delve: add linux-riscv64 support

Documentation/backend_test_health.md

@@ -29,12 +29,19 @@ Tests skipped by each supported backend:
 	* 1 broken in linux ppc64le
 * linux/ppc64le/native/pie skipped = 3
 	* 3 broken - pie mode
+* linux/riscv64 skipped = 2
+	* 1 broken - cgo stacktraces
+	* 1 not working on linux/riscv64
 * pie skipped = 2
 	* 2 upstream issue - https://github.com/golang/go/issues/29322
 * ppc64le skipped = 12
 	* 6 broken
 	* 1 broken - global variable symbolication
 	* 5 not implemented
+* riscv64 skipped = 6
+	* 2 broken
+	* 1 broken - global variable symbolication
+	* 3 not implemented
 * windows skipped = 7
 	* 1 broken
 	* 2 not working on windows

_fixtures/asmnilptr/main_riscv64.s

@@ -0,0 +1,7 @@
+#include "textflag.h"
+
+TEXT ·asmFunc(SB),0,$0-16
+	MOV arg+0(FP), R5
+	MOV (R5), R5
+	MOV R5, ret+8(FP)
+	RET

_fixtures/cgostacktest/hello.c

@@ -14,6 +14,8 @@
 #else
 #define BREAKPOINT asm("brk 0;")
 #endif
+#elif __riscv
+#define BREAKPOINT asm("ebreak;")
 #endif
 
 void helloworld_pt2(int x) {

_fixtures/testvariablescgo/test.c

@@ -12,6 +12,8 @@
 #else
 #define BREAKPOINT asm("brk 0;")
 #endif
+#elif __riscv
+#define BREAKPOINT asm("ebreak;")
 #endif
 
 #define N 100
@@ -37,6 +39,6 @@ void testfn(void) {
 	strcpy(s, s0);
 
 	BREAKPOINT;
-	
+
 	printf("%s %s %p %p\n", s, longstring, v, v_align_check);
 }

_scripts/make.go

@@ -112,7 +112,7 @@ This option can only be specified if testset is basic or a single package.`)
 	test.PersistentFlags().StringVarP(&TestBuildMode, "test-build-mode", "m", "", `Runs tests compiling with the specified build mode, one of either:
 	normal		normal buildmode (default)
 	pie		PIE buildmode
-	
+
 This option can only be specified if testset is basic or a single package.`)
 	test.PersistentFlags().BoolVarP(&TestIncludePIE, "pie", "", true, "Standard testing should include PIE")
 

go.mod

@@ -16,7 +16,7 @@ require (
 	github.com/spf13/cobra v1.7.0
 	github.com/spf13/pflag v1.0.5
 	go.starlark.net v0.0.0-20231101134539-556fd59b42f6
-	golang.org/x/arch v0.6.0
+	golang.org/x/arch v0.10.1-0.20240910142527-7874f23b9c06
 	golang.org/x/sys v0.17.0
 	golang.org/x/tools v0.14.0
 	gopkg.in/yaml.v3 v3.0.1

