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features: add HaveV4ISA probe for checking ISA v4 support in the kernel #1608

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Merged
ti-mo merged 2 commits into from
Dec 12, 2024
Merged

features: add HaveV4ISA probe for checking ISA v4 support in the kernel #1608

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6d2a32e
features: add haveV4ISA probe for checking ISA v4 support in the kernel
smagnani96 Nov 11, 2024
e987b16
features: consider ENOTSUPP in v2 and v4 ISA probes as conclusive
ti-mo Dec 12, 2024
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44 changes: 42 additions & 2 deletions features/misc.go
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Original file line number Diff line number Diff line change
@@ -1,9 +1,12 @@
package features

import (
"errors"

"github.com/cilium/ebpf"
"github.com/cilium/ebpf/asm"
"github.com/cilium/ebpf/internal"
"github.com/cilium/ebpf/internal/sys"
)

// HaveLargeInstructions probes the running kernel if more than 4096 instructions
Expand Down Expand Up @@ -62,7 +65,7 @@ func HaveV2ISA() error {
}

var haveV2ISA = internal.NewFeatureTest("v2 ISA", func() error {
return probeProgram(&ebpf.ProgramSpec{
err := probeProgram(&ebpf.ProgramSpec{
Type: ebpf.SocketFilter,
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
Expand All @@ -71,6 +74,11 @@ var haveV2ISA = internal.NewFeatureTest("v2 ISA", func() error {
asm.Return().WithSymbol("exit"),
},
})
// This sometimes bubbles up from the JIT on aarch64.
if errors.Is(err, sys.ENOTSUPP) {
return ebpf.ErrNotSupported
}
return err
}, "4.14")

// HaveV3ISA probes the running kernel if instructions of the v3 ISA are supported.
Expand All @@ -83,7 +91,7 @@ func HaveV3ISA() error {
}

var haveV3ISA = internal.NewFeatureTest("v3 ISA", func() error {
return probeProgram(&ebpf.ProgramSpec{
err := probeProgram(&ebpf.ProgramSpec{
Type: ebpf.SocketFilter,
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
Expand All @@ -92,4 +100,36 @@ var haveV3ISA = internal.NewFeatureTest("v3 ISA", func() error {
asm.Return().WithSymbol("exit"),
},
})
// This sometimes bubbles up from the JIT on aarch64.
if errors.Is(err, sys.ENOTSUPP) {
return ebpf.ErrNotSupported
}
return err
}, "5.1")

// HaveV4ISA probes the running kernel if instructions of the v4 ISA are supported.
//
// Upstream commit 1f9a1ea821ff ("bpf: Support new sign-extension load insns").
//
// See the package documentation for the meaning of the error return value.
func HaveV4ISA() error {
return haveV4ISA()
}

var haveV4ISA = internal.NewFeatureTest("v4 ISA", func() error {
err := probeProgram(&ebpf.ProgramSpec{
Type: ebpf.SocketFilter,
Instructions: asm.Instructions{
asm.Mov.Imm(asm.R0, 0),
asm.JEq.Imm(asm.R0, 1, "error"),
asm.LongJump("exit"),
asm.Mov.Imm(asm.R0, 1).WithSymbol("error"),
asm.Return().WithSymbol("exit"),
},
})
// This sometimes bubbles up from the JIT on aarch64.
if errors.Is(err, sys.ENOTSUPP) {
return ebpf.ErrNotSupported
}
return err
}, "6.6")
4 changes: 4 additions & 0 deletions features/misc_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,3 +21,7 @@ func TestHaveV2ISA(t *testing.T) {
func TestHaveV3ISA(t *testing.T) {
testutils.CheckFeatureTest(t, HaveV3ISA)
}

func TestHaveV4ISA(t *testing.T) {
testutils.CheckFeatureTest(t, HaveV4ISA)
}
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