[lld-macho] Mark local personality functions as INDIRECT_SYMBOL_LOCAL (#95171)

This expands on the fix in 4e572db. The issue is pretty similar: we
might put symbols in the GOT which don't need run-time binding, locally
defined personality symbols in this case. We should set their indirect
symbol table entries to `INDIRECT_SYMBOL_LOCAL` to help `strip` remove
these local names from the symbol table.

Checking if the symbol is private-extern doesn't cover all cases; it can
also be a non-weak extern function too, for instance; use the
`needsBinding()` helper to determine it. This was the case for the
personality function in statically linked Rust executables.

The extra non-`LOCAL` symbols triggered a bug in Apple's `strip`
implementation. As the indirect value for the personality function was
not set to the flag, but the symbol didn't require binding, it tried to
make the symbol local, overwriting the GOT entry with the function's
address in the process. This normally wouldn't be a problem, but if
chained fixups are used, the fixup also encodes the offset to the next
fixup, and it effectively zeroed this offset out, causing the remaining
relocations on the page to not be performed by dyld.

This caused the crash in https://issues.chromium.org/issues/325410295

The change in tests is a bit ugly, as a lot of symbol information is now
removed by turning more symbols `LOCAL`.

Author: BertalanD

lld/MachO/SyntheticSections.cpp

@@ -1478,11 +1478,8 @@ void IndirectSymtabSection::finalizeContents() {
 }
 
 static uint32_t indirectValue(const Symbol *sym) {
-  if (sym->symtabIndex == UINT32_MAX)
+  if (sym->symtabIndex == UINT32_MAX || !needsBinding(sym))
     return INDIRECT_SYMBOL_LOCAL;
-  if (auto *defined = dyn_cast<Defined>(sym))
-    if (defined->privateExtern)
-      return INDIRECT_SYMBOL_LOCAL;
   return sym->symtabIndex;
 }
 

lld/test/MachO/arm64-reloc-pointer-to-got.s

@@ -8,8 +8,8 @@
 ## POINTER_TO_GOT, we should still be able to relax this GOT_LOAD reference to
 ## it.
 # CHECK:      _main:
-# CHECK-NEXT: adrp x8, [[#]] ;
-# CHECK-NEXT: ldr  x8, [x8] ; literal pool symbol address: _foo
+# CHECK-NEXT: adrp x8, [[#]] ; 0x100004000
+# CHECK-NEXT: ldr  x8, [x8]
 # CHECK-NEXT: ret
 
 # CHECK: Idx   Name          Size     VMA              Type

lld/test/MachO/compact-unwind-both-local-and-dylib-personality.s

@@ -45,16 +45,16 @@
 # A:      Indirect symbols for (__DATA_CONST,__got) 4 entries
 # A-NEXT: address                    index name
 # A:      0x[[#%x,GXX_PERSONALITY_LO:]] [[#]] ___gxx_personality_v0
-# A:      0x[[#%x,PERSONALITY_1:]]      [[#]] _personality_1
-# A:      0x[[#%x,PERSONALITY_2:]]      [[#]] _personality_2
-# A:      0x[[#%x,GXX_PERSONALITY_HI:]] [[#]] ___gxx_personality_v0
+# A:      0x[[#%x,PERSONALITY_1:]]      LOCAL
+# A:      0x[[#%x,PERSONALITY_2:]]      LOCAL
+# A:      0x[[#%x,GXX_PERSONALITY_HI:]] LOCAL
 
 # BC:      Indirect symbols for (__DATA_CONST,__got)
 # BC-NEXT: address                    index name
 # BC:      0x[[#%x,GXX_PERSONALITY_LO:]] LOCAL
-# C:       0x[[#%x,GXX_PERSONALITY_HI:]] [[#]] ___gxx_personality_v0
-# BC:      0x[[#%x,PERSONALITY_1:]]      [[#]] _personality_1
-# BC:      0x[[#%x,PERSONALITY_2:]]      [[#]] _personality_2
+# C:       0x[[#%x,GXX_PERSONALITY_HI:]] LOCAL
+# BC:      0x[[#%x,PERSONALITY_1:]]      LOCAL
+# BC:      0x[[#%x,PERSONALITY_2:]]      LOCAL
 # BC-EMPTY:
 