pkg/dwarf/regnum/riscv64.go

@@ -0,0 +1,92 @@
+package regnum
+
+import "fmt"
+
+// The mapping between hardware registers and DWARF registers, See
+// https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-dwarf.adoc
+
+const (
+	// Integer Registers
+	RISCV64_X0 = 0
+	// Link Register
+	RISCV64_LR = 1
+	// Stack Pointer
+	RISCV64_SP = 2
+	RISCV64_GP = 3
+	RISCV64_TP = 4
+	RISCV64_T0 = 5
+	RISCV64_T1 = 6
+	RISCV64_T2 = 7
+	RISCV64_S0 = 8
+	// Frame Pointer
+	RISCV64_FP  = RISCV64_S0
+	RISCV64_S1  = 9
+	RISCV64_A0  = 10
+	RISCV64_A1  = 11
+	RISCV64_A2  = 12
+	RISCV64_A3  = 13
+	RISCV64_A4  = 14
+	RISCV64_A5  = 15
+	RISCV64_A6  = 16
+	RISCV64_A7  = 17
+	RISCV64_S2  = 18
+	RISCV64_S3  = 19
+	RISCV64_S4  = 20
+	RISCV64_S5  = 21
+	RISCV64_S6  = 22
+	RISCV64_S7  = 23
+	RISCV64_S8  = 24
+	RISCV64_S9  = 25
+	RISCV64_S10 = 26
+	// G Register
+	RISCV64_S11 = 27
+	RISCV64_T3  = 28
+	RISCV64_T4  = 29
+	RISCV64_T5  = 30
+	RISCV64_T6  = 31
+
+	RISCV64_X31 = RISCV64_T6
+
+	// Floating-point Registers
+	RISCV64_F0  = 32
+	RISCV64_F31 = 63
+
+	// Not defined in DWARF specification
+	RISCV64_PC = 65
+
+	_RISC64_MaxRegNum = RISCV64_PC
+)
+
+func RISCV64ToName(num uint64) string {
+	switch {
+	case num <= RISCV64_X31:
+		return fmt.Sprintf("X%d", num)
+
+	case num >= RISCV64_F0 && num <= RISCV64_F31:
+		return fmt.Sprintf("F%d", num)
+
+	case num == RISCV64_PC:
+		return fmt.Sprintf("PC")
+
+	default:
+		return fmt.Sprintf("Unknown%d", num)
+	}
+}
+
+func RISCV64MaxRegNum() uint64 {
+	return _RISC64_MaxRegNum
+}
+
+var RISCV64NameToDwarf = func() map[string]int {
+	r := make(map[string]int)
+	for i := 0; i <= 31; i++ {
+		r[fmt.Sprintf("x%d", i)] = RISCV64_X0 + i
+	}
+	r[fmt.Sprintf("pc")] = RISCV64_PC
+
+	for i := 0; i <= 31; i++ {
+		r[fmt.Sprintf("f%d", i)] = RISCV64_F0 + i
+	}
+
+	return r
+}()

pkg/proc/bininfo.go

@@ -126,6 +126,7 @@ var (
 		elf.EM_AARCH64: true,
 		elf.EM_386:     true,
 		elf.EM_PPC64:   true,
+		elf.EM_RISCV:   true,
 	}
 
 	supportedWindowsArch = map[_PEMachine]bool{
@@ -802,6 +803,8 @@ func NewBinaryInfo(goos, goarch string) *BinaryInfo {
 		r.Arch = ARM64Arch(goos)
 	case "ppc64le":
 		r.Arch = PPC64LEArch(goos)
+	case "riscv64":
+		r.Arch = RISCV64Arch(goos)
 	}
 	return r
 }
@@ -1803,6 +1806,9 @@ func (bi *BinaryInfo) setGStructOffsetElf(image *Image, exe *elf.File, wg *sync.
 	case elf.EM_PPC64:
 		_ = getSymbol(image, bi.logger, exe, "runtime.tls_g")
 
+	case elf.EM_RISCV:
+		_ = getSymbol(image, bi.logger, exe, "runtime.tls_g")
+
 	default:
 		// we should never get here
 		panic("architecture not supported")

pkg/proc/core/linux_core.go

@@ -40,6 +40,7 @@ const _NT_FPREGSET elf.NType = 0x2
 const (
 	_EM_AARCH64          = 183
 	_EM_X86_64           = 62
+	_EM_RISCV            = 243
 	_ARM_FP_HEADER_START = 512
 )
 
@@ -49,6 +50,8 @@ func linuxThreadsFromNotes(p *process, notes []*note, machineType elf.Machine) p
 	var currentThread proc.Thread
 	var lastThreadAMD *linuxAMD64Thread
 	var lastThreadARM *linuxARM64Thread
+	var lastThreadRISCV *linuxRISCV64Thread
+
 	for _, note := range notes {
 		switch note.Type {
 		case elf.NT_PRSTATUS:
@@ -66,12 +69,23 @@ func linuxThreadsFromNotes(p *process, notes []*note, machineType elf.Machine) p
 				if currentThread == nil {
 					currentThread = p.Threads[int(t.Pid)]
 				}
+			} else if machineType == _EM_RISCV {
+				t := note.Desc.(*linuxPrStatusRISCV64)
+				lastThreadRISCV = &linuxRISCV64Thread{linutil.RISCV64Registers{Regs: &t.Reg}, t}
+				p.Threads[int(t.Pid)] = &thread{lastThreadRISCV, p, proc.CommonThread{}}
+				if currentThread == nil {
+					currentThread = p.Threads[int(t.Pid)]
+				}
 			}
 		case _NT_FPREGSET:
 			if machineType == _EM_AARCH64 {
 				if lastThreadARM != nil {
 					lastThreadARM.regs.Fpregs = note.Desc.(*linutil.ARM64PtraceFpRegs).Decode()
 				}
+			} else if machineType == _EM_RISCV {
+				if lastThreadRISCV != nil {
+					lastThreadRISCV.regs.Fpregs = note.Desc.(*linutil.RISCV64PtraceFpRegs).Decode()
+				}
 			}
 		case _NT_X86_XSTATE:
 			if machineType == _EM_X86_64 {
@@ -147,6 +161,8 @@ func readLinuxOrPlatformIndependentCore(corePath, exePath string) (*process, pro
 			bi = proc.NewBinaryInfo("linux", "amd64")
 		case _EM_AARCH64:
 			bi = proc.NewBinaryInfo("linux", "arm64")
+		case _EM_RISCV:
+			bi = proc.NewBinaryInfo("linux", "riscv64")
 		default:
 			return nil, nil, errors.New("unsupported machine type")
 		}
@@ -181,6 +197,11 @@ type linuxARM64Thread struct {
 	t    *linuxPrStatusARM64
 }
 
