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delve: add ppc64le support #2963

Merged
merged 2 commits into from
Jul 7, 2023
Merged

delve: add ppc64le support #2963

merged 2 commits into from
Jul 7, 2023

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alexsaezm
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This adds support to PPC64LE architecture. This is still in an early stage of development but I'm opening this draft pull request to keep track of suggestions about the port and other things that might happen.

Currently runtime.Breakpoint is broken for ppc64le so I'm using a patched version of Go.

@derekparker derekparker added this to the v1.9.1 milestone Jul 5, 2022
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derekparker commented Jul 5, 2022

Adding the v1.9.1 milestone as I'd like to get this in for the next release. Of course this also depends on CI availability so we might slip a bit, but I wanted to at least aim for it to be included.

@aarzilli
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Is this marked as Draft by accident or is it still a draft?

@alexsaezm
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Is this marked as Draft by accident or is it still a draft?

It's still not 100% functional so I guess it's still a draft...?

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No problem, I just thought I'd remind you.

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Removed the draft status. Some tests are still failing but it is functional.

Related issue #1564

@derekparker
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@alexsaezm thanks for this! Any test that is still failing please just skip explicitly and provide some explanation.

We can work on adding CI for this as well.

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If there's going to be a builder for teamcity there should be a builder for teamcity before this is merged. If there isn't going to be a builder for teamcity this should be gated behind a build flag in support_sentinel_linux.go much like the windows/arm64 backend is gated behind a build flag in support_sentinel_window.go.

pkg/proc/ppc64le_arch.go Outdated Show resolved Hide resolved
pkg/dwarf/regnum/ppc64le.go Show resolved Hide resolved
pkg/dwarf/regnum/ppc64le.go Outdated Show resolved Hide resolved
@@ -365,8 +366,19 @@ func FindFunctionLocation(p Process, funcName string, lineOffset int) ([]uint64,
// If sameline is set FirstPCAfterPrologue will always return an
// address associated with the same line as fn.Entry.
func FirstPCAfterPrologue(p Process, fn *Function, sameline bool) (uint64, error) {
// The DWARF prologue_end statement is incorrect in ppc64le and
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I'm very skeptical that this code can be correct. How does this skip the prologue? Not skipping the prologue will cause a number of problems. If the prologue_end position is wrong then:

  1. there should be a PR to fix it against cmd/link
  2. the disassembly method should be used

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I agree, we should be using the disassembly method as with other arches. Looks like we just need to update the disassemble patterns for matching against.

Also, I'll look into the upstream patch to fix the prologue_end position.

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I've taken a second look at this, the patch to add prologue_end markers (63fd764502e08d067293a93d6d1a566951255ce5) still looks correct to me, even when observing where the prologue_end marker is placed in the executables.

pkg/proc/bininfo.go Show resolved Hide resolved
pkg/proc/target_exec.go Outdated Show resolved Hide resolved
pkg/proc/target_exec.go Outdated Show resolved Hide resolved
pkg/proc/target_exec.go Outdated Show resolved Hide resolved
pkg/proc/target_exec.go Show resolved Hide resolved
pkg/proc/target_exec.go Outdated Show resolved Hide resolved
pkg/dwarf/regnum/ppc64le.go Outdated Show resolved Hide resolved
@@ -365,8 +366,19 @@ func FindFunctionLocation(p Process, funcName string, lineOffset int) ([]uint64,
// If sameline is set FirstPCAfterPrologue will always return an
// address associated with the same line as fn.Entry.
func FirstPCAfterPrologue(p Process, fn *Function, sameline bool) (uint64, error) {
// The DWARF prologue_end statement is incorrect in ppc64le and
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I agree, we should be using the disassembly method as with other arches. Looks like we just need to update the disassemble patterns for matching against.

Also, I'll look into the upstream patch to fix the prologue_end position.

pkg/proc/bininfo.go Show resolved Hide resolved
pkg/proc/linutil/regs_ppc64le_arch.go Outdated Show resolved Hide resolved
pkg/proc/linutil/regs_ppc64le_arch.go Outdated Show resolved Hide resolved
pkg/proc/native/threads_linux_ppc64le.go Outdated Show resolved Hide resolved
@@ -3324,6 +3324,11 @@ func logStacktrace(t *testing.T, p *proc.Target, frames []proc.Stackframe) {
name = fmt.Sprintf("%s inlined in %s", frames[j].Call.Fn.Name, frames[j].Current.Fn.Name)
}

t.Logf("\t%#x %#x %#x %s at %s:%d\n",
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Probably a rebase error but I agree this should be removed.