 # CHECK:        Personality functions: (count = 3)
@@ -70,11 +70,11 @@
 # D:      Indirect symbols for (__DATA_CONST,__got) 6 entries
 # D-NEXT: address                    index name
 # D:      0x[[#%x,GXX_PERSONALITY_HI:]] [[#]] ___gxx_personality_v0
-# D:      0x[[#%x,PERSONALITY_1:]] [[#]] _personality_1
-# D:      0x[[#%x,PERSONALITY_2:]] [[#]] _personality_2
-# D:      0x[[#%x,PERSONALITY_3:]] [[#]] _personality_3
-# D:      0x[[#%x,PERSONALITY_4:]] [[#]] _personality_4
-# D:      0x[[#%x,GXX_PERSONALITY_LO:]] [[#]] ___gxx_personality_v0
+# D:      0x[[#%x,PERSONALITY_1:]]      LOCAL
+# D:      0x[[#%x,PERSONALITY_2:]]      LOCAL
+# D:      0x[[#%x,PERSONALITY_3:]]      LOCAL
+# D:      0x[[#%x,PERSONALITY_4:]]      LOCAL
+# D:      0x[[#%x,GXX_PERSONALITY_LO:]] LOCAL
 
 # D: Contents of __unwind_info section:
 # D:  Personality functions: (count = 1)

lld/test/MachO/compact-unwind.s

@@ -29,12 +29,12 @@
 # FIRST:      Indirect symbols for (__DATA_CONST,__got)
 # FIRST-NEXT: address                    index name
 # FIRST-DAG:  0x[[#%x,GXX_PERSONALITY:]] [[#]] ___gxx_personality_v0
-# FIRST-DAG:  0x[[#%x,MY_PERSONALITY:]]
+# FIRST-DAG:  0x[[#%x,MY_PERSONALITY:]] LOCAL
 
 # SECOND:      Indirect symbols for (__DATA_CONST,__got)
 # SECOND-NEXT: address                    index name
 # SECOND-DAG:  0x[[#%x,GXX_PERSONALITY:]] [[#]] ___gxx_personality_v0
-# SECOND-DAG:  0x[[#%x,MY_PERSONALITY:]]  [[#]] _my_personality
+# SECOND-DAG:  0x[[#%x,MY_PERSONALITY:]] LOCAL
 
 # CHECK:      SYMBOL TABLE:
 # CHECK-DAG:  [[#%x,MAIN:]]       g  F __TEXT,__text _main

lld/test/MachO/dead-strip.s

@@ -35,7 +35,7 @@
 # EXEC-DAG:   g {{.*}} __mh_execute_header
 # EXECDATA-LABEL: Indirect symbols
 # EXECDATA-NEXT:  name
-# EXECDATA-NEXT:  _ref_com
+# EXECDATA-NEXT:  LOCAL
 # EXECDATA-LABEL: Contents of (__DATA,__ref_section) section
 # EXECDATA-NEXT:   04 00 00 00 00 00 00 00 05 00 00 00 00 00 00 00
 # EXECDATA-LABEL: Exports trie:

lld/test/MachO/invalid/compact-unwind-personalities.s

@@ -14,9 +14,9 @@
 # DWARF: Indirect symbols
 # DWARF: address            index name
 # DWARF: 0x[[#%x,GXX_PERSONALITY:]]     {{.*}} ___gxx_personality_v0
-# DWARF: 0x[[#%x,PERSONALITY_1:]]     {{.*}} _personality_1
-# DWARF: 0x[[#%x,PERSONALITY_2:]]     {{.*}} _personality_2
-# DWARF: 0x[[#%x,PERSONALITY_3:]]     {{.*}} _personality_3
+# DWARF: 0x[[#%x,PERSONALITY_1:]]       LOCAL
+# DWARF: 0x[[#%x,PERSONALITY_2:]]       LOCAL
+# DWARF: 0x[[#%x,PERSONALITY_3:]]       LOCAL
 # DWARF: .eh_frame contents:
 # DWARF: Personality Address: [[#%.16x,GXX_PERSONALITY]]
 # DWARF: Personality Address: [[#%.16x,PERSONALITY_1]]