+type linuxRISCV64Thread struct {
+	regs linutil.RISCV64Registers
+	t    *linuxPrStatusRISCV64
+}
+
 func (t *linuxAMD64Thread) registers() (proc.Registers, error) {
 	var r linutil.AMD64Registers
 	r.Regs = t.regs.Regs
@@ -195,6 +216,13 @@ func (t *linuxARM64Thread) registers() (proc.Registers, error) {
 	return &r, nil
 }
 
+func (t *linuxRISCV64Thread) registers() (proc.Registers, error) {
+	var r linutil.RISCV64Registers
+	r.Regs = t.regs.Regs
+	r.Fpregs = t.regs.Fpregs
+	return &r, nil
+}
+
 func (t *linuxAMD64Thread) pid() int {
 	return int(t.t.Pid)
 }
@@ -203,6 +231,10 @@ func (t *linuxARM64Thread) pid() int {
 	return int(t.t.Pid)
 }
 
+func (t *linuxRISCV64Thread) pid() int {
+	return int(t.t.Pid)
+}
+
 // Note is a note from the PT_NOTE prog.
 // Relevant types:
 // - NT_FILE: File mapping information, e.g. program text mappings. Desc is a LinuxNTFile.
@@ -286,6 +318,8 @@ func readNote(r io.ReadSeeker, machineType elf.Machine) (*note, error) {
 			note.Desc = &linuxPrStatusAMD64{}
 		case _EM_AARCH64:
 			note.Desc = &linuxPrStatusARM64{}
+		case _EM_RISCV:
+			note.Desc = &linuxPrStatusRISCV64{}
 		default:
 			return nil, errors.New("unsupported machine type")
 		}
@@ -333,6 +367,15 @@ func readNote(r io.ReadSeeker, machineType elf.Machine) (*note, error) {
 			}
 			note.Desc = fpregs
 		}
+
+		if machineType == _EM_RISCV {
+			fpregs := &linutil.RISCV64PtraceFpRegs{}
+			rdr := bytes.NewReader(desc)
+			if err := binary.Read(rdr, binary.LittleEndian, fpregs.Byte()); err != nil {
+				return nil, err
+			}
+			note.Desc = fpregs
+		}
 	}
 	if err := skipPadding(r, 4); err != nil {
 		return nil, fmt.Errorf("aligning after desc: %v", err)
@@ -446,6 +489,19 @@ type linuxPrStatusARM64 struct {
 	Fpvalid                      int32
 }
 
+// LinuxPrStatusRISCV64 is a copy of the prstatus kernel struct.
+type linuxPrStatusRISCV64 struct {
+	Siginfo                      linuxSiginfo
+	Cursig                       uint16
+	_                            [2]uint8
+	Sigpend                      uint64
+	Sighold                      uint64
+	Pid, Ppid, Pgrp, Sid         int32
+	Utime, Stime, CUtime, CStime linuxCoreTimeval
+	Reg                          linutil.RISCV64PtraceRegs
+	Fpvalid                      int32
+}
+
 // LinuxSiginfo is a copy of the
 // siginfo kernel struct.
 type linuxSiginfo struct {

pkg/proc/dump.go

@@ -138,6 +138,8 @@ func (t *Target) Dump(out elfwriter.WriteCloserSeeker, flags DumpFlags, state *D
 		fhdr.Machine = elf.EM_AARCH64
 	case "ppc64le":
 		fhdr.Machine = elf.EM_PPC64
+	case "riscv64":
+		fhdr.Machine = elf.EM_RISCV
 	default:
 		panic("not implemented")
 	}