Save R15 before global access (#255)

In -buildmode=plugin R15 is used when accessing global variables but we need to save it since we are actually called from C code. We save the R15 register before we access any globals to avoid clobbering the register.

Closes #254

commit: 573eba027cb6d037833ae1fdb23bca0228ac0e4c
author: TotallyGamerJet · 2y ago · 2024-06-20 02:45 UTC
committer: GitHub · 2y ago · 2024-06-20 02:45 UTC
parent: 8ebc748
signature: GPG UnverifiedB5690EEEBB952194 The key is unknown

2 files · +18 -3

M .github/workflows/test.yml +15 -0


@@ -39,6 +39,12 @@ jobs:
39	39		run: \|
40	40		go vet -v ./...
41	41
	42	+	- name: go build plugin
	43	+	if: runner.os == 'Linux' \|\| runner.os == 'macOS'
	44	+	run:
	45	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
	46	+	go build -buildmode=plugin ./examples/libc
	47	+
42	48		- name: go build
43	49		run: \|
44	50		go build -v ./...

@@ -97,6 +103,11 @@ jobs:
97	103		env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-nocgo -test.shuffle=on -test.v -test.count=10
98	104		env GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go test -c -o=purego-test-cgo .
99	105		env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-cgo -test.shuffle=on -test.v -test.count=10
	106	+
	107	+	echo "=> go build plugin"
	108	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
	109	+	env GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go build -buildmode=plugin ./examples/libc
	110	+
100	111		go env -u CC
101	112		go env -u CXX
102	113

@@ -147,6 +158,10 @@ jobs:
147	158
148	159		# verify Go is available
149	160		go version
	161	+
	162	+	echo "=> go build plugin"
	163	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
	164	+	go build -buildmode=plugin ./examples/libc
150	165
151	166		echo "=> go build"
152	167		go build -v ./...


@@ -39,6 +39,12 @@ jobs:
39	run: \|	39		run: \|
40	go vet -v ./...	40		go vet -v ./...
41		41
		42	+	- name: go build plugin
		43	+	if: runner.os == 'Linux' \|\| runner.os == 'macOS'
		44	+	run:
		45	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
		46	+	go build -buildmode=plugin ./examples/libc
		47	+
42	- name: go build	48		- name: go build
43	run: \|	49		run: \|
44	go build -v ./...	50		go build -v ./...

@@ -97,6 +103,11 @@ jobs:
97	env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-nocgo -test.shuffle=on -test.v -test.count=10	103		env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-nocgo -test.shuffle=on -test.v -test.count=10
98	env GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go test -c -o=purego-test-cgo .	104		env GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go test -c -o=purego-test-cgo .
99	env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-cgo -test.shuffle=on -test.v -test.count=10	105		env QEMU_LD_PREFIX=/usr/aarch64-linux-gnu qemu-aarch64 ./purego-test-cgo -test.shuffle=on -test.v -test.count=10
		106	+
		107	+	echo "=> go build plugin"
		108	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
		109	+	env GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go build -buildmode=plugin ./examples/libc
		110	+
100	go env -u CC	111		go env -u CC
101	go env -u CXX	112		go env -u CXX
102		113

@@ -147,6 +158,10 @@ jobs:
147		158
148	# verify Go is available	159		# verify Go is available
149	go version	160		go version
		161	+
		162	+	echo "=> go build plugin"
		163	+	# Make sure that plugin buildmode works since we save the R15 register (#254)
		164	+	go build -buildmode=plugin ./examples/libc
150		165
151	echo "=> go build"	166		echo "=> go build"
152	go build -v ./...	167		go build -v ./...

M sys_amd64.s +3 -3


@@ -122,6 +122,9 @@ TEXT callbackasm1(SB), NOSPLIT\|NOFRAME, $0
122	122
123	123		PUSHQ R10 // push the stack pointer below registers
124	124
	125	+	// Switch from the host ABI to the Go ABI.
	126	+	PUSH_REGS_HOST_TO_ABI0()
	127	+
125	128		// determine index into runtime·cbs table
126	129		MOVQ $callbackasm(SB), DX
127	130		SUBQ DX, AX

@@ -130,9 +133,6 @@ TEXT callbackasm1(SB), NOSPLIT\|NOFRAME, $0
130	133		DIVL CX
131	134		SUBQ $1, AX // subtract 1 because return PC is to the next slot
132	135
133		-	// Switch from the host ABI to the Go ABI.
134		-	PUSH_REGS_HOST_TO_ABI0()
135		-
136	136		// Create a struct callbackArgs on our stack to be passed as
137	137		// the "frame" to cgocallback and on to callbackWrap.
138	138		// $24 to make enough room for the arguments to runtime.cgocallback

 	PUSHQ R10 // push the stack pointer below registers
+	// Switch from the host ABI to the Go ABI.
+	PUSH_REGS_HOST_TO_ABI0()
 	// determine index into runtime·cbs table
 	MOVQ $callbackasm(SB), DX
 	SUBQ DX, AX
 	DIVL CX
 	SUBQ $1, AX               // subtract 1 because return PC is to the next slot
-	// Switch from the host ABI to the Go ABI.
-	PUSH_REGS_HOST_TO_ABI0()
 	// Create a struct callbackArgs on our stack to be passed as
 	// the "frame" to cgocallback and on to callbackWrap.
 	// $24 to make enough room for the arguments to runtime.cgocallback