diff options
Diffstat (limited to 'src/runtime/mkpreempt.go')
| -rw-r--r-- | src/runtime/mkpreempt.go | 92 |
1 files changed, 81 insertions, 11 deletions
diff --git a/src/runtime/mkpreempt.go b/src/runtime/mkpreempt.go index ec900a23d2..e3dd5046f3 100644 --- a/src/runtime/mkpreempt.go +++ b/src/runtime/mkpreempt.go @@ -9,8 +9,10 @@ package main import ( + "bytes" "flag" "fmt" + "go/format" "io" "log" "os" @@ -122,14 +124,19 @@ type gen struct { goarch string } -func (g *gen) asmHeader() { +func (g *gen) commonHeader() { fmt.Fprintf(g.w, "// Code generated by mkpreempt.go; DO NOT EDIT.\n\n") if beLe[g.goarch] { base := g.goarch[:len(g.goarch)-1] fmt.Fprintf(g.w, "//go:build %s || %sle\n\n", base, base) } +} + +func (g *gen) asmHeader() { + g.commonHeader() fmt.Fprintf(g.w, "#include \"go_asm.h\"\n") if g.goarch == "amd64" { + fmt.Fprintf(g.w, "#include \"go_tls.h\"\n") fmt.Fprintf(g.w, "#include \"asm_amd64.h\"\n") } fmt.Fprintf(g.w, "#include \"textflag.h\"\n\n") @@ -145,6 +152,43 @@ func (g *gen) label(l string) { fmt.Fprintf(g.w, "%s\n", l) } +// writeXRegs writes an architecture xregs file. +func writeXRegs(arch string, l *layout) { + var code bytes.Buffer + g := gen{&code, arch} + g.commonHeader() + fmt.Fprintf(g.w, ` +package runtime + +type xRegState struct { +`) + pos := 0 + for _, reg := range l.regs { + if reg.pos != pos { + log.Fatalf("padding not implemented") + } + typ := fmt.Sprintf("[%d]byte", reg.size) + switch { + case reg.size == 4 && reg.pos%4 == 0: + typ = "uint32" + case reg.size == 8 && reg.pos%8 == 0: + typ = "uint64" + } + fmt.Fprintf(g.w, "\t%s %s\n", reg.reg, typ) + pos += reg.size + } + fmt.Fprintf(g.w, "}\n") + + path := fmt.Sprintf("preempt_%s.go", arch) + b, err := format.Source(code.Bytes()) + if err != nil { + log.Fatalf("formatting %s: %s", path, err) + } + if err := os.WriteFile(path, b, 0666); err != nil { + log.Fatal(err) + } +} + type layout struct { stack int regs []regPos @@ -152,7 +196,7 @@ type layout struct { } type regPos struct { - pos int + pos, size int saveOp string restoreOp string @@ -165,17 +209,17 @@ type regPos struct { } func (l *layout) add(op, reg string, size int) { - l.regs = append(l.regs, regPos{saveOp: op, restoreOp: op, reg: reg, pos: l.stack}) + l.regs = append(l.regs, regPos{saveOp: op, restoreOp: op, reg: reg, pos: l.stack, size: size}) l.stack += size } func (l *layout) add2(sop, rop, reg string, size int) { - l.regs = append(l.regs, regPos{saveOp: sop, restoreOp: rop, reg: reg, pos: l.stack}) + l.regs = append(l.regs, regPos{saveOp: sop, restoreOp: rop, reg: reg, pos: l.stack, size: size}) l.stack += size } func (l *layout) addSpecial(save, restore string, size int) { - l.regs = append(l.regs, regPos{save: save, restore: restore, pos: l.stack}) + l.regs = append(l.regs, regPos{save: save, restore: restore, pos: l.stack, size: size}) l.stack += size } @@ -239,6 +283,8 @@ func gen386(g *gen) { } func genAMD64(g *gen) { + const xReg = "AX" // *xRegState + p := g.p // Assign stack offsets. @@ -251,12 +297,13 @@ func genAMD64(g *gen) { l.add("MOVQ", reg, 8) } } - lSSE := layout{stack: l.stack, sp: "SP"} + lXRegs := layout{sp: xReg} // Non-GP registers for _, reg := range regNamesAMD64 { if strings.HasPrefix(reg, "X") { - lSSE.add("MOVUPS", reg, 16) + lXRegs.add("MOVUPS", reg, 16) } } + writeXRegs(g.goarch, &lXRegs) // TODO: MXCSR register? @@ -265,17 +312,40 @@ func genAMD64(g *gen) { p("// Save flags before clobbering them") p("PUSHFQ") p("// obj doesn't understand ADD/SUB on SP, but does understand ADJSP") - p("ADJSP $%d", lSSE.stack) + p("ADJSP $%d", l.stack) p("// But vet doesn't know ADJSP, so suppress vet stack checking") p("NOP SP") + p("// Save GPs") l.save(g) - lSSE.save(g) + // In general, the limitations on asynchronous preemption mean we only + // preempt in ABIInternal code. However, there's at least one exception to + // this: when we're in an open-coded transition between an ABIInternal + // function and an ABI0 call. We could more carefully arrange unsafe points + // to avoid ever landing in ABI0, but it's easy to just make this code not + // sensitive to the ABI we're preempting. The CALL to asyncPreempt2 will + // ensure we're in ABIInternal register state. + p("// Save extended register state to p.xRegs.scratch") + p("// Don't make assumptions about ABI register state. See mkpreempt.go") + p("get_tls(CX)") + p("MOVQ g(CX), R14") + p("MOVQ g_m(R14), %s", xReg) + p("MOVQ m_p(%s), %s", xReg, xReg) + p("LEAQ (p_xRegs+xRegPerP_scratch)(%s), %s", xReg, xReg) + lXRegs.save(g) + p("CALL ·asyncPreempt2(SB)") - lSSE.restore(g) + + p("// Restore non-GPs from *p.xRegs.cache") + p("MOVQ g_m(R14), %s", xReg) + p("MOVQ m_p(%s), %s", xReg, xReg) + p("MOVQ (p_xRegs+xRegPerP_cache)(%s), %s", xReg, xReg) + lXRegs.restore(g) + + p("// Restore GPs") l.restore(g) - p("ADJSP $%d", -lSSE.stack) + p("ADJSP $%d", -l.stack) p("POPFQ") p("POPQ BP") p("RET") |