@@ -158,6 +158,9 @@ func (g *G) Stacktrace(depth int, opts StacktraceOptions) ([]Stackframe, error)
if err != nil {
return nil, err
}
if it.err != nil {
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This was done to not hide there error when the full stack could not be unwound, because otherwise it gets hidden. Can likely be removed now.

switch rule.Rule {
default:
fallthrough
case frame.RuleUndefined:
return nil, nil
case frame.RuleSameVal:
if it.regs.Reg(regnum) == nil {
return nil, nil
return nil, fmt.Errorf("register %d undefined", regnum)
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Yeah, we can just return nil here.

@alexsaezm alexsaezm requested review from aarzilli and derekparker and removed request for aarzilli March 8, 2023 18:27
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I updated the PR with several modifications according to your comments @aarzilli & @derekparker

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aarzilli commented Mar 8, 2023

I'll take a better look tomorrow but also there are several failing tests on existing platforms.

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I marked a bunch of things as merge errors but it could also be that github is being weird about the diff because of the merge conflict in proc_test.go.

case num <= 31:
return fmt.Sprintf("R%d", num)
case num <= 62:
return fmt.Sprintf("F%d", num)
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Judging from the reference document this should be num-32

case num == PPC64LE_PC:
return "PC"
case num == PPC64LE_LR:
return "Link"
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LR

const (
PPC64LE_R0 = 0 // General Purpose Registers: from R0 to R31
PPC64LE_F0 = 0 // Floating point registers: from F0 to F31
PPC64LE_V0 = 0 // Vector (Altivec/VMX) registers: from V0 to V31
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Is this the same as VR0? Shouldn't it be 77?

case num == PPC64LE_LR:
return "Link"
case num >= PPC64LE_V0 && num <= 108:
return fmt.Sprintf("V%d", num-64)
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Should 64 be PPC64LE_V0?


const (
PPC64LE_R0 = 0 // General Purpose Registers: from R0 to R31
PPC64LE_F0 = 0 // Floating point registers: from F0 to F31
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Shouldn't this be 32?

// with gdb once AsyncPreempt was enabled. While implementing the port,
// few tests failed while it was enabled, but cannot be warrantied that
// disabling it fixed the issues.
DisableAsyncPreempt: runtime.GOOS == "windows" || runtime.GOOS == "freebsd" || (runtime.GOOS == "linux" && runtime.GOARCH == "arm64") || (runtime.GOOS == "linux" && runtime.GOARCH == "ppc64le"),
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Readding freebsd here is also a merge error.

@@ -1,6 +1,6 @@
// This file is used to detect build on unsupported GOOS/GOARCH combinations.

//go:build linux && !amd64 && !arm64 && !386
// +build linux,!amd64,!arm64,!386
//go:build linux && !amd64 && !arm64 && !386 && !ppc64le
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What's the story going to be with CI? Are we going to have a ppc64 builder? Otherwise we should do the same thing we did with windows/arm64 and put it behind a build tag I think.

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I requested a PPC64LE machine to put it into the CI system. I already have it.

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What's the status on getting TeamCity agent installed there?

var prologuesPPC64LE []opcodeSeq

func init() {
// Note: these will be the gnu opcodes and not the Go opcodes. Verify the sequences are as expected.
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I still don't think these should be here unless the comment in FirstPCAfterPrologue is wrong.

@@ -586,6 +586,7 @@ func TestNextGeneral(t *testing.T) {
}

func TestNextConcurrent(t *testing.T) {
skipOn(t, "broken", "freebsd")
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A bunch of these have been reintroduced due to merge errors. In fact a lot of changes in this file seem to be merge errors and should be rolled back.

Unless maybe there are no merge errors and github UI is just lying to me because of the merge conflict.

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There was a merge error as you said. I think is now fixed.

