[BPF] put not-section-attribute externs into BTF ".extern" data section

Currently for extern variables with section attribute, those
BTF_KIND_VARs will not be placed in any DataSec. This is
inconvenient as any other generated BTF_KIND_VAR belongs to
one DataSec. This patch put these extern variables into
".extern" section so bpf loader can have a consistent
processing mechanism for all data sections and variables.

5 files changed, 50 insertions, 15 deletions

diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp b/llvm/lib/Target/BPF/BTFDebug.cpp
index 9dce734ea08..bdc7ce71a88 100644
--- a/llvm/lib/Target/BPF/BTFDebug.cpp
+++ b/llvm/lib/Target/BPF/BTFDebug.cpp
@@ -1065,6 +1065,10 @@ void BTFDebug::processGlobals(bool ProcessingMapDef) {
         SecName = ".rodata";
       else
         SecName = Global.getInitializer()->isZeroValue() ? ".bss" : ".data";
+    } else {
+      // extern variables without explicit section,
+      // put them into ".extern" section.
+      SecName = ".extern";
     }
 
     if (ProcessingMapDef != SecName.startswith(".maps"))
@@ -1113,8 +1117,7 @@ void BTFDebug::processGlobals(bool ProcessingMapDef) {
         std::make_unique<BTFKindVar>(Global.getName(), GVTypeId, GVarInfo);
     uint32_t VarId = addType(std::move(VarEntry));
 
-    if (SecName.empty())
-      continue;
+    assert(!SecName.empty());
 
     // Find or create a DataSec
     if (DataSecEntries.find(SecName) == DataSecEntries.end()) {
@@ -1167,7 +1170,7 @@ void BTFDebug::processFuncPrototypes() {
 
     StringRef SecName = F.getSection();
     if (SecName.empty())
-      continue;
+      SecName = ".extern";
 
     if (DataSecEntries.find(SecName) == DataSecEntries.end()) {
       DataSecEntries[SecName] = std::make_unique<BTFKindDataSec>(Asm, SecName);
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll
index e841fafc4da..539ff3efd02 100644
--- a/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-func-weak.ll
@@ -23,9 +23,9 @@ declare !dbg !4 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .long   24
 ; CHECK-NEXT:        .long   0
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   72
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   80
 ; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
 ; CHECK-NEXT:        .long   218103808               # 0xd000000
 ; CHECK-NEXT:        .long   2
@@ -49,6 +49,12 @@ declare !dbg !4 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed
 ; CHECK-NEXT:        .long   234881024               # 0xe000000
 ; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   72                      # BTF_KIND_DATASEC(id = 7)
+; CHECK-NEXT:        .long   251658241               # 0xf000001
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   global_func
+; CHECK-NEXT:        .long   8
 ; CHECK-NEXT:        .byte   0                       # string offset=0
 ; CHECK-NEXT:        .ascii  "int"                   # string offset=1
 ; CHECK-NEXT:        .byte   0
@@ -62,6 +68,8 @@ declare !dbg !4 extern_weak dso_local i32 @global_func(i8 signext) local_unnamed
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .ascii  "global_func"           # string offset=60
 ; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".extern"               # string offset=72
+; CHECK-NEXT:        .byte   0
 
 attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll
index a91e1c53c12..3243dcfd6b3 100644
--- a/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-func.ll
@@ -22,9 +22,9 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .long   24
 ; CHECK-NEXT:        .long   0
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   72
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   80
 ; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
 ; CHECK-NEXT:        .long   218103808               # 0xd000000
 ; CHECK-NEXT:        .long   2
@@ -48,6 +48,12 @@ entry:
 ; CHECK-NEXT:        .long   234881024               # 0xe000000
 ; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   72                      # BTF_KIND_DATASEC(id = 7)
+; CHECK-NEXT:        .long   251658241               # 0xf000001
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   global_func
+; CHECK-NEXT:        .long   8
 ; CHECK-NEXT:        .byte   0                       # string offset=0
 ; CHECK-NEXT:        .ascii  "int"                   # string offset=1
 ; CHECK-NEXT:        .byte   0
@@ -61,6 +67,8 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .ascii  "global_func"           # string offset=60
 ; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".extern"               # string offset=72
+; CHECK-NEXT:        .byte   0
 
 declare !dbg !4 dso_local i32 @global_func(i8 signext) local_unnamed_addr #1
 
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll
index 1400d4b2f39..70e19744138 100644
--- a/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-struct-weak.ll
@@ -24,9 +24,9 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .long   24
 ; CHECK-NEXT:        .long   0
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   73
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   81
 ; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
 ; CHECK-NEXT:        .long   218103808               # 0xd000000
 ; CHECK-NEXT:        .long   2
@@ -50,6 +50,12 @@ entry:
 ; CHECK-NEXT:        .long   234881024               # 0xe000000
 ; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   73                      # BTF_KIND_DATASEC(id = 7)
+; CHECK-NEXT:        .long   251658241               # 0xf000001
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   global
+; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .byte   0                       # string offset=0
 ; CHECK-NEXT:        .ascii  "int"                   # string offset=1
 ; CHECK-NEXT:        .byte   0
@@ -67,6 +73,8 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .ascii  "global"                # string offset=66
 ; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".extern"               # string offset=73
+; CHECK-NEXT:        .byte   0
 
 attributes #0 = { norecurse nounwind readonly "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 
diff --git a/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll b/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll
index 7a354e68662..a8ec7851def 100644
--- a/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll
+++ b/llvm/test/CodeGen/BPF/BTF/extern-var-struct.ll
@@ -25,9 +25,9 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .long   24
 ; CHECK-NEXT:        .long   0
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   92
-; CHECK-NEXT:        .long   73
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   116
+; CHECK-NEXT:        .long   81
 ; CHECK-NEXT:        .long   0                       # BTF_KIND_FUNC_PROTO(id = 1)
 ; CHECK-NEXT:        .long   218103808               # 0xd000000
 ; CHECK-NEXT:        .long   2
@@ -51,6 +51,12 @@ entry:
 ; CHECK-NEXT:        .long   234881024               # 0xe000000
 ; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .long   2
+; CHECK-NEXT:        .long   73                      # BTF_KIND_DATASEC(id = 7)
+; CHECK-NEXT:        .long   251658241               # 0xf000001
+; CHECK-NEXT:        .long   0
+; CHECK-NEXT:        .long   6
+; CHECK-NEXT:        .long   global
+; CHECK-NEXT:        .long   4
 ; CHECK-NEXT:        .byte   0                       # string offset=0
 ; CHECK-NEXT:        .ascii  "int"                   # string offset=1
 ; CHECK-NEXT:        .byte   0
@@ -68,6 +74,8 @@ entry:
 ; CHECK-NEXT:        .byte   0
 ; CHECK-NEXT:        .ascii  "global"                # string offset=66
 ; CHECK-NEXT:        .byte   0
+; CHECK-NEXT:        .ascii  ".extern"               # string offset=73
+; CHECK-NEXT:        .byte   0
 
 attributes #0 = { norecurse nounwind readonly "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }