Makefile: don't compile all targets into target binaries

Currently target binaries contain support for all OS/arch combinations.
However, obviously a fuchsia target binary won't test windows.
For target binaries we need support only for a single target
(with the exception of 386/arm target in amd64/arm64 binaries).
So compile in only _the_ target into target binaries.
This reduces akaros/amd64 fuzzer binary from 33 to 7 MB
and execprog from 28 to 2 MB.

7 files changed, 36 insertions, 12 deletions

diff --git a/sys/linux/gen/386.go b/sys/linux/gen/386.go
index 972193818..82bb7aa81 100644
--- a/sys/linux/gen/386.go
+++ b/sys/linux/gen/386.go
@@ -1,10 +1,14 @@
 // AUTOGENERATED FILE
+// +build !syz_target syz_target,syz_os_linux,syz_arch_386 syz_target,syz_os_linux,syz_arch_amd64
 
 package gen
 
 import . "github.com/google/syzkaller/prog"
+import . "github.com/google/syzkaller/sys/linux"
 
-var Target_386 = &Target{OS: "linux", Arch: "386", Revision: revision_386, PtrSize: 4, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_386, Resources: resources_386, Structs: structDescs_386, Consts: consts_386}
+func init() {
+	RegisterTarget(&Target{OS: "linux", Arch: "386", Revision: revision_386, PtrSize: 4, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_386, Resources: resources_386, Structs: structDescs_386, Consts: consts_386}, InitTarget)
+}
 
 var resources_386 = []*ResourceDesc{
 	{Name: "assoc_id", Type: &IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int32", TypeSize: 4}}}, Kind: []string{"assoc_id"}, Values: []uint64{0}},
@@ -39509,4 +39513,4 @@ var consts_386 = []ConstValue{
 	{Name: "bpf_insn_load_imm_dw", Value: 24},
 }
 
-const revision_386 = "d16df4bd3b5d63c53207d8d48f0e7aa8375ae471"
+const revision_386 = "c026c82f557e0fb27209b060f233071e8ba38eab"
diff --git a/sys/linux/gen/amd64.go b/sys/linux/gen/amd64.go
index 6fffdec69..c2747f266 100644
--- a/sys/linux/gen/amd64.go
+++ b/sys/linux/gen/amd64.go
@@ -1,10 +1,14 @@
 // AUTOGENERATED FILE
+// +build !syz_target syz_target,syz_os_linux,syz_arch_amd64
 
 package gen
 
 import . "github.com/google/syzkaller/prog"
+import . "github.com/google/syzkaller/sys/linux"
 
-var Target_amd64 = &Target{OS: "linux", Arch: "amd64", Revision: revision_amd64, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_amd64, Resources: resources_amd64, Structs: structDescs_amd64, Consts: consts_amd64}
+func init() {
+	RegisterTarget(&Target{OS: "linux", Arch: "amd64", Revision: revision_amd64, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_amd64, Resources: resources_amd64, Structs: structDescs_amd64, Consts: consts_amd64}, InitTarget)
+}
 
 var resources_amd64 = []*ResourceDesc{
 	{Name: "assoc_id", Type: &IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int32", TypeSize: 4}}}, Kind: []string{"assoc_id"}, Values: []uint64{0}},
@@ -40196,4 +40200,4 @@ var consts_amd64 = []ConstValue{
 	{Name: "bpf_insn_load_imm_dw", Value: 24},
 }
 
-const revision_amd64 = "22bac64bd4f91440dd851726a290b9eb1f1ae092"
+const revision_amd64 = "c06fc3bdc53ae8ee708128ddd51d14a679aa12f0"
diff --git a/sys/linux/gen/arm.go b/sys/linux/gen/arm.go
index 160738afd..8192e252a 100644
--- a/sys/linux/gen/arm.go
+++ b/sys/linux/gen/arm.go
@@ -1,10 +1,14 @@
 // AUTOGENERATED FILE
+// +build !syz_target syz_target,syz_os_linux,syz_arch_arm syz_target,syz_os_linux,syz_arch_arm64
 
 package gen
 
 import . "github.com/google/syzkaller/prog"
+import . "github.com/google/syzkaller/sys/linux"
 
-var Target_arm = &Target{OS: "linux", Arch: "arm", Revision: revision_arm, PtrSize: 4, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_arm, Resources: resources_arm, Structs: structDescs_arm, Consts: consts_arm}
+func init() {
+	RegisterTarget(&Target{OS: "linux", Arch: "arm", Revision: revision_arm, PtrSize: 4, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_arm, Resources: resources_arm, Structs: structDescs_arm, Consts: consts_arm}, InitTarget)
+}
 
 var resources_arm = []*ResourceDesc{
 	{Name: "assoc_id", Type: &IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int32", TypeSize: 4}}}, Kind: []string{"assoc_id"}, Values: []uint64{0}},
@@ -39367,4 +39371,4 @@ var consts_arm = []ConstValue{
 	{Name: "bpf_insn_load_imm_dw", Value: 24},
 }
 
