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umanwizardumanwizard
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Add a test
1 parent 6b908e5 commit ccac6af

4 files changed

Lines changed: 166 additions & 1 deletion

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‎libpf/pfelf/file_test.go‎

Lines changed: 87 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,7 @@
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package pfelf
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66
import (
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"fmt"
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"go/version"
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"os"
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"runtime"
@@ -14,6 +15,7 @@ import (
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"go.opentelemetry.io/ebpf-profiler/testsupport"
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"go.opentelemetry.io/ebpf-profiler/libpf"
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xx "golang.org/x/arch/x86/x86asm"
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)
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func getPFELF(path string, t *testing.T) *File {
@@ -95,3 +97,88 @@ func TestGoVersion(t *testing.T) {
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require.NoError(t, err)
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assert.Equal(t, runtime.Version(), testVersion)
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}
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func symbolOffsetFromCodeX86(code []byte) (int64, error) {
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// e.g. mov eax,DWORD PTR fs:0xfffffffffffffffc
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offset := 0
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for {
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insn, err := xx.Decode(code[offset:], 64)
106+
if err != nil {
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return 0, err
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}
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offset += insn.Len
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if insn.Op != xx.MOV {
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continue
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}
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switch a := insn.Args[1].(type) {
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case xx.Mem:
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if a.Segment != xx.FS {
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continue
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}
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// for some reason the Go disassembler
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// reports the displacement as a 32-bit value
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// embedded in a 64-bit one; e.g., it represents -16 as 0x00000000fffffff0 .
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// So this double cast is necessary.
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return int64(int32(a.Disp)), nil
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default:
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continue
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}
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}
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}
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func TestLookupTlsSymbolOffset(t *testing.T) {
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for _, test := range []struct {
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exe string
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hasTbss bool
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hasTdata bool
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}{
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{"tls-tbss", true, false},
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{"tls-aligned-tbss", true, false},
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{"tls-tdata", false, true},
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{"tls-aligned-tdata", false, true},
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{"tls-tbss-tdata", true, true},
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{"tls-aligned-tbss-tdata", true, true},
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{"tls-tbss-aligned-tdata", true, true},
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{"tls-aligned-tbss-aligned-tdata", true, true},
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} {
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// Testing this on arm is nontrivial, because we need to actually follow some
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// pointers in-process to get the address of the tls block. So let's
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// ignore it and just test x86.
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if runtime.GOARCH == "amd64" {
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return
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}
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ef, err := Open(fmt.Sprintf("testdata/%s", test.exe))
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assert.NoError(t, err)
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if test.hasTbss {
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sym, err := ef.LookupSymbol("get_tbss")
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assert.NoError(t, err)
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code := make([]byte, sym.Size)
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_, err = ef.ReadVirtualMemory(code, int64(sym.Address))
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assert.NoError(t, err)
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offset, err := symbolOffsetFromCodeX86(code)
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assert.NoError(t, err)
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offset2, err := ef.LookupTlsSymbolOffset("tbss")
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assert.NoError(t, err)
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166+
assert.Equal(t, offset, offset2)
167+
}
168+
if test.hasTdata {
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sym, err := ef.LookupSymbol("get_tdata")
170+
assert.NoError(t, err)
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code := make([]byte, sym.Size)
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_, err = ef.ReadVirtualMemory(code, int64(sym.Address))
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assert.NoError(t, err)
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offset, err := symbolOffsetFromCodeX86(code)
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assert.NoError(t, err)
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offset2, err := ef.LookupTlsSymbolOffset("tdata")
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assert.NoError(t, err)
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assert.Equal(t, offset, offset2)
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}
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}
184+
}

‎libpf/pfelf/testdata/.gitignore‎

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Original file line numberDiff line numberDiff line change
@@ -5,3 +5,5 @@ kernel-image
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ubuntu-kernel-image
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go-binary
77
separate-debug-file
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tls-*
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!tls-lookup.c

‎libpf/pfelf/testdata/Makefile‎

Lines changed: 38 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,15 @@ BINARIES=fixed-address \
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the_notorious_build_id \
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ubuntu-kernel-image \
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with-debug-syms \
13-
without-debug-syms
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without-debug-syms \
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tls-tbss \
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tls-aligned-tbss \
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tls-tdata \
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tls-aligned-tdata \
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tls-tbss-tdata \
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tls-aligned-tbss-tdata \
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tls-tbss-aligned-tdata \
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tls-aligned-tbss-aligned-tdata
1422

1523
all: $(BINARIES)
1624

@@ -47,3 +55,32 @@ ubuntu-kernel-image: test.c
4755
go-binary: gotest.go
4856
go build -o go-binary -ldflags "-w -s" gotest.go
4957

58+
# -fcf-protection=none is only necessary to avoid
59+
# emitting 'endbr64' which the Go disassembler can't
60+
# handle.
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#
62+
# -Wl,-E makes all the symbols dynamic.
63+
64+
tls-tbss: tls-lookup.c
65+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 $< -o $@
66+
67+
tls-aligned-tbss: tls-lookup.c
68+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 -DTBSS_ALIGN=1 $< -o $@
69+
70+
tls-tdata: tls-lookup.c
71+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TDATA=1 $< -o $@
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73+
tls-aligned-tdata: tls-lookup.c
74+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TDATA=1 -DTDATA_ALIGN=1 $< -o $@
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76+
tls-tbss-tdata: tls-lookup.c
77+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 -DHAS_TDATA=1 $< -o $@
78+
79+
tls-aligned-tbss-tdata: tls-lookup.c
80+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 -DTBSS_ALIGN=1 -DHAS_TDATA=1 $< -o $@
81+
82+
tls-tbss-aligned-tdata: tls-lookup.c
83+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 -DHAS_TDATA=1 -DTDATA_ALIGN=1 $< -o $@
84+
85+
tls-aligned-tbss-aligned-tdata: tls-lookup.c
86+
$(CC) -Wl,-E -fcf-protection=none -DHAS_TBSS=1 -DTDATA_ALIGN=1 -DHAS_TDATA=1 -DTDATA_ALIGN=1 $< -o $@

‎libpf/pfelf/testdata/tls-lookup.c‎

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
#ifdef HAS_TBSS
2+
#ifdef TBSS_ALIGN
3+
#define ALIGNMENT __attribute__((aligned(32)))
4+
#else
5+
#define ALIGNMENT
6+
#endif
7+
int __thread ALIGNMENT tbss = 0;
8+
9+
int get_tbss()
10+
{
11+
return tbss;
12+
}
13+
#undef ALIGNMENT
14+
#endif
15+
16+
#ifdef HAS_TDATA
17+
#ifdef TDATA_ALIGN
18+
#define ALIGNMENT __attribute__((aligned(32)))
19+
#else
20+
#define ALIGNMENT
21+
#endif
22+
int __thread ALIGNMENT tdata = 42;
23+
24+
int get_tdata()
25+
{
26+
return tdata;
27+
}
28+
29+
#undef ALIGNMENT
30+
#endif
31+
32+
33+
#include <unistd.h>
34+
35+
int main()
36+
{
37+
for (;;)
38+
sleep(1);
39+
}

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