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runtime: support new callbackasm1 calling convention on windows/arm

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This updates the callbacks implementation on windows/arm for the
changes made in CL 258938. At the time, that was left as a TODO.

At the same time, it also extends the previous support for only 4
arguments to also support additional arguments on the stack. This is
required for functions like SetWinEventHook, which take 7 arguments. It
does this by pushing r0-r3 onto the stack before the normal prologue,
and then pointing the args struct to that location.

This is derived from CL 270077 and CL 270078.

Updates #40724.
Fixes #42591.

Change-Id: Icc199e7f2c24205e41be4e00015283c7e2a9b797
Reviewed-on: https://go-review.googlesource.com/c/go/+/271178
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Jason A. Donenfeld 2020-11-18 21:38:57 +01:00
parent 5ba1c3f290
commit 4d048194cd
2 changed files with 53 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
src/runtime/sys_windows_arm.s
View File

@ -314,48 +314,42 @@ TEXT runtime·externalthreadhandler(SB),NOSPLIT|NOFRAME,$0
GLOBL runtime·cbctxts(SB), NOPTR, $4
TEXT runtime·callbackasm1(SB),NOSPLIT|NOFRAME,$0
// TODO(austin): This needs to be converted to match changes
// in cgocallback, but I have no way to test. See CL 258938,
// and callbackasm1 on amd64 and 386.
MOVM.DB.W [R4-R11, R14], (R13) // push {r4-r11, lr}
SUB $36, R13 // space for locals
// On entry, the trampoline in zcallback_windows_arm.s left
// the callback index in R12 (which is volatile in the C ABI).
// save callback arguments to stack. We currently support up to 4 arguments
ADD $16, R13, R4
MOVM.IA [R0-R3], (R4)
// Push callback register arguments r0-r3. We do this first so
// they're contiguous with stack arguments.
MOVM.DB.W [R0-R3], (R13)
// Push C callee-save registers r4-r11 and lr.
MOVM.DB.W [R4-R11, R14], (R13)
SUB $(16 + callbackArgs__size), R13 // space for locals
// load cbctxts[i]. The trampoline in zcallback_windows.s puts the callback
// index in R12
MOVW runtime·cbctxts(SB), R4
MOVW R12<<2(R4), R4 // R4 holds pointer to wincallbackcontext structure
// extract callback context
MOVW wincallbackcontext_argsize(R4), R5
MOVW wincallbackcontext_gobody(R4), R4
// we currently support up to 4 arguments
CMP $(4 * 4), R5
BL.GT runtime·abort(SB)
// extend argsize by size of return value
ADD $4, R5
// Build 'type args struct'
MOVW R4, 4(R13) // fn
ADD $16, R13, R0 // arg (points to r0-r3, ret on stack)
MOVW R0, 8(R13)
MOVW R5, 12(R13) // argsize
// Create a struct callbackArgs on our stack.
MOVW R12, (16+callbackArgs_index)(R13) // callback index
MOVW $(16+callbackArgs__size+4*9)(R13), R0
MOVW R0, (16+callbackArgs_args)(R13) // address of args vector
MOVW $0, R0
MOVW R0, (16+callbackArgs_result)(R13) // result
// Prepare for entry to Go.
BL runtime·load_g(SB)
BL runtime·cgocallback_gofunc(SB)
ADD $16, R13, R0 // load arg
MOVW 12(R13), R1 // load argsize
SUB $4, R1 // offset to return value
MOVW R1<<0(R0), R0 // load return value
// Call cgocallback, which will call callbackWrap(frame).
MOVW $0, R0
MOVW R0, 12(R13) // context
MOVW $16(R13), R1 // R1 = &callbackArgs{...}
MOVW R1, 8(R13) // frame (address of callbackArgs)
MOVW $·callbackWrap(SB), R1
MOVW R1, 4(R13) // PC of function to call
BL runtime·cgocallback(SB)
ADD $36, R13 // free locals
MOVM.IA.W (R13), [R4-R11, R15] // pop {r4-r11, pc}
// Get callback result.
MOVW (16+callbackArgs_result)(R13), R0
ADD $(16 + callbackArgs__size), R13 // free locals
MOVM.IA.W (R13), [R4-R11, R12] // pop {r4-r11, lr=>r12}
ADD $(4*4), R13 // skip r0-r3
B (R12) // return
// uint32 tstart_stdcall(M *newm);
TEXT runtime·tstart_stdcall(SB),NOSPLIT|NOFRAME,$0

29
src/runtime/syscall_windows.go
View File

@ -109,14 +109,19 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
// passed as two words (little endian); and
// structs are pushed on the stack. In
// fastcall, arguments larger than the word
// size are passed by reference.
// size are passed by reference. On arm,
// 8-byte aligned arguments round up to the
// next even register and can be split across
// registers and the stack.
panic("compileCallback: argument size is larger than uintptr")
}
if k := t.kind & kindMask; GOARCH == "amd64" && (k == kindFloat32 || k == kindFloat64) {
if k := t.kind & kindMask; (GOARCH == "amd64" || GOARCH == "arm") && (k == kindFloat32 || k == kindFloat64) {
// In fastcall, floating-point arguments in
// the first four positions are passed in
// floating-point registers, which we don't
// currently spill.
// currently spill. arm passes floating-point
// arguments in VFP registers, which we also
// don't support.
panic("compileCallback: float arguments not supported")
}
@ -128,6 +133,7 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
// argument word and all supported Windows
// architectures are little endian, so src is already
// pointing to the right place for smaller arguments.
// The same is true on arm.
// Copy just the size of the argument. Note that this
// could be a small by-value struct, but C and Go
@ -139,7 +145,7 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
abiMap = append(abiMap, part)
}
// cdecl, stdcall, and fastcall pad arguments to word size.
// cdecl, stdcall, fastcall, and arm pad arguments to word size.
src += sys.PtrSize
// The Go ABI packs arguments.
dst += t.size
@ -205,7 +211,18 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
type callbackArgs struct {
index uintptr
args unsafe.Pointer // Arguments in stdcall/cdecl convention, with registers spilled
// args points to the argument block.
//
// For cdecl and stdcall, all arguments are on the stack.
//
// For fastcall, the trampoline spills register arguments to
// the reserved spill slots below the stack arguments,
// resulting in a layout equivalent to stdcall.
//
// For arm, the trampoline stores the register arguments just
// below the stack arguments, so again we can treat it as one
// big stack arguments frame.
args unsafe.Pointer
// Below are out-args from callbackWrap
result uintptr
retPop uintptr // For 386 cdecl, how many bytes to pop on return
@ -216,7 +233,7 @@ func callbackWrap(a *callbackArgs) {
c := cbs.ctxt[a.index]
a.retPop = c.retPop
// Convert from stdcall to Go ABI.
// Convert from C to Go ABI.
var frame [callbackMaxFrame]byte
goArgs := unsafe.Pointer(&frame)
for _, part := range c.abiMap {