-const revision_arm = "c46361b24a9d8c4d25f99c6a74ed373b73b0cdd1"
+const revision_arm = "b4f6cbe7c414a45bfaf3dcccf7f1040502de3980"
diff --git a/sys/linux/gen/arm64.go b/sys/linux/gen/arm64.go
index 8bf0d11df..d783efc8b 100644
--- a/sys/linux/gen/arm64.go
+++ b/sys/linux/gen/arm64.go
@@ -1,10 +1,14 @@
 // AUTOGENERATED FILE
+// +build !syz_target syz_target,syz_os_linux,syz_arch_arm64
 
 package gen
 
 import . "github.com/google/syzkaller/prog"
+import . "github.com/google/syzkaller/sys/linux"
 
-var Target_arm64 = &Target{OS: "linux", Arch: "arm64", Revision: revision_arm64, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_arm64, Resources: resources_arm64, Structs: structDescs_arm64, Consts: consts_arm64}
+func init() {
+	RegisterTarget(&Target{OS: "linux", Arch: "arm64", Revision: revision_arm64, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_arm64, Resources: resources_arm64, Structs: structDescs_arm64, Consts: consts_arm64}, InitTarget)
+}
 
 var resources_arm64 = []*ResourceDesc{
 	{Name: "assoc_id", Type: &IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int32", TypeSize: 4}}}, Kind: []string{"assoc_id"}, Values: []uint64{0}},
@@ -39561,4 +39565,4 @@ var consts_arm64 = []ConstValue{
 	{Name: "bpf_insn_load_imm_dw", Value: 24},
 }
 
-const revision_arm64 = "e1ce203bf0cb9e092e65fc6ca9cd1cde96e19316"
+const revision_arm64 = "70ff2aa900dc3911170ab814adc6a362bb014580"
diff --git a/sys/linux/gen/empty.go b/sys/linux/gen/empty.go
new file mode 100644
index 000000000..5baff07bf
--- /dev/null
+++ b/sys/linux/gen/empty.go
@@ -0,0 +1,3 @@
+// AUTOGENERATED FILE
+// This file is needed if OS is completely excluded by build tags.
+package gen
diff --git a/sys/linux/gen/ppc64le.go b/sys/linux/gen/ppc64le.go
index d8f088418..8ffa0b43f 100644
--- a/sys/linux/gen/ppc64le.go
+++ b/sys/linux/gen/ppc64le.go
@@ -1,10 +1,14 @@
 // AUTOGENERATED FILE
+// +build !syz_target syz_target,syz_os_linux,syz_arch_ppc64le
 
 package gen
 
 import . "github.com/google/syzkaller/prog"
+import . "github.com/google/syzkaller/sys/linux"
 
-var Target_ppc64le = &Target{OS: "linux", Arch: "ppc64le", Revision: revision_ppc64le, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_ppc64le, Resources: resources_ppc64le, Structs: structDescs_ppc64le, Consts: consts_ppc64le}
+func init() {
+	RegisterTarget(&Target{OS: "linux", Arch: "ppc64le", Revision: revision_ppc64le, PtrSize: 8, PageSize: 4096, NumPages: 4096, DataOffset: 536870912, Syscalls: syscalls_ppc64le, Resources: resources_ppc64le, Structs: structDescs_ppc64le, Consts: consts_ppc64le}, InitTarget)
+}
 
 var resources_ppc64le = []*ResourceDesc{
 	{Name: "assoc_id", Type: &IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int32", TypeSize: 4}}}, Kind: []string{"assoc_id"}, Values: []uint64{0}},
@@ -36992,4 +36996,4 @@ var consts_ppc64le = []ConstValue{
 	{Name: "bpf_insn_load_imm_dw", Value: 24},
 }
 
-const revision_ppc64le = "1ccba534d5c6adaffc5ebfbea33c22833f5cb846"
+const revision_ppc64le = "be0af9fd447e9ac157423f3260f414d60066f653"
diff --git a/sys/linux/init.go b/sys/linux/init.go
index 8d7231fcd..035ffee2f 100644
--- a/sys/linux/init.go
+++ b/sys/linux/init.go
@@ -7,10 +7,10 @@ import (
 	"runtime"
 
 	"github.com/google/syzkaller/prog"
-	"github.com/google/syzkaller/sys/linux/gen"
 	"github.com/google/syzkaller/sys/targets"
 )
 
+/*
 func init() {
 	prog.RegisterTarget(gen.Target_amd64, initTarget)
 	prog.RegisterTarget(gen.Target_386, initTarget)
@@ -18,8 +18,9 @@ func init() {
 	prog.RegisterTarget(gen.Target_arm, initTarget)
 	prog.RegisterTarget(gen.Target_ppc64le, initTarget)
 }
+*/
 
-func initTarget(target *prog.Target) {
+func InitTarget(target *prog.Target) {
 	arch := &arch{
 		unix:                      targets.MakeUnixSanitizer(target),
 		clockGettimeSyscall:       target.SyscallMap["clock_gettime"],