelExitToEl0()
 
-	regs.TPIDR_EL0 = GetTLS()
 	SaveFloatingPoint(switchOpts.FloatingPointState)
 
 	vector = c.vecCode
diff --git a/pkg/sentry/platform/ring0/offsets_arm64.go b/pkg/sentry/platform/ring0/offsets_arm64.go
index 1d86b4bcf..45eba960d 100644
--- a/pkg/sentry/platform/ring0/offsets_arm64.go
+++ b/pkg/sentry/platform/ring0/offsets_arm64.go
@@ -125,4 +125,5 @@ func Emit(w io.Writer) {
 	fmt.Fprintf(w, "#define PTRACE_SP       0x%02x\n", reflect.ValueOf(&p.Sp).Pointer()-reflect.ValueOf(p).Pointer())
 	fmt.Fprintf(w, "#define PTRACE_PC       0x%02x\n", reflect.ValueOf(&p.Pc).Pointer()-reflect.ValueOf(p).Pointer())
 	fmt.Fprintf(w, "#define PTRACE_PSTATE   0x%02x\n", reflect.ValueOf(&p.Pstate).Pointer()-reflect.ValueOf(p).Pointer())
+	fmt.Fprintf(w, "#define PTRACE_TLS      0x%02x\n", reflect.ValueOf(&p.TPIDR_EL0).Pointer()-reflect.ValueOf(p).Pointer())
 }