@@ -211,6 +226,9 @@ func (it *stackIterator) Next() bool {
}

callFrameRegs, ret, retaddr := it.advanceRegs()
if it.err != nil {
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Still wondering about this.

@@ -365,8 +366,19 @@ func FindFunctionLocation(p Process, funcName string, lineOffset int) ([]uint64,
// If sameline is set FirstPCAfterPrologue will always return an
// address associated with the same line as fn.Entry.
func FirstPCAfterPrologue(p Process, fn *Function, sameline bool) (uint64, error) {
// The DWARF prologue_end statement is incorrect in ppc64le and
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I've taken a second look at this, the patch to add prologue_end markers (63fd764502e08d067293a93d6d1a566951255ce5) still looks correct to me, even when observing where the prologue_end marker is placed in the executables.

@@ -3337,7 +3337,7 @@ func TestCgoStacktrace(t *testing.T) {
}

skipOn(t, "broken - cgo stacktraces", "386")
skipOn(t, "broken - cgo stacktraces", "windows", "arm64")
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merge problem

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I think it's now fixed

@@ -3900,6 +3903,9 @@ func TestInlinedStacktraceAndVariables(t *testing.T) {
}

func TestInlineStep(t *testing.T) {
if runtime.GOARCH == "ppc64le" {
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skipOn(t, "broken", "ppc64le")

@@ -2465,6 +2465,7 @@ func TestGlobalScopeAndVariables(t *testing.T) {
// got loaded. It then steps into a function in another package and tests that
// the registers were updated by checking PC.
func TestRegistersScopeAndVariables(t *testing.T) {
t.Skip("skipped on ppc64le: broken")
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Should be guarded by an if

@@ -858,6 +858,7 @@ func Test1Issue355(t *testing.T) {
}

func Test1Disasm(t *testing.T) {
t.Skip("skipped on ppc64le: broken")
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should be guarded by an if

@@ -1359,6 +1359,7 @@ func TestIssue355(t *testing.T) {
}

func TestDisasm(t *testing.T) {
t.Skip("skipped on ppc64le: broken")
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should be guarded by an if

@@ -2855,6 +2856,7 @@ func assertLine(t *testing.T, state *api.DebuggerState, file string, lineno int)
}

func TestPluginSuspendedBreakpoint(t *testing.T) {
t.Skip("skipped on ppc64le: broken")
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should be guarded by an if

pkg/proc/ppc64le_arch.go Outdated Show resolved Hide resolved
@@ -690,6 +690,7 @@ func traceCmd(cmd *cobra.Command, args []string) {
fmt.Fprintf(os.Stderr, "unable to set tracepoint on function %s: %#v\n", funcs[i], err)
continue
}
fmt.Fprintf(os.Stderr, "Addrs %#v\n", addrs)
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Leftover print.

pkg/dwarf/regnum/ppc64le.go Show resolved Hide resolved
@@ -1,6 +1,6 @@
// This file is used to detect build on unsupported GOOS/GOARCH combinations.

//go:build linux && !amd64 && !arm64 && !386
// +build linux,!amd64,!arm64,!386
//go:build linux && !amd64 && !arm64 && !386 && !ppc64le
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What's the status on getting TeamCity agent installed there?

pkg/proc/bininfo.go Show resolved Hide resolved
pkg/proc/ppc64le_arch.go Outdated Show resolved Hide resolved
@@ -2863,6 +2873,7 @@ func TestNextInDeferReturn(t *testing.T) {
}

func TestAttachDetach(t *testing.T) {
skipOn(t, "broken", "ppc64le")
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This test shouldn't be arch specfic, unless it's failing on PIE on ppc.

@@ -3920,6 +3935,7 @@ func TestInlinedStacktraceAndVariables(t *testing.T) {
}

func TestInlineStep(t *testing.T) {
skipOn(t, "broken", "ppc64le")
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This shouldn't be arch specific, what's the failure in ppc?

@@ -4080,6 +4096,7 @@ func TestIssue951(t *testing.T) {
}

func TestDWZCompression(t *testing.T) {
skipOn(t, "broken", "ppc64le")
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This shouldn't be broken based on arch, what's the failure?

@@ -5838,6 +5864,9 @@ func TestNilPtrDerefInBreakInstr(t *testing.T) {
func TestStepIntoAutogeneratedSkip(t *testing.T) {
// Tests that autogenerated functions are skipped with the new naming
// scheme for autogenerated functions (issue #2948).
if runtime.GOARCH == "ppc64le" {
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nit: use skipOn.

@@ -2457,6 +2457,9 @@ func TestGlobalScopeAndVariables(t *testing.T) {
// got loaded. It then steps into a function in another package and tests that
// the registers were updated by checking PC.
func TestRegistersScopeAndVariables(t *testing.T) {
if runtime.GOARCH == "ppc64le" {
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What's the failure on ppc?

if entryLine == line {
return pc, nil
}
pc, _, line, ok := fn.cu.lineInfo.PrologueEndPC(fn.Entry, fn.End)
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Is this undoing the changes for the no-dwarf stuff?

@@ -76,3 +76,11 @@ else
exit $x
fi

export GOARCH=ppc64le
go run _scripts/make.go --tags exp.linuxppc64le
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There's a bunch of test failures in CI, I think this might be what's causing them.

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I think it was the TestGeneratedDoc. It should be fix now

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You are right: this isn't even running currently in CI because other failures (TestStaticcheck) are causing the script to exit before this is even executed. However I don't think it's going to work. The export GOARCH=ppc64le makes go run produce a ppc64le binary for make.go, which won't run.

I think the way to do this is to do GOARCH=ppc64le go build -tags exp.linuxppc64le github.com/go-delve/delve/cmd/dlv directly.

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The tests now pass, this line however is never executed because of the exit above.

@@ -76,3 +76,11 @@ else
exit $x
fi

export GOARCH=ppc64le
go run _scripts/make.go --tags exp.linuxppc64le
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You are right: this isn't even running currently in CI because other failures (TestStaticcheck) are causing the script to exit before this is even executed. However I don't think it's going to work. The export GOARCH=ppc64le makes go run produce a ppc64le binary for make.go, which won't run.

I think the way to do this is to do GOARCH=ppc64le go build -tags exp.linuxppc64le github.com/go-delve/delve/cmd/dlv directly.

}
}

// According to LLDB's documentation, there is 172 registers in total, across 4 categories:
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This comment needs to start with PPC64LEMaxRegNum or there needs to be an exclusion directive for staticcheck.

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aarzilli commented Jul 7, 2023

I'm not sure what's causing the new test failures on macOS, the only thing that sticks out is the if err return in the stacktracing code.

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aarzilli commented Jul 7, 2023

PS. builds of master pass the test normally, so it doesn't look like it's something broken in CI but something in this PR. Other possibility is that it's screwing up something with the automatic merge (it's 60 commits), in which case squashing should fix it.

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For some reason ( I think it might be the latest rebase) in linux amd64 several tests fail but they pass on ppc64le. @derekparker suggested me yesterday a change that make it pass again locally but new tests fails on ppc64le.

PS. builds of master pass the test normally, so it doesn't look like it's something broken in CI but something in this PR. Other possibility is that it's screwing up something with the automatic merge (it's 60 commits), in which case squashing should fix it.

I'll squash the whole thing because there's a lot of commits that means nothing.

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alexsaezm commented Jul 7, 2023

Squashed and rebased, hopefully now we can find out what is going on.

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LGTM

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alexsaezm commented Jul 7, 2023

Looks like TestFindReturnAddressTopOfStackFn now fails (on ppc64le)... working on it 😞

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aarzilli commented Jul 7, 2023

As far as I am concerned it's fine to merge this with TestFindReturnAddressTopOfStackFn failing on ppc64le, especially since it's behind a build tag. That test isn't that important either.

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Looks like all that's needed now is to fix TestGeneratedDoc and then this is good to merge.

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Looks like all that's needed now is to fix TestGeneratedDoc and then this is good to merge.

Done

pkg/proc/ppc64le_arch.go Outdated Show resolved Hide resolved
pkg/proc/ppc64le_arch.go Outdated Show resolved Hide resolved
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LGTM

@derekparker derekparker merged commit 71f1220 into go-delve:master Jul 7, 2023
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